New Technologies for
Urban Safety of Mega Cities in Asia
October 18-19, 2005
Singapore-EditorHisashi Kanada
ICUS, IISThe University of Tokyo, Japan

Organised By

Protective Technology Research Centre,
School of Civil and Environmental Engineering
Nanyang Technological University,
Singapore
International Center for Urban Safety Engineering (ICUS),
Institute of Industrial Science, The University of Tokyo,
Tokyo, Japan

NEW TECHNOLOGIES FOR URBANSAFETY OF MEGA CITIES IN ASIA
KIMIRO MEGURO
Professor, ICUS
IIS, University of Tokyo, Japan
ICUS Report No 12, FEBRUARY, 2006
PREFACE
Rapid urbanization has characterized the world’s development in thelast decades and it will become more dramatic in the years to come. In the
beginning of the 21st Century, over 50 % of the world’s total population willconcentrate in urban areas, especially in Asia. More than sixty percent of theworld’s mega cities (more than ten million inhabitants), i.e. 14 cities among
22, are located in Asia.
Fast urban growing poses several challenges, such as land use
administration, infrastructure maintenance, vulnerable building management,
environment preservation, among others, for the sustainability of theseemerging metropolises. Considering the increasingly important role of theseurban areas and the large number of people that they concentrate, thenecessity of addressing the previously mentioned issues is clear. Modern
technologies such as Geographic Information Systems, Global Positioning
System, Remote Sensing and satellite image analysis, computer simulations,and non traditional construction materials as well as innovative solutions
combining existing and/or conventional technologies can be very useful forthis purpose. Based on this understanding, the International Symposium of
Urban Safety of Mega Cities in Asia has been organized every year, since
2002, in order to provide a forum for discussion among decision makers,
practicing professionals, and researchers.
Following the success of previous gatherings at Bangkok, Thailand(2002), Tokyo, Japan (2003), and Agra, India (2004), the 4th International
Symposium was co-organized by the Protective Technology ResearchCenter, School of Civil and Environmental Engineering, Nanyang
Technological University, Singapore and the International Center for Urban
Safety Engineering, Institute of Industrial Science, The University of Tokyo,
Japan. It was sponsored by the Center for Sustainable Urban Regeneration,
The University of Tokyo, 21st Century Center of Excellence Program.
The objective of bringing together experts in areas of design,
construction and maintenance of urban infrastructure, urban planning,disaster mitigation, and environment preservation was successfully
accomplished. As on previous occasions, the symposium served to createnew and strengthen existing networks of people addressing rapid
urbanization issues in the Asian region.
I hope that the present volume, which contains the papers presented
during the symposium, provides valuable reference material. Finally, I
would like to gratefully acknowledge the efforts of organizers, participants,
and sponsors, who contributed to the success of this event.

ICUS Report 11

Gate of Nanyang Technological University

Symposium Venue

Entrance of Nanyang Exrctive Centre

Welcome Board

Reception

ICUS Corner

Auditorium

Recture Roomⅰ

October 2005, Singapore

ⅱ

Opening Ceremony

John HARRISON (p.1)

Yoshifumi YASUOKA (p.3)

Kimiro MEGURO (p.9)

Teddy BOEN (p.19)

Weicheng FAN (p.31)

Pennung WARNITCHAI (p.41)

Tso-Chien PAN (p.267,277,333,341,519)

ICUS Report 11

Laboratory Tour of PTRC

Shaking Table

Experiment Facility of PTRC

View from Dinner Venue

Symposium Dinner

Tat-Seng LOK (p.399)

Ceremony during Symposium Dinnerⅲ

October 2005, Singapore

Tea BreakTea Break

Lunch

Lunch

High-Level Talks

Ceremony at Plenary Speechⅳ

ICUS Report 11

Channel NewsAsia

Closing Ceremony

After-Symposium DinnerParticipants PhotoOctober 2005, SingaporeⅵOpening Session

THE NEW FACE OF AL QAEDA:
THE THREAT FOUR YEARS AFTER 9-11
DR ROHAN KUMAR GUNARATNA
Head, International Centre for Political Violence and Terrorism ResearchInstitute of Defence and Strategic Studies, Nanyang Technological University
ISRKGunaratna@ntu.edu.sg

ABSTRACTThe terrorist threat environment has changed significantly in the past
four years. First, Iraq has replaced Afghanistan as the epicentre of terrorism.
Second, Al Qaeda has morphed from a group into a movement. Third, Al
Qaeda has been able to influence three dozen local jihad groups toideologically and operational emulate Al Qaeda's mandate of a global jihad.
The presentation will discuss the changing global threat environment
and its implications for the Asia-Pacific. The presentation will focus on how
Jemaah Islamiyah has taken over the role of Al Qaeda, both as an ideologicaland an operational vanguard. The presentation will conclude with anassessment of the threat to Southeast Asia by existing and emerging groups,
particularly those with close links to the global jihad movement.

1October 2005, Singapore

2

New Technologies for Urban Safety of Mega Cities in Asia

SATELLITE OBSERVATION NETWORKFOR ENVIRONMENT AND DISASTER
MONITORING IN ASIA
Yoshifumi Yasuoka, W. Takeuchi, T. Nemoto, P. J. Baruah and T. Endo
Institute of Industrial Science, The University of Tokyo
4-6-1 Komaba, Meguro-ku, Tokyo, Japan 153-8505
Tel: +81-3-5452-6409, Fax: +81-3-5452-6408
E-mail: yyasuoka@iis.u-tokyo.ac.jp

ABSTRACTThe Institute of Industrial Science, University of Tokyo (IIS/UT) establisheda satellite data receiving network, SEASON (Southeast and East Asia
Satellite Observation Network), for monitoring environment and disaster in
Asian regions. The SEASON receives satellite data from TERRA/MODIS
and AQUA/MODIS as well as NOAA/AVHRR at Tokyo (IIS/UT Campus)
and at Bangkok (Asian Institute of Technology; AIT Campus). The datafrom two receiving stations cover Southeast and East Asian regions.
Although MODIS and AVHRR have coarse spatial resolution (MODIS; 1km,
500m and 250m, AVHRR; 1km) their frequent observation function (around
twice a day at one point) enables us to monitor land/ocean surface in almost
near-real time manner. Also their wide observation swath (more than
2000km) enables to observe regional to global scale phenomena such as
deforestation, urbanization or land degradation. It is also expected that they
may provide data for urban safety assessment in Asian mega-cities.
This presentation introduces overview of the SEASON, and demonstrates its
application examples.

1. INTRODUCTION
Monitoring of environment and disaster requires the measurements of awide variety of parameters covering physical, chemical, biological, or
geographical fields. Furthermore it requires observation from local toregional/global spatial scale, and from short to long time scale.
Comprehensive and efficient environment and disaster monitoring system
may not be realized only with conventional ground observation methods.
Remote sensing from satellite is expected to provide an effective tool forobserving a wide range of environment and disaster variables from local to
global scale regularly.
AVHRR on NOAA and MODIS on TERRA and AQUA are the typicalearth observation sensors primarily for regional or global scale monitoring.
Although their spatial resolution is coarse (MODIS; 1km, 500m and 250m,

3

October 2005, Singapore

AVHRR; 1km), their frequent observation function (around twice a day at
one point) enables us to monitor land/ocean surface and atmosphereconditions in almost near-real time manner. Additionally, their wide
observation swath (more than 2000km) enables to observe regional to global
scale phenomena such as deforestation, desertification and urbanization.
They are also expected to provide timely data for monitoring urban
conditions such as urban expansion, heat island or damages due to flooding
or forest fires.
The Institute of Industrial Science (IIS), the University of Tokyo (UT) has
been receiving and processing satellite data from NOAA/AVHRR,TERRA/MODIS and AQUA MODIS in order to observe environmental
changes and disasters in Asian regions. The IIS/UT started the reception of
NOAA/AVHRR data since 1980 at Tokyo (IIS/UT Campus), and in 1997
the data receiving station of NOAA/AVHRR was deployed at Bangkok(Asian Institute of Technology; AIT Campus) in order to cover more
extensive areas including Southeast Asian regions. It also started thereception of satellite data from TERRA/MODIS since 2001 and from
AQUA/MODIS since 2003 both at Tokyo and at Bangkok together with
NOAA/AVHRR.
The data received at AIT, Bangkok is transferred to IIS/UT within 24hours,
and all data from these stations are archived in a massive data archive
system at IIS/UT (600TB). All of the archived data can be accessed uponrequests from users through WWW (http://yasulab.iis.u-tokyo.ac.jp). The
IIS/UT has also been producing a variety of thematic maps forenvironmental and disaster monitoring including time series vegetationindex maps, land and ocean surface temperature maps or forest fire maps.
The system is named as SEASON (Southeast and East Asia Satellite
Observation Network).
This presentation gives an overview of the SEASON and its application
examples in monitoring of urban environment and disasters.

2. SYSTEM OUTLINE OF SEASON
2.1

Data Reception and Processing

Both of the satellite data receiving stations at Tokyo (IIS/UT) and at
Bangkok (AIT) are equipped with L-band antenna for AVHRR HRPT
signal and with X-band antenna for MODIS HRPT signal, and with dataprocessing facilities to produce Level 1B product (geo-corrected data) for
AVHRR and MODIS raw data. The data received at Bangkok is transferred
to IIS/UT data archiving system via network (NECTEC and SINET) in
midnight (6-7 GB/night). The system block diagram of the SEASON is
illustrated in Figure 1. Satellite data coverage of two stations is illustrated inFig. 2.

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ICUS Report 11

Data Receiving Station
at Bangkok (AIT)

Data Archiving and Processing
Facilities at IIS/ Univ. of Tokyo

ModelsAssessment andPrediction

Data Receiving Station
at IIS/ Univ. of Tokyo

Ground observation

Fig. 1 System Block Diagram of SEASON

Fig. 2 Satellite data coverage of SEASON
2.2

Data Archiving and Distribution

All of the data received at Tokyo and at Bangkok have been archived at
IIS/UT with a massive data archive system (600TB). So far the total dataamount for AVHRR and MODIS is around 150TB. The SEASON provides
all of the archived data to any users in the world free of charge through
WWW (http://yasulab.iis.u-tokyo.ac.jp). Any user may download AVHRR
and MODIS data from the ftp site by specifying satellite (AVHRR or
MODIS), year/month/date, requested bands, longitude/latitude, spatial
resolution (for MODIS; 250m, 500m, 1000m). The SEASON send data aftergeometric correction and other necessary processings.

Satellite Observation Network in Asia

5

October 2005, Singapore

3. TIME SERIES DATA SET FROM SEASON
Although spatial resolution of AVHRR and MODIS is coarse, periodic andfrequent observation capability enables us to produce regular time series
data set observing land/ocean surface or atmosphere. The SEASON has
been producing time series satellite mosaic images over Asia, and a varietyof thematic maps for monitoring and assessing environment and disasters.
Figure 4 shows an example of time series NDVI (Normalized Difference
Vegetation Index) images derived from cloud free composite AVHRR data
(10 days composite; May to September, 1990). The NDVI is a satellite
derived index showing how each point is covered by vegetation, and timeseries NDVI data may be used to assess deforestation, desertification or
urbanization.

May 1

May 2

May 3

Jun 1

Jun 2

Jun 3

Jul 1

Jul 2

Jul 3

Aug 1

Aug 2

Aug 3

Sep 1

Sep 2

Sep 3

NDVI

0

255

1 : 1 – 10 day
2 : 11 – 20 day
3 : 21 – 30 day

Fig. 4 Time series NDVI images (10days composite) from May to
September, 1990.

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ICUS Report 11

Figure 5 illustrates an example of the applications of long-term NDVI data
set indicating a trend of early spring with respect to vegetation green-up. In
Figure 5 an inverse relationship between changes in air temperature and in
the green-up day of vegetation in spring (Julian day from 1st of January)
over East Asian region shown in Figure 4. The green-up day of vegetation isdetermined by the sharp increase in the annual NDVI pattern. Figure 5
indicates that the green-up of vegetation has been getting earlier by fivedays in average during these 17 years associated with temperature increase(Ooyoshi, 2002).

5days

Spring
Green-up

.
p
m
e
T
d
e
t
a
l
u
m
u
c
c
A

Temp.

Fig. 5 Long-term trends of air temperature and the green-up in springassessed from the NDVI data shown in Figure 4.

4. URBAN SCALE ALLICATION OF SEASON DATA SET
Monitoring of urban expansion, heat island or land cover change in andaround city requires intensive spatial and geographic data. It is, however,
not easy to collect spatial data over a big city area. Satellite remote sensing
is one of effective tools to collect spatial data in a short period. The datafrom SEASON may be also applied to the monitoring of environment anddisasters in urban areas.
Figure 6 shows land surface temperature distribution derived from MODIS
data around Tokyo area (Fig. 6 (a)), and its temporal change in a summer
season (Fig .6 (b)). Figure 6 (b) shows that the temperature in urban area ishigher than that in surrounding forest or cropland by around ten degrees,
and it clearly indicates that heat island occurs in urban area (Hung, 2002).

Satellite Observation Network in Asia

7

October 2005, Singapore(a)310 0K

273

Time Series of Land Surface Temperature
313

Surface Temperature (K)

308
303
298
293
288
283
278
273
217

225

Urban

233

241

249

257

265

273

Mixed Forest

281

289

297

305

Julian day

Day (2001)

Croplands(b)
Fig. 6

Urban heat island, (a) Distribution of land surface temperature(LST) from MODIS (July, 2001), (b) Temporal change of LST in
urban area, forest area and cropland area around Tokyo.

5. SUMMARIESAn Asian satellite observation network system at the IIS/UT was introducedwith applications to the assessment of urban environment and disasters.
Remote sensing from space is a new technology enabling us to observe awide range of variables over extensive urban areas at a regular interval.
Recent developments in remote sensing technologies have been remarkableand very rapid. It is expected to develop more practical application
examples of remote sensing to urban safety management.
REFERENCES
Hung, T., et. al. : Acquiring, Managing and Utilizing MODIS data for
Research at the IIS / UT. Proc. of ACRS, 2002.
Ooyoshi, K., et.al. : Analysis of Vegetation Phenology in East Asia, Proc. of
JSPRS, Tokyo, 2004 (in Japanese with English abstract).

8

New Technologies for Urban Safety of Mega Cities in Asia

SHAKING TABLE TESTS OF¼ SCALED MASONRY MODELSRETROFITTED WITH PP-BAND MESHESKIMIRO MEGURO
Professor, Institute of Industrial Science, The University of Tokyo, Japanmeguro@iis.u-tokyo.ac.jp
PAOLA MAYORCA
Post Doctoral Fellow, The University of Tokyo, Japanpaola@iis.u-tokyo.ac.jp
NAVARATNARAJAH SATHIPARAN
Master Degree Student, The University of Tokyo, Japansakthi@risk-mg.iis.u-tokyo.ac.jp
RAMESH GURAGAIN
Master Degree Student, The University of Tokyo, Japanramesh@risk-mg.iis.u-tokyo.ac.jp
NASROLLAHZADEH NESHELI
Post Doctoral Fellow, The University of Tokyo, Japannesheli@iis.u-tokyo.ac.jp

ABSTRACT`
Retrofitting of low earthquake-resistant masonry structures is the key
issue for earthquake disaster mitigation in developing countries as only thatcan reduce the probable casualty significantly. Promotion of retrofitting ispossible only if the retrofitting technique considers issues of economicalaffordability and social acceptability together with technical feasibility. An
appropriate PP-band retrofitting technique, which considers all these issues,
has been developed and being studied at Meguro Laboratory, ICUS,
Institute of Industrial Science, the University of Tokyo since some years.
Shaking table experiment of two masonry building models was
carried out in this year to test the effectiveness of the newly developed
technique. The test reveled that the technique is very effective which could
enhance the seismic capacity of masonry buildings by 10 times in terms of
maximum base displacement and 4 times in terms of maximum velocity. The
retrofitted model survived with life safety level damage until 15 moreshakings than the shaking at which the non-retrofitted building model was
totally collapsed. The result suggested that the technique can enhance safetyof existing masonry buildings to survive even in worst case scenario ofearthquake ground motion like JMA 7. This paper describes the process andpreliminary outcomes of the experiment conducted.

1. INTRODUCTION
It is seen in past and recent earthquakes that unreinforced masonry buildings,
if not retrofitted, are the number one killer during earthquakes. Human

9

October 2005, Singapore

casualties due to earthquakes in 20th century are mostly due to structural
damage most of which is assigned to unreinforced masonry buildings(Coburn and Spence, 2002). So, retrofitting of low earthquake-resistantmasonry structures is the key issue for earthquake disaster mitigation to
reduce the casualty significantly. Seismic retrofitting not only reduces thedamage to buildings during earthquakes, but also the costs of rescue andfirst aid activities, rubble removal, temporary residence building, andpermanent residence reconstruction to re-establish normal daily life
(Yoshimura and Meguro, 2004).
Different masonry retrofitting techniques are available however,effective retrofitting technique should guarantee not only its efficiency interms of improvement of the seismic resistant characteristics of the structure(strength, ductility and energy dissipation) but also locally and economicallyavailability of material and easy-to-use method. Considering these issues ofdeveloping appropriate seismic retrofitting techniques for masonry buildings
to reduce the possible number of casualties from future earthquakes indeveloping countries, a technically feasible and economically affordable PPband retrofitting technique has been developed and different aspects arebeing studied in Meguro Laboratory, ICUS, Institute of Industrial Science,
The University of Tokyo since some years (Mayorca and Meguro, 2004).
This year, shaking table experiments were carried out to understanddynamic response of buildings, propagation and distribution of crack
patterns, failure behavior, and overall effectiveness of seismic retrofitting
technique.

2. EXPERIMENT PROGRAM
2.1 Specimens Construction
For shaking table experiment, two models were built in the reduced
scale 1:4 using the burnt bricks as masonry unit and cement, lime and sand(1:8:20) mixture as mortar. Attention has been made to make the models astrue replica of brick masonry buildings in developing countries in terms ofmasonry strength even though the construction materials used were thoseavailable in Japan. Both the models represented a one-storey box-likebuilding without roof. Both the buildings were of dimension 950x950x720
mm3 with wall thickness 50mm. The sizes of door and window in opposite
walls were of size 243x485mm2 and 325x245mm2 respectively.
One of the buildings was retrofitted with PP-band mesh after
construction. The geometry, construction materials and proportion,
construction process and technique, cement/water ratio and other conditions
that can make difference in strength of the building models were kept
identical for better comparison of the effectiveness of the newly developed
retrofitting technique for enhancing the seismic safety of masonry buildings.
The cross-section of the band used was 6x0.24mm2 and the pitch of themess was 40mm. The retrofitting procedure is described in section 2.2. The
non-retrofitted model is named as “N-B-40” and retrofitted one by “R-B40” to use in this paper. The mechanical properties of masonry in terms of

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compressive, shear and bond strength was similar to the material used forconstruction in both the cases (Table 1).
Table 1: Mechanical Properties of the Masonry
Property
N-B-40R-B-40Compressive strength (MPa)

20.96

20.30

Shear strength (MPa)

0.074

0.075

Bond strength (MPa)

0.085

0.074

Diagonal compression strength (MPa)

0.173

0.181

2.2 Retrofitting Process
Most of the residential buildings in developing countries are of nonengineered type and owner built. The case of Nepal has been taken here as
an example, where more than 98 % of the buildings are constructed by theowners following the advice of local craftsmen. In both urban and rural
areas the traditional craftsmen, who are not given any specific training onseismic safety and they do not have adequate access to information related
to safer building practices, play the pivotal role (Dixit, 2004). So theimplementation procedure for retrofitting technique for masonry buildings
should be as simple as possible to be applicable for developing countries.
Installation procedure (Figure 1) for PP-band retrofitting technique
is simple enough to understand and apply by the craftsmen and homeowners
without any prior knowledge and expertise on earthquake engineering. Thus,
it is expected to meet the very critical requirement of developing countries,
the “easy-to-use” method, for promoting safer building construction.

1. Cutting of PP-bandmesh in size

2. Wrapping the building from inside and outside by
cut mesh with some overlap and fixing of the PPband meshes at foundation layer

4. Overlap of cut mesh of
openings to another side andfixing by connecters

3. Connecting inner and outer meshes bywires and aluminum plate (2cmx2cm) except
than openings and around openings andcutting of meshes in openings to overlap innext side

Figure 1: Retrofitting Process

Shaking Table Tests of ¼ Scaled Masonry Models Retrofitted with PP-band Meshes

11October 2005, Singapore

2.3 Instrumentation
The tests were carried out in the shaking table facility available in
the Institute of Industrial Science, the University of Tokyo. The size of theshaking table is 1.5x1.5 m2 and it has six degrees of freedom which operates
in frequencies ranging from 0.1 to 50 Hz. It has a maximum displacement
capacity of ±100mm and maximum weight of the specimens that can betested is 2 tons.
To study the global and local behavior of the buildings during
shakings, accelerations and displacements at different places were measured
with accelerometers and lasers, respectively. During the tests, twelve
accelerometers, four with three-dimensional measurement capacity andeight with one-dimensional measurement capacity were installed. Sevenlasers, four in N-S direction and three in E-W direction were used tomeasure displacements.
2.4 Input Motion

Accel. [g]Simple easy-to-use sinusoidal motions of frequencies ranging from
2Hz to 35 Hz and amplitudes ranging from 0.05g to 1.4g were applied toobtain the dynamic response of both retrofitted and non-retrofitted structures.
This simple input motion was applied because of its adequacy for later use
in the numerical modeling. Figure 2 shows the typical shape of the appliedsinusoidal wave.
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5

10 Cycles

30 Cycles

10 Cycles(Amplitude = 1.0 g and Frequency = 5Hz)
4
6
8
10
2

Time [S]Figure 2: Typical Shape of Input Sinusoidal Motion
Loading was started with a sweep motion of amplitude 0.05g withall frequencies of 2Hz to 35Hz for identifying the dynamic properties of themodels. A total of 46 runs were applied to N-B-40 while as 16 more runs
were applied to R-B-40 with 62 as a final run. Sequence of loadings for eachsuccessive runs is given in Table 2. The numbers in table indicate the run
numbers. General trend of loading was from high frequency to low
frequency and from lower amplitude to higher amplitude. Higher
frequencies motions were skipped towards the end of the runs.

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Table 2: Loading Sequence
Frequency
Amplitude
2Hz 5 Hz 10 Hz 15 Hz 20 Hz 25 Hz 30 Hz 35 Hz
1.4 g
59
58
57
1.2 g
56
55
54
53
1.0 g
62
52
51
50
49
0.8 g
61
47
44
41
38
35
32
29
0.6 g
60
46
43
40
37
34
31
28
0.4 g
48
45
42
39
36
33
30
27
0.2 g
26
25
24
23
22
21
20
19
0.1 g
18
17
16
15
14
13
12
11
0.05 g
10
09
08
07
06
05
04
03
Sweep
01, 02
Loading steps for both non-retrofitted and retrofitted models
Loading steps for retrofitted model after non-retrofitted model building collapsed

3. FINDINGS
3.1 Crack Patterns and Energy Dissipation Mechanism
Initial cracks pattern in both the models, non-retrofitted andretrofitted were similar with some variation. The cracks get widened andwidened in each successive loading after major cracks occurred in case of
non-retrofitted model. However, more new cracks were propagated in
retrofitted case.

East SideSouth SideWest Side

North Side
stInitial cracks after 41 run (amax = 0.8g, f= 15 Hz, dmax=0.9mm)
Final cracks before collapse at 46th run (amax=0.6g, f= 5 Hz, dmax=6 mm)
Collapsed part after 46th run

Figure 3: Crack Patterns of Non-retrofitted Building Model

Shaking Table Tests of ¼ Scaled Masonry Models Retrofitted with PP-band Meshes13October 2005, Singapore

Figure 3 shows the crack patterns of the non-retrofitted model while
as Figure 4 is the case of retrofitted one. In case of non-retrofitted building
model, cracks started from top corner of the openings in the 27th run.
Horizontal cracks at base level of east and north walls were observed in the
28th run; cracks at corner of the openings propagated up to top layer of thewall, significant diagonal cracks were observed in both walls with openings
and flexural crack at the bottom layer of the south side wall was also
observed in the 35th run. The 44th run was the critical run to the nonretrofitted model in which, a large vertical crack was observed in top part ofsouth side wall and was bent inside tentatively by 14 mm at the top-middle
and partially separated from bottom wall. The top part of the west wall (part,
above the door opening) was totally separated from the specimen and it wasremoved from specimen before next test run proceed. The 46th run led thenon-retrofitted structure collapse.

East SideSouth Side

North SideWest Side
stInitial cracks after 41 run (amax = 0.8g, f= 15 Hz, dmax=0.9mm)
Cracks after 60th run (amax=0.6g, f= 2 Hz, dmax=37.3mm)

Figure 4: Cracks Pattern of Retrofitted Building Model
In case of retrofitted building model, similar cracks as nonretrofitted building was started from top corner of the opening in the 27th run.
Horizontal cracks at base layer of east and south walls were observed in the
28th run, cracks propagated horizontally from top and bottom corner of the
openings in the 29th run, some diagonal cracks were observed at top part of
the walls with openings in the 35th run, many cracks in all four walls wereobserved in the 44th run, and many new cracks were observed until the 46th
run. The process of widening of the cracks already occurred andpropagation of new cracks was continued to 15 more times until the run 61.
In later stages, there was significant permanent deformation to the structure.
At the final stage of the test, by the 62nd run, with 63.4mm base14

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displacement, 10 times more than the input displacement applied in the 46th
run and 4 times more velocity, almost all the brick joints were cracked andbuilding had substantial permanent deformations. However, building did notloose the overall integrity and stability and collapse was prevented in such ahigh intensity of shaking. Thus, the PP-band retrofitting techniquemaintained the integrity of the structural elements preventing fromseparation and collapse. Further, the retrofitted model showed the better
energy dissipation mechanism as many new cracks were propagated withoutloosing the overall integrity and stability of the structure.
3.2 Failure Behavior and Performance Evaluation
The performances of the non-retrofitted and retrofitted models areassessed based on the damage level of the buildings at different levels of
shaking. Performances were evaluated in reference to three levels of
performances: Immediate Occupancy, Life safety and Collapse Prevention
based on damage levels described in (FEMA 356, 2000). The criteria fordifferent performance levels in case of non-retrofitted case were taken as
criteria for Unreinforced Masonry (Nonfill) Walls defined in FEMA 356,
Table C1-3: Structural Performance Levels and Damage. The equivalent
JMA intensities were calculated based on the input motions to the structuresat different runs. Table 3 below shows the performances of non-retrofitted
building models with different JMA intensities.
Table 3: Performance of Non-retrofitted Building Model in Different JMA
Intensities
Frequency (Hz)
Acceleration
(g)
2
5
10
15
20
25
30
35
1.4
1.2
1.0
PC
LS
LS
LS
IO
IO
0.8
TC
LS
LS
LS
IO
IO
IO
0.6
PC
LS
LS
LS
IO
IO
IO
0.4
IO
IO
IO
IO
IO
IO
IO
IO
0.2
IO
IO
IO
IO
IO
IO
IO
IO
0.1
IO
IO
IO
IO
IO
IO
IO
IO
0.05
Index

JMA ~4

JMA 5-

IO: Immediate Occupancy
LS: Life Safety
CP: Collapse Prevention

JMA 5+JMA 6-JMA 6+JMA 7

PC: Partial Collapse
TC: Total Collapse

Partial collapse of the non-retrofitted building was occurred at the
44 run at intensity JMA~4 (Photo 1) and total collapse at the 46th run(Photo 2) at intensity JMA 5- but it should be noted that the model was
already cracked in different loadings as discussed in section 3.1.
thShaking Table Tests of ¼ Scaled Masonry Models Retrofitted with PP-band Meshes

15

October 2005, Singapore

Photo 1: Partial Collapse of Nonretrofitted Building Model at the 44thrun (Seismic Intensity, 4 JMA Scale)

Photo 2: Collapse of Non-retrofitted
Building Model at the 46th run(Seismic Intensity, 5- JMA Scale)

The damage criteria for retrofitted building model are taken from
FEMA 356, Table C1-3 for reinforced masonry walls. The drift limit criteria
which are only 0.6% and 1.5% for life safety and collapse prevention level
for reinforced masonry building was exceeded by the tested model
retrofitted by PP-band technique. However, the overall damage level was
not much as described in FEMA in relation to the drift. More drift thanreinforced masonry building is logical if the characteristics of the PP-band
mesh, which is many times less stiff than steel, is considered. So the drift
criteria for reinforced masonry buildings could not be directly applied in thiscase and performance evaluation was done based on the overall damage tothe structure. Table 4 below shows the performance of the retrofitted
building model at different JMA intensities.
Table 4: Performance of Retrofitted Building Model with Different JMA
Intensities
Acceleration
Frequency (Hz)
(g)
2
5
10
15
20
25
30
35
LS
LS
LS
1.4
LS
LS
LS
LS
1.2
CP
LS
LS
LS
LS
1.0
LS
LS
LS
IO
IO
IO
IO
IO
0.8
LS
LS
IO
IO
IO
IO
IO
IO
0.6
LS
LS
IO
IO
IO
IO
IO
IO
0.4
IO
IO
IO
IO
IO
IO
IO
IO
0.2
IO
IO
IO
IO
IO
IO
IO
IO
0.1
IO
IO
IO
IO
IO
IO
IO
IO
0.05
Index

JMA ~4

JMA 5-

IO: Immediate Occupancy
LS: Life Safety
CP: Collapse Prevention

16

JMA 5+JMA 6-JMA 6+JMA 7

PC: Partial Collapse
TC: Total Collapse

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ICUS Report 11

The retrofitted building performed at life safety level of damage at
46th run at which the non-retrofitted building was collapsed. Moreover, life
safety level of performance was maintained until 15 more runs after the 46th
run leading to intensity JMA 6+. In the 62nd run, another JMA 6+ intensity
shaking, the building got the collapse prevention level of damage, which iscrushing, extensive cracking, damage around openings and corners andsome fallen units according to FEMA 356 definition.
Considering the pre-damage level of building during previous
loadings including very high intensity shakings it can be interpreted that theretrofitting technique can achieve reasonable safety even in worst casescenario of earthquake like JMA 7. Further, this technique may also be
applicable to retrofit earthquake damaged buildings as it was effective evenafter masonry had severe cracks.
As the model was already considerably deformed beyond the limit ofmeasurement system, test was stopped after the 62nd run. Photos 3 and 4
show the retrofitted building after the 46th run and at the final stage of thetest after the 62nd run, respectively.

Photo 3: Retrofitted Building Model
after 46th run (Seismic Intensity 5JMA Scale)

Photo 4: Retrofitted Building Model
after 62nd run (Seismic Intensity 6+
JMA Scale)

It should be noted again that this building model survived 15 moreshakings in which many runs were with higher intensities than JMA 5- at
which the non-retrofitted building was collapsed before reaching to the final
stage at the 62nd run.

CONCLUSION
Two brick masonry building models, identical in terms of masonry strengthand geometry were constructed and one model was retrofitted with an easyto-install and economic retrofitting technique. Both models were tested onshaking table by applying similar input motions. Dynamic behaviors of themodels were studied. Cracks patterns were analyzed and failure behavior
and performances were evaluated. The result showed that the pp-band
retrofitting technique enhanced the seismic resistance capacity of thebuilding model significantly, specifically the life safety performancecapacity of the building was enhanced from JMA~4 to JMA 6+ and collapse

Shaking Table Tests of ¼ Scaled Masonry Models Retrofitted with PP-band Meshes17October 2005, Singapore

prevention safety level was achieved until the final stage. From the result, it
was found that this retrofitting technique can enhance safety of existing
masonry buildings even in worst case scenario of earthquake ground motion
like JMA 7 and thus is one of the optimum solutions for promoting safer
building construction in developing countries.
REFERENCES
Coburn, A. and Spence, R. 2002. Earthquake Protection. West Sussex: John
Wiley & Sons Ltd.
Yoshimura, M. and Meguro, K., 2004. Proposal of Retrofitting Promotion
System for Low Earthquake-Resistant Structures in Earthquake Prone
Countries. Proceedings on 13th World Conference on Earthquake
Engineering, Vancouver, Canada.
Paola Mayorca, P. and Meguro, K., 2004. Proposal of an EfficientTechnique for Retrofitting Unreinforced Masonry Dwellings.
Proceedings on 13th World Conference on Earthquake Engineering,
Vancouver, Canada.
Dixit, A.M., 2004. Promoting Safer Building construction in Nepal.
Proceedings on 13th World Conference on Earthquake Engineering,
Vancouver, Canada.
FEMA 356, 2000. Prestandard and Commentary for the Seismic
Rehabilitation of Buildings. Federal Emergency Management Agency

18

New Technologies for Urban Safety of Mega Cities in Asia

RECONSTRUCTION OF HOUSES IN ACEH
SEVEN MONTHS AFTER THE
EARTHQUAKE & TSUNAMI,
DECEMBER 26, 2004
TEDDY BOEN
Senior Advisor of WSSI (World Seismic Safety Initiative)
Jakarta, Indonesia
tedboen@cbn.net.id
ABSTRACTThe Dec 26, 2004 earthquake of M 9.0 that shook Aceh and thesubsequent Tsunami catastrophe was one of the worst natural disasters inmodern history. The world - governments and people – responded with
unprecedented generosity in solidarity with the rescue and relief efforts of
the affected communities and local and national authorities. This has beenvery useful in reducing or mitigating the consequences of the disaster, andparticularly in speeding the current recovery and reconstruction efforts. In
the wake of the recovery and reconstruction of houses in Aceh, many NGOs
and donors tried to re-invent the wheel in earthquake resistant houses byintroducing house types that are not compatible with the local culture andalso neglect social problems.
Key Words: Earthquake, Tsunami, Non-Engineered, Reconstruction, Local
Culture1.

INTRODUCTION

In general, buildings can be divided into two main categories, namely
engineered buildings and non-engineered buildings. Approximately 70 % of
the buildings inventory in Indonesia consists of urban and rural nonengineered buildings, about 20 % mid rise buildings and 10 % high-risebuildings.
Non-engineered buildings are buildings which are spontaneously andinformally constructed in various countries in the traditional manner without
any or little intervention by qualified architects and engineers in their designand can be divided into two main categories. The first category; dwellings(non-engineered buildings) constructed in small towns and villages are built
according to tradition, their types suiting the culture and materials available
in that area. This type of buildings is generally also called indigenous orvernacular buildings. Indigenous buildings are gradually fading and replacedwith the second category of non-engineered buildings, namely either city typemasonry construction or a combination of traditional look only (very few) but
not adopting the traditional skills and crafts in detailing, material use, etc. The
traditional houses generally have a good record or performance in pastearthquakes.

19

October 2005, Singapore

Figure 1: Indigenous or Vernacular Houses in Aceh
However, as the economic condition is prospering, there is a strong
trend towards the construction of masonry houses and measure of status isassociated with the owners of such masonry houses. Such type of masonry
construction has become a new culture all over Indonesia and from pastearthquakes it is evident that provided they were built with good quality
materials and good workmanship, they survived the most probable strongest
earthquake in accordance with the Indonesian seismic hazard map
From documenting past earthquake damages in various areas inIndonesia over the past 30 years, it can be stated that in almost all rural aswell as urban areas all over Indonesia, a good earthquake resistant design
feature can be identified, namely almost all masonry buildings are built withreinforced concrete framing, consisting of the so called “practical columns
and beams”. In Indonesia, the damage and collapse of the new culture“non-engineered” masonry buildings are mostly caused by the poor qualityof materials and poor workmanship, resulting in, among others poor
detailing, poor concrete quality, and poor brick lying.

Figure 2: “New Culture”, One or Two Story Masonry Houses

2. AREAS IN BANDA ACEH AFFECTED BY THE DEC 26, 2004
TSUNAMIIn general there are two zones affected by the tsunami, zone 1 is thecoastal areas which were destructed by the tsunami forces such as battering,scouring, impact and buoyancy. In Banda Aceh this zone goes up to 3 km
inland. Zone 2 was only inundated, where the tsunami force is already20

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ICUS Report 11

reduced and only caused flooding, dumping mud and debris. This area isapproximately 0.5 to 1.5 km further inland.

Source of map: OYO International

Figure 3: Damaged & Inundation Zones in Banda Aceh

Banda Aceh

Lhok Nga

Figure 4: Settlement Destroyed in Zone 1

Banda Aceh

MeulabohFigure 5: Wreckage and mud in Zone 2

Reconstruction of Houses in Aceh
Seven Months after the Earthquake & Tsunami, December 26, 200421

October 2005, Singapore

3. NON ENGINEERED BUILDINGS IN ACEH
The majority of the buildings that collapsed in Banda Aceh city, andvillages in Lhok Nga, Krueng Raya, Meulaboh city and villages along theWest coast of Aceh, are non engineered buildings consisting of two types.
The first type is a one or two stories buildings made of burnt brick confined
masonry using sand and Portland cement mortar. The roof mostly consists ofgalvanized iron sheets. All those buildings used RC “practical” columns andbeams as confinement. The second type is timber construction consisting ofa timber frame and also timber planks walls and usually use galvanized ironsheets as roof. This is in line with the facts obtained during past earthquakes
surveys in various areas all over Indonesia as mentioned in the introduction.
And such timber and masonry houses are in accord with the local culturethat should be rebuilt because it is sustainable. If necessary improve thequality and strength and not trying to re-invent the wheel.

Satellite Image, Source: Digital Globe

Figure 6: Banda Aceh Northern Shore One or Two Story Masonry or Timber
HousesSatellite Image, Source: Digital Globe

Figure 7: Meulaboh, One or Two Story Masonry or Timber Houses

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ICUS Report 11

Figure 8: One or Two Stories Masonry Buildings (First Type)

Figure 9: Timber Houses (Second Type)
Almost none of the people’s housing, one to two story masonrybuildings, collapsed by the Dec 26, 2004 earthquake shaking, even thoughsome had cracks in the walls. The destruction was caused by the tsunami
forces.
The ratio of those two types of structures is estimated to be 30 % to
70 %. The epicenter of the M9.0 earthquake is approximately 240 km SW ofBanda Aceh, therefore the shaking was not too significant and timber aswell as masonry structures were reasonably built and could withstand theM9.0 earthquake shaking.

4. RECONSTRUCTION OF HOUSES IN ACEH
As mentioned above, the costal areas up to approximately several km
inland were practically “wiped out” and buildings wrecked and disintegrated.
Approximately 120,000 houses were destroyed. As is well-known, rightafter the Dec 26, 2004 tsunami, the world - governments and people –responded with unprecedented generosity in solidarity with the rescue andrelief efforts of the affected communities and local and national authorities.
Approximately $ 7 billion has been pledged for humanitarian emergency
relief and reconstruction assistance to Tsunami affected areas. This has been
instrumental in reducing or mitigating the consequences of the disaster, andin boosting the current recovery and reconstruction efforts. Apart from thepledged funds from donor countries, funds in the possession of NGOs
working in Aceh are estimated $ 1 billion.

Reconstruction of Houses in Aceh
Seven Months after the Earthquake & Tsunami, December 26, 200423

October 2005, Singapore

In Aceh, the government declared that the emergency response must
be terminated on March 26, 2005. Subsequently all foreign armies pulled
out and NGOs as well as UN agencies started activities related to thereconstruction of houses and infrastructure. Normaliter, in preparation ofsuch reconstruction, an in-depth study must be conducted regarding
available site-specific information, studying the local social, economic, andcultural constraints, and the limitations of local material as well as humanresources. Such study is necessary to absorb an appreciation of the local
family life as well as social life and the cultural patterns. Reconstructing
destroyed settlements as is the case with Aceh in fact is a special case,different from areas with lower level of damage. In heavily damaged
settlements, the social structure of the community is disrupted and many
village chiefs died during the tsunami. Building in such cases is not only
about the physical but also the social order of the community must be
re-established. In fact, in such heavily damaged areas, it is easier to focus on
repair and reactivation of the physical infrastructure and is usually the firstpriority for reconstruction. Also, such areas could be viewed as a site for“urban renewal”. However, due to land titles of the tsunami survivors,
drawing new plans will be difficult. The National Planning Board completed
the master plan for the rehabilitation and reconstruction of Aceh and Nias
three months after the tsunami and the master plan introduced buffer zones
for Aceh and suggested that the areas with total destruction shall not bereoccupied. If strictly followed this means an area up to approximately 2 km
inland will be vacated and in Banda Aceh it covers an area of approximately
15 km2. The plans prepared were not practical and lack sufficient vision.
The main reason is, all planning authorities are dependent upon theirarchitects and engineers. Architects and engineers usually work for clients intowns, they, in fact, have experience in buildings only under the peculiar
conditions prevailing in towns. Therefore, the rebuilding plans wereprepared without adequate site specific input and understanding of the risk,
thus undermining their political acceptability. Apart from that, the plans forrebuilding were untimely, three months after the disaster. The stipulations
about the buffer zones are very confusing and not rational. In the meantime,
as a result, some victims returned to their lands and started rebuilding, somewithout any consideration of future losses.

Krueng Raya

Figure 10: People Started Rebuilding Using Salvaged Materials

24

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ICUS Report 11

Several weeks after the master plan was issued, the government
activated the Aceh Rehabilitation and Reconstruction Agency (BRR).
Apparently BRR took a more rational approach regarding the buffer zoningby allowing people to return to their original places and rebuild their houseson their respective original lands. However, some villages were relocatedand many of the new sites do not take into account of the following; access towater, access to public services, access to public transportation, access to andintegration with adjacent neighborhoods; access to religious site, recreation,etc. Most probably those sites are socially unacceptable. Post earthquake
disaster relocation is frequently used but seldom studied. Appropriate
planning and analysis shall be made prior to recommending implementing
post earthquake disaster relocation. Post earthquake disaster relocation
attempt most often cast in terms of increasing physical safety and in doing so,
may have unintended consequences of increasing social disruption.
In the meantime, numerous NGOs started to “adopt” several villages tobe reconstructed and started discussing with village chiefs about theirintentions and some NGOs even discussed the reconstruction plan with the to
be recipients. Many NGOs signed an MOU, subsequently built one or two“model houses” and put their respective banners in front of those model
houses. Numerous organizations did not follow up their pledges and could
not be contacted because they were no longer at the registered addresses.
In many cases, the lack of immediately available site-specificinformation is coupled with the influx of many so-called “experts” (local andforeign) offering an endless number of earthquake resistant building type“solutions”. Unfortunately, those “experts” lack technical capacity and aclear understanding of the local building culture and the social order of thecommunity as well as the ability to adapt disaster resistant techniques to local
styles and situations. Many NGOs ended in trying to “re-invent the wheel” byintroducing house types defying the local culture. Their experts (local andforeign) tend to take into account the resources of their work environments intheir respective countries; they assume the existence of the experiencedbuilding contractors and the sophisticated materials that are always used into
building and they assume naturally that their client can pay for them.
However, there are few NGOs that construct houses based on the prevailingculture in Aceh.

Figure 11: “Re-Invent the Wheel”: House Types Defying the Local Culture

Reconstruction of Houses in Aceh
Seven Months after the Earthquake & Tsunami, December 26, 200425

October 2005, Singapore

Figure 11(cont’d): “Re-Invent the Wheel”: House Types Defying the Local
CultureThere is reason to believe that several NGOs do not differentiate type ofhouses between immediate shelter needs (which were already built by thegovernment); medium term / transition houses and permanent houses (which
are appropriate to restore their livelihood). Most of the houses already built
are of the transition type but built on permanent former lands belonging torecipients. From past experiences all over the world, such“temporary/transition” houses become permanent and the final
reconstruction stage fails to materialize.
Also no phase construction which will allow phasing of occupancy isobserved. Usually phase construction is adopted to construct transition
houses on the site and allow early occupation while the permanent houses arebeing constructed.
From built houses it can also be observed that no needs assessments
were performed prior to the construction of the houses. There is nodifferentiation made in the range of the target group among the disastervictims, whether they belong to the very low income or the moderate income
group or even middle class up group. From the houses that were not destroyed
it is clear that many of them belong to the middle class up group. Even BRR
did not consider this social constraint and generalized the requirement for
victims need and stipulate a house of 36 m2 with a budget Rp. 28,000,000,-.
It will be more appropriate if the requirement is the quality and not the cost.
The site developments by NGOs also do not consider roads and path,drainage systems, sanitary systems, provision for water supply and electric
power as parallel activities when planning the site layout. In almost all sitesthat are already reconstructed sofar, no clear indication can be seen
regarding the planning of the infrastructure mentioned earlier and no26

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ICUS Report 11

indication of the application of progressive occupation with a continuous
upgrading of services. Only few organizations prepared layout plans thatconsider the long term living environment. Inappropriate layout plans could
end up in creating slums long after the memory of the disaster has faded.

Figure 12: Site Developments by NGOs with no Planning of Roads andPaths, Drainage, Sanitary Systems, Provision for Water Supply
and Electric Power
Most of the NGOs subcontract the construction of houses and the to
be recipients were left as by standers. NGOs should in fact play a role offacilitator instead of construction agencies and direct participation of therecipients would be more appropriate.
It is also not clear which seismic standards were being adopted bysome NGOs since many houses were built based on “nail and hammer”
methodology without considering the slightest basic principles of carpentry.
One organization built “precast” houses that consist of 1 m elements for thefoundation, columns as well as beams. The joints of the elements used bolts.
Such types of “precast” construction defy any established standards forearthquake resistant design of “precast” buildings.

Reconstruction of Houses in Aceh
Seven Months after the Earthquake & Tsunami, December 26, 200427

October 2005, Singapore

Figure 13: Timber Beams & Columns Connection by “Nail & Hammer”

Figure 14: “Precast” Houses, Joints Using Bolts

5.

CONCLUSIONS
•
•
•

•

28

The houses compatible with the local culture in Aceh are one story
timber houses and one or two story masonry houses.
The main design parameter for houses is resistance to groundshaking.
Organizations involved in the reconstruction of houses in Acehshould study past local experiences and local research in therespective field and it is not advisable to complicate the matter bytrying to re-invent the wheel.
Organizations involved in the reconstruction of houses in Acehshould act as facilitators and not as contractors or developers.

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ICUS Report 11

REFERENCES
World Bank, 2005. Rebuilding A Better Aceh & Nias. Preliminary Stockingof the Reconstruction Effort, Six Months after the Earthquake &Tsunami.
Directorate General of Human Settlement Ministry of Public Works, 2005.
Post Disaster Damage Assessment in Nanggroe Aceh Darussalam.
Boen, T., 2005. Nias / Simeulue Earthquake March 28, 2005. EERI Journal,
Vol.39.
Boen, T., and Jigyasu, Rohit, 2005. Cultural Considerations for Post
Disaster Reconstruction Post-Tsunami
Challenges. UNDP
Conference.
Boen, T., 2005. Sumatra Earthquake, 26 December 2004. Special Report
ICUS.
Boen, T., 2003. Earthquake Resistant Design of Non-Engineered Buildingsin Indonesia. EASEC Conference, Bali.
Boen, T., 2001. Earthquake Resistant Design of Non Engineered Buildingsin Indonesia. EQTAP Conference, Kamakura.
Boen, T., 2001. Earthquake Resistant Design of Non Engineered Buildingsin Indonesia. EQTAP Conference, Bali.
Boen, T., et.al., 2001. Post Earthquake Disaster Relocation: Indonesia’s
Experience. APEC Conference, Taiwan.
Boen, T., 2001. Impact of Earthquake on School Buildings in Indonesia.
EQTAP Conference, Kobe.
Boen, T., 2000. Disaster Mitigation of Non Engineered Buildings inIndonesia. EQTAP Conference, Manila.
Shah, H., and Boen, T., 1996. Seismic Hazard Model for Indonesia.
Vilacis, C., and Katayama, T., 1995. Catastrophe and National Development.
Boen, T., 1994. Earthquake Hazard Mitigation in Developing Countries, theIndonesian Experience.
Boen, T., 1994. Manual, Repair and Strengthening of Buildings Damaged
During the Liwa (South Sumatra) Earthquake (in Indonesian).
Boen, Teddy, 1994. Manual, Repair and Strengthening of Buildings
Damaged During Halmahera Earthquake (in Indonesian).
Boen, T., 1992. Manual, Repair and Strengthening of Buildings Damaged
During the Flores Earthquake (in Indonesian).
Federal Emergency Management Agency, 1990. Seismic Considerations Elementary and Secondary Schools. FEMA 149 / Revised May 1990.
Arya, A.S., 1987. Protection of Educational Buildings against Earthquakes.
UNESCO Principal Regional Office for Asia and the Pacific,
Thailand.
IAEE Committee on Non-Engineered Construction, 1986. Guidelines for
Earthquake Resistant Non-Engineered Construction. The International
Association for Earthquake Engineering.
CIB/W-73, 1984. Small Buildings and Community Development.
Proceedings, International Conference on Natural Hazards Mitigation
Research and Practice.
Boen, T., 1978. Detailer’s Manual for Small Buildings in Earthquake Areas.

Reconstruction of Houses in Aceh
Seven Months after the Earthquake & Tsunami, December 26, 200429

October 2005, Singapore

30

New Technologies for Urban Safety of Mega Cities in Asia

PROGRESS IN EMERGENCY MANAGEMENTRESEARCH FOR A MEGA-CITY IN CHINA
W.C. FAN1,2 G.F. SU2
State Key Laboratory of Fire Science, University of Sci. & Tech. of China1
Center for Public Safety Research, Tsinghua University, P.R.China2 100084
wfan@tsinghua.edu.cn, sugf@tsinghua.edu.cn

ABSTRACTThe accident to the public safety of a mega-city could result in largescale loss of life and major economic impact. In order to improve the public
safety for a mega-city, a series of emergency management research is
ongoing in China. The emergency management research is structured
around the science, engineering, and technology that support all emergency
response plan and activities. Now research progress focuses oncontinuously improving city-level response plan, designing the prototype of
emergency response platform and putting it in practice, and developing the
key technologies of emergency management activities. These researchranges are involved in the whole emergency response process, including
monitoring and control, forecast and alert, command and decision-making,as well as analysis and assessment before and after the events.
Keywords: emergency, public safety, response plan, response platform,
multi-scale, double nested, decision-making, alert level.
1. Introduction
Urbanization, the exodus from rural areas to cities, will be a majordemographic phenomenon of the 21st century. The disasters are more
destructive when they strike large cities, given the growing trend of highurban-population densities. Mega-cities, a term coined in the 1970s by theUnited Nations to define urban settlements of ten million inhabitants or
more, are particularly at risk. Currently, 280 million people live in about 30
mega-cities across the world. This figure is expected to rise to 350 million
by 2015. Several of mega-cities, such as Beijing, Shanghai, Tianjin, etc. arelocated in China.
Natural disasters in mega-cities are likely to cause large numbers ofcasualties because of the high demographic density in urban areas. Many of
the casualties when a emergency event as flood, earthquake or fire - strikesa mega-city are due to the collapsing of buildings and other infrastructure
which were designed for large numbers of residents. High concentrations ofpeople and buildings mean that even moderate disasters can lead to heavy
losses.
We will enhance our capabilities for responding to an emergency event
all across the city. Today, many departments or agencies have little or no31

October 2005, Singapore

capability to respond to a coupling incident with mass destruction. Even thebest prepared departments do not possess adequate resources to respond to
the full range of disasters we face. Many do not yet have in place mutual aid
agreements to facilitate cooperation with others in time of emergency.
Emergency management activities include prevention, preparedness,
response, and recovery actions. Generally speaking, the calamity incident
will always happen, is impossible to totally avoid. Effective incident
management begins with a host of preparedness activities in advance of any
potential incident. Past experience has shown that preparedness plans are thekey to providing an effective response to major incidents and natural
disasters. At the same time, when the accident has already happened, theresponse on the basis of plan is the focus too that we pay close attention to.

2. Emergency Management Plan
The emergency management plan focuses on those activities that are
directly related to an evolving incident or potential incident. Sometimes wecall it emergency response plan.
The national response plan and a series of response plans for public
emergency event have been studied and developed in China since 2003, andwere established and issued until the beginning of 2005.
The national response plan is an all-hazards plan that provides the
structure and mechanisms for national level policy and operational
coordination for emergency management. It can be partially or fully
implemented in the context of a threat, anticipation of a significant event, or
the response to a significant event. Selective implementation through theactivation of one or more of the system’s components allows maximum
flexibility in meeting the unique operational and information-sharing
requirements of the situation at hand and enabling effective interaction
between various ministries and commissions, local, and other entities.
For a mega-city, it is the most important to direct based on the emergency
response plan of the city. A basic premise of the national response plan isthat incidents are generally handled at the lowest jurisdictional levelpossible. Police, fire, public health and medical, emergency management,
and other personnel are responsible for emergency management at the local
level. That’s to say, a city in the local area may act as a first responder andmay provide direction or assistance consistent with its specific authorities
and responsibilities. In the vast majority of incidents, local city resources
and intercity mutual aid normally provide the first line of emergency
response and incident management support.
The city-level plan for emergency response provides a framework to
enable the management of cascading impacts and multiple incidents as wellas the prevention of and preparation for subsequent events. Examples of
emergency management plan from a city perspective include:
Increasing citywide public awareness;
Assessing trends that point to potential hazards;
Elevating the city public safety advisory system alert condition andcoordinating protective measures across departments;
■
■
■

32

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ICUS Report 11

■

■
■

■

■
■

Increasing countermeasures such as monitoring, forecast, fighting,aid decision-making and infrastructure protection;
Conducting public safety surveillance and assessment processes;
Providing immediate and long-term public safety and rescue response
assets;Providing strategies for coordination of city resources required tohandle subsequent events;
Evaluating in the aftermath of an incident;
Enabling immediate recovery activities, as well as addressing longterm consequences in the impacted area.

3. Designing the prototype of emergency response platform
The emergency management actions range from initial notification toearly coordination efforts to assess and disrupt the incident, to preparatory
activation of the response plan, to deployment of city resources in support ofemergency response and recovery operations. These actions do notnecessarily occur in sequential order; many may be undertaken concurrently
in response to single or multiple disasters or incidents. Under mostsituations where it is apparent that an incident may be imminent or has
already occurred, assessment and pre-incident interagency coordination
typically are simplified. City authority moves quickly to coordinate multiple
department activities to include the following: information-sharing,
integration of the resources, analysis coupling multi-disasters andforecasting, alert and decision-making, interagency course of action
development, operational coordination, and other assistance as required. Inorder to implement the emergency management and realize the purpose toresponse plan, all of these need a comprehensive city system for public
emergency response to bring together and make use of all necessary
response resources quickly and effectively.

Fig. 1 the prototype of
emergency response
platform for urban
region of a city

Progress in Emergency Management Research for a Mega-city in China

33

October 2005, Singapore

Technologies developed for a variety of purposes are often directly
applicable, or quickly adaptable, for public safety needs. We are working toprovide a prototype system of emergency response platform for the city
public safety, based on existing technologies and developing of technology.
The safety management and emergency response platform is designed to
improve the response operations more scientific, effective, and efficient. It
is a centralized solution for event correlation, information sharing, resources
aggregation, disaster analysis, response and investigation of emergency
events with the networked matrix mode.
The response platform can quantify the risk for a study area of any size,
whether for a building, region, city, or neighborhood. Using simulation and
GIS technology, the public safety platform combines hazard layers with city
databases, and then applies standardized loss estimation and risk assessment
methodology. The platform environment allows users to create graphic
presentations, helping users visualize and understand their hazard risks andsolutions.
The emergency response platform gives decision-makers the tools to
make better decisions. It establishes a mechanism for sharing theinformation all cross city including basic geographical information andpublic safety information, enhances the analysis of available options forrescue operation, optimizes the decision-making process, and can greatly
improve the ability to select the best course of response plan.

4. Some key technologies of developing for emergency management
4.1 Exploring multi-scale disaster modeling, simulation, and forecastingin emergency response platform, building a fully integrated capability
across all different disaster sectors and the key factors.
The public incidents often have double characteristics (determinacy andrandomicity). According to such dual law, the development trend, affecting
range and probability taking place of the incident can be forecasted.
Scientific decision-making must be set up on the basis of predicting theaccident accurately. That is to set up the multi-scale prediction models that,say, dangerous materials leak and spread under different scene andenvironmental condition (wind speed, wind direction, temperature, humidity,
topographical, urban buildings, etc.), and to store in the model database of
the response platform. For example, when the chlorine leakage accident
happens, we can obtain spot information of the accident from themonitoring system with the aid of GIS system, use the information in the
public safety platform database, such as volume, pressure, physics &chemical property of this dangerous source, etc., then choose the model
which accords with present terms from the model database, input the data toforecast accident and analyze its grade of risk. The results of calculation ofthese models, can offer scientific basis for the alert grading and rescuing.
Namely, according to the predicting result and resource distribution, theresponse plan is selected from the plan database, to optimize decisionmaking, and implement it.

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Fig. 2 the simulation of chlorine leakage accident in response platform
4.2 Advancing risk assessment and decision-making aid systems based on
spatial technique, including information sharing and analysis on thecritical public safety information found within massive data sets.
In order to fulfill the prediction of the public incident and decisionmaking, it is necessary to gain the full and accurate geographicalinformation and public-safety related information. The city response
platform have already included a large amount of relevant basic information,such as topographical data of the city, pipe network data of the urban
lifeline, information of the dangerous source, key place and infrastructure,
rescue force, population distribution and layout of refuge area, etc. The data
involved are extensive and complicated in space distribution to meet anurgent need for public safety.

Dangerous source
Substance: Cl2

Buildings needed evacuate
ASET:12 minutes
RSET:5 minutes

Available refuge area
People number contained

Unavailable
refuge area

Resceforce

Fig. 3 the risk assessment and decision-making aid analysis

Progress in Emergency Management Research for a Mega-city in China

35

October 2005, Singapore

Intelligent analysis and data sharing are vital for emergency management.
The intelligent capabilities of response platform support all aspects ofemergency management: planning, response and recovery. The decisionmaking aid system is a part of response platform. Decision-making aid
system adds a comprehensive set of advanced spatial modeling and analysis
tools to desktop of response platform. These tools can help you predict thescope of a disaster, where the damage would be the greatest, what lives andproperty would be at highest risk, and where specific resources would be
required.
4.3 Initiating a double nested city evacuation model considering the big
region of urban and large quantity of people.
When the public incident happens suddenly, it is required to evacuate thepersonnel in the larger area, to choose the route evacuated safely, then to
estimate out the time needed for reaching the refuge area. On the basis of
GIS platform, using the information of urban area, such as kind of building,story of building, population distribution, topological structure of road
network, etc., we can adopt different numerical models to simulate theevacuation of crowd
inside and outside thebuilding. Combined withthe prediction of accident
development and route of
rescueoperation,
determine the range, routeevacuated and tactics
guided, avoid jams andblocking as much as
possible, guarantee thepersonal security.
Considering the big
region of urban and large
quantity of people, aframework method of
doublenestedcity
evacuationmodel
isdeveloped
under
thesituation of urban fire or
gas leak.
Fig. 4 the evacuation model of urban region

4.4 Establishing the method and standard of alert response level about
emergency event
Based on the modern crisis management theory, considering the factors,
such as casualties, property loss, environmental disruption, etc., andconsidering the controllability, affecting range and future development of36

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

the incident, utilizing the method with the fuzzy neural network, we canestablish the weight of each evaluation index, obtain the severity of the incident,
and put forward alert response levels.

Principle
Casualties
Property loss
Environmental disruption......
Controllability
Affecting range
Severity of incident……

Technic process

Theory support

Establish guideline system

Crisis management theory

Weight of evaluation index

Neural network analysis

Integrated alert levels

Fuzzy identify theory
Decision-making theory

blue

yelloworangefeedback

redInformation issue

Response plan startup

generalgreat

severeextra
severeFig. 5 the alert response level of emergency event

The level of risk of response activity is specified by building on thecommon colors of traffic lights that everyone understands, but adds a fourthcolor, orange, and changes a color, green to blue, as shown in Fig. 5.
Another warning scheme used to indicate response activity is the alert levels(ONE, TWO, THREE, and FOUR). It indicates the level of hazards anddegree of imminence. Alert level notifications are accompanied by brief
explanatory text to clarify hazard implications as fully as possible. The
actual level of event maybe is different from the alert level, the response
plan should been developed that specifies the appropriate actions that should
be taken when the alert level changes.
4.5 Improving the response plan, and studying the techniques that could
make the response plan more active and more optimizing
The digitized plan is integrated and combined by many kinds of resources
on many networks. Only a plan melts dynamically, that is could fully giveplay to the role of information system and public safe science andtechnology. Generally, that only the digitized dynamic plan can be very
well realized on the emergency response platform.

Progress in Emergency Management Research for a Mega-city in China

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October 2005, Singapore

Alarm and warnmonitorGrade of event, alert level, affecting range..
Response Plan module

Event kind

Organization and personnel makeup
Communication, announce, alarm

Location
Optimizing and assigning of fire fighting force
Time
Preparing and distributing of rescuing material
WeatherSpot info

Medical aid services
Crowd evacuation from dangerous area
Disaster controlling and fighting

Traffic
Disaster recovery
Training and exercising

Fig. 6 the digitized and dynamical plan for emergency response
5. Conclusions
Urbanization is still fast going on in China. Many safety technologies
needed for protection of a mega-city against natural disasters and manactivity related incidents. Among them emergency management technology
is crucial.
The emergency management research is multi-disciplinary research areaof great potential, which has drown an increasing attentions of scientist,
engineer, manager and officer with various backgrounds in China.
Emergency management research should not only make cities safer, but also
make our daily lives better, while protecting against the emergency events.
Thus, the technologies developed for emergency response should fit wellwith the city planning, infrastructure and habits.
Research efforts needed of a constant examination of the cityvulnerabilities, continual testing of our public safety systems, updating
evaluations of the emergency response capability and its weaknesses andexercising different response actions through the research progress.
Natural disasters and man-activity related incidents are common enemy
for human being. International and regional exchange and cooperation play
an important role to enhance public safety research.

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ACKNOWLEDGEMENTS
This paper was supported by the National 985 Project, and based on
Sci.&Tech. ‘Eleventh Five-Year’ pre-plan (Research and demonstration of
the key technologies for public emergency response).
The authors deeply appreciate the supports, and thanks for the works ofCenter for Public Safety Research, Tsinghua University and State Key
Laboratory of Fire Science, University of Science and Technology of China.
REFERENCES
State Council of P.R. China, 2005. National Public Emergency Response
Plan.
Fan W.C., 2004. Surveying the science and technology support of the public
safety management of city from the fire science. In Ding, S.S.
Operating Mechanism for Disaster Management. Public Saying Press,
Beijing, 107~137.
State Administration of Work Safety, 2004. The guide for working out the
response plan of dangerous chemicals accident.
Ding, S.S., 2004. The Management of Urban Disaster. Public Saying Press,
Beijing.
Yuan, H.Y., Su, G.F., Chen, T., Yang, R., Shen, S.F., and Fan, W.C., 2005.
Research of the system of emergency response platform and plan for
petrochemical industry enterprises. Seminar about precautions against
disasters with the industrial safe practice in the urban, Taipei.
Chen, T., Song, W.G., Fan W.C., and Lu, S.X., 2002. Jamming transition ofpedestrian evacuating flow in crossing exit. In Huang, P., Wang, Y.,
Li, S., Qian, X.(eds) Progress in Safety Science and Technology, Vol.
Ⅲ, Science Press, Beijing, 507~512.
Chen, T., Yuan, H.Y., Su, G.F., and Fan, W.C., 2004. An automatic firesearching and suppression system for large spaces, Fire Safety of
Journal, 39(4): 297~307.

Progress in Emergency Management Research for a Mega-city in China

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40

New Technologies for Urban Safety of Mega Cities in Asia

LESSONS LEARNED FROM
THE 26 DECEMBER 2004 TSUNAMIDISASTER IN THAILANDPENNUNG WARNITCHAI
Asian Institute of Technology, Thailand
Pennung@ait.ac.th

ABSTRACT
Triggered by a massive earthquake (Mw =9.3) in the area off thewestern coast of northern Sumatra, a series of destructive tsunami waves
propagated through out the Indian Ocean and devastated communities
along thousands of kilometers of exposed coastline. In Thailand, allprovinces facing Andaman Sea were seriously attacked by tsunami waves,
where the total death toll including missing of more than 8000 was
reported. An international survey team, comprising members from Thailand,
Japan, and USA, spent four days from 8 to 11 January 2005 in several
hard-hit areas to collect information on tsunami inundation, building
damage characteristics, ground and foundation failures, and associateddata from eyewitnesses and survivors. The areas investigated include Khao
Lak (Phang-Nga), Phi Phi Island, and Phuket Island. Many lessons learned
from this post-tsunami reconnaissance survey are briefly summarized in thispaper.

1. INTRODUCTION
Triggered by a massive earthquake (Mw = 9.3) in the area off thewestern coast of northern Sumatra, a series of destructive tsunami waves
propagated throughout the Indian Ocean and devastated communities along
thousands of kilometers of exposed coastline. Along with Thailand, deathsby this ocean-wide tsunami have been reported in 10 other countries—
Indonesia, Sri Lanka, India, Malaysia, Myanmar, Maldives, Bangladesh,
Somalia, Tanzania and Kenya. The total death toll including missing ismore than 280,000. It can be ranked as one of the world’s most catastrophic
events in recent times.
In Thailand, all provinces facing Andaman Sea were attacked bytsunami waves. The death tolls including missing in Phang-Nga, Phuket,
Krabi, Ranong, Trang, and Stool provinces are, respectively, 6026, 921,
1384, 171, 6, and 6. The numbers of severely damaged buildings are,respectively, 4615, 1235, 632, 349, 165, and 57. These are statistics
provided by the Department of Disaster Mitigation and Prevention, Ministryof Interior, Royal Thai Government, on 24 January 2005. Nearly half of41

October 2005, Singapore

those confirmed dead and half of those missing were foreign tourists who
were spending their holidays in the resort areas.

2. POST-TSUNAMI RECONNAISSANCE SURVEY
An international survey team, comprising members from Asian
Institute of Technology, Chiba University (Japan), EDM/NIED (Japan),
JICA, MCEER (USA), GISTDA (Thailand) and Thai Meteorological
Department, was formed to collect information on tsunami inundation,building damage characteristics, ground and foundation failures, andassociated data from eyewitnesses and survivors. The team, coordinated bymyself, spent four days from 8 to 11 January 2005 in several hard-hit areas,such as Khao Lak (Phang-Nga), Phi Phi Island, and Phuket Island. Many
lessons learned from this post-tsunami reconnaissance are briefly
summarized in the following section. In addition, 11 hours of georeferenced digital video footage were recorded along the survey route, andabout 1,500 GPS-located digital photos were also collected by the team andwere linked to satellite images (IKONOS, Quickbird). It is envisioned thatthese geo-referenced data will be invaluable for future research inevaluating damage from tsunami waves. Further details about these georeferenced data and their possible applications can be found in Yamazaki(2005) and Ghosh (2005).

3. LESSONS LEARNED
Among several beaches in Phuket Island, the impact of tsunami wasreported to be highest in Kamala and Patong Beaches. The maximum
height of tsunami waves above the tide level at that time was about 4 to 5
meters, while the inundation depth was about 2 meters. The first sign oftsunami attack was the withdrawal of the sea. People were surprised andwent to see the exposed seabed. Many of them were killed or seriously
injured as the sea withdrawal was shortly followed a high tsunami wave.
At Kamala Beach, three tsunami waves struck the shore at 9.54, 10.14
and 10.57 am, respectively, and the 2nd and 3rd waves were higher than the
1st wave. The waves swept onto the land at high velocity as a sheet of water.
The flow depth in Kamala beach area was about 2 meters or less, so only the
first story was flooded as shown in Fig. 1. But the flow velocity was
roughly estimated to be about 3 to 4 m/s or higher. Hence, a lateralhydrodynamic pressure greater than 5.0-8.0 kN/m2 was exerted on buildings
and obstacles by the high-velocity water. After the water has receded, agreat amount of debris which was floating during the tsunami flooding
finally deposited on ground (Fig. 2), and water marks could be observed onbuilding walls. The damage seemed disproportionately severe comparedwith that would be expected from a normal flooding of similar height. The
high hydrodynamic pressure due to high-velocity water and the collision of
floating debris appeared to be the main causes of the severe damage.

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Figure 1 Tsunami flooding in Kamala Beach

Maximum Water

Figure 2 A scene in Kamala Beach after the water has receded
Tsunami wave heights at various sites shown in Fig. 3 were measured
by a Japanese team led by Prof. Matsutomi (2005) and a Thai team led by
Dr. Nakhorn Poovarodom of Thammasart University. The heights varyconsiderably from site to site, and the maximum height occurred at Khao
Lak in Phang-Nga Province. This area has many luxurious hotels and wasquite popular for foreign tourists, especially those from Europe.
Water marks in the form of stripped roof tiles on the 2-story buildingin Fig. 4 indicate that the flow depth in Khao Lak area was as high as 7 to 8
meters. The flow velocity in this area was estimated to be about 6 to 8 m/s,
and hence a very high hydrodynamic pressure of about 20 to 30 kN/m2 wasexerted on buildings and obstacles by tsunami waves. Due to these
extremely high flow depth and pressure, Khao Lak was the hardest-hit areawith the largest death toll. Most of the resorts surveyed sustained heavy tocomplete damage. As shown in Fig. 5, a reinforced concrete building facing
Kuk-kak Beach in Khao Lak was completely destroyed by tsunami impact.
This is only an example of many completely damaged buildings in this area.

Lessons Learned from the 26 December 2004 Tsunami Disaster in Thailand

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October 2005, Singapore

1. Suk Somran
2. Phra-Thong Island

Ranong3. Ban Nam Khem
4. Ban Bang Sak
5. Phakarang Cape

Ranong

6. Kuk-Kak Beach

1

7. Ban Bang Neing
8. Tab-Lamu Pier

Phra-Thong Island

2

Khao Lak

3
4
5
6
7
8

9. Khao Lak
9

10. Kamala Beach

Surat Thani

11. Patong Beach
12. Karon Beach
13. Phi Phi Don Island

Phang-Nga

Phuket(west coast)

10

8

6

Krabi

10
11
12
4

2

Phuket(east coast)

13
Phuket2

2
4
10

Phi Phi Don Is.

86

Phuket(south coast)

Tsunami Height (m)Tsunami Height (m)

4

6

8

10

Tsunami Height (m)Figure 3 Tsunami wave height distribution

Maximum
Water Level
Maximum Water

Figure 4 Maximum flow depth of about 7 to 8 meters in Khao Lak

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Figure 5 An RC building in Khao Lak was completely destroyed

Figure 6 Breaking of masonry infill walls by wave impact in Phi Phi Island
One damage pattern commonly found in RC frame buildings is thebreaking of frame-infill masonry walls (Fig. 6). These walls are generally
100 mm thick. They are much weaker than RC frame members, and they
could not withstand high hydrodynamic pressure or impact of major floating
debris carried by the strong current. Breaking of infill masonry walls,
particularly in the first story, can be found in many sites where the flow
depth was about 2 m or higher. As shown in Fig. 6 the flow height did notreach the 2nd story of a 2-story building, but it was able to demolish all infill
masonry walls in the 1st story. We observed that in general RC frames inwhich infill walls had been completely ripped away were still in goodcondition—no damage or major cracks found in RC columns, beams, andbeam-column joints. The breaking of infill walls seemed to help saving the
RC frame structures by reducing the lateral pressure load on the structures.
Therefore, to improve the safety of RC frame buildings in the tsunami
affected areas, infill masonry walls in the 1st story (and the 2nd story in someareas) might be replaced by weaker (and lighter) panels that could be easily

Lessons Learned from the 26 December 2004 Tsunami Disaster in Thailand

45

October 2005, Singapore

ripped away by the water. These observation and design improvement
concept are well in line with those made by several investigators of pasttsunami disasters (Wiegel, 1970).

Figure 7 Floating foundations of a building in Phuket

Figure 8 Displaced buildings at Ton Sai Bay in Phi Phi Island
Another type of frequently observed damage to buildings in tsunami
affected areas is the severe scouring of supporting sand underneath building
spread footings, leading to foundation failure as shown in Fig. 7. This
severe scouring was caused by highly turbulent and strong tsunami-induced
currents. We have also found severe scouring of roads and wall foundations
in many sites, particularly in beach front areas. Another type of failure
associated with shallow spread footings is shown in Fig. 8. Here, several
buildings at Ton Sai Bay in Phi Phi Island were floated and displaced fromtheir original positions.

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As spread footings were commonly used for low-rise buildings in
Phuket and many southern provinces of Thailand, this issue was widely
discussed among design engineers in several forums. Some engineers
suggested that the use of spread footings for buildings in tsunami hazard
areas should be forbidden, and that pile foundations should be used instead
to improve the resistant to scouring, undercutting, and flotation effects.
One important feature of tsunami flooding we have learned from thissurvey is that strong-current tsunami waves carried with them a greatamount of debris including cars and boats. Figure 9 gives us a clear idea
about the extent of debris carried by tsunami waves during the tsunami
flooding. We found pieces of wood, furniture parts, refrigerators, trees,
metal (zinc) roof sheets, sand and mud in the debris. High-density debris in
tsunami waves is certainly one of the key factors that are responsible for alarge number of tsunami victims.

Figure 9 Debris deposited on a beach in Khao Lak

Figure 10 A car on the roof of a building in Phakarang Cape

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October 2005, Singapore

Figure 11 A battleship was tossed on to the shore at Tab-lamu Pier
Many cars were rolled, pushed around, hit by floating debris, or
thrown against buildings (Fig. 10) and obstacles. Many fishing boats were
pushed from the shore toward the land and crashed into buildings. One
patrol boat was transported into as far as 1.2 km in land at Ban Bang Neing
in Khao Lak area. The largest object that was displaced by tsunami waves
is a battleship of Royal Thai Navy as shown in Fig. 11. The ship was tossedon to the shore in front of a naval base at Tab-lamu pier in Phang-Nga.
While the southern and central parts of Phang-Nga have several resort
hotels, the northern part is still a rural area with fishery and agriculturalvillages. In a populated fishery village named Ban Nam Khem, more than athousand of residents were killed, and most RC residential buildings andmasonry structures for shrimp farming suffered heavy damage. The survey
team also visited one fisherman village named Ban Pak Jok in Phra-thong
Island—a small island located just off the northern coast of Phang-Nga (seeFig. 3). In this village, all wooden fisherman houses and small light-frame
concrete buildings were completely wiped out as shown in Fig. 12. All
survivors were evacuated from the island and resettled in the northern coastof Phang-Nga.

Figure 12 Devastated fisherman houses in Phra-thong Island

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We saw evidence in this village and in many other sites (such as
Phakarang Cape) that wooden houses, compared with normal RC framebuildings, are much more vulnerable to tsunami impact. At sites where RC
buildings were lightly or moderately damaged, wooden houses would beseverely damaged or completely destroyed. The finding suggests that woodconstruction should be as much as possible avoided in tsunami hazard areas.
In Ban Pak Jok village, only one structure was left intact: an RC water tanktower. It reminded us of a tsunami tower in Japan, in which people caneasily evacuate from low-lying ground to its high-level platform during thetsunami flooding (Fig. 13). Since the whole area of Phra-thong Island isvery flat and surrounded by sea, it would be very difficult to find a safe
(high-level) ground for the evacuation in the next tsunami event. Hence,
RC tsunami towers seem to be a practical solution in this case.

Water Tank Tower
Phra-thong Island

Tsunami Tower
Japan

Figure 13 Water tank tower & Tsunami tower

Ton Sai Bay

Loh Dalum Bay

Figure 14 Sand belt area in Phi Phi Island was attacked
by tsunami waves from both side

Lessons Learned from the 26 December 2004 Tsunami Disaster in Thailand

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October 2005, Singapore

By interviewing several eyewitnesses and survivors, the survey teamlearned that tsunami waves at some sites were quite complex. These sites
include Phi Phi Island, which was among the worst affected areas. Looking
from the tsunami source area, this island is located outside the shadow ofPhuket Island, and thus was hit by large tsunami waves of about 5 to 6 m
maximum height (see Fig. 3). The number of casualties in this island was
691 and that of missing was 951. Most of them were tourists and residents
in a highly populated sand belt between two bays as shown in Fig. 14. The
elevation of this sand belt area is only 2 to 3 m above the sea level. Whenthe first tsunami wave attacked from Loh Dalum Bay, people were panic
and they tried to escape by running to Ton Sai Bay on the other side.
However, by the time they reached Ton Sai Bay, a much larger tsunami
wave was also arriving in this bay and then swept across the whole sand belt
area, killing a large number of people.

4. CONCLUDING REMARKS
Prior to this event, a tsunami disaster of this scale was considered by
the Thai public to be impossible. This general belief was simply based on
the fact that such disaster has never happened before in the history ofThailand. They also believed that the risks from other natural disasters(such as earthquakes) were also very low and limited to a small scale. Most
decision makers in the government did not pay much attention to planningand preparation to mitigate the risks or supporting more scientific researches
to understand the risks. The emphasis was only placed on emergency
response measures. After the event, the attitude of the general public andgovernment officials towards natural disasters has changed significantly.
They are now much more interested to learn about these natural disasters
and their potential impacts. They are also more ready invest their money on
making and ensuring a safe environment. It seems that the Thai public has
also learned a very important lesson from this tsunami disaster.

REFERENCES
Yamazaki, F., Matsuoka, M., Warnitchai, P., Polnga, S. and Ghosh, S., 2005.
Tsunami Reconnaissance Survey in Thailand Using Satellite Images
and GPS, Asian Journal of Geo-informatics, Vol. 5, No. 2, pp. 53-61.
Ghosh, S. et al., 2005. Post-Tsunami Urban Damage Survey in Thailand
Using the VIEWS Reconnaissance System.
http://mceer.buffalo.edu/research/tsunami/Tsunami032505.pdf
Matsutomi, H. et al., 2005. The December 26, 2004 Sumatra Earthquake
Tsunami, Tsunami Field Survey around Phuket, Thailand.
http://www.drs.dpri.kyotou.ac.jp/Sumatra/Thailand/phuket_survey_e.html
Wiegel, R. L., 1970. Chapter 11: Tsunamis. Earthquake Engineering, editedby Wiegel R. L., Prentice-Hall, New Jersey, USA.

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New Technologies for Urban Safety of Mega Cities in Asia

Technical Sessions

STRUCTURAL PERFOMANCE MONITORING
OF REINFORCED CONCRETE BRIDGESMITSUYOSHI TSUNEKUNI1, TSUGIO NISHIMURA2,YOSHITAKA KATO2 AND TAKETO UOMOTO2
1
Tokyo Electric Power Services Co., Ltd., Japan
2
International Center for Urban Safety Engineering,
Institute of Industrial Science, University of Tokyo, Japan
tunekuni@tepsco.co.jp

ABSTRACTIn Japan, the deterioration of some concrete bridges constructed in
1960s is beginning to be detected. For the future increase of maintenancecost for deteriorated bridges, the quantitative evaluation of deterioration
degree and/or soundness for structural performance, e.g. safety orserviceability performance, will become an important task. In this study, themonitoring method of soundness evaluation of the structural performance ofreinforced concrete bridges is discussed through loading tests of reinforced
concrete beams in laboratory and the behavior measurement of areinforcement concrete (hereafter referred to a “RC”) road bridge in situ.
For in-situ measurement of a 35-year-old RC road bridge, some
sensors, i.e. optical fiber sensors and velocity meters, were mounted on themain girders. Using the data measured by these sensors, the soundness ofstructural performances of the bridge in terms of safety and serviceability
performances were evaluated.
1. INTRODUCTION
A large number of concrete bridges were constructed since the era ofhigh economic growth in Japan. Among about 130,000 bridges with spanlonger than 15m, the number of concrete bridges, e.g. reinforced concreteor pre-stressed concrete, is about 71,000 (MLIT, 2002). Due to the steadyincrease of old and decaying bridges in the future, the evaluation of thesoundness of existing concrete bridges will be becoming an important task
to decide whether a bridge is still in serviceable condition or not.
Currently, the maintenance of concrete road bridges is carried out
mainly by periodic visual inspections. On the basis of the inspection results,
the degree of deterioration and the main cause of deterioration aredetermined. In this process, however, it is difficult to evaluate the safety andserviceability performances, which are criteria mentioned in standard
specification (JSCE, 2002). Therefore the measurement method related tothe structural performance for RC road bridges is firstly considered throughthe load tests in laboratory in this study. By applying similar measurement
methods, then, the evaluation of soundness of a 35-year-old RC road bridge
were performed.

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October 2005, Singapore

2. LOADING TEST OF SPECIMENS IN LABORATORY
2.1 Outline of loading test
In order to clarify the measurement method for soundness evaluationof RC road bridges in advance, the loading tests of RC beams were carriedout in laboratory. Basing on results of the test, the structural behavior
measurement method and soundness evaluation method were considered.
The two RC beams were tested in flexure supposing the main girders ofroad bridges; the one was for static test and the other was for fatigue test.
Details of specimens are shown in Figure 1. The compressive strengthof concrete was 30 MPa whereas the yield strength of steel was 399MPa.
The beams were 3400 mm long, 200 mm wide and 300 mm thick and were
simply supported over a span of 3000mm. Two 19 mm diameter steel bars
were used as reinforcement. The flexural and shear reinforcement was
designed to ensure flexural failure. Sixteen 10mm stirrups were placed in
the beam as shear reinforcement at spacing of 200mm.There was a 40mm
clear cover of concrete. The tests were carried out using a 294 kN capacity
hydraulic servo actuator as shown in Figure 2. The actuator was operated
under load control. Strains of reinforcement bar, concrete of extreme
compressive fiber and deflections at mid-span were recorded during testing.
D16

40

ｃ
Ｌ

400
D16

1100
D10

D10
300

D19
7＠200＝1400

200

200

D19

Figure1:Details of test beam (mm)Figure2:Test set-up

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2.2 Results of tests
2.2.1 Results from static test
The result of the static test is shown in Figure 3. This result showsthat the flexural stiffness abruptly degrades after reinforcement yielding;
The failure of RC beam initiated by yielding of reinforcement. That is to say,the flexural failure of main girders of RC road bridges must be check for thereinforcement yielding not for the ultimate strength in actual.

Load(kN)

80
60

Yield

40
20

Cracking

0
0

20

40

60

80

Deflection(mm)Figure3:Loads vs Deflection diagram for static loading
Even if the sectional force would be important to access the behavior,
the evaluation of that for structural members, especially main girders of RC
bridges, may be difficult in general. So the estimation method of thebending moment utilizing the measurement of beam was considered in thetest.
The estimation of acting load on the beam was calculated using
strain of extreme compressive fiber and of reinforcement bar as follows:
M=C･y1+T･y2(１)

where M: Acting bending moment
T: Resultant tensile force of the steel
C: Resultant compressive force of concrete
y1, y2: Distance from the neutral axis to C and T.
Strain of extreme compressive fiberC
Neutral axis

T
Strain of reinforce bar
Figure4: Distribution of strain of cross section

Structural Performance Monitoring of Reinforced Concrete Bridges

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October 2005, Singapore

Estimated load(kN)

Figure 5 shows the comparison of measured and estimated load.
Though the estimation load is 1.2 times the measured one, the estimation ofacting sectional force seems to be possible using the strain distribution incross section. The cause of error in estimation seems to be the increase instrain of steel exposed to crack planes (Okamura, H. and Maekawa, K.,
1991).
100
80
60
40
20

y = 1.2 x0020 40 60 80 100
Measured load(kN)

Figure5:Estimation result of applied load
2.2.2 Results from fatigue test
The fatigue test of a RC beam is tested under cycling load withconstant minimum load of 20kN. In order to accelerate the damage, the test
was performed while increasing the maximum load, such as 17, 37 and 60
kN. The number of cycles was 30,000 cycles for each maximum load. The
test was conducted at 1 Hz.
The result is shown in Figure 6. The deflection at mid-span and load
were recorded at cycle numbers of 1, 1,000, 10, 000 and 30,0000 for eachmaximum load case. From this result, it is seemed that the deflections
increase according to the increase in cycle number. Figure 7 shows thecomparison the measured deflection at minimum load for each minimum
load and one calculated using secant flexural stiffness between 2 to 17kN.
The increase in the deflection at minimum load may be caused by concrete
creep, whereas the increase in the deflection at maximum load, in otherwords, the degradation of flexural stiffness, may be caused by the fatigue
crack extensions. The increase in deflection at minimum load can beconsidered as the residual deflection of the actual deflection.
The correlation of the measured deflection and the one considering
cyclic creep expressed as Eq.(2) (Balaguru and Shah, 1982) is demonstrated
in Figure 8. It turns out that the creep will significantly affect on thedeflection. Therefore the effect of concrete creep should be taken into
consideration in the soundness evaluation.
εc=129･Sm･t1/3+17.8･Sm･Sr･N1/3(2)
where εc: the cyclic creep strain
Sm: (σmax+σmin)/2f’c,Sr: (σmax-σmin)/f’c
σmax,σmin: the maximum and minimum
applied compressive stress in concretet: the time from start of loading (h),N: the number of cycles,
f’c: the compressive strength of concrete54

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

0.4

2-60kN60

Calculated
deflection(mm)Load(kN)

80
2-37kN40
2-17kN200

y = 0.061 x

0.3
0.2
0.1
0.0

0

5

10

15

0

Deflection(mm)

2

3

4

Measured deflection(mm)Figure6:Loads vs Deflection
diagram for faigue loading
Deflection consideringwith creep(mm)1Figure7: Scatter gram of measured
and calculated deflection

4
1:1

3
2
1
0
0

1

2

3

4

Measured deflection(mm)Figure8: Scatter gram of measured and deflection with creep
3. MONITORING AND SOUNDNESS EVALUATION
3.1 Monitoring concrete bridge
The pilot monitoring was carried out on a 35-year-old RC road bridge(Figure 9) from April 2004. The outline of the bridge is summarized on
Table 1. Due to increasing traffic load in recent years, bending cracks
occurred in each main girder, as shown in Figure 10. Then, by the use ofsome sensors such as optical fiber sensors and velocity meters, behaviors,
i.e. the deflection and strain of main girder against vehicle loads, aremeasured.

Figure 9: Monitored concreteroad bridge

Structural Performance Monitoring of Reinforced Concrete Bridges

Figure10: Cracks of a main girder55

October 2005, Singapore

Table 1: Outline of monitoring concrete road brige
Span
15m
Type
3 span-continuous RC T- girder bridge
Erection
1970
Traffic volume
24,000(from 8a.m.to 8 p.m.)
3.2 Applied sensor for monitoring and example of measured data
Types of sensor mounted on the bridge are listed on Table 2, and theset situation of the sensors is shown in Figures 11 and 12. These sensors arearranged on two main girders, called G7 and G5. The main girder G7 isplaced in position under a up lane, and G5 is under the opposite one.
Optical fiber sensor with length of 1.5m was used for measurement of
the extreme tensile fiber strain against vehicle loads. And velocity meter
was utilized for estimating the deflection and vibration.
As the road bridge considered in this research is 3-span continuous
bridge, the bending moment against vehicle loads has maximum value at the
point of 6m from the end of girder. Sensors were firmly mounted on themain girders at this point.
Example of data measured by each sensor in October 21, 2004 is
illustrated in Figure 13. The passage of a vehicle can be clearly detected at
the peak point of the time history.
Table 2:Sensors applied for monitoring
Type of Sensor
Name
Sampling rate
Optical fiber
G7-FB, G5-FB
100 Hz
Velocity meter
G7-V, G5-V
200 HzFigure 11: Optical fiber sensor

Figure 12: Velocity meter

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a tuck passage of 196 kN
G7-FB
G5-FB

Strain(×10 -6)

250
200
150
100
50
0

0

5

10

15

20 25 30 35 40
Elapsed time(sec)

45

50

55

60

(a)Time history of strain of extreme tensile fiber

Velocity(kine)a truck passage of 196 kN

G7-V
G5-V

1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
0

10

20

30

40

50

60

(b)Time history of velocity
Figure 13:Example of measured data
3.3 Soundness Evaluation
3.3.1 Soundness for structural performance
In this section, the evaluation method based on measurements will be
discussed. In this paper, the term of soundness means the satisfaction degreeof structural performance specified in “Japan Standard Specifications forConcrete Structure” (JSCE, 2002), e.g. safety or serviceability. The
soundness for each performance is quantitatively evaluated with index listedon Table 3.
By comparing bending moment induced by vehicle loads with
flexural strength of main girders, the soundness in items of safety
performance is evaluated. By the use of measured deflection and natural
frequency against vehicle loads, the soundness for serviceability is assed on
the basis of allowable limit of vibration.
Table 3:Evaluated soundness for each structural performance
Structural Performance
ObjectIndices
SafetyMain girder
Bending moment andFlexural strength
Strain of steel bar
Serviceability
Superstructure
Deflection andNatural frequency

Structural Performance Monitoring of Reinforced Concrete Bridges

57

October 2005, Singapore

3.3.2 Evaluation of soundness for safety performance(1)Evaluation based on acting bending moment
The evaluation method of the soundness regarding the safety
performance is described on the basis of measured data. The flexuralstrength, e.g. cracking or yield moment, are calculated for the monitored
cross section of main girders. The acting flexural moment can be estimatedby the way as follows. Owing to the characteristic of RC members, thedistance from extreme compression fiber to neutral axis is constant on
condition that the flexural moment is less than the yield one. Assuming thatthe neutral axis may be equivalent to the height of crack propagation
detected in-situ, then, the acting flexural moment can be calculated by theequation satisfying the condition of equilibrium of bending moment asfollows:
M=C･y1+T･y2(2)

where M: Acting flexural moment on a cross section
T: Resultant tensile force of the steel
C: Resultant compressive force of concrete
y1, y2: Distance from the neutral axis to C and T.
In Eq.(2), C and T can be evaluated on the basis of the strain
distribution on the assumption that strain is proportional to the distance fromneutral axis and that the strain at extreme tensile fiber is equal to the strain
measured by the optical fiber sensor (Figure 14). The flexural moment was
860 kN･m for the passage of truck of 198 kN. The moment is greater thancracking moment, 331 kN, whereas less than yield moment, 3,700 kN. From
the results, the monitored girders seem to be still sound condition based on
the result of RC beams loading test.

210180

Neutral axis
D-13

Height of crack propagation

80

55

135

960

5-D32

中立軸高さ

1,350

300 210 100
80
300
90

500
4@100

5-D32

5-D32

Strain obtained by optical fiber
下縁ひずみ
sensors.

Figure 14: Cross section of main girder and distribution of strain(2)Evaluation based on strain of reinforcement bar
The method described above is considered as the evaluation on thecase in the acting load increment. By an analogy of loading test results of
RC beams, it is possible that the degradation of the safety performance may

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occur due to the increment in strain of the reinforcement bar by some causes,
e.g. the vehicle load, concrete creep and so on.
In accordance with the standard specification (JSCE, 2002), the creep
strain is 950×10-6; the strain is 2.5 times as big as the strain caused by thedead load of main girder own.
The histograms of measured strain took account of the creep strain are
illustrated in Figure 15. From these observation data, the probability ofexceeding the yielding strain can be thought of almost zero on assumptionof logarithms distribution. Consequently the measured main girder is safety
form the point of view of the strain of reinforcement bar.
940～690×10-6

6,000

940～690×10-6

5552

6,000

3,000

2907
1105×10-6

2,000
0

400
107
2612

4,000
3,000
1,000

1

2,275

2,000
0

1205×10-6

297
107
327

1

900
920
940
960
980
1,000
1,020
1,040
1,060
1,080
1,100
1,120
1,140
1,160
1,180
1,200
1,220
1,240
1,260
1,280
1,300

1,000

Frequency

4,000

5,000

900
920
940
960
980
1,000
1,020
1,040
1,060
1,080
1,100
1,120
1,140
1,160
1,180
1,200
1,220
1,240
1,260
1,280
1,300

Frequeccy

5,000

5,875

-6

Strain of reinforcemnt bar(×10 )Strain of Rainforcement bar(×10 )(a)data of October 21, 2004

-6(b)data of July 23, 2004

Figure 15:Frequency distribution of reinforcement steel bar
3.3.3 Evaluation of Soundness for serviceability performance
The bending cracks which occur in main girder may cause the declineof flexural stiffness. As a result, the soundness regarding serviceability
performance may deteriorate. Since there are no specifications for theconcrete bridge serviceability in Japan, the soundness was checked on thebasis of allowable limit of vibration mentioned in standards of highway
bridges of Canada in this study. The allowable limit of vibration isexpressed as the relation between static deflection and natural frequency as
shown in Figure 14. The static deflection of main girder is obtained by
dividing the measured dynamic deflection by the impact coefficient for theconsidering bridge, 0.2. The dynamic deflection is obtained by the
integration of velocity time history (Figure 13b); the natural frequency inflexure is attained by performing the FFT of measured velocity time history
in free vibration after the vehicle passage.
The evaluation results, which are calculated by the use of themeasured maximum deflection data on October 21, 2004 and January 23,
2005, are illustrated in Figure 16. Since the considering road bridge
corresponds to one with frequently walker, the results shows that theconsidered road bridge is acceptable in serviceability.

Structural Performance Monitoring of Reinforced Concrete Bridges

59

October 2005, Singapore

Static deflection (mm)Not acceptable zone

no walker
rare walker
frequently walker

acceptable zone

July 23, 2005
October 21, 2004

Natural frequency for bending (Hz)Figure 15:Frequency distribution of reinforcement steel bar against vehicle
4. CONCLUSIONSIn this paper, the measurement method for soundness evaluation is
discussed through the load test of RC beams. And the pilot monitoring
based on behavior measuring of RC road bridge in situ by the use of some
sensors, such as optical fiber sensor and velocity meter, was performed.
The following conclusions can be drawn:
a. Based on the result of loading tests of RC beam, the flexural stiffness
degrades after reinforcement yield.
b. The effect of concrete creep on the deflection might be taken into
considering in the evaluation of safety performance from point of viewof reinforcement bar safety.
c. Obtaining the strain distribution in considered cross section utilizing
optical fiber, the soundness for safety performance could be evaluated.
The safety performance was assessed by comparison the flexuralstrength and acting flexural moment.
d. As the result of behavior measurement utilizing the sensors, such as
optical fiber to measure the extreme tensile concrete fiber and thevelocity meter to measure the deflection and frequency, the soundness ofstructural performance, i.e. safety and serviceability performances, could
be evaluated based on measurement data.
REFERENCES
Ministry of Land, Infrastructure and Transport of Japan (MLIT), 2002.
Annual statistics report of road, Japan Highway Users Conference.
Japan Society of Civil Engineers (JSCE), 2002. Standard specification for
concrete structures “Structural performance verification”, 14-16.
Balaguru, P.N. and Shah, S.P., 1982. A method of predicting crack widths
and deflection for fatigue loading. ACI Special Publication 75-5,
Detroit, 153-175.
Okamura, H. and Maekawa, K., 1991. Nonlinear analysis and constitutive
models of reinforced concrete. Gihoudou publishing company, 44-45.

60

New Technologies for Urban Safety of Mega Cities in Asia

DEVELOPMENT OF MONITORING SYSTEMFOR RC BRIDGE BASED ON
RESTORATION DESIGN METHODSHINICHIRO OKAZAKI1TAKETO UOMOTO2
1
Department of Civil Engineering, University of Tokyo
2
International Center for Urban Safety Engineering,
Institute of Industrial Science, University of Tokyo
okazaki@iis.u-tokyo.ac.jp

ABSTRACT
There are about 670,000 road Bridges in Japan. As for these bridges,
standard design code has been greatly revised in order to reflect theincrease of live load and earthquake especially after Hanshin-Awaji
earthquake. For example, for structures, designed followings the code used
before Hanshin-Awaji earthquake may be in appropriate for seismic load.
In addition, most of the bridges are inspected only by visual inspection,
causing difficulty to inspect all bridges in details. Therefore it is required tobuild an effective and efficient maintenance system for increasing number ofbridges. To maintain those old bridges, we cannot estimate the deterioration
without design drawings and calculated details. However, old bridges
usually don’t have this information. In this case, used to restore those
information can be restoration design method.
This research shows that, it can extract the bridge which has no design
drawing and calculated details and estimated their structural performance
every revision of design code by applying restoration design method. This
result shows that the supper structure of this bridge is safe enough to becontinually used, but pier does not have enough capacity for seismic wave.
So it is develop a new monitoring system for pier to evaluate condition ofbridges at any time by accelerometer attached t piers for measuring seismic
damage, and estimating condition of the bridge.
1. INTRODUCTION
In Japan, we have a lot of highway road bridges almost 670,000.Theseof bridges stocks which are serviced more than 50 years are increasing
greatly. So it can be said that it is necessary to construct an effective,
efficient maintenance management, in order to do the priority level of theselection of the bridge for the maintenance management program more
simply and objectively.
In addition, although various inspections are required when themaintenance management is actually conducted, it is necessary to know theinitial condition of the structure to predict the deterioration extent. The
deterioration cannot be estimated without design drawings and calculated
details. However, old bridges usually do not have this information. In this61

October 2005, Singapore

Figure 1: Focus Bridge

case, it is generally restore that information by using restoration design
method.
This research shows that we can extract the bridges which have no
initial design drawing and calculated details and estimate the structural
performance in addition with every revision of design code by applying
restoration design method. This research is also developed a new monitoring
system for RC bridges to evaluate, current condition of bridges at any timeby using accelerometer attached to piers for measuring seismic damage.
45 , 8 0 0
45,000

7,300

6,500

400

1,250

1,250

2,500

40 0

1200

1,250

1,250
2,500

5,000

5,000

3,250

18 , 3 0 0
14,250

3,250

400

400

400

7,400

6,600

40 0

1,000

1,300
1,270

18,30014,250

5@3170

1,270

1,000

1,000

1 ,0 0 0

3＠ 4 3 4 0

1,300

15 , 6 2 0

Figure2: Cross-Section of the Focus Bridge

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Table 1: Major Modification of the Design Codes
Before 1973

The design
Supperstructure weight of car
as live load
work
is 20tf

Substructure
work-

Seismic
force isculculated by
Seismic design
0.2×W(W:weight ofbridge)1973～78-

Changing
the bearing
capacity
formula ofpile

1978～80
・Applyingultimate
strength design
method・Minimumstrength of
concrete ischanged 21N/mm2

1980～90

-

-

-

-

1990～94

1994～96

1996～2002

2002～

-

Reducedallowabletensile stressof concrete-

Applying ultimate
lateral strength
design method forall members--

・Applying ultimate
lateral strength
design method for Two levels ofseismic wave
all members
is defined・Two types ofdesign seismic wave
is defined

Changing
The design
calculatio
weight of
n of
car as live
minimamload isthickness
25tf
of slab-

Applying
ultimate
Applyinglateralmodifiedstrengthseismic
designcoefficien
t method method forpier

2. RESTORATION DESIGN METHOD
Restoration design method is used to restore the arrangement of
restoring reinforcing bars and stress condition based on the cross-section
information of a bridge (length, width of bridge and girder, pier, etc.) andthe then design code.
The example bridge showing figure 2) has been from 1970, and length ofbridge is 45m, width is 18.3m, type of superstructure and pier is rigid-frame
structure. The road bridge specification and JSCE guidelines for concrete
are based on. And there is no information about property of concrete. It is
assumed that designed compressive stress of concrete is 18N/mm2, andallowable compressive stress due to bending is 8N/mm2. The type of steal
bar is SD295, and allowable tensile stress is 140N/mm2.
REVISION OF DESIGN CODE
In addition to the restoration of the design drawing and calculated
details, the same information at restoring them every transition of designcode, are also restored for evaluating the safety is also conducted. Table 1
shows main changes of design codes. In 1990, new seismic design method,and ultimate lateral strength design method were introduced. Then in1996,
design live load was changed to 25tf from 20tf, the value that has been usedsince 1973.
ABOUT EVALUATING SAFETY
When evaluating the safety, the latest code of JSCE, “JSCE guidelines
for concrete, standard specifications for concrete Structures-2002 structural
performance verification”, was applied. For super structure work, the safety,
serviceability, and fatigue were evaluated. For substructure work, we safety
to seismic load was evaluated.

Development of monitoring system for RC bridge based on restoration design method63

October 2005, Singapore

RESULT OF RESTORATION DESIGN METHOD
Figure 3, 4, 5 shows the results of restoration design method for theexample bridge. In this case, we focus only the pier of substructure work
because pier received the largest damage from seismic wave. Comparison
between restored designs information and the design drawings which isavailable only upper structure work, show almost the same result. So thisfact shows that this method has high reliability and accuracy.
Figure 3 shows that ratio of tension reinforcement of girder and slabchange only 0.1% in 1994. But figure shows that ratio of tension
reinforcement and hoop tie is largely changes in 1990 and 1996.For theseamounts of reinforcement, are inadequate when compared to that of thelatest design code. Figure 4, 5 shows that ratio of tension reinforcement andtie hoop is greatly changed at 1990 and 1996, the year of changing thedesign code.
At first, girder of super structure was estimated. And place which isreceived the largest bending moment from living load of this bridge is in thecircle on Figure 2, In this case, the amount of reinforcement changes only in
1994. Figure 6 shows that the original slab’s cracking moment is less thandesign moment of the latest design code, but yield moment is more thandesign moment. In figure 7 girder’s clacking moment is more than design
moment. So, this result shows that super structure work has enough capacity
to ensure its safety all during period at all era.
And next, table 2 shows the result of comparison between the safety
ratio for fatigue of the girder by the newest code, and old one. The safety
rate f is calculated from the following equation (1).

σ rd
1
= γi
f
f rd / γ b(1)（f: safety ratio for fatigue γi: structural analysis factor, γb: member
factor, σrd: variable load, frd: design fatigue strength of material）
Each era of bridge also have enough safety for fatigue.
And next we estimate serviceability by displacement due to bending
which is calculated by following equation (2).
1u=
∬ Mdxdx(2)
EI(u: displacement of girder, E: Young’s modulus I: effective moment oftransformed cross section，M: designed bending moment)
The limit displacement is not specified description on the code, so it isapplied highway bridge that of Railway Bridge instead. The strictest value
in this criterion is L/1800 (L: span of the bridge (m)), the code for the
Shinkansen, super express in Japan. In this case, the limit is 8.3mm and Fig
shows the calculated displacement of this bridge in case of designed load.
Each era of bridge also have enough serviceability.
Next, pier is estimated. In this case, Figure 6 shows the result forverifying only the axial direction of bridge. By using the ultimate lateralstrength method, verifying the proof stress of bridge at each era for seismic
wave. And safety ratio of ultimate lateral strength for seismic wave isdefined by followed equation (3), and makes safety fixed quantity.

64

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

0.8
0.8
0.6
0.6

主桁
Girder

1.09倍

床版
Slab

1.03倍

1.5
Tension reinforcement ratio(%)

Tension reinforcement ratio(%)

1
1

2.54倍

0.4
0.4

Cross
girder
横桁
0.2
0.2
0
0

44
昭45
44
1970

54
昭53
54
1978

64
64

1

Pile foundation（pier）

0.5
Pier

0

平6 74 平141994 74 2002

1970
44

Figure3: Modification of Tension
Reinforcement(Super structure)

1980
54

1990
64

199674 2002

Figure4: Modification of Tension
Reinforcement(Sub structure work)

Tension reinforcement ratio(%)

0.3

0.2
Pier

0.1
Pile foundation（pier）

0
1970
44

1980
54

1990
64

199674 2002

Figure5: Modification of hoop tie (substructure work)
6000
5000

80

60

40
De s i g n e d m o m e n t by l at e s t c o de

20
1970
2002

Bending M om ent M （K N･m ）Bending M om ent M （K N･m ）

100

4000
3000
2000

De s i g n e d m o m e n t by l at e s t c o de

1000

0

1970
2002

0
0

0.00040.0008C ur v a t ur e φ

00.0012

Figure6: M-φgraph of slab

0.00010.0002
C ur v a t ur e φ

0.0003Figure7: M-φgraph of girder

Table2: Result of estimating the focus bridge at each era

GirderSlab

Year

Yield moment ofsteel(kN･m)

1970
2002
1970
2002

3.96×103
4.74×10
50.0
79.4

3

Ultimate
moment(kN･m)
3

4.09×103
4.92×1051.0
82.3

Safety ratio for
Safety ratio forfatigue of steel fatigue of concrete
f
f

4.44
4.19
1.65
2.86

Development of monitoring system for RC bridge based on restoration design method

2.42
2.60
1.42
1.81

65

October 2005, Singapore

Designed seism ic for ce a nd ult im a t e la t er a l
st r em gt h (kN)

12000
10000

Designed seismic force
Ultimate lateral strength

8000
6000
4000
2000
F= 0 .3 5 4

F= 0 .8 7 7 F= 1 .4 1 2

0
144
970

154
980

164
990

1 9 9 674 2 0 0 2

Figure8: Modification of designed seismic force andultimate lateral strength (substructure work)

F=

Pu

(3)

Pq

(Pu: ultimate lateral strength of pier，Pq: designed seismic load)
Figure 8 show that designed seismic load is decrease as proceeding era due
to allowable plastic ratio is increasing and, and ultimate lateral strength isincreasing because of the increasing amount of the tension reinforcement.
So the safety ratio is less than 1.0 at the era of before 1996, it is suggested
that they are required to reinforce.
3

MONITORING SYSTEM FOR RC BRIDGE

For maintaining concrete structures properly, it is required to estimate
their condition precisely. And based on the result, it is required to plan how
to repair that structure. In future, the number of aged bridge becomes
rapidly increase. So it will be very difficult to conduct visual inspection on
to all bridge. So it is recommended to estimate health of bridge by using
network system. The outline of this system is that, the instruments which are
set up on girder and pier and so on measure at and send these data to any
place on the network at all time. And estimating the health by processing
health of structure is estimated by processing these data.
Nowadays, RC bridges are measuring flexure and vibration of girders
by any kind of instruments experimentally, but couldn’t estimate structure
condition because systems are not developed the systems theoretically. So
we develop new system for estimating theoretically.

Data

RC bridge

Workstation

Figure8: Example of Monitoring System

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

3.1 DEVELOPMENT OF MONITORING SYSTEM

This system is that, measuring any data at the target bridge and saved
instant data are sent by fiber optic and received and save them atworkstation in IIS (Institute of Industrial Science, University of Tokyo). The
results of section 2, the upper structure of this bridge is safe enough to becontinually used, but pier does not have enough capacity for seismic wave.
So pier is required to be monitored the damage by seismic wave at any time.
For estimating the load of seismic wave and displacement of pier, twoaccelerometers which can measure triaxial direction are put on the top of thepier and inside the ground. In case of earthquake, the accelerometer in the
ground observes seismic wave and each accelerometer start measuring theacceleration of the wave. In the next section, the method shows how toestimate the damage to pier by these data.
3.2 ESTIMATING DAMAGE TO PIER

Figure 9 shows the wave which observes in the ground at Oct 23,
2004 (Niigata Earthquake). The maximum differential displacement whichis integrating this wave twice on time direction of each data is 0.078mm. By
using this displacement, calculate the maximum bending moment iscalculated, at the root of the pier. Figure 10 shows the model for calculating
the bending moment at any place of pier on the axial direction of bridge.
This model shows that displacement δis given by load P on the top of thepier. In this case, relative displacement of the top of the pier and the groundis defined δ, the inertial force of upper structure is P, and the bending
moment at root of the pier is M. Then we can calculate P and M bymeasured δ in case we supposed that the pier has elastic behavior(following equation (4),(5)). In addition the stiffness of member is 4 timesof the stiffness of one element of pier because 4 bodies of the rigid-framedpier receive the seismic wave on axial direction of the bridge.
P = 3EI'δ 3
L
M = PL= 3EI ' δ

(4)

L2

(5)

(P: inertial force of upper structure, M: bending moment at root of pier, EI’:
stiffness of pier on axial direction of the bride, δ:relative displacement of
the pier and the ground L: height of the pier over the ground)Figure 11 shows calculated bending moment on the M-φ graph of theelement of the pier. On present stage, only comparing measured moment tocapacity of the pier, it has enough safety to this seismic wave. Applying thisequation to the collected data into workstation, this system can evaluate thedamage to the pier immediately.

Development of monitoring system for RC bridge based on restoration design method67

October 2005, Singapore

15

Acce ler a t ion (cm /sec 2)

10
5
0
-5
-1 0
-1 5
0

10

20

30
Tim e (sec)

40

50

60

Fig9: Acceleration Data of Niigata Earthquake
δ
P

4EI

L

M

Fig10: Model for Calculating the Bending Moment

Bending m om ent (kN･m )3000

U ltim ate m o m e n t 2 7 0 0 k N ･ m

2500
Y ie ld m o m e n t 2 2 0 4 k N ･ m

2000
1500
1000

C rac k in g m o m e n t 7 1 3 k N ・ m

500

Bending m om ent due t o
ea r t h qua ke

0
0

0.005
0.01
C ur v a t ur e φ

0.015

Fig11: Calculated bending moment on the M-φ graph of the element of the pier4

CONCLUSION

The result of this research is as follows.
(1) It is possible to restore reinforcing bar arrangement by using restoration
design method(2) Result of restore design method by each era of changing design codeshows that super structure have enough safety but pier which is before
1996 don’t have enough resistance against earthquake.
(3) By developing monitoring system, it is possible to evaluate the damageon pier by calculating the bending moment.

68

New Technologies for Urban Safety of Mega Cities in Asia

STUDY ON DURABILITY OF RC DECK
OF EXISTING PIER
Ema Kato, Atsushi Yokozawa, Yoshikazu Akira, Hiroshi Yokota
Port and Airport Research Institute, JAPANkatoh-e@pari.go.jp

ABSTRACT
To keep harbor structures in good condition during their service period,
it is necessary to implement a well organized maintenance strategy and to
conduct suitable maintenance work according to the degree of deterioration.
For this purpose, it becomes very important to quantitatively evaluate thepresent and future structural performance of deteriorated structures.
This paper discusses the structural performance and material
deterioration of reinforced concrete deck of the existing pier which has been
in service for 39 years. Reinforced concrete slabs were extracted from thedeck and were load tested in the laboratory. The degree of material
deterioration was analyzed with the extracted slabs by measuring themechanical properties of concrete and the degree of rebar corrosion.

1. INTRODUCTION
Reinforced concrete structures in harbors are attacked by chloride ion,
which may cause deterioration of materials. As a result, corrosion of rebar
embedded into concrete may induce cracks in concrete and subsequently
cause spalling of cover concrete. The material deterioration, particularly
corrosion of rebar decreases structural performance (Yokota et al., 1998),
but the relationship between the rebar corrosion and structural performance
has not been made clear.
In this study, the material deterioration and the remaining structural
performance of the existing structure were experimentally investigated. Test
slabs were extracted from the deck of the existing pier that has been inservice for about 39 years.

2. OUTLINES OF INVESTIGATION
2.1

Test Slabs

Figure 1 shows a general cross section of the pier that has been inservice for 39 years. Three test slabs were extracted from the reinforced
concrete deck of the pier, shaded regions in Figure 1. The structural detailsof the slabs are given in Table 1. The distances from the bottom surface ofthe slabs to H.W.L. and L.W.L. were about 0.1 m and 2.2 m respectively;
therefore, all the extracted slabs were located in the splash zone. The

69

October 2005, Singapore

deterioration grades of slabs were judged visually according to the Manualon Maintenance and Rehabilitation of Port and Harbour Structures assummarized in Table 2 (Port and Harbour Research Institute ed., 1999).
Partial delamination of cover concrete was observed in slab No. 1. In slab
No. 2, many cracks and delamination were observed. In slab No. 3, all thecover concrete disappeared and heavy rebar corrosion was observed.
Moreover, the white products were observed around the aggregate in No.3.
Since the mechanical properties of the rebar were not stated in thedesign documents, tensile tests of non-corroded rebars sampled from No. 1
were conducted to examine their fundamental mechanical properties, which
is summarized in Tables 3.

15.00 m1.50 3.50

3.50

3.50

3.00

H.W.L +2.16 m
L.W.L +0.07m

Slab Nos.2 and 3

Slab No.1

Figure 1: Outline of the pier.
Table 1: Outlines of slabs.
Slab No.
No. 1
Width (mm)1513
Length (mm)1518
Thickness of slab (mm)269
Thickness of pavement (mm)－Diameter (mm)13
Number of upper rebar
4
Transverse
Position below the top (mm)98
rebar
Number of lower rebar
8
Position below the top (mm)215
Diameter13
Number of upper rebar
4
Position below the top (mm)111
Longitudinal
Number of lower rebar
8
rebar
Position below the top (mm)200
Deterioration gradeII
All rebars are a deformed bar.

70

No. 2
1465
1523
373
86
13
4
199
7
309
13
4
205
8
292
III

No. 3
1498
1510
309
71
13
4
189
7
306
13
4
204
8
300
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Table 2: Definition of the deterioration grade.
Grade
0
I
II
III
IV
Localized Small
Rebar
Much
Heavy
No spotted
extent ofcorrosion
rust stain rust stain
rust stain rust stain
Only a
Many
Some
Many
Crack
No few small
widecrackscrackscrackscracksPartialCover
PartialNo
No
delaminat
Spalling
concretespalling
ion

V
Large
extent ofrust stain－
Large
extent ofspalling

Table 3: Mechanical properties of rebar.
Yield strength
386 N/mm2
Tensile strength
544 N/mm2
Young’s modulus
192 kN/mm2

2.2

Investigations

2.2.1 Measurements of compressive strength and Cl- contents
The concrete cores of 100 mm in diameter were taken from each slab
after the loading test. The compressive test was conducted with these corescut by 200 mm long. To measure the chloride ion contents in concrete,concrete samples in slabs Nos. 1 and 2 were milled into powder sample after
cutting into small pieces. Then, chloride ion contents were measured withthe dissolved powder samples as per the JCI Standard (Japan Concrete
Institute, 1987). Then, diffusion coefficients of chloride ion in concrete were
calculated according to Fick’s second law of diffusion.
2.2.2 Evaluation of Rebar corrosion
After the loading test, the upper and lower longitudinal rebars in theloading span, which carried tensile force in the loading test, were taken out
from the concrete and visually inspected. In slabs Nos. 1 and 2, corrosion of
the upper longitudinal rebar was not observed, therefore, the weight lossesof these rebars were set at 0.0 %. The weight losses of the other longitudinal
rebars were measured by the following procedures: At first, the rebar was
cut into 2 pieces of 100mm long each. Rebars were sand blasted to remove
corrosion products and concrete sticking to the surface of rebars. Then,
rebars were immersed in 10% diammonium hydrogen citrate solution tocompletely remove corrosion products.
2.2.3 Loading test
Figure 2 shows the test setup. Slabs were simply supported with aloading span of 1000 mm. A monotonically increased load was applied
symmetrically at three points. During the test, the applied load anddeflection at the supporting points and at the midspan were measured andStudy on Durability of RC Deck of an Existing Pier71

October 2005, Singapore

recorded. Because the cover concrete had already spalled in slab No.3, thesupporting area of the slab was reinforced by mortar.

Load

Main rebar

Transverse section≒250

Subsidiary rebar

Longitudinal section

≒1500

≒250

1000 mmFigure 2: Test setup

3. RESULTS AND DISCUSSIONS
3.1

Material deterioration

3.1.1 Compressive strength and Young’s modulus
Figure 3 shows the relationship between the compressive strength andYoung’s modulus of concrete of each slab. The line in this figure shows therelation for general concrete specified in the Standard Specifications forConcrete Structures (Japan Society of Civil Engineers, 2002a). If concrete
is not deteriorated, experimental results are the same or slightly larger thanthe values indicated by the line. However, all the experimental results were
smaller than those. Especially, decrease in Young’s modulus and its
scattering were remarkable in slab No. 3. This decrease was probably
caused by the alkali silica reaction of aggregate (Kobayashi et al, 1993).

Young's modulus (kN/mm2)

35
30
25
20
15
10

No. 1
No. 2
No. 3
Japan Society of Civil Engineers, 2002

5
0
20

25
30
35
Compressive strength (N/mm2)

40

Figure 3: Compressive strength vs. Young’s modulus

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3.1.2 Chloride ion profiles
Figures 4 and 5 show the apparent diffusion coefficient and the surface
chloride ion content of all concrete samples and results of visual inspections
respectively. Though the concrete samples were extracted from nondeteriorated regions of the slab, diffusion coefficients and surface chloride
ion contents varied with the extracted points.
Figure 6 shows the distribution of chloride ion contents based on the
profile of normal distribution. They were measured with the concrete
samples at 40 to 60 mm deep, which was in the cover concrete for thetransverse rebars. The chloride ion contents in slab No. 1 were widelydistributed compared with No. 2, while these averaged contents were not so
different. As one of these causes, the difference in the sampling point of

Stain

Crack
3.8

5.9

Spalling

Delamination

3.8
4.4

2.8

2.2

3.7

4.6

6.6

3.0

2.7

4.8

3.0

3.3

3.2

3.0

6.7

2.3

3.1

3.7

4.6

3.8
3.2

4.6

3.5

3.9

4.8

1.5

4.6

1.6

3.6

2.9

2.9

2.7

3.4

No. 1

No. 2

Figure 4: Distribution of apparent diffusion coefficient (cm2/year)

Stain

Crack
13.6

Spalling

Delamination

11.8
9.9

13.5

12.7

9.2

10.7

10.8

10.5
10.5

11.4

12.7

15.3

12.3

14.5

8.6

7.1

10.6

7.8

8.0

15.4

6.3

12.8

11.5

15.3

8.0

15.5

11.0

15.1

11.5

12.8

13.5
10.6

11.5

No. 1

No. 2

Figure 5: Distribution of surface chloride ion content (kg/m3)

Study on Durability of RC Deck of an Existing Pier73

October 2005, Singapore

0.7

1.2 kg/m 3

No. 1

0.5
Probability

No. 2

at 40 - 60 mm
at 80 - 100 mm

0.6

Average: 6.2 kg/m 3
Standard deviation:

0.4

0.8 kg/m 3

0.3

Average: 6.9 kg/m 3
Standard deviation:

0.2

1.7 kg/m 3

0.1
0
0

2

4

6

8

10

12

14

16

3

Chloride ion content (kg/m )Figure 6: Distribution of Cl- content

concrete was considered. Especially in slab 2, the sampling was done after
obviously deteriorated parts were removed.
The measured chloride ion contents in the concrete at 80 to 100 mm
deep were also plotted in the same figure. They showed less variationcompared to those at 40-60 mm deep.
According to the Japan Society of Civil Engineers (2002b), the design
chloride threshold value to start the rebar corrosion is set at 1.2 kg/m3.
Because the chloride ion contents at the position of rebar in slabs Nos. 1 and2 were larger than the threshold value, corrosion of the lower and the upperrebars in each slabs were considered to have already started.
According to the same standard specifications, the design chloride ioncontent at the position of rebar can be set at 1.3 times the calculated resultswith considering the dispersion. In this paper, the coefficients of variation of
measured data were smaller than 0.25. Therefore, for the prediction ofchloride ion content at the position of rebar, the value of 1.3 times theaverage data was considered to have enough accuracy.
In the investigation of existing structures in marine environment,
chloride ion profile of concrete has generally been estimated according to
one sampled concrete. Consideration of dispersions of material properties
and environmental conditions is necessary to evaluate and to predict thepresent and future performance of the RC member.
3.1.2 Corrosion profiles
Figure 7 shows the frequency of weight loss of rebar in slab Nos. 2 and3 based on the normal distribution. Rebar corrosion did not ocuur in slab No.
1, where the chloride ion content at the lower rebar was larger than thethreshold value. In slab No.2, rebar corrosion occurred only in the
delaminated and cracked areas. Because of the localized corrosion, these
distributions were not considered to be suitable for the normal distribution.

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Slab No. 3 had a wide distribution in weight loss of rebar ranging from
10 % to 60 %.

16

0.8

A verage: 7.1 %Standard deviation:13.6 %

0.6

14
12
10
8

A verage: 41.3 %Standard deviation:15.0 %

0.4

No. 2
No. 3
Meas. No. 2
Meas. No.3

0.2
0
0

20

40
60
80
W eight loss of rebar (%)

6

Frequency

Accumulative probability

1

4
2
0
100

Figure 7: Probability and frequency of weight loss of rebar

3.2

Structural performance

The relationship between applied load and midpan deflection is shownin Figure 8. Because of the different positions of rebar, structural
performance of each slab cannot be directly compared. However, theapparent stiffness decreased with an increase in the deterioration grade. It isconsidered that this is due to the corrosion cracks and deterioration of bondproperty between rebar and concrete (Japan Concrete Institute, 1998).
Figure 9 shows the relationship between ultimate load ratios and weightloss of rebar due to corrosion. The ultimate load ratio is defined as the ratio

1000
No.2

荷重（kN）
AppliedLoad (kN)

800
600

Breakageof rebar

No.1

400
200

No.3

0
0

10

20

30
40
Midspan変位（mm）
deflection (mm)5060Figure 8: Applied load and midspan deflection

Study on Durability of RC Deck of an Existing Pier75

October 2005, Singaporeof the ultimate load to that of slab No.1. Those were modified with thedimension of each slab. In the same figure, the calculated ultimate load ratio
taking into account the cross-sectional loss of rebars is also plotted as a
broken line. The experimental ultimate load ratio of slab Nos. 2 and 3 were
smaller than the calculated result. Horizontally straight lines in the same
figure represent the maximum and minimum weight losses of rebar. The
ultimate load ratios of the both slabs were not evaluated by the averaged
weight loss of rebar. In slab No. 2, the ultimate load could be almost
calculated with considering the maximum weight loss, however, that in slab
No. 3 was not evaluated. Therefore, the difference between the calculated
and measured ultimate loads was considered to become increase with anincrease in the weight loss of rebar. Taking into account the localized
corrosion, decreases in bond property and in elongation of rebar (Kobayashi,2005) were simultaneously needed to evaluate the structural performance ofheavily deteriorated RC members with good accuracy.

No. 1

Uotimate load ratio

1
0.8
No. 2

0.6
0.4

No. 3
0.2
0
0

10

20
30
40
50
W eight loss of rebar (%)

60

70

Figure 9: Weight loss vs. ultimate load ratio

4. CONCLUSIONSIn this study, the structural performance and material deterioration of areinforced concrete deck of the existing pier that has been in service for 39
years were discussed. Influence of ASR on Young’s modulus of concrete
was considerably larger than that on compressive strength of concrete. The
chloride ion profiles in the slabs were widely distributed; therefore,
consideration of dispersions of material properties and environmental
conditions was necessary to evaluate and predict the present and future
durability of RC members. Moreover, the localized corrosion, the bondproperty and the mechanical properties of rebar were necessary to evaluate
the structural performance of heavily deteriorated RC members with good
accuracy.

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REFERENCES
Japan Concrete Institute, 1987. Corrosion of Concrete Structures, Standards
and Test Methods for Corrosion Protection. (in Japanese).
Japan Concrete Institute, 1998, Committee Report on Rehabilitation ofConcrete Structures. (in Japanese)
Japan Society of Civil Engineers, 2002a. Standard Specifications forConcrete, Structures-2002, Structural Performance Verification, JSCE
Guidelines for Concrete, No.3, pp.32-33.
Japan Society of Civil Engineers, 2002b. Standard Specifications forConcrete Structures-2002, Materials and Construction, pp.24-25. (InJapanese)
Kobayashi, K., 2005. Experimental Study on Seismic Behaviour of RC
Member Deteriorated by Chloride Induced Corrosion, Concrete
Research and Technology, Vol. 16, No. 2, pp.49-59
Kobayashi, K. et al., 1993, Method of Diagnosing Alkali-Silica Reaction byCompressive Loading Test, Journal of Materials, Concrete Structures
and Pavements, Japan Society of Civil Engineers, No. 460 / V-18,
pp.151-154 . (In Japanese)
Port and Harbour Research Institute ed., 1999. Manual on Maintenance andRehabilitation of Port and Harbour Structures, Coastal Development
Institute of Technology, pp.91-103. (In Japanese)
Yokota, H., Fukute, T., Hamada, T., and Akiyama, T., 1988. Structural
Assessment of Deteriorated RC and PC beams Exposed to Marine
Environment for More Than 20 Years, Proceedings of the 2nd
International RILEM/CSIRO/ACRA Conference, Melbourne, pp.209219.

Study on Durability of RC Deck of an Existing Pier77

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New Technologies for Urban Safety of Mega Cities in Asia

SIMULATION STUDY ON RELATIONBETWEEN LOCAL RAINFALLCONDITIONS AND AMOUNT OF
MOISTURE SUPPLIED TO CONCRETE
YOSHITAKA KATO and NAOKI TAKESHITAInternational Center for Urban Safety Engineering,
Institute of Industrial Science, University of Tokyo, Japankatoyosh@iis.u-tokyo.ac.jp
Department of Civil Engineering, University of Tokyo

ABSTRACT
It is well known that deteriorations of concrete structures and these
speeds depend on environmental conditions. There are few researches dealt
with the evaluation of actual environmental impacts that can be used asboundary conditions for predicting the deteriorations progress of concrete
structures though several types of simulation tools to predict thedeteriorations progress of concrete structures have been developed. As afirst step to address this matter, we tried to clarify the relation between thelocal rainfall conditions and the amount of adhering raindrops on concretesurface based on the simulation study.
The amount of adhering raindrops is necessary to predict moisture
content of concrete structure appropriately. Therefore, a water absorption
velocity of concrete was obtained experimentally. As a result, it was foundthat the water absorption velocity was quite small compared with theamount of rainfall. Therefore, the presence of adhering raindrops isimportant to discuss the effect of rainfall on the moisture content of concrete.
Finally, the treatment method of rainfall as boundary condition forpredicting moisture content in concrete was proposed based on the analysis
and experiment results. And the example of processing method of a large
amount of weather data was also introduced as one example of utilization ofthis research result.

1. INTRODUCTION
It is well known that deteriorations of concrete structures are causedby several environmental impacts. For instance, carbon dioxides andchloride ions destroy passive state file formed on surface of reinforcing bar,
as a result the reinforcing bar easily corrode with existences of water andoxygen. These deteriorations of concrete structure cause failure of concrete
structure without conducting remedial measures. Proper remedial measures
should be conducted based on a diagnosis result of an existing concrete

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structure as well as a prediction result of a future performance of existing
concrete structure before a damage of concrete structure becomes severe. To
address this matter, several kinds of prediction models for deteriorations
progress of concrete structures have been proposed. These proposed models
can predict the deteriorations progress with certain accuracy under anapplicable range of each model, especially in case of laboratory tests.
However, it is usually difficult to apply these proposed models to predict thedeteriorations progress of existing concrete structures because change ofactual environmental conditions are larger than that of laboratory test.
Environmental conditions, such as temperature, humidity, amount of
supplied chloride ions and so on, are treated as boundary conditions inproposed models so that proposed model can predict the deteriorations
progress of concrete structures considering actual environmental conditions.
The reason why it is difficult to predict the deteriorations progress ofconcrete structures is that treatment methods of actual environmental
conditions as boundary conditions of proposed models have not beenclarified yet.
There are many environmental factors that should be considered to
predict the deteriorations progress of concrete structures. Moisture affects
on several kinds of deteriorations of concrete structure indirectly althoughmoisture is not a factor to cause a deterioration of concrete structures
directly. Moisture content of concrete is usually affected by rainfall andsteam. The boundary condition of steam may be able to be set by using
measurement results of humidity. On the other hand, the effect of rainfall on
concrete surface might be complicate due to effects of rainfall, wind andstructure form. Therefore, the adhering raindrop on concrete surface wassimulated considering these effects. And the treatment method of rainfall as
a boundary condition for predicting the moisture content of concrete wasproposed based on the analysis results.

2. OUTLINE OF PREDICTION MODEL FOR AMOUNT OFADHERING RAINDROPS ON CONCRETE SURFACE
Calculation of amount of adhering raindrops on concrete surface wasconducted based on the following procedure.
- Basic input-data obtained from EA AMeDAS (Automated Meteorological
Data Acquisition System) Weather Data (Akasaka 2003)- Calculation of mean diameter of raindrops using Marshal-Palmer
distribution (Marshal 1948)- Calculation of terminal velocity of raindrops using empirical equation(Fabien 2002) based on experimental data (Gunn 1949)- Simulation of rainfall using the finite volume method- Calculation of amount of adhering raindrops on concrete surface fromsimulation result
2.1 Calculation of Raindrop Properties

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Diameter, terminal velocity and density of raindrop in atmosphere arenecessary to calculate the amount of adhering raindrops on concrete surface
as input data-sets. Marshall and Palmer (1948) proposed probability density
function of diameter distribution of raindrops per unit volume as follows(equation 1 and see Figure 1).
N d = 8000 exp(−4.1DR −0.21 )
(1)
-3
-1
where, Nd (m mm ): probability density function of diameter
distribution of raindrops per unit volume, D (mm): diameter of raindrops, R(mm/h): amount of rainfall per one hour.
Total number of raindrops per unit volume (K) and its weight (W) canbe expressed as follows, respectively.
∞

K = ∫ N d dD = 1951R 0.21

(2)

0

∞

1 3
πD N d dD = 89 R 0.84
(3)
0 6
Average weight of raindrops can be calculated using equation (2) and
(3).
M
(4)
=
0.63
0.0456 R
Average diameter of raindrops(Dave (mm)) can be calculated asK
follows with density of water (1000kg/m3).
Dave = 0.65R 0.21
(5)Terminal velocity of raindrops (V (m/s)) was proposed by previous
research result (Fabien 2002).
V = 9.4(1 − exp(−1.57 × 10 3 ( Dave × 10 −3 )1.15 ))(6)
3
Finally, density of raindrops per unit volume (ρw (kg/m )) can beobtained using equation (7).
R
ρ w = 2.8 × 10− 4(7)VFigure 2 shows the relationships between raindrop properties thatwere obtained by the above mentioned procedure.
M =∫

10000
R=1
R=10
R=50

Nd (/m3mm)

1000

R=5
R=25

100

10

1
0

2

4

6

D (mm)

Figure 1: Marshall-Palmer probability density function

Simulation Study on Relation between Local Rainfall Conditions and Amount of Moisture Supplied toConcrete81

October 2005, Singapore

x 10-3
1.4
1.2

4

1
3

V

ρ w (kg/m )Dave (mm), V (m/s)

5

3

0.8
ρw

2

0.6
0.4

1

0.2

Dav e
0

0
0

5

10
15
R (mm/h)20

Figure 2: Relations between raindrop properties
2.2 Analysis Conditions
Simulation of rainfall was conducted using the finite volume method.
It was assumed that raindrops were transported by air transportation. It iseasy to simulate air transportation because air can be treaded as continuous
elements in this simulation. On the other hand, it is difficult and takes a longtime to simulate raindrops itself because raindrops should be treaded as
discontinuous elements.

Structure condition of analytical object is shown in Figure 3 as a casestudy of this research. Analysis area is shown as the hexahedron (4 x 5 x 3)
in same figure. One element of the analysis area is a cube of 0.25 in thelength. In this research, a wind direction was assumed to be a transverse
direction of the pier though a wind direction against structure is also very
important factor to evaluate the amount of adhering raindrops on concretesurface. The effect of wind direction will be considered in our future
research.
Analysis cases are shown in Table 1. These cases were determinedbased on the weather data measured at weather central in Tokyo. Namely,
the range of analysis cases were determined based on maximum amount of
rainfall (19 (mm/h)) and maximum wind velocity (8.2 (m/s)). And “1.74(mm/h) is the ratio of total amount of rainfall of one year to total rainfall
frequency of one year.

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3

rainfall

slab

0.5
1
4

wind

2.5

pier

Unit: (m)5

Figure 3: Analytical object

Windvelocity
(w)
(m/s)

1
2
3
4
5
7
10

Table 1: Analysis cases
Amount of rainfall (R) (mm/h)
1
1.74
3.54
7
12
○
○
○
－
－
○
○
○
－
－
－
○
○
－
－
－
○
○
○
○
○
○
○
○
○
－
○
○
○
○
－
○
○
○
○

20
－
－
－
○
○
○
○

3. ANALYSIS RESULTS AND DISCUSSIONS

The amount of adhering raindrops is necessary to predict the moisture
content of concrete structures appropriately so that it is important to discuss
about the amount of adhering raindrops from this viewpoint. Before
discussing the analysis results, a water absorption velocity of concrete wasobtained experimentally because an amount of moisture penetrated into
concrete is governed by the water absorption velocity of concrete.
3.1 Water absorption velocity of mortar

The water absorption velocity of concrete was obtained
experimentally using mortar specimen. The reason why mortar specimen
was used is to secure an accuracy of experiment with a reasonable level.
The water absorption velocity was measured by an increment of specimen
weight. The increment of specimen weight due to water absorption wasconsidered to be quite small so that it was necessary to thin a thickness of
specimen as much as possible. Moreover, an actual concrete surface wasconsidered to be covered with a mortar layer.
The mix-proportion of mortar specimen was W/C = 0.5 and S/C = 1.5.
Dimensions of the specimen are 60 x 60 x 5 (mm). The moisture content of

Simulation Study on Relation between Local Rainfall Conditions and Amount of Moisture Supplied toConcrete83

October 2005, Singapore

specimen is set to 0 (%) using D-dry processing. Figure 4 shows the methodof supplying water to the specimen that simulated the raindrops.
syringeraindrop

specimen

Figure 4: Experiment situation

Water absorption velocity(mm/h)

Figure 5 shows the experiment results. It is found that the maximum
water absorption velocity is around 0.6 (mm/h) and this value is quite smallvalue for the rainfall. Therefore, it can be concluded that the presence ofadhering raindrops is more important than the amount of adhering raindrops
when the effect of rainfall on the moisture content of concrete is discussed.
2
1.6
1.2
0.8
0.4
0
0

1

2

Supply water velocity (mm/h)

Figure 5: Water absorption capacity of mortar
3.2 Analysis results

Figure 6 shows the examples of analysis results. From these results,
it can be found that there is no adhering raindrop on the concrete surface ofthe pier when the wind velocity (w) is small. In the case of amount of
rainfall (R) = 1.74 (mm/h), raindrops never adhere to the concrete surface ofthe pier in that case the wind velocity = 1 and 2 (m/s). And an area of theconcrete surface wet by adhering raindrops (wet area) is larger the higher
velocity of wind (w). These phenomenons are caused by combination
effects of rainfall, wind and structure form (slab width). The wet area can be
determined using analysis results and corresponds to the relationshipbetween the amount of rainfall (R) and the wind velocity (w).

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w = 1 (m/s)

w = 2 (m/s)

w = 3 (m/s)
w = 4 (m/s)
Figure 6: Examples of analysis results (R = 1.74 (mm/h)
Figure 7 shows a distance from a grand to a top of the wet area. An
area below the line means the wet area, in other words, an area above theline means the dry area to which the raindrops never adhere. This
relationship is naturally affected by the structure form so that this relation
should be changed according to the structure form.
2.5

Distance from grand (m)w = 10
2
w=7
1.5
w=5
1
w=3

0.5

w=4

w = 1,2
0
0

5

10

15

20

Amount of rainfall (mm/h)

Figure 7: Calculation results of wet area

Simulation Study on Relation between Local Rainfall Conditions and Amount of Moisture Supplied toConcrete85

October 2005, Singapore

3.3 Utilization of analysis results to treat rainfall as boundary conditionof concrete structure

Figure 8 shows the example of EA AMeDAS weather data. Then,
how should we utilize these data as a boundary condition for predicting the
moisture content in concrete.
7
Amount of rainfall

R (mm/h) & w (m/s)

6Wind velocity
5
4
3
2
1
0
1

3

5

7

9 11 13 15 17 19 21 23

Figure 8: Example of EA AMeDAS weather data
As we already discussed, the presence of adhering raindrops isimportant when the effect of rainfall on the moisture content of concrete is
discussed. Namely, the boundary conditions are simply divided into “Wetcondition” and “Dry condition”. From this viewpoint, the boundary
condition in the case of Figure 8 can be expressed as follows.
1 – 11: wet condition, 12 – 24: dry condition
However, this boundary condition may not be appropriate because
the weather data does not show the presence of adhering raindrops on
concrete surface. Figure 9 shows the calculation results of the distance from
grand and top of the wet area that was discussed in previous section using
the weather data. The boundary condition can be expressed as follows basedon this calculation results.
1: dry2-3: wet (below 0.75 (m)) dry (above 0.75 (m))
4: wet (below 0.5 (m)) dry (above 0.5 (m))
5: wet (below 0.75 (m)) dry (above 0.75 (m))
6: wet (below 1.25 (m)) dry (above 1.25 (m))
7: wet (below 1 (m)) dry (above 1 (m))
8-11: wet (below 1.25 (m)) dry (above 1.25 (m))
12-24: dry

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7

R (mm/h) & w (m/s)

6

2

5
4

1.5

3

1

2
0.5

1
0

Distance from grand (m)2.5
Amount of rainfall
Wind velocity
Wet area

0
1

3

5

7

9 11 13 15 17 19 21 23

Figure 9: Calculation results of wet area using the weather data
Finally, the weather data of one year is statistically processedfollowing the above mentioned method. The total rainfall time in one year is
500 hours according to the weather data. Figure 10 shows the relationshipbetween the distance from grand to top of the wet area and distribution of its
frequency as bar charts. It is found that the total time of wet condition is 247
hours in one year and the distance from grand to top of the wet area isalmost below 1.25 (m). The boundary condition of concrete pier below 1(m) in height is wet condition in the case that the distance from grand to topof the wet area is 1.0 (m). Therefore, the frequency of wet condition in eachsection can be expressed as cumulative of the distribution of frequency. The
calculation result is also drawn in Figure 10 as a line chart. The boundary
condition of concrete structure can be set appropriately considering theeffects of rainfall, wind and structure form. And a large amount of weather
data can be concisely processed using this proposed method.
250
Distribution of frequency

200

100
80

150

64
60

100
34

40
13

20
3

50

13
4

1

1

Cumulative frequency

114

120

0
0

0
0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5Distance from grand (m)Figure 10: Relationship between wet area and frequency in one year

Simulation Study on Relation between Local Rainfall Conditions and Amount of Moisture Supplied toConcrete87

October 2005, Singapore

4. CONCLUSION

To develop treatment methods of actual environmental conditions asboundary conditions for predicting deteriorations process of concrete
structures, the rainfall was selected as a first step of our research.
The amount of adhering raindrops is necessary to predict moisture
content of concrete structures appropriately. The water absorption velocity
of concrete was obtained experimentally because an amount of moisturepenetrated into concrete is governed by the water absorption velocity ofconcrete. As a result, it was found that the water absorption velocity ofconcrete was quite small compared with the amount of rainfall. Therefore,
the presence of adhering raindrops is important to discuss the effect ofrainfall on the moisture content of concrete.
Finally, the treatment method of rainfall as boundary condition forpredicting moisture content in concrete was proposed based on the analysis
and experiment results considering the effects of rainfall, wind and structure
form. And a large amount of weather data can be concisely processed using
this proposed method.
REFERENCES

Marshall, J. S. and Palme, W. M., 1948. The Distribution of Raindrops with
Size. J.Meteor, Vol.5, 165-166.
Gunn, R. and Kinzer, G. D., 1949. The Terminal Velocity of a Fall for
Water Droplets in Stagnant Air, J.Meteor, Vol.6, 243-248.
Akasaka, H. et all, 2003. Expanded AMeDAS Weather Data, Architectural
Institute of Japan
Fabien J.R. van Mook, 2002. Driving Rrain on Building Envelopes.
Technische Universiteit Eindhoven, 28-37

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New Technologies for Urban Safety of Mega Cities in Asia

USING DIGITAL CLOSE RANGE
PHOTOGRAMMETRY TO ESTIMATE
DEFLECTIONS IN A BRIDGES FAISAL HASHMI1, ONKAR DIKSHIT2 AND SUDHIR MISRA3
Department of Civil Engineering
Indian Institute of Technology Kanpur, India 208 016
1

2

Former graduate student
Associate Professor, onkar@iitk.ac.in
3
Associate Professor, sud@iitk.ac.in

ABSTRACTDeflections in bridges can be taken as a quantitative measure of theiroverall structural integrity. Whereas accurate measurement of deflection
under load using conventional methods is very cumbersome, Digital Close
Range Photogrammetry (DCRP) offers an easy, quick and accuratealternative. Results obtained in a study where the method was used toestimate deflections in a railway steel truss bridge are reported here.
The DCRP system is based on the principle of Direct Linear
Transformation (DLT), wherein an effort is made to establish a relation
between 3-D space coordinates in an object and the plane coordinates in a
2-D image, using DLT equations, whose coefficients called DLT parameters,
reflect the relationship between the object space and image plane.
In the present study, 27 targets were fixed on a single 33m span of amultispan truss bridge, including 12 targets at locations not likely to be
disturbed under application of load, which was done by having a goods
train stop at predetermined locations on the bridge. The 3D spatial
coordinates of all targets were determined using total stations, and imagesof the truss taken under varying load from two stations where digital
cameras had been appropriately stationed. Using DLT, deflection underloading was calculated using the difference in coordinates of a given target
before and after application of load. The observed deflection was found tovary between about 8.5mm to 18mm, depending on target locations. Further
work on estimating the errors and accuracies is presently in progress.
1. INTRODUCTION
Deflection in bridges can be used as an indicator of its overall
integrity. Conventional measurement of deflection can be carried out using
dial gages, etc. but such methods require elaborate scaffolding andphysically approaching the structure to record the observations. It may be
noted that non-contact methods for estimation of deflections have also been89

October 2005, Singapore

suggested in the recent past to enable better monitoring of concrete bridges(Markus and Mass, 1997; Tsakiri et al., 2004).
Now, though photogrammetry has been routinely used in several
applications, rapid developments in the areas of digital photography, image
processing, etc. have led to the evolution of Digital Close Range
Photogrammetry, which can also be used as a simple yet effective tool foran accurate estimate of the deflections in bridges under the action of live
loads. Results obtained in a study where the method was used to estimate
deflections in a railway steel truss bridge are reported here. The loads on thebridge were applied by stopping a goods train at pre-determined locations
on the bridge.
2. BASIC DIGITAL CLOSE RANGE PHOTOGRAMMETRY
In the recent years, DCRP has been used in diverse fields such as
CAD, architecture, archaeology, medicine (Slama, 1980; Atkinson, 1996),
and also in structural engineering in estimating deflections in laboratory
tests, etc. (Markus and Mass, 1997, Tsakiri et al., 2004). In principle, the
DCRP seeks to estimate the 3D coordinates of a point in an object using the
2D coordinates available for that point from two (or more) photographs
taken from different locations (constituting a set of ‘stereo images’). Thus,in simple terms, from a set of (x, y) coordinates {xia, yia} and {xib, yib}obtained for the point i from two images taken from locations, a and b,
DCRP seeks to obtain the 3D coordinates of the ith location [Abdel-Aziz andKarara, 1971, 1974; Marzan and Karara, 1975]. The method uses theprinciple of Direct Linear Transformation (DLT), which yields a set ofcollinearity equations, whose coefficients, called the DLT parameters can be
defined as below (Ghosh, 1979)
x=

L1 X + L2Y + L3 Z + L4
L9 X + L10Y + L11Z + 1y=

L5 X + L6Y + L7 Z + L8
L9 X + L10Y + L11Z + 1

In the overall setup, there are 11 unknown parameters in DLTequations (L1 to L11), which can be solved by using at least 6 known points
in terms of object coordinates (X, Y, Z) and corresponding image
coordinates (x, y) (Mikhail and Bethel, 2001) .
3. METHODOLOGY
A multispan railway steel truss bridge was identified for studying thepossible application of DCRP in estimating deflections in field underservice loads applied by the action of passing trains. The bridge consisted ofseveral simply supported spans of 33m and all experiments were conducted
on a single representative span (Span no. 4). Targets were fixed at different
points of the truss in the central portion of the span and the change in theircoordinates were studied under varying positions of the load, which wasapplied by having a goods train stop at predetermined location on the span.

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3.1 The procedure adopted and targets used
The following is a summary of the procedure adopted in the study.
1. Targets are pasted at ‘positions of interest’. Targets used were Oshaped with a 100mm outer diameter as shown in Figure 1(a). Thissize of the targets was adopted on the basis of preliminary studies
and after ensuring that the average number of pixels in each target
should not be less than 64 (8×8), (Kadari, 2003; Sagar, 2004).

Figure 1: (a) Ring shaped target (b) Zoomed image of the same
2. A total of 27 targets were used, and were pasted at different points
on the truss, piers and electric poles. Of these, 14 were pasted at
locations likely to remain stationary (or their movements can beneglected), such as locations on the piers. These targets were used as
reference or control points to estimate the changes in coordinates ofthe other ‘live’ targets, fixed on the truss.
3. 3D coordinates of at least six of the targets are determined directly
using a Total Station (TS). These six points were not likely to moveon account of application of load, and are referred to as control orreference points, as against others, which were ‘live’ in nature.
4. Two photographs are taken from two different camera stations toconstitute a stereo pair used for computation of coordinates. It may
be mentioned that the targets as they appear in a photograph wereappropriately zoomed, as shown in Figure 1(b). It can be clearly seenthat the edges of the ‘well-defined’ circle appear jagged, and it is noteasy to uniquely identify the centre of the circle, as discussed later.
5. Using coordinates of control points measured on photograph andthose by TS, a DLT model is established for both camera stations in
the form of aforementioned DLT equations.
6. The model established in (4) above is used and the photo coordinatesof control targets from the stereopair, the DCRP system computes
3D coordinates for all targets points. The details of the systemdevelopment are available elsewhere (Hashmi, 2005).
7. Using the set of coordinates obtained without any loading as
reference, the deflections under different loading conditions arecalculated from the difference in corresponding values.

Using Digital Close Range Photogrammetry to Estimate Deflections in a Bridge91

October 2005, Singapore

Figure 2 Experimental set up used in the field showing different targets
fixed to the bridge and camera positions

3.2 Set up used at site
Figure 2 shows schematically the arrangement adopted with twocamera stations separated by about 30m at a distance of approximately 45mfrom the bridge being used for taking appropriate photographs of targets
pasted on the bridge and numbered from 1 to 27. It is clear that the study
concentrated on estimating the deflection in the central part of the truss. The
camera configuration indicates that the base (separation between camera
stations) and distance of the target ratio (B/D ratio) used was 0.67. This low
value of the ratio was due to physical inaccessibility at certain locations onsite, though higher values have been clearly recommended (Kadari, 2003).

3.3 Data reduction process
Ground coordinates of all target points were measured with Trimble
5600 TS. Coloured (RGB) images were acquired using Nikon digital
cameras (DX100) and were processed using Matlab 7.0 software. Only redband of all images was used for further processing to reduce memory
needed in the computer, and since its use gave better visual appearance(needed as centre of target was manually picked) than the green and blue
layers. Centers of targets in an image were recorded manually by zooming
the image and manually clicking on the ‘apparent’ centre of each target.

4. OBSERVATIONS
After initial measurement of coordinates with the total station, without
any load, images from the two cameras were taken in the four loading
conditions (LCs) briefly described below, and illustrated in Figure 3.

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11a) LC1 [Figure 3 (a)]: There is no loading on the bridge, and the data inthis condition was used as a reference to determine the changes in (x, y,z) coordinates of each of the targets.
b) LC2 [Figure 3 (b)]: In this condition, the front of the engine is at midspan, i.e., the remaining portion of the span was not loaded, though theadjacent span (span no. 3) had wagons on it. It can be seen that in thiscondition, the loading is practically only on account of the engine. It
may be noted that the engine is six axle (with the design load of eachaxle being about 18 tonnes) (Raina, 2005)(a) Loading condition LC1(b) Loading condition LC2(c) Loading condition LC3(d) Loading condition LC4

Figure 3 Loading conditions LC1, LC2, LC3 and LC4c) LC3 [Figure 3 (c)]: Here the whole span is loaded, though the loading is
not symmetric – one half is loaded with the engine and the other one with
one luggage carrying wagon (four axles, design load of 20 tonnes foreach).
d) LC4 [Figure 3 (d)]: In this condition, the engine has crossed out of the
span under study (# 4), and the entire span is under the action of loads
due to the wagons only, which also extend to other spans.

5. RESULTS AND DISCUSSIONS
5.1 Comparing 3D coordinates determined using DCRP and TS
As mentioned above, coordinates were determined with respect to a
fixed coordinate frame using an arbitrary origin. To ensure reliability ofUsing Digital Close Range Photogrammetry to Estimate Deflections in a Bridge93

October 2005, Singapore

results, the coordinates computed by DCRP were compared with thosemeasured using by TS, assuming the latter as the reference. The comparison
was made in terms of the absolute value of difference in coordinates in the X,
Y and Z direction, as computed by the two methods and recorded as εX, εY,
and εZ, which can be looked upon as the X, Y, and Z components of an error
vector. Thus, εXi for the ith point was determined as |{XDCRP - XTS}|. Though
the details are not described here, the εX, εY, and εZ were found to vary
between 0.4-4.2mm, 0.1-5.6, and 0.2-13.5mm, respectively, with theiraverage values being 2.5mm, 3.0mm, and 7.3mm. The corresponding
standard deviations (SD) for these were 1.2, 1.9, and 3.0mm (Hashmi, 2005).
This result thus established that at least in the X and Y directions, thecoordinates obtained using DCRP and the TS are in reasonable agreement,
though the same cannot be said for the coordinates in the Z direction (out ofplane). Possible reasons for the relatively larger error in the Z direction are
discussed in greater detail subsequently.

5.2 Deflection in control targets
As mentioned above, that control points are relatively fixed is an
inherent assumption in DCRP, and thus an effort was made to first establishthat these six targets (1, 2, 3, 17, 18 and 19) fixed on the pier and poles on
the piers did not move under applied load. This was done by finding the
average standard deviations in X, Y and Z coordinates (SDX, SDY, and SDZ)
computed by DCRP under the different loading conditions for these points
for all loading conditions. First, the standard deviation in X direction for the
ith target is determined from the set {xi1, xi2, xi3, xi4}, where individual values
represent the X-coordinate for that target in the four loading conditions.
Then, SDX is computed by averaging individual standard deviations for the
six locations. SDY, and SDZ were calculated similarly. The values of SDX,
SDY, and SDZ were found to be 1.19, 2.25, and 4.84mm respectively. In thiscase also, it can be seen that the small values of SDX and SDY, validate theassumption that control points do not move appreciably under loading. The
issue of the larger value obtained in the Z direction is discussed separately.

5.3 Deflection in truss
After calculating the 3D coordinates of all the targets using DCRP,
the deflection vector (comprising of X, Y and Z components) for each point
was calculated for the different LCs using the difference in thecorresponding coordinates, with the values determined under LC1 (no loadon the bridge) serving as reference in all cases. Thus, the X component ofdeflection at point i under loading condition 2 and 3 were calculated as {xi2
– xi1} and {xi3 – xi1}, respectively. Now, the discussion here focuses on the
results for targets 6, 9, 10, 11, and 16, set at the upper part of the truss(Figure 2), and a summary of the results is given in Table 1.

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Table 1 Observed deflections at five representative targets under load
Point
6
9
10
11
16

∆X
5.4
7.8
13.7
8.1
9.9

2
∆Y
10.1
8.7
0.2
-1.0
5.0

∆Z
16.3
20.0
20.2
1.8
10.5

Loading condition
3
∆X
∆Y
∆Z
11.7
-2.8 46.9
15.5
5.3 62.4
17.2-4.6 43.8
17.5-4.3 45.7
17.1-2.2 52.2

∆X
10.6
13.3
15.6
13.1
11.8

4
∆Y
4.2
6.3
7.2
2.2
2.7

∆Z
20.5
30.1
16.8
18.7
15.9

5.3.1 Deflection in the X direction
In the chosen coordinate system as shown in Figure 2, ∆X can belooked upon as ‘deflections’ under applied load, and the results given in
Table 1 are plotted in Figure 4. When closely examining these deflections, it
should be borne in mind that, (a) load from locomotive is transferredthrough six axles (three each in front and rear), (b) load in the case ofwagons is transferred through four axles (two each in front and rear), (c) the
loads in the wagons used is not clearly known here. However, the following
observations can, nonetheless, be made.
(a) The deflection varies between 5.4mm and 17.5mm depending upon theloading condition and the location.
(b) Though there is an aberration at target 11, the deflection on the loaded
half span in LC2 is clearly larger than that in the unloaded half.
(c) The maximum deflections were observed in the case of LC3, as can be
expected given the fact that the load is being applied through a total of
12 axles [Figure 5 (a)], and the fact that the loads transferred throughthe locomotive axles are likely to be higher than those from the wagons(where they are likely to vary depending upon the cargo, and the extent
of loading of the wagons).
(d) Given that the loading is most symmetric in LC4 [Figure 5 (b)], thedeflections observed in that case are also balanced.

Figure 6 Displacements of points 6, 9, 10, 11, and 16 by DCRP

Using Digital Close Range Photogrammetry to Estimate Deflections in a Bridge95

October 2005, Singapore

5.3.2 Deflection in the Y direction
It should be noted that observations here show negative values also,
and are lower in magnitude compared to the deflections in the X direction.
Results show that the deflection in the Y direction, also tabulated in Table 1,varies between -4.6mm and 10.1mm depending upon the loading condition
and the location. In other words targets undergo some relative movement in
the Y direction also as the truss deflects primarily in the X direction underapplication of load. Though some such movement can be expected fromconsiderations of geometrical compatibility, an exact analysis cannot be
carried out from the limited data collected during this study.

5.3.3 Deflection in the Z direction
Results from Table 1 show that observed deflections in the Z direction(out of plane deflections) are quite large, which is contrary to what should
be expected – given that there was no out of plane loading. Thus, thisaberration can only be attributed to different sources of errors, and the issue
is discussed from that perspective in the following section.

6. ERRORS IN MEASUREMENTS
6.1 Sources of error
Precision of 3D coordinates determined by DCRP is related to anumber of parameters, including the following:• accuracy of the 3D coordinates of control points (which in the present
study were determined using the total station)• accuracy in measurement of various distances such as between two or
more camera stations, camera stations and control field, etc.
• accuracy of establishing the centre of targets in photographs• network geometry adopted for data acquisition, in terms of camera
positions and the ratio of the distance between the camera to that fromthe objects involved (B/D ratio), etc.
• rounding-off errors of the DCRP system
It may be also mentioned that the mathematical structure of DLTequations, which forms the basis of DCRP, is such that any error in x, y
coordinates (determined from an image, for example) leads to a muchhigher error in the computed Z direction than in the X or Y directions (Fraser,
1984). The situation deteriorates further, i.e., the errors are aggravated incase when the intersection geometry for control points is poor or these arelocated in a single plane (Athyala, 2003; Kadari, 2003). As mentioned
above it was found in the present study, that the in most of cases, the error
in Z direction was nearly twice that in the X or Y direction. In fact, similarfindings with higher errors in the Z direction have also been reported by
Athyala (2003) and Kadari (2003) and attributed to poor B/D ratio.

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6.2 Remedies
Some of the steps that can be taken to minimize errors in estimates
made using DCRP can be summarized as follows
a)

b)
c)

d)

Photo coordinates of targets should be determined using an average ofvalues from repeated observations. This will reduce error on accountof not being able to identify the ‘true’ centre. In the present research,
the process (of clicking the centre of the same target) was repeatedfive times and the average reading was taken as the photo coordinateof the target and was used in the DLT model. The precision of picking
the centre of target manually was about 1/10th of the pixel dimension.
Matrices should be appropriately scaled during transformation. This isespecially important given the special structure of matrices that areformed during the processing of DLT equations
Special attention should be paid to the layout and geometry used during
imaging, (distance between cameras (B), their positions relative to theobject, and the distance from the object (D)). It has been suggested
that in order to obtain good results, the B/D ratio should be higher, as
an improved convergent geometry of intersecting rays, can beachieved under these conditions (Fraser, 1992).
Accuracy can be further improved by either using multiple pairs ofstereo images from the two sets of cameras, or increasing the numberof cameras. In the present preliminary study, where the object was toestablish the applicability of the method and test the softwaredeveloped, only a single set of images taken from only two cameras
has been used.

7. SUMMARY AND CONCLUDING REMARKSThis research has proposed a DCRP based system for monitoring
deflection of a railway bridge. The accuracy of the DCRP measurements is
closely related to parameters such as the dimensions of the control field,
properties of the camera used, the setup geometry used in taking images, etc.
Efforts to estimate the deflections in the bridge yielded encouraging results,
though efforts are needed to improve the accuracy obtained in themeasurement of coordinates, deflections, etc.
It was found that the standard error in 3D coordinates calculated by
DCRP in the X, Y, Z directions was 3.2, 1.6, and 5.2mm respectively, which
may be considered acceptable at least in the X and Y directions. Deflectionin the bridge was found to range between about 5mm to 18mm, dependingon the location and loading condition.

ACKNOWLEDGEMENT
The field work reported here was carried out at a railway bridge, and thecooperation and help extended by the Indian Railways during the exercise is

Using Digital Close Range Photogrammetry to Estimate Deflections in a Bridge97

October 2005, Singapore

gratefully acknowledged. The authors would like to specially thank Shri RK
Gupta, Executive Director, Bridges & Structures, Railway Design andStandardization Organization, Lucknow, and other members of his team.

REFERENCES
Abdel-Aziz, Y. I and Karara, H. M., 1971. Direct linear transformation fromcomparator coordinates into object space coordinates in close-range
photogrammetry. In: proceedings of the symposium on close-range
photogrammetry. American Society of Photogrammetry, Falls Church,
VA.
Abdel-Aziz, Y. I. and Karara, H. M., 1974. Accuracy aspects of non-metricimageries. Photogrammetric Engineering 40, pp. 1107-1117.
Atkinson, K. B. (Ed.), 1996. Close range photogrammetry and machine
vision. Engineering and Science. Whittles Publishing, Scotland, UK.
Athyala, A. S., June 2003. Design considerations for digital close range
photogrammetric system. Master’s thesis, Civil Engineering
Department, IIT Kanpur, India
Fraser, C. S., 1984, Network design considerations for non-topographic
photogrammetry, Photogrammetric Engineering & Remote Sensing,50, pp. 1115-1126.
Fraser, C. S., 1992, Photogrammetric measurement to one part in a million,
Photogrammetric Engineering & Remote Sensing, 58, pp. 305-310.
Ghosh, S. K., 1979. Analytical Photogrammetry. Pergamon Press Inc.
Hashmi, S. F., 2005, Monitoring of Engineering Structures using Digital
Close Range Photogrammetry, Master’s thesis, Civil Engineering
Department, IIT Kanpur, India.
Kadari, R., 2003. Network design of a digital close range photogrammetricsystem. Master’s thesis, Civil Engineering Department, IIT Kanpur,
India.
Markus, N. and Maas, H. G., 1997. Automatic deformation measurementswith a digital still video camera. In: Optical 3-D Measurement
Techniques IV. Zurich; Wichmann Verlag, pp. 266-271.
Mikhail, E. M. and Bethel, J. S., 2001, Introduction to Modern
Photogrammetry, John Wiley & Sons.
Raina, S.K. 2005. Executive Director, RDSO, Indian Railways, Personalcommunication
Sagar, S. D., 2004. Measurement of displacement using digital close range
photogrammetry. Master’s thesis, Civil Engineering Department, IIT
Kanpur, India.
Slama, C., 1980, Manual of Photogrammetry, American Society of
Photogrammetry, Falls Church, Virginia.
Tsakiri, M., Charalambos, I., Papankios, P. and Kattis, M., 2004, Load
Testing Measurements for Structural Assessment using Geodetic and
Photogrammetric Techniques, 1st FIG International Symposium on
Engineering Surveys for Construction Works and StructuralEngineering Nottingham, United Kingdom, 28 June – 1 July, 2004.

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RESEARCH ON DURABILITYEVALUATION FOR IN-PLACE CONCRETE
EFFECT OF EARLY DRYING ON THE
QUALITY OF COVER CONCRETE
PHAN HUU DUY QUOC
quoc@iis.u-tokyo.ac.jp
TOSHIHARU KISHI
kishi@iis.u-tokyo.ac.jp
Institute of Industrial Science,
The University of Tokyo, Japan

ABSTRACT
Commonly, the verification of concrete durability properties likecarbonation rate, diffusion coefficient of chloride ions, etc, is carried out
using laboratory tests on specimens cured in standard conditions. However,these tests fail to reflect the influence of actual factors, especially theconstruction quality, on the quality of in-place concrete. Therefore, it isdesirable to select criteria in terms of measurable items for durability
performance and corresponding nondestructive test methods applicabledirectly on existing structure. Undoubtedly, items that represent theresistance of a concrete against the ingress of deleterious substances, ineither gaseous or liquid form, from surrounding environment into concrete
are criteria for the durability performance of that concrete.
This research focuses on the use of nondestructive testing methods for
direct measurement of transport properties of concrete, including air
permeation, water absorption, which are selected as criteria for durability
performance of in-place concrete. In this paper, the experimental results on
the effect of early drying on concrete transport properties are reported. It
was found that the effect of early drying on transport properties is verymuch higher than on compressive strength. This research may contribute to
the improvement of construction quality, the early judgment of concrete
quality as well as the prediction of service life of concrete structures.
1. INTRODUCTION
Concretes produced nowadays are quite different from the conventional one,both in good and bad aspects. As for good aspects, there have been
tremendous improvements in concrete technology such as the utilization ofchemical admixture (superplasticizer, air entraining agent...), industrial byproduct (fly ash, silica fume...), the mechanization of concreting works(transporting concrete by pumping, compacting by vibration), the99October 2005, Singapore

development of advanced concretes like high performance concrete, theapplication of computer-aided analysis in design of structure, etc.
Unfortunately, in contrast to such positive developments, there has not beenremarkable improvement in controlling and evaluating the quality ofconcrete, especially concrete in structure (Hereafter, in-place concrete).

Performance

In many cases, in-place concrete appears to be good at the beginning but
deteriorates sooner than expected, resulting in high total cost, shortening theservice life and threatening the safety of users (Figure 1.) It is because thein-place concrete doesn’t possess sufficient ability to withstand the given
environmental conditions, such as carbonation, acid attack, salt attack, etc,
like the example shown in Figure 2.
Deterioration
Initial performanceEnd-of-service performance
Ultimate limit state
Designed service lifea) Normal concrete

Performance

Time
Repair, strengthening
Initial performanceEnd-of-service performance
Ultimate limit state
Early deterioration, damageb) Bad concreteTime

Figure 1: “Normal concrete” versus “bad concrete”

Figure 2: Corrosion of reinforcing bars due to bad cover concrete

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The problems lie at the following points:(i)
Most of the current performance verifications of concrete propertiesare carried out on specimens (which do not represent in-place
concrete) cured under standard conditions.
(ii)
Criteria for evaluating the quality of in-place concrete areinsufficient or improper. Compressive strength is nearly the only
verified item.
In short, the quality of construction, the effect of environmental conditions
are not properly taken into account in verification, or not suitably covered indesign code.
To solve the above short-coming, it is important to identify the criteria forthe durability performance of in-place concrete. In term of durability, thecriteria must be those that represent the resistance of concrete against the
ingress of deleterious substances, in either gaseous or liquid form, fromsurrounding environment into concrete.
Cover concrete, as its name implies, acts as a shield that protects the innerconcrete and reinforcing bars from the attack of environmental factors.
However, this important layer tends to have lower quality compared with
the inner part due to various factors, such as insufficient compaction, early
drying, thermal cracking, or even due to bad practices in construction likeadding water, removing formwork so early, etc. (Figure 3). If cover concrete
is not really a “cover”, structure will soon deteriorate.
Therefore, the objective of this research is to evaluate the transport
properties of cover concrete. It has two important meanings: one is toprovide necessary information for improving the quality of cover concrete,
and the other is to find appropriate methods for controlling and evaluating
the quality of cover concrete.
Insufficient compaction,
Early drying
Thermal cracking

Cover concrete

Concrete
Rebar

Figure 3: Cover concrete
In this research, by varying the demolding time of concrete specimen to
simulate actual formwork removal time, the effect of drying on transport
properties of cover concrete was investigated using simple tests. This study

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is an important preparation to provide fundamental concepts andexperiences for further measurement on actual concrete structure, rather
than an actual investigation on in-place concrete.
2. EXPERIMENTAL OUTLINES
2.1

Materials and specimen preparation

Twelve concrete cylinders with diameter of 10cm and height of 20cm weremade from concrete mixture with water-cement ratio of 0.5.
To investigate the effect of drying on the quality of cover concrete, 3cylinders were demolded at 1, 3, 7 and 27 day-ages and immediately
exposed to ambient conditions after being kept in sealed condition (noadditional water is provided after mixing).. The demolding timing wasvaried to simulate different formwork removal time in actual structure andobserve the extent of drying effect on transport properties of concrete.
The exposure started in January, which has very how humidity, so
specimens are subjected to drying condition. During the exposure,specimens were kept away from the reach of rain or any kind of water.
2.2 Testing items and apparatuses
Three kinds of test were carried out on the side and the top of the
exposed concrete cylinders after 8-month exposure. Air permeation, water
absorption and compressive strength tests were carried out as follows:
2.2.1 Air permeation test
This testing method was firstly developed by Figg (1973) and enhanced by
Kasai et. al. (1984). In this test, a cylinder hole with diameter of 10mm is
drilled into the concrete specimen (Figure. 4). Then, the hole is plugged by arubber cap. A needle is inserted through this rubber cap to bring the pressure
inside the hole to a pre-decided vacuum pressure using a vacuum pump.
This pressure will increase gradually because air from all directions aroundthe hole will find theirs way through the pore network to fill the hole until
the pressure equilibrium is reached. The rate of pressure change will becalculated as air permeation rate of concrete.
Concrete
Air
Measuring unit

Vacuum Pump

Needle50mm

Figure 4: Air permeation test

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Because the direction of air movement as well as the exact affected area inthis test is unknown, the air permeation coefficient cannot be directly
obtained using this test. The accuracy of this kind of measurements, factors
influencing its measurement, etc, will be discussed later in this paper. It wasreported that the air permeation measured using this apparatus has a goodcorrelation with carbonation depth. Torrent (1992) reported a goodcorrelation between air permeation coefficient and carbonation rate ofconcrete.
2.2.2 Water absorption test
In water absorption test, the amount of water absorbed by concrete on a unit
surface area is measured using the apparatus called Porositester developedby Proceq Co. Ltd (Switzerland) (Figure 5). This apparatus has nothing
special compared with common water absorption test using a tube of water,
except the way of providing water source and absorption area.
In this apparatus, a “cell” is created by attaching a large rubber ring at thebottom of a steel plate. At the middle of the plate, there is a small holethrough which vacuum pressure is applied to attach the plate onto the target
surface by suction force.
Scaled tubes are mounted on this plate, pressed against the target surface,sealed by rubber ring and filled with water. By this way, the absorption area
is kept constant through out the measurement to enable a stable and accurate
measurement. The amount of absorbed water is recorded every 30 minutes
up to three hours.
The advantage of this simple apparatus is that it causes no damage to thetarget surface. In addition, it can be operated using portable DC power
supply (For example, the car battery). Different kinds of water tube are usedfor vertical wall (Figure 5a) and horizontal surfaces (Figure 5b).

(a) For vertical wall(b) For horizontal surface

Figure 5: Apparatus for measuring water absorption

Effect of early drying on the quality of cover concrete103

October 2005, Singapore

2.2.3 Compressive strength
Compressive strength was measured using
Schmidt’s hammer (Figure 6). Thisapparatus were selected in this study
because it is a commonly used nondestructive testing method for obtaining thecompressive strength of in-place concrete.
In this method, an impacting force isapplied on the surface of concrete. The
compressive strength is calculated from thereaction of concrete surface. In addition, thecompressive strength calculated from theresult of Schmidt’s hammer can beunderstood as the strength of cover concreteat the vicinity of impacting point. In thistest, the specimen was kept firmly at
horizontal position and 15 measuring times
were applied downward on different
Figure 6: Schmidt’s hammer
positions on the side of the specimen.
3. EXPERIMENTAL RESULTS AND DISCUSSIONS
Experimental results show that the transport properties (air permeation,water absorption) are greatly affected by the early drying when specimens
are demolded early than 1 week. Certainly, the sooner the demolding time,
the worse the transport properties are. Compressive strength of concrete isrelatively less influenced than transport properties.
3.1 Air permeation rate
As mentioned above, the air permeation rate is calculated from thechange of air pressure in the cylinder hole and the corresponding time
duration. Figure 7 shows the measured results of air permeation rate for both
top and side positions of the cylinder specimens. The result indicates thatthe air permeation is greatly affected by the early drying. This influence isvery severe if the specimen is demolded before 7 days. Compared between
1-day and 7-day demolded cases, the air permeation of the former is about
twofold of air permeation of the latter. This result emphasizes the
detrimental effect of early formwork removal on concrete property.
Regarding the effect of measured positions, the air permeation rate of
the top surface was anticipated to be larger than that of side due to bleedingat the top surface. However, experimental result shows just a slightdifference between two positions. It is attributed to the small size of cylinder
specimens and the way of making this sample (compacted by rod andfinished by surface tapping). For large specimens or actual structures, thedifference in air permeation property between top and side may be observed.

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Air-permeation rate (mmHg/s)

6

Top

1day

5
4

Side

3

Side

3 days7 days2

Top1

28 days

Measured at 8-month age
0
0

5

10

15

20

25

30

Demolded time (day)Figure 7: Variation of air-permeation rate and demolded time
3.2 Water absorption coefficient
Figure 8 shows the result of water absorption measured on specimens
demolded at 1, 3, 7 and 28 days. It is clear that there is a linear relationshipbetween the amount of absorbed water and measuring time. It means that
there is steady state absorption under capillary suction. The gradients ofthese lines are the coefficients of water absorption for each case.

Absorbedwater
water (kg/m2)
Absorbed(kg/m2)

25

Top

1 day
3 day
7 day
28 dayLinear (28 day)Linear (7 day)Linear (3 day)Linear (1 day)

20
15
10

y = 6.3841x
R2 = 0.9803

Measured at 8-month age

SteadySteadystate flow
Steadyy = 4.4098x
R2 = 0.9929
y = 2.7488x
R2 = 0.972

5

y = 0.5014x
R2 = 0.9669

0
0

0.5

1

1.5

2

2.5

3

3.5

Measuring Time
Measuringtime(hour)(hour)

Figure 8: Water absorption measurement
The water absorption seems to reach the steady state after around 1.5 hours
from the start of measurement. Therefore, it may be recommended that thetime for water absorption measurement should be around 1.5 hours. Since
this conclusion may be applied for other cases of water-cement ratios andcuring conditions as well, though confirming experiments should be carried

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October 2005, Singapore

out. Certainly, in other to ensure a steady state flow, the absorption area
should be maintained while the water evaporation prevented.

2
Water absorption
coefficient(kg/mwater absorption
coefficient
afdad.h)

Plotting the coefficient of water absorption obtained from results in Figure 8
against the demolded time, one can see a similar trend with air permeation
rate: the water absorption coefficient is quite sensitive to the early drying
caused by early formwork removal in the first week. If demolded after one
week, the effect of drying is less severe but still remarkable (Figure 9).
7

Top

1day

6
5

3 days4

7 days3
2

28 days1

Measured at 8-month age

0
0

5

10

15

20

25

30

Demolded(day)
Demoldedtime
time (day)Figure 9: Variation of water absorption coefficient with demolded time
3.3 Air permeation rate versus water absorption coefficient
Figure 10 shows a relatively good correlation between air permeation rate
and water absorption coefficient. This may not be a conclusion for generalcases because of limited number of tests and variables in this study.

permeationrate
rate(mmHg/s)(mmHg/s)
AirAirpermeation

However, the result in Figure 10 is believed due to the fact that in bothprocesses (air permeation and water absorption) transport properties aregoverned by the same pore network of concrete.
6

1 day

5

3 days4
7 days3Top

28 days2
1

Measured at 8-month age

0
0

1

2

3

4

5

6

7

Waterabsorption
absorption coefficient
coeffcient (kg/m2.h)
Water(kg/m2.h)Figure 10: Air permeation rate versus water absorption coefficient106

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These transport properties are governed by different transport mechanisms:
air permeation is a flow under applied pressure, while water absorption is aflow of water under capillary suction. The measurement of air permeation
takes a few minutes, while it takes one hour and a half to obtain water
permeation coefficient. Therefore, if a good correlation is obtainable, water
absorption coefficient can be derived from air permeation rate.
3.4 Compressive strength

Compressive strength
strength (kgf/cm
Compressive(kgf/cm2)

While transport properties show a high vulnerability to early drying,compressive strength of concrete was observed to be less influenced (Figure11). Compressive strength of concrete demolded at 1 day is just 10% lower
than that of concrete demolded at 28 days while the air permeation of theformer is 12.4 times higher than the latter. This result indicates thatstrength-based evaluation of in-place concrete will not provide valuable
information as long as the long term durability is concern.
360
340
320
300
280
260

335

342

3 days7 days

348

314

240
220
200
1 day

28 days

Demoldedtime (day)Demoldedtime

Figure 11: Compressive strength obtained by Schmidt’s hammer
3.5 Factors influencing the measurement of transport properties
In this study, the measurements were carried out on specimens
without any special treatment. Intentionally, it was to simulate the actual site
investigation when the measurement has to be carried out at arbitrary
condition. Due considerations must be given on the effect of mostinfluential factors: temperature and moisture content of concrete.
It is reported that temperature has little influence on air permeation,
but has rather remarkable influence on water absorption, mainly because thechange of water viscosity with temperature. The moisture content of
concrete which changes with ambient relative humidity has great influenceon the transport properties as well as the their on-site measurement.
Obviously, a “wet” concrete may behave as a “tight” concrete, because
saturated pores will block the paths of mass transportation. Without properconsideration, over (or under) estimation result may be mistakenly obtained.

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October 2005, Singapore

Figure 12 shows the variation of atmospheric relative humidity inTokyo. It is easy to recognize which period in a year new concrete will be
more vulnerable to drying, as well as when the measurement of transport
properties of in-place concrete will end up with over/under estimated results.

Ambient
relative
humidity(%)(%
Ambient
relative
humidity

120

Standard condition for lab-tests

100
80
60
40
20

Dry period

Dry period

Humid period

0
1

51

101

151

201

251

301

351

Day
Day
ofofthetheyearyear

Figure 12 Variation of atmospheric relative humidity in a year (Tokyo)
5. CONCLUSIONS- The effect of drying on transport properties of cover concrete is more
remarkable than on the compressive strength. Therefore, to ensure thedurability of cover concrete, transport properties have to be selected as
criteria of concrete performance over time.
- It was found that steady state absorption of water can be achieved after one
hour and a half. The accuracy and stability of measurement can be ensured
by maintaining constant absorption area and preventing water evaporation.
- It is important to find a way to cancel out effect of moisture content andtemperature on the measurement of transport properties of cover concrete.
- To evaluate the durability performance and to estimate the life span ofconcrete structures, more study on the relationship between transport
properties (air permeation, water absorption, etc.) and durability properties(carbonation rate, chloride diffusion coefficient...) are extremely important.

REFERENCES
Figg, J.W., 1973, Methods of measuring the air and water permeability ofconcrete, Magazine of Concrete Research, Vol. 25(85), 213-219
Kasai, Y., Matsui, I and Nagano, M., 1984, On-site rapid air permeability
test for concrete, ACI SP-82, 501-524
Torrent, R. J., 1992, A two-chamber vacuum cell for measuring thecoefficient of the permeability of air of the concrete cover on site, Vol.
25, 358-365

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SAFETY EVALUATION OF AGED STEELTRUSS BRIDGE WITH CRACKING
MEMBERS
Xianjie XU Ri GAO Lanchao Jiang Weiguo Yang
School of Civil & Architecture Engineering, Beijing
Jiaotong University, Beijing, 100044, China
rigao@center.njtu.edu.cn

ABSTRACTThe safety of aged steel truss bridges, especially those with cracking
members, has aroused a great deal of attention. In this paper, theapplication of fracture mechanics for evaluating the safety and ultimate
load-carrying of the aged steel truss bridge is proposed. Three-point
bending tests of three specimens for the mode-I fracture were done to get theultimate load-carrying capacity, when specimens were destroyed. Fracture
toughness KIC, and the steel allowable stress [σ] with certain crack length
were formulated. Field nondestructive load test and magnetic method formeasuring cracks of steel members were done. By comparing the results ofthe calculation and those of the field test, it is concluded that the fracture
method is necessary in the safety evaluation of aged steel truss bridges withcracking members.

1. INTRODUCTION
Nowadays, many bridges that were built in the fifth decade of previous
century or even earlier are still in running. And these bridges have disrepair
phenomena more or less (Zheng, 2003). Therefore, the safety of thesebridges becomes the matter we care.
For the steel members without cracks, it is doable that carrying throughsafety evaluation of steel bridge depends on the design guideline such as
strength and fatigue capability that can be obtained from the current designcodes. However, for the cracking members, it is necessary recurring to thetheory of fracture mechanics. The allowable stress and fatigue allowablestress and other material capability can be calculated according to the stressstrength factor and the doorsill value of crack extension, consequently, thesafety capability of members or steel bridge can be evaluated (Xu, et al,1994).
The Nenjiang steel bridge that locates at Qiqihaer city, Northwest of
China, was built in 1935 (Gao, 2005). The whole length of the bridge is548.1m, which consists of 6 through steel truss girders with span of 63.9m
each. Figure 1 and Figure 2 show the structure of the one span of the bridge.

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Figure 1: Front view of the bridge

Figure 2: Structure of the bridge
The bridge was renovated technically in1986, but the bridge appeared
new damage (cracks) in some steel members. As the appearance of various
problems, the security of the bridge cannot but arousing public attention. In
June of 2005, field test and theoretical analysis were taken to the bridge, toevaluate the safety capability of the bridge and give disposal advice. In thispaper, the safety evaluation of cracking members is analyzed mainly.

2. RESULTS OF THE NONDESTRUCTIVE TEST
According to the results of the nondestructive test taken to the main
bearing members of the first truss span and some members of other truss
spans of the bridge, some cracks were found in the members (Gao, 2005 andLiu, 1994). The crack length and number of the vertical and inclined web
members are listed in Table 1 and Table 2 respectively.
Table 1: Crack length and number of the vertical web members
crack length(mm) 50~100 101~150 151~200 201~300 301~500
crack number(mm)
1
5
6
4
1
Table 2: Crack length and number of the inclined web members
crack length(mm) 50~100 101~150 151~200 201~300 301~500
crack number(mm)626Nondestructive test shows that the crack percentage of vertical web
members of the bridge reaches to 63%, and the crack depth lies between
0.2mm and 2mm. The crack percentage of inclined web members reaches to
53.8%, and the crack depth of one member even reaches to 6mm. Thus, it
can be considered that the crack condition of this bridge is very serious.
Moreover, it shows the fundamentality of safety evaluation to cracking
members of aged steel truss bridge.

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3．TEST OF MATERIAL MECHANICS
Test facility: Material Test System of MTS－810.
Loading mode: Axis-pulling.
Sample dimension: 120mm×15mm×8mm, sample numbers: 9.
Test temperature: room temperature is about 25ºC.
Test results are shown in Table 2-1, Table 2-2 and Table 2-3.
Table 2-1: Test result of transverse brace members
Ultimate
Yield strength
Reduction of
No. tensile strength
Elongation (%)(MPa)
area (%)
(MPa)
H1
506
299
33.0
36.7
H2
512
324
28.6
32.8
H3
498
308
31.8
35.3
Average
505
310
31.1
34.9
Table 2-2: Test result of inclined web members of the truss
Ultimate
Yield strength
Reduction of
No. tensile strength
Elongation (%)(MPa)
area (%)
(MPa)
H1
523
340
34.8
40.1
H2
531
346
32.7
39.0
H3
059
313
38.6
43.3
Average
521
333
35.4
40.8
Table 2-3: Test result of vertical web members of the truss
Ultimate
Yield strength
Reduction of
No. tensile strength
Elongation (%)(MPa)
area (%)
(MPa)
H1
548
317
31.0
38.2
H2
516
328
27.0
31.8
H3
500
294
28.5
36.7
Average
521
313
28.8
35.6
According to the references 5 and 6, the intensity of the steel of thisbridge is between the intensity of Q235 and Q345. According to the Table
1.2.2, Table 1.2.16-2 and Table 1.2.17-2 of the reference (GB/T 700-1988，
GB/T 1591-1994), the allowable stress of this steel is about 140MPa if there
is no crack in the members.
4 ． FRACTURE TOUGHNESS AND ALLOWABLE STRESS OF
CRACKING MEMBERS
To get the fracture toughness and allowable stress of cracking members,
the theory of fracture mechanics is adopted in the test and calculation.

Safety Evaluation of Aged Steel Truss Bridge with Cracking Members

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4.1 Fracture toughness and Allowable stress
For cracking members, the stress nearby the crack tip can be expressed
as follows (Ding, and Sun, 1997):

σ ij =

K m  12 
 r  fij (θ )2π  

(1)

where： r —— the distance between stress point and crack tip;
f ij (θ ) —— the function about the polar angle θ ;K m —— stress strength factor m = Ⅰ、Ⅱ、Ⅲ, which is shownin Figure 3.

Figure 3: Stress of some point where the crack is interrupted
For the question of mode- I fracture:
KI = σ π a(2)where: σ —— additional stress;a —— half length of the crack;
K IC is fracture impact toughness, which is a material capability tomeasure crack spread resistance and can be obtained from the test.
Three-point bending tests of standard samples will be taken to get thepressure P when the samples are destroyed. And the fracture toughness canbe calculated from the following formula.
KI =

PS
a
f( )
32
BW
W

(3)

The standard three-point bending sample is shown in Figure 4.

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Figure 4: The standard Three-point bending test
Test facility: electronic multipurpose experiment-machine.
Loading mode: three-point bending.
Test temperature: room temperature is about 25ºC.
The dimensions of three samples with the crack length a are given as
follows: No.1: B = 8mm ; S = 64mm ; W = 16mm ; a = 3.6mm;
No.2: B = 8mm ; S = 64mm ; W = 16mm ; a = 4.0mm;
No.3: B = 8mm ; S = 64mm ; W = 16mm ; a = 4.4mm;
The relationships between force and displacement ( P ~ ∆ curve) gotten
from the three tests are shown in Figure 5 (Gao, 2005). Consequently, theultimate carrying capacities described with the ultimate loads for the
specimens are obtained, they are P = 7.1KN ; P = 6.5 KN and P = 12.5 KN .

Figure 5: Relationship between force and displacement on three specimens
The factor K IC can be calculated from Formula 3. They are

KIC = 52.3183Mpa m ; KIC = 48.3183Mpa m ; KIC = 74.3183Mpa m . Herein,
the minimum K IC = 48.3183Mpa m is chosen for further discussion.
4.2 Allowable stress

Considering safety factor K, the allowable stress of the steel can be

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gotten under the crack length from Formula 4.

[σ ] =

K IC
K πa

(4)

Assuming K = 2 ( K ≥ 2 ), consequently:
When crack length is 50mm, [σ ] = 86Mpa ;When crack length is 100mm, [σ ] = 61Mpa ;When crack length is 150mm, [σ ] = 50 Mpa ;When crack length is 200mm, [σ ] = 43Mpa .

5. SAFETY EVALUATION OF THE STEEL TRUSS BRIDGES

For actual stress of the steel truss members, the ANSYS software andfield dynamo-static test are adopted for analysis. The live-load considered inanalysis and test includes auto-load, human load and wind load.
Via analysis and test, the theoretical and actual stress value of somemain members can be obtained. The stress value of each case is combined
and compared with the allowable stress value of members. The results areshown in Table 3-1 and Table 3-2.
Table 3-1: Results under dead load and auto-loadStress (MPa)No.

A

U4L5 8.67
U5L4 8.67
U4L4 12.42
U1L2 83.82
U1L1 -78.32
U0L1 81.75
L4L5 42.88
U4U5 -69.30
L0L0， 84.55
L4L5 39.73

B
11.97
12.15
9.66
23.63
-22.15
19.46
11.54-19.17
15.99
10.34

C

A+B

A+C

8.00 20.64 19.97
8.40 20.82 17.07
4.20 22.08 16.62
23.70 107.45 107.52-17.20 -100.47 -95.52
14.30 101.21 96.05
10.10 54.42 52.98-18.30 -88.47 -87.60
8.60 100.54 93.15
3.20 50.07 42.93

Allowable Allowablestress 1
stress 2
130
130
145
145
145
145
145
145
145
145

50
50
50
50
50
50
50
50
50
50

Note: A means the calculating results under dead load, B means the calculating results
under auto load, C means the testing results under auto load.

In the three tables above, U4L5、U5L4、U1L2、U0L1 are inclined web
members; U4L4、U1L1 are vertical web members, and L4L5、U4U5、L0L0、
L4L5 are upper chord, lower chord, cross beam and longitudinal beam
respectively. Allowable stress 1 leaves cracks out of account but Allowablestress 2 takes cracks into account. Allowable stress 1 comes from thereference (JTJ 025-86, 1998), which is multiplied by the coefficient 2 in thetable 3-2.

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Table 3-2: Results under load case of downwind side (upwind side)
Stress (MPa)No.
A+B+ A+B+ Allowable
A
B
C (E)
D
C+D D+E stress 1(2)U4L5
8.67 11.97 -0.96 (0.97)
1.31
20.98 22.92 163 (50)U5L4
8.67 12.15 -1.43 (1.44)
1.31
20.69 22.26 163 (50)
U4L4 12.42 9.66 1.91 (-1.93)
1.30
25.29 21.45 181 (50)
U1L2 83.82 23.63 -5.05 (5.06)
7.13 109.53 119.64 181 (50)
U1L1 -78.32 -22.1516.56 (-16.57) -6.98 -90.89 -124.02 181(50)U0L1 81.75 19.46 -9.29 (9.31)
7.18
99.11 117.70 181 (50)
L4L5 42.88 11.54 -5.48 (5.48)
4.52
53.46 63.23 181 (50)
U4U5 -69.30 -19.17 -3.49 (3.46)-5.94 -97.89 -87.54 181 (50)
L0L0 84.55 15.99 12.62 (15.99) 5.19
118.35 118.35 181 (50)
L4L5 39.73 10.34 5.11 (5.11)
4.06
59.23 59.23 181 (50)Note: A means the calculating results under dead load, B means the calculating results
under auto load, C means the calculating results of downwind side under wind load, Dmeans the calculating results under human load, E means the calculating results of
upwind side under wind load.

The max stress value of each member is less than the allowable stress 1
and satisfies the requirement of the codes, which can be seen fromcomparison above. But about half of the members dissatisfy the requirementof steel strength if considering the cracks.
So, existence of cracks is an important factor which cannot but being
considered in the evaluation of steel bridge especially aged steel bridge.

6．FATIGUE CHECKOUT OF GENERAL MEMBERS

As the members of this bridge are connected by rivets, the sort of theallowable stress is considered as D, according to the reference (JTJ 025-86,
1998). The allowable stress of the members and joint can be calculated fromthe formula (5) and (6).
When the max stress is tensile stress:145
and ≤ [σ ](5)[σ n ] =1 − 0.6 ρWhen the max stress is compressive stress:145
and ≤ [σ ][σ n ] =0.6 − ρWhere: [σ ] ——basic allowable stress of steel.

ρ＝σ min σ(6)——ratio of stresses.
max

To different load case, the stress of some members, such as inclined
web members, will change between positive and minus, and these members
should be carried out fatigue checkout. The checking stress comes from
calculation results, and is shown in Table 4.

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October 2005, Singapore

Member
U4L5
U5L4
L0L0’

Table 4: Fatigue checkout of membersρσ n (MPa) [σ n ] (MPa)Sidesdownriver -0.027
20.64
142.4
upriver-0.00916.91
144.2
downriver 0.007
20.82
145.0
upriver
0.162
18.16
145.0
0.761
100.54145.0

σ n < [σ n ]
Yes
Yes
Yes
Yes
Yes

For the members without stress changing, their stresses do not exceed
the allowable stress, and so satisfies the requirement.
7．FATIGUE CHECKOUT OF CRACKING MEMBERS

The material fatigue capability research of cracking members mainly
rests with seeking the mathematical expression between the speed of crack
expansion and concerned mechanics parameter, according to the theory of
fracture mechanics (Ding, and Sun, 1997). If the number of stresscirculation is ∆N and the crack spread is ∆a , the crack expansion is∆a / ∆N (mm/time) at every stress circulation, which is called crack
expansion speed and expressed by the differential coefficient da / dN interms of limit. Commonly, the crack expansion speed can be written as
formula 7 in the event of monoaxial circulation alternative stress.
dadN= f (σ , a, C ) ，(7)

Where: N —— stress circulation number; σ —— positive stress;a —— crack length; C —— constant related with material.
According to stress intensity factor of PARIS, under high-cycle andidentical range load, the data gained from the tests can be plotted in thereference frame of lg da~ lg ∆k I after being trimmed, as shown indN
Figure 6. The curve is divided into three phases, and in the first phase, therange of stress intensity factor ∆k I is very low. When ∆k I is less than acertain limit value ∆kth , the crack doesn’t expand basically, and the limit
value ∆kth is called doorsill value of crack expansion.

Figure 6: The curve of lg

116da~ lg ∆k1
dN

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Provided that the stress ratio is the ratio of the max stress of dead load
and live-load to the stress of dead load, we know that, according to thereference (Liu, 1994), for the mild steel:KσWhen stress ratio R = min ＝ min = 0.13 ; ∆kth = 6.6 MPa m ;σ max K max

When stress ratio R = 0.35 , ∆kth = 5.2 MPa m ;When stress ratio R = 0.49 , ∆kth = 4.3MPa m ;When stress ratio R = 0.64 , ∆kth = 3.2 MPa m ;When stress ratio R = 0.75 , ∆kth = 3.8MPa m .
The middle value can be calculated through insertion method.
The doorsill stress value for crack not expanding can be worked out
from formula 8 on condition that knowing the doorsill value of certain stressratio.

[ ∆σ th ] =

∆K th
πa

(8)

Where: a —— half length of cracks, assuming a = 75mm = 0.075m
here. The checkout result is shown in Table 5.
Table 5: Fatigue checkout of cracking members
Stress (MPa)
No.

A

∆K th
R=A/
B
A+B
（ ∆σ ）（A+B） MPa m

U4L5 8.67
11.97 20.64
U5L4 8.67
12.15 20.82
U4L4 12.42 9.659 22.08
U1L2 83.82 23.63 107.45
U1L1 -78.32 -22.15 -100.47
U0L1 81.75 19.46 101.21
L4L5 42.88 11.54 54.42
U4U5 -69.30 -19.17 -88.47
L0L0， 84.55 15.99 100.54
L4L5 39.73 10.34 50.07

0.420
0.416
0.563
0.780
0.780
0.808
0.788
0.783
0.841
0.992

4.75
4.80
3.77
3.96
3.96
4.12
4.00
3.98
4.30
5.12

Doorsill
∆σ ≥
value
∆σ th
∆σ th (MPa)
9.78
9.95
7.77
8.16
8.16
8.49
8.24
8.20
8.86
10.55

Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No

Note: A means the calculating results under dead load, B means the calculating results
under auto load.

Through checking computations it can be found that the change ofworking stress of most cracking members exceeds the doorsill stress value[ ∆σ th ] . This means that the original crack will expand continuously and themembers will come forth fatigue destroy. It can be kwon obviously that thefatigue stress of cracking members is less than that of the ordinary members,
which is\about tenth that of the ordinary members.

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8．CONCLUSION

By the comparison above, it is concluded that crack is a very importantfactor steel bridge for safety evaluation. To a new steel bridge, whose
members have no cracks, the allowable stress value and the fatigue
allowable stress value, according to the current design codes, can be used toevaluate the safety of the steel bridge. However, for old or aged steel truss
bridges, such as Nenjiang Bridge which is located at Qiqihaer city in China
and has served for nearly 70 years and has been found cracks in its members,
it is not suitable to evaluate the safety using allowable stress value. It isnecessary to consider the influence of the cracks based on the theory of
fracture mechanics, and to evaluate the safety of steel bridge after having
theoretical analysis and field test.
In this paper, we analyze the safety of steel bridge only from thestrength and the fatigue. As a matter of fact, safety evaluation should betaken from more aspects including defection examination coefficient, static
defection, transverse accretion coefficient, natural period of vibration,
displacement amplitude of vibration and so on.

9．REFERENCES

Zheng, Z.X., 2003. The fatigue diagnoses and the safety evaluation systemof steel bridge, Nondestructive Testing 5, Beijing, 9-13.
Xu, J.M., Tu, W.D., Tang, G.Y., Lai, K.Y., Ren, Y.S., Shi, Y.J., Yang, Y.M.,
Li, Z.R., 1994. The natural life research of fatigue crack expansion inaged railway bridges. Journal of the China railway society 3. Beijing,106-111.
Gao, R., Jiang, L.C., and Qi, M.L., 2005. The examination report of the
Nenjiang highway steel bridge of Qiqihaer city. 1-4. Beijing.
Liu, B., 1994. Measuring Technique of Experimental Fracture And Damage
Mechanics. China Machine Press, Beijing.
Ministerial Criterion of the Ministry of Communications of the People ’s
Republic of China. 1998. Design Code of Steel Structure and Timber
Structure of Highway Bridges and Culverts JTJ 025-86. China
Communications Press, Beijing.
National Criterion of the People ’s Republic of China. 1994. High Strength
Low Alloy Structural Steels GB/T 1591-1994. Standards Press ofChina, Beijing.
National Criterion of the People ’s Republic of China. 1988. Carbon
Structural Steel GB/T 700-1988. Standards Press of China, Beijing.
Ding, S.D., Sun, L.M., 1997, Fracture Mechanics. China Machine Press,
Beijing.

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FAILURE MECHANISM OF SHIH-KANG
DAM BY APPLIED ELEMENT METHODWORAKANCHANA KAWIN
Ph.D. fellow, Institute of Industrial Science,
The University of Tokyo, Japankawin@risk-mg.iis.u-tokyo.ac.jp
KIMIRO MEGURO
Professor, ICUS, Institute of Industrial Science,
The University of Tokyo, Japanmeguro@iis.u-tokyo.ac.jp

ABSTRACTThe non-linear analysis of Shih-Kang dam by Applied Element
Method (AEM) was carried out to study the failure mechanism. According
to analysis result, Shih-Kang dam can resist a very low amount of fault
induced ground rupture and deformation. The damage mechanism starts
from the separation of the dam from its foundation, a crack from the top of
the dam, shear cracks and compression failure. The force-deformation
relationship from numerical simulation indicates the resisting force isalmost diminished after shear crack on the dam body. Parametric studies
including the changing dip angle of the fault, fault location were carried out.
In case of the reverse fault, first, the dam separate from its foundation thenfollow with the shear failure of crack from the top surface. Unlike the caseof reverse fault, the fault movement tends to break the dam by the tensile
force. The fault location affects in the shear span length of the concrete
dam which the longer shear span results in the higher resisting
displacement. A redesign of Shih-Kang dam for damage prevention was
proposed by placing the slip joint and reinforcement，FRP or expansive
agent to control the crack width.
1. INTRODUCTION
In some of the past earthquakes, many structures have been destroyed by thefault action. Among them, one of the most spectacular events is the damage
to the Shih-Kang dam in the 1999 Taiwan, Chi-Chi Earthquake. The
movement of the Chelungpu fault resulted in the M7.7 earthquake and also
produced a large scale ground surface rupture and deformation thatdamaged a lot of structures in the fault area. The Shih-Kang Dam, locatingon the fault trace, was directly hit under its foundation and was severely
damaged. Fortunately, there is no report on the damage from flooding after
dam breaking. However, it is still questionable that if a fault movement
occurs in the different dam, it may inflict the unexpected amount of damage
to lives and facilities of the people living in the downstream.

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Among all dams in the high seismicity region, there are few inlocations where faults were not recognized or suspected to exist (Sherard etal., 1974). Some of these in the active fault zones are concrete dams which
are known as low ductility material. Despite this fact, very little among
them has been designed against the possible fault movement action. The
slip joint of the Clyde dam (Hatton et al., 1987) is merely an example of thecountermeasure. For those which were not carefully designed against fault
movement, they are at risk of failure as the Shih-Kang dam if there is fault
movement.
The behavior of the concrete dam under the fault rupture is not wellunderstood since the occurrence of the event is rare. Although the ShihKang dam is the first case in the history, there are several cases that the fault
movement break near the dam location as shown by Sherard et al (1974).
The study of the concrete dam under the fault rupture has never been carriedout before.
Some of the closest to this study, both numerical andexperimental models, has been found in the study of behavior of the soil
deposit under the fault movement (Bray et al., 1994a, Bray et al., 1994b).
However, the studies were mainly to predict the deformation of the groundsurface, not to study the failure behavior of the structure itself.
Applied Element Method (AEM) is a numerical model for simulating
the structural behavior from an elastic range to a total collapse proposed by
Meguro, K., and Tagel-Din, H (1998). In AEM, a structure is modeled as
an assembly of rigid elements connected together with a zero-length normal
and shear springs. The major advantages of AEM are simple modeling andprogramming, and high accuracy of the results with relatively short CPU
time. By using AEM, highly non-linear behavior, i.e. crack initiation, crack
propagation, separation of the structural elements, rigid body motion of
failed elements and totally collapse process of the structure can be followedwith high accuracy. With these advantages, AEM will be suitable to use foranalysis of the dam under the large deformation.
The first objective of this paper is to study and understand the
behavior of the Shih-Kang dam under fault rupture. The second objective is
to carry out the parametric study including dip angle of the fault, fault
location, ground deformation shape and dam height. The last objective is to
propose the redesign of Shih-Kang dam to prevent the damage due to fault
movement.
2. SHIH-KANG DAM SITE CHARACTERISTIC AND GEOMETRY
Shih-Kang Dam is located on the Ta-Chia River in Taiwan. The damsites lies over a shallow sandy and gravelly soil deposit spreading over alaminated mass of mud stone, silt stone and sand stone of Pliocene Epoch,
Tertiary Period. The dam foundation was constructed on the underlying
rock surface under the excavated shallow sandy and gravelly soil deposit.
The dam is 25 m tall and 357 m long with 18 gates lined up, has a total

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concrete bulk of 141,300 m3. Figure 1 shows the dimension of the ShihKang Dam.

Figure 1. Shih-Kang Dam geometry (Source: Sugiyama, 2001)

Shih-Kang
Dam

Figure 2. Shih-Kang Dam and its vicinity (Source: Konagai, 1999)
2.1 Ground surface rupture and deformation in the vicinity of the dam
The fault rupture trace in the Shih-Kang area is shown in Figure 2.
Three major fault trace are composed of Line A, Line B and Line C. Line C
has crossed the northern end of the Shih-Kang Dam. The different height
between the two sides of line C is reported to be 10 m (Konagai et al., 1999).
The line B has crossed the intake tunnel of Shih-Kang Dam. This line
sheared the intake tunnel at the south of Shih-Kang Dam, completely.
According to the result from the survey (Chen-Shan et. al., 2001), theground surface of the Shih-Kang Dam has become a wavy deformation after
the Chi-Chi Earthquake. It was also reported that the downstream area has
been changed into bow-shape and up-lift terrain.

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2.2 Reported damage in Shih-Kang Dam
The full report of Shih-Kang Dam damage can be found in reference(Sugimura et. al, 2001 and Chen-Shan et. al., 2001). To give an idea on the
dam damage, the brief description is provided here. The damage in ShihKang Dam can be separated into two zones according to the level of damage
which is the zone just above the fault and far from the fault. Figure 3 shows
sketch of Shih-Kang Dam. The dam was slightly tilted spillways #15 and#16 and seriously slanting spillways #17 and #18, the latter deeply
immersed in the water. The crack distribution on the spillways is shown in
Figure 4. Major crack was observed between spillway #6 and #16. The
diagonal cracks were found on the most damaged spillway. And transverse
joints between blocks were opened in such a way that the openings on the
upstream side were wider than those on the downstream side.

Figure 3. Sketch of damage to Shih-Kang Dam (Source: Sugiyama, 2001)

1

2

Figure 4. Sketch of actual crack pattern (Source: Konagai, 2001)
3. NUMERICAL MODEL FOR SHIH-KANG DAM
The AEM mesh representing Shih-Kang dam is shown in Figure 5.
The total numbers of elements is 4578. An element size in the AEM is 1 m.
The concrete thickness varies according to the depth of the dam as shown incross-section in Figure 1. Strain energy release rate (Gcr) in concrete is
2x10-4 MN/m and Elastic modulus (Ec) is 20 GPa. The fault location isassumed at the 38 m at the bottom of the dam from the left side. The left
path of the fault is fixed and the right side is the moving one.

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4. NONLINEAR ANALYSIS
Concrete in Shih-Kang dam was not placed at the same time therefore
there are construction joints in the dam concrete. The effect of theconstruction joints will be studied in future. In this study, the dam wasmodeled by assuming that the construction joint has no effect on the dam
behavior during fault action. The input displacement in the model waschosen according to survey data (Konagai, 1999 and Chen-Shan et. al.,2001). The input displacement is composed of two parts (Figure 4). First, a
shear displacement representing the reverse fault movement of dip angle
approximately 20o (H:V=1:0.35) at the bottom boundary. The second input
is the surface deformation along the dam foundation. This deformation was
calculated from the measured deformation at the trunion girder (Chen-Shanet. al., 2001) of the dam after being damaged by assuming that there is no
gap between the dam and the bed rock.
20.0 m18@14.0 = 252.0 m

Fault location

298.0 m12.0 mApproximate bed rock curve after deformation (not to scale)φδφ

Bed rock before deformation, flat

Figure 5. Shih-Kang Dam model and input ground displacement
4.1 Crack patterns in spillways just above the fault
As shown in Figure 6(a), during the first 1 mm, the dam was separated
from its support. At this state, in case of no special treatment in the dam, it
is possible that the water will leak through this gap. At the relative verticaldisplacement (δv) between 2 sides increased to 2 mm, the crack at the top of
the dam was appeared due to tension stress from bending action. This crack
is also considered to be dangerous because it can cause water leakage if thecrack propagates below the water level. After the δv=45 mm, shear crack
was started to propagate and the dam was found to be severely damage
beyond this point (Figure 6(b)).
The further increasing applied
displacement will not largely increase strain energy in the dam however itwill generate the crack instead until the dams from both sides arecompletely separated. As a result, the flooding from the reservoir is

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possible at this state. At δv=150 mm, the remaining compression struts aredamaged by compression failure. At this point, the damage becomesseverer (Figure 6(c)). It is noted that although the dam just above the fault
becomes severely damaged, the shear transferring between each parts of thedam is still possible due to the friction of the concrete rupture undercompressive force (Figure 6(d)). However, due to the damage, the ability toretain the water is totally loss and the dam is considered to be unsafe. In thefar from fault zone, the flexural damage from the surface deformation canbe observed at δv =75 mm. These cracks are also able to cause the waterleakage from the dam. It is important to note that although the surface
deformation does not cause as high damage to the dam structure, it spreadwider and has higher opportunity to damage the dam.

Crack at the top of the dam due to tension

Separation from the support due to the tension force(a) δ= 1 mm
Tensile stress due to due to deformation of the bed rock

Brittle shear crack(b) δ= 45 mm
Flexural crack due to deformation of the bed rock

Heavily damaged and loss shear transferring capacity(c) δ= 150 mm

3

1

4

2
(d) δ= 830 mm

Figure 6. Crack patterns obtained by numerical simulation
representing the Shih-Kang Dam

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4.2 Force-displacement relationship
Figure 7 shows the force-deformation relationship of numerical model
representing Shih-Kang Dam. From position 0 to 1, the behavior is linear
and elastic. However, after the position 1, the stiffness of the curve drops
suddenly. This coincides with the separation of the dam from its support.
After the position 1, as the fault tends to lift the dam upward, the crack at
the foundation propagates further into the left side of the fault. The dam
will behave like a short beam under the shear action that causes the shear
crack at the position 2. After shear crack, the resisting shear force is almost
reduced by half however the damage area is still able to continue resisting
the shear force through the compression strut until these compression struts
fail by the compression stress.
60000062

5Force (kN) x10

55000004

01 elastic range

12 ground separation

2

3 brittle shear failure

3

4 Compression
failure of strut

40000033000001

232000004

1

100000

0
0

0.00

0.02

0.04

0.06

0.08

0.10

Displacement (m)Figure 7. Vertical force-displacement relationshipof the Shih-Kang Dam under 20o dip angle reverse fault
4.3 Crack pattern in the farther area from the fault
The cracks are the result of bending effect due to the curve
deformation of the ground surface (Figure 5(d)). These cracks propagate
from the top of the dam. As state in the previous section, this dam can also
cause the water leaking and the prevention of this crack is required in orderto keep the dam serviceability. By comparing the crack patterns to theinvestigated one, cracks from static simulation match well with the verticalcrack from the investigated one; however, the diagonal crack in the areacannot be simulated. At this state, those diagonal cracks are expected to be
the result of dynamic action. The displacement at the trunion girder was
also compared to the measured one (Chen-Shan et. al., 2001). The
comparing result shows a good agreement between observed and themeasured one.
4.4 Comparison to the actual damage
Figures 4, 6 and 8 show the comparison of between real damage andcrack distribution obtained by AEM. The crack distribution obtained from
AEM in the zone just above the fault is very similar to actual damage in the

Failure mechanism of Shih-Kang Dam by Applied Element Method125

October 2005, Singapore

Shih-Kang Dam as can be seen at the locations 3 and 4 in Figure 6(d), 8(a)and 8(b), respectively. For the far from fault zone, the AEM result shows
the cracks in the transverse joint between block in the same area as in theactual damage however the diagonal cracks is not exhibited. It is expectedthat this crack comes from the movement perpendicular to the dam axes,
torsion or dynamic effect.

3

4
(a)

(b)

Figure 8. Damage to Shih-Kang dam above the fault(Source: Jack, Yung-Wan Lien, 1999)
5. PARAMETRIC STUDY
In this section, the parameters that may affect the Shih-Kang dam
behavior and damage under fault action are studied. The parameters
including dip angle, fault location and the underlying bedrock are selected.
5.1 Effect of dip angle of the fault
The numerical model representing Shih-Kang Dam was subjected tofault movement with the different dip angles. The dip angle was varied
from 30o, 45o, 60 o, 70 o (approximation of actual case) to 90 o for reverse
fault and 30 o, 70 o and 90o for the normal fault. The failure behavior of thedam in each case is explained as the followings:
5.1.1 Reverse fault
From the numerical result of the dam subjected to the reverse fault, it
was observed that, regardless of the fault dip angle, the dam has the same
failure pattern i.e. starting from the separating of the dam from thefoundation. Then, the shear crack appears in the dam and compressive
failure. With different dip angle, it was noted that shear crack occurs in thedam at smaller displacement for larger dip angle.
5.1.3 Normal fault
Unlike the case of reverse fault, normal fault causes tensile stress inthe dam. This tensile stress can cause the separate of the dam from the126

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foundation. Because concrete is weak in tension, the dam failure at thesmaller displacement compared to reverse fault case.
5.2 Effect of fault location
In this section, the effect of faulting location is studied. In the actual
damage, the fault location is near to the left end of the dam. It is interestingthat how the faulting location affects on the failure behavior of the dam.
The numerical model representing the Shih-Kang Dam was subjected to the
70o dip angle at (a) the middle and (b) the other end of the dam. In case(a), fault was moved from the left side in the previous analysis to the centerof the dam. The damage also occurred at the center of the dam at 3 mm
which is the same as in the previous case. However, this crack propagatedfurther into the left side of the fault. At the δr=6 mm, crack started
propagating from the top of the dam. At δr=310 mm, it was found that thebrittle shear failure occurred and crack passed through all section. Later, thedam was totally separated as shown in Figure 9. Comparing this to the casethat the fault was applied at the left end, the dam could resist higher amountof the fault displacement (150 mm). In case (b), the same failure
mechanism was observed however a slightly increasing in displacement wasobserved at the total separation (410 mm). However, because the shear
force was transferred through the longer span, the total damage to the dam
occurred at the larger deformation

Figure 9. Crack patterns on the dam in case that fault movement
Occurs at the other end of the dam
6. REDESIGN OF THE SHIH-KANG DAM TO ACCOMMODATETHE FAULT MOVEMENTFor Shih-Kang Dam to survive, it must be able to resist both surface
rupture and deformation.
The Shih-Kang Dam was redesigned toaccommodate the 11 m of reverse fault (Figure 10). Two adjustments havebeen added to the previous design. First is to add slip joint in the samemanner as one constructed in Clyde dam (New Zealand), to accommodate
the 11 m movement and the second is to place reinforcement, FRP or
expansive concrete to control the crack width of the dam.
7. CONCLUSION
The static non-linear analysis of the Shih-Kang Dam was carried out.
Parametric study including dip angle of the fault, fault location were studied.
Also, the redesign of Shih-Kang dam was proposed. It was found that

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Concrete dam like the case of Shih-Kang Dam can resist very low amountof fault induced ground rupture and deformation. From numerical result,Shih-Kang dam damage mechanism starts from the separation of the damfrom its foundation, crack from the top of the dam, shear crack andcompression failure. According to the parametric study, it was found thatthe normal fault, if occur under the dam will damage the dam at the lower
displacement than the reverse fault. Also, different fault location affects inthe different shear span length. The longer the shear span’s length, the more
displacement the dam can resist. The proposal for the rehabilitation of ShihKang dam is proposed by placing the slip joint and reinforcement, FRP or
expansive concrete to control the crack width of the dam. To place the slip
joint, the accurate knowledge of fault characteristic in the area must be
known.
Slip joint to accommodate 11 m movement
Reinforcement, FRP or expansive
Drainage system to prevent the corrosion from the leakage water
Figure 10. Redesign of Shih-Kang dam
REFERENCES
Bray, J. D., Seed R. B. and Seed H. B. (1994a). “Earthquake Fault Rupture
Propagation through Soil.” J. Geotech. Eng., 120(3), 543-561.
Bray, J. D., Seed R. B. and Seed H. B. (1994b). “Analysis of Earthquake
Fault Rupture Propagation through Cohesive Soil.” J. Geotech. Eng.,
120(3), 562-580.
Broek D. (1986) Elementary Engineering Fracture Mechanics, 4th Ed.,
Martinus Nijhoff Publishers, Boston
Chen-Shan K., Wei-Pin, N., Yun-Jen, C., (2001). “Damage andRehabilitation work of Shih-Kang Dam.” Seismic Fault Induced Failures,Tokyo, Japan, 33-48
Jack, Yung-Wan Lien (1999). Taiwan Chi-Chi Earthquake 9.21.1999,
Bird’s Eye View of Cher-Lung-Pu Fault, 1st Ed., Sino-Geotechnics
Research and Development Foundation.
Konagai, K., Miura, S., and Sugimura Y. (1999). Reconnaissance Report ofthe 1999 JiJi Earthquake, Taiwan (1st draft), Japan Society of Civil
Engineers
Meguro, K., and Tagel-Din, H. (1998). “Applied Element Simulation of RC
Structures under Cyclic Loading.” J. Struct. Eng., 127(11), 1295-1305.
Sherald, J. S., Cluff L. S. and Allen C. R. (1974). “Potentially Active Fault
in Dam Foundations.” Géotechnique., 24(3), 367-428.
Sugimura, Y., Miura, S., and Konagai, K. (2001). “Damage to Shihkang
Dam Inflicted by Faulting in the September 1999 Chichi Earthquake.”
Seismic Fault Induced Failures, Seismic Fault Induced Failures, Tokyo,
Japan, 143-154.

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UTILIZATION OF NEAR-INFRARED
SPECTRAL IMAGING SYSTEM FOR
INSPECTION OF CONCRETESTRUCTURESHISASHI KANADA1, YUKIHIRO ISHIKAWA2, TAKETO UOMOTO1
1
International Center for Urban Safety Engineering,
Institute of Industrial Science, The University of Tokyo, Japan2
Department of Civil Engineering, Graduate School of Engineering
Shibaura Institute of Technology, Japan
kanada@iis.u-tokyo.ac.jp

ABSTRACT
Recently, the authors have developed a new non-destructive
inspection method for concrete structures using near-infrared [NIR]
spectroscopic technique. Near-infrared [NIR] spectroscopy had beendeveloped in the area of food and agriculture. Electromagnetic waves areabsorbed or reflected from any substance depending on the characteristicsof their components. Therefore, unknown components can be estimated if its
optical properties have been understood. This enables us to obtain chemical
information of concrete by just sensing reflected near-infrared rays from themeasuring plane.
Since typical spectrometer can measure only spectral information of
one point, a new near-infrared spectral imaging system was assembled toscan a large area using equipment already available. This system consistsof near-infrared irradiation equipment, imaging spectroscope and nearinfrared CCD camera. Dispersed near-infrared rays through thespectroscope can be received in each wavelength by light-sensitive element
on CCD camera. Clear spectral images can be captured due toimprovement of performance. This paper describes how to obtain
distribution of deleterious substances of concrete from spectral image, andintroduces experimental results.

1. INTRODUCTION
The market for maintenance and repairing existing structures in
Europe and America accounts for approximately 30 to 50 percent of theentire construction market. This percentage is expected to increase further inthe future. In the case of social infrastructures, the inspection area is large
and environmental condition or location may be tough, therefore, it often
requires high labor and cost in order to inspect concrete structures.
Therefore, efficient and low-cost inspection methods are required formaintenance. Many non-destructive inspection methods have recently been129

October 2005, Singapore

developed for concrete structures. However, these methods can obtain only
physical information of concrete, such as crack depth, delamination or
position of reinforcement etc. near its surface. For example, delamination orloose portion of concrete can be detected by using the infrared
thermography method, and the ultrasonic method is used for measurementof crack depth. Core boring or sampling may be carried out forcomponential analysis in order to cover the lack of chemical information.
Remote non-destructive componential analysis using spectroscopy
would prove to be a powerful tool for inspectors. This enables us to scan
distribution or concentration of deleterious substances two-dimensionally.
Availability of this system for inspection of deteriorated concrete has been
corroborated by experimental results.

2. COMPONENTIAL ANALYSES FOR INSPECTION OF
CONCRETE
Considering the deterioration mechanisms of concrete, degenerationof cement hydrates or penetration of detrimental constituents are main cause
except in case of fractures due to external force or use of harmful aggregates.
Carbonation and chloride attack are typical deterioration causes, therefore,carbonation depth and chloride content are often measured in order to assess
serviceability of concrete structures. This information can not be obtained
remotely and instantly, advantages of spectroscopic technique are shown
below compared to traditional methods
2.1 Traditional analytical methods for concrete components
Carbonated area can be colored by spraying phenolphthalein alcohol
solution. This method is usually carried out as a simple test. EPMA analysis
is performed to detect target element if necessary, in the case of carbonation,
two dimensional distribution of carbon should be measured.
Chloride content in concrete is an important index indicating the statusof reinforced concrete. This is measured by potentiometric titration methodor fluorescent X-ray analysis. Chloride penetration area can be estimated byspraying silver nitrate solution on a concrete surface, chloride in concrete
reacts with silver to produce white colored silver chloride which determines
the area containing chloride. EPMA analysis can also be carried out tomeasure distribution of chloride. Except for spray method, thesecomponential analyses require pretreatment, labor, time or reagent.
Moreover, it is difficult to measure in the field as equipments are notdesigned for field use.
2.2 Advantages of near-infrared spectroscopy
Near-infrared spectroscopy has some advantages compared to
traditional componential analyses. This method can measure objects directly
and non-destructively without pretreatment of sample or chemical agent.
Unknown components and their concentration can be estimated instantly if

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their optical properties are known. This is a low-energy, pollution-freeenvironment-friendly, cost effective inspection method which operates
efficiently. Two-dimensional measurement is realized through theintroduction of near-infrared spectral imaging system. Table 1 shows thecomparison between near-infrared spectroscopy and traditional
componential analyses.

Table 1 : Comparison between near-infrared spectroscopy andtraditional componential analyses

Sampling
Analyzingarea
Duration ofanalysisAnalysis
methodChemical
agent
Field use
Pretreatment
Equipment
Cost ofanalysis
3.

Traditional componential
analyses
Destructive, chipping
Fixed point

Near-infrared spectroscopy
Remote, non-destructive
Two-dimensional
distribution.

Long

Short

Different methods are
required to detect target
component

Multi-component
simultaneous analysis

Use

NonuseUnsuitable
Required
Inside installation

Suitable
Not required
Field use, handy type

High

Low

DETECTION OF DELETERIOUS SUBSTANCES BY
NEAR-INFRARED SPECTROSCOPY

Causes or grades of deterioration can be estimated from presence of
substances such as chloride, calcium carbonate, calcium sulfate, alkali silica
gel, rust etc. on concrete surface. In this research, steel corrosion due tocarbonation, chloride penetration and sulfuric acid attack were primarily
focused upon, and spectrum change due to deterioration was investigated.
3.1 Near-infrared spectrum change due to deterioration of concrete
Spectrum changes of concrete due to deterioration were observed
from experimental results (Kanada et al., 2004). Figure 1 shows spectrum
changes due to deterioration of concrete. Increase of absorbance at 2266nm
can be observed as chloride content increases. This behavior is attributed to
the fact that the vibration mode of cement hydrates is changed by the actionof chloride. 2266 nm can be selected as characteristic waveband to quantify
chloride content of cement paste.

Utilization Of Near-Infrared Spectral Imaging System For Inspection Of Concrete Structures131

Absorbance: A=log(1/R)

October 2005, Singapore

0.4

Normal concrete
Chloride containing concrete
Carbonated concrete
Deteriorated concrete due to sulfate attack

0.35

Deteriorated concretedue to sulfate attack

0.3
0.25
0.2

Chloride containing concrete
1410nm 1750nm
2266nmNormal concrete

0.15
Carbonated concrete

0.1
500

1000

1500
2000
Wavelength (nm)2500

Figure 1: NIR spectrum change due to deterioration
Decrease of absorbance at 1410nm can be observed due tocarbonation. Ca(OH)2 in hydrated cement changes to CaCO3, therefore,
absorption properties of hydroxyl (-OH) were found absent. Absorption
peak at the wavelength is caused by 1st overtone spectroscopy of thehydroxyl stretch vibration in calcium hydroxide. Wavelength of 1410nm
can be selected as characteristic waveband to verify carbonation.
Deterioration due to sulfuric acid is often concern for sewage
treatment equipments or structures in hot-spring area. Calcium sulfate
dihydrate is produced due to chemical reactions between calcium hydroxideand sulfuric acid (equation 1).
(1)
Ca(OH)2+H2SO4→CaSO4·2H2O
Some optical absorption peaks can be observed after deterioration due
to sulfate attack and absorption peak at 1410nm was found to be absent due
to neutralization. Wavelength 1750nm was selected as characteristic
waveband to verify deterioration caused by sulfuric acid since compared toother peaks, it was independent and clear (F. M. Howari, et.al., 2002).
Specific wavelengths were selected to detect deterioration factors (Table 2).
Table 2: Specific wavelengths to detect deleterious substances
Wavelength
Mechanism
Absorbance at 2266nm increases as
Chloride penetration
2266nmchloride content increases.
Absorbance at 1410nm decreases due
Carbonation
1410nmto carbonation.
Absorbance at 1750nm increases due
Sulfate attack
1750nmto deterioration by sulfate attack

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3.2 Introduction of near-infrared spectral imaging system
Near-infrared spectral imaging system was introduced in order todetect distribution or concentration of deterioration factors remotely.
Deteriorated area can be detected to capture spectral image of specificwavelength because deleterious substance absorbs (reflects) NIR ray at the
wavelength, then the area appears dark (bright). In case of chloride
penetration, chloride containing cement paste absorbs NIR ray of 2266nm,
so high chloride concentration area is captured as dark. Similarly,
carbonated area appears bright when spectral image of 1410nm is captured,and sulfate attacked area appears dark by capturing spectral image at
1750nm.
Absorption properties at specific wavelength is in proportion toconcentration of deleterious component. If its absorption properties areproperly understood, concentration of target can be estimated by analyzing
spectral images. 2nd derivative spectrum is commonly used for regression
analysis when NIR spectrum is measured by spectrometer. Unfortunately,
resolution of NIR spectrum obtained by current spectral imaging system is
not high, therefore, difference spectrum is introduced to estimate
concentration of target component. Figure 2 shows relationship between
difference spectrum and chloride content of cement paste.
Differences of absorbance from reference (0.0kg/m3) at 2266nm are

0.265

3
0.0kg/m3
3
4.5kg/m3
3
9.0kg/m3
3
16.0kg/m3
3
20.0kg/m3
330.0kg/m3

0.26
0.255

30

m3

20

.0 k
g/ m
3
16
. 0k
g
9.0kg 3 /m 3/m
4.5kg/m3
3
0.0kg/m

Chloride content

0.25
Difference spectrum

2266nm

0.245
0.24
0.235
2230

.0 k
g/

2240

2250 2260 2270 2280
Wavelength (nm)

2290

2300

Figure 2: Difference spectrum of chloride containing cement paste
treated as difference spectrums. In case of spectrum imaging system,
difference spectrum can be calculated from shading of three spectral images.
Two values (wavelengths) that do not shift, even if its concentration
changes, should be selected around specific wavelength. The baseline canbe drawn by connecting the two selected points, length of perpendicularfrom the absorption peak is adopted as difference spectrum (Figure 3).

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October 2005, Singapore

c
Con

Ab

Co

atio
entr

n(3)
)
n(2
o
i
t
ra

nt
nce )
o
C
(1 A
ion
c
t
a
r
t
n
nce

∆Ab

AbsorbanceDifference spectrum

Absorption peak

Aa

λa

∆λ

λb

λc

Wavelength
Figure 3: How to obtain difference spectrum
Difference spectrum of absorption peak:∆Ab can be calculated fromthree absorbances (equation 2). Observed absorbance depends on color orroughness of measuring plane, this can remove the baseline offset and slopeof the turbid interference.
A − Aa∆Ab = Ab −  Aa + c
× (λb − λa )
(2)
∆λ


3.3 Results of laboratory experiments
Laboratory experiments were carried out in order to verify theperformance and availability of NIR spectral imaging system. Reflected
near-infrared light from measuring plane through the spectroscope is
received, and then spectral image at arbitrary wavelength can be shown.
Specific examples are described follow to illustrate actual measurement.
3.3.1 Estimation of chloride content of cement paste from spectral images
Reference standard samples should be prepared in advance,
concentration of unknown sample can be estimated by referring topreliminary test results. In this experiment, φ5 mm in size, of chloride
containing cement paste specimens were prepared for reference. Figure 4
shows scanning of NIR spectral images of reference standard samples.
Figure 5 shows chloride content and spectral image of reference standard
samples. Concentration difference of chloride can not be observed from raw
spectral image.

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Reflecting
mirrorSpectral Imaging System

NI
R

Reference standard
samples

lig

ht

so
u

rc
e

Figure 4: Actual scanning of NIR spectral images of reference standard samples
Chloride content of reference samples
3.0kg/m3

Spectral image of reference samples

1.5kg/m3 0.0kg/m3

12.0kg/m3 9.0kg/m3 6.0kg/m3

20.0kg/m3 16.0kg/m3

Figure 5: Chloride content of reference standard samples

Difference spectrum image(Monochrome image)

Difference spectrum image(Color gradation)

kg/m3
20.0

15.0

10.0

5.0

0.0

Figure 6: Difference spectrum image of reference standard samples

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Difference spectrum image was introduced using the equation (2) toestimate chloride content of surface (Figure 6). The figure on the left ismonochrome image of difference spectrum, black pixels indicate low
concentration, gray pixels indicate high concentration. Right figure is
gradation image colored concentration level, distribution can be visualized.
Clear image could not be obtained due to noise, but it will be improved toincrease its performance. It was confirmed that the average different
spectrum of each specimen depends on chloride content from spectral
analysis.
EPMA analysis is commonly applied to detect chloride penetration(Figure 7). However, processes of polishing or carbon coating are required
before analysis, it takes a long time to obtain the result. NIR spectral
imaging system may be used as alternative procedure of EPMA, this may beable to reduce the analysis time.
Result of EPMA analysis(Target : Cl)

Sliced concrete sample
Cl
Concrete exposedto the splash zone

Figure 7: Result of EPMA analysis of concrete exposed to the splash zone
Spectral image(2266nm)Difference spectrum image Difference spectrum image(Color gradation)(Monochrome image)

0

5

(cm)

Figure :8 Difference spectrum images of sample
Figure 8 shows difference spectrum images of sliced concrete sample
exposed to the splash zone. It was observed that chloride penetrated fromtop surface. Good agreements between penetration area detected bydifference spectrum image and result of EPMA analysis were observed.
Potentiometric titration method was also carried out to confirm the validity

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of concentration which was estimated from spectral images. Figure 9 shows
comparison of estimated chloride content from difference spectrum withresults of petentiometric titration, approximate agreement can be seen.
3.3.2 Detection of deteriorated area due to sulfuric acid attack
Chloride content (kg/m 3)

18.0

Estimated from difference spectrum image
Obtained by Potentiometric titration method

16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
0.0

1.0

2.0 3.0 4.0 5.0 6.0
Distance from top surface (cm)

7.0

8.0

Figure :9 Comparison of chloride content obtained from difference
spectrum with potentiometric titration method
Prepared two specimens (cement paste bar and mortar bar) were
soaked in 10% sulfuric acid solution, calcium sulfate dihydrate wasproduced on surface. Deteriorated area due to sulfuric acid attack can bedetected by capturing spectral image at 1750nm. Difference spectrum at1750 nm increases as deterioration level increases as production of calcium
sulfate dihydrate rises (Figure 10).
3.3.3 Application of quality control of coating agents
Level of deteriorationHigh

Difference spectrum image(Color gradation)

Low

Difference spectrum image(Monochrome image)
Soaked in sulfuric acid

Paste barMortar bar

Spectral image(1750nm)

Figure :10 Detection of deteriorated area due to sulfuric acid attack
Surface coating agents are often used for the purpose of curing, butsome of them are crystal-clear type, therefore it is difficult to investigate byvisual check whether specified quality is achieved or not. Investigation ofconcentration of coating agent on concrete surface was attempted byspectral imaging system. Coating agent of water dilution type (ethylenevinyl acetate copolymer) was adopted as sample. Diluted coating agentswith water were painted on surface of mortar bar. This agent has the featureof absorption properties at 2138nm, absorption peak at the wavelength iscaused by [=C−H] and [+C=C] stretching vibration in the agent. Quality ofcoating can be estimated by spectral imaging system since difference

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October 2005, Singapore

Visible image

Spectral image(2138nm)Difference spectrum image Difference spectrum image(Color gradation)(Monochrome image)No coating
1:4

1:1

1:3

1:0.5

1:2 undiluted
Dilution ratio (weight)
coating agent : water

Concentration
Low

High

Figure 11: Quality check of coating agent by spectral imaging
spectrum depends on the concentration (Figure 11). Although volume ofcoating agent per area was adjusted, density could not be kept constant due
uneven coating. It was confirmed that the average difference spectrum insquare depended on concentration of coating agent. This technique will beutilized for inspection of finishing on concrete surface.

4. CONCLUSIONSIt has been shown that distribution of deterioration factors such as
sulfuric acid attack or chloride penetration can be detected from theirdifference spectrum images. Compared with traditional analytical methods,
the accuracy of estimated values by spectral imaging system were
acceptable. If the sensitivity of light detecting element on the system isimproved, noise will be reduced and stable measuring will be possible.
Application of field measurement is an issue in the future

ACKNOWLEDGEMENTS
Measurement of NIR spectrum and scanning by NIR spectral imaging
system were supported by Sagara lab, The University of Tokyo and JFE
Techno-research Corp. EPMA analysis was carried out by Mr. Tomio
Hoshino, Institute of Industrial Science, The University of Tokyo.

REFERENCES
Hisashi Kanada, Yukihiro Ishikawa and Taketo Uomoto, 2004.
Development of New Method to Detect Deleterious Substances ofConcrete Using Near-infrared Spectral Imaging System. The FirstInternational Conference of Asian Concrete Federation
F. M. Howari，P. C. Goodell，S. Miyamoto：Spectral Properties of Salt
Crusts Formed on Saline Soils. Journal of Environmental Quality，
31:1453-1461, 2002.

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INTERNAL DAMAGE OF REINFORCED
CONCRETE AND CHEMICALLYPRESTRESSED CONCRETE UNDERUNIAXIAL LOADRAKTIPONG SAHAMITMONGKOL
Graduate School of Civil Engineering, the University of Tokyo, Japansahamit@iis.u-tokyo.ac.jp
TOSHIHARU KISHI
Institute of Industrial Science, the University of Tokyo, Japankishi@iis.u-tokyo.ac.jp

ABSTRACT
Deterioration of structure is a major problem in most mega cities. In
several cases, the mechanical damage such as flexural cracks or splitting
cracks caused by external loads can accelerate the ingress of thedeteriorating substances. The chemically prestressed concrete (CPC) has
been used to suppress cracking of concrete structure. The outstanding
cracking resistance and structural properties of CPC have been reported inpast researches. Those studies indicate that the application of CPC is one ofthe promising methods to control the durability and structural performanceat the same time. However, the resistance to splitting cracks and internal
damage has not been studied so far.
The study on the damages of RC and CPC under uniaxial loads wastherefore done. The terms ‘damage’ includes both transverse crack, splitting
crack, and internal crack (or damage condition around rebar). It isreconfirmed that CPC can reduce number of transverse cracking even when
the reinforcement already yielded. The occurrence of splitting crack load issuppressed to higher load when compared with the case of RC. However,
the attention should be paid to the fast growing of splitting cracks of CPC
once they formed. The internal cracking condition was visually observed byinjecting ink into specimens during loading and split the loaded specimens
by concrete cutter. The results show that CPC can inhibit the propagation ofinternal cracks to surface. However, there is no clear difference in shape ofinternal cracks between RC and CPC.

1. INTRODUCTION
Cracking is probably the most unfavorable properties of reinforced
concrete (RC). Once crack takes place in the structure, the durability andaesthetic condition can be severely downgraded. It is very difficult tocompletely prevent cracking in RC structure because concrete is weak under
tension and cracking can be created by numerous reasons. However, it isrecommended, in the limit state design, that the crack width of RC should be139

October 2005, Singapore

limit under a certain value which is decided based on environmental
condition and function of structure.
The employment of expansive concrete is one of well-known methods
to improve structural performance and resolve cracking problems (Okamura,1978). The usage of expansive concrete can be categorized broadly into theshrinkage compensating concrete, of which the expansion rate isapproximately 200 µ and chemically prestressing concrete of which the
expansion rate is between 200 µ and 700 µ (JSCE, 1994). The shrinkage
compensating concrete is widely used to solve the cracking problem caused
by volume change of concrete while the chemically prestressing concrete isused to induce the prestress in structure. However, there has been a lot of
research showing the outstanding performance of chemically prestressed
concrete (hereinafter, CPC) which is not explainable by the effect ofprestress. A brief review on a unique performance of CPC is made in next
section.
Although several properties of CPC to transverse cracking have been
considerably investigated, there has been no investigation on the splitting
cracks and internal damage condition of CPC. This study is thus an attempt
to investigate the cracking behaviors of CPC under uniaxial load, especiallythe splitting crack and internal damage which is not observable externally.

2. CRACKING BEHAVIOR AND STRUCTURAL PERFORMANCEOF CHEMICALLY PRESTRESSED CONCRETE
2.1 Deformability of Restrained Expansive Concrete
When the expansive concrete is well restrained, special tensile
mechanical properties can be largely evolved. The non-linear tensile
properties and remarkable plasticity can be achieved. Hosoda (2001)
showed these properties of restrained expansive concrete under both
uniaxial tensile loading and under flexure. These properties are referred asthe ‘deformability’ which cover the nonlinearity, plasticity, and timedependent deformation. It was proposed that this deformability of restrained
expansive concrete is a result of the uneven distribution of strain cause by
the expansion of expansive additives and different rate of reaction between
cement and expansive additives.
2.2 Cracking Properties of Flexural CPC Member
The superior cracking resistance of CPC under flexure has beenreported (Sahamitmongkol, 2003). It was shown that CPC can increasecracking load, control crack width while reduce number of cracks at thesame time. The experimental result indicates an outstanding performance of
CPC to resolve cracking problem. Although the cracking resistance, whichis, higher cracking load and smaller crack width of CPC, is partly increased

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due to the effect of prestress, the effect of prestress can not clearly explain
how CPC reduce number of cracks.
2.3 Tension Stiffening Effect of CPC
The superior tension stiffening effect of CPC was reported(Sahamitmongkol, 2004). It was shown that the abrupt reduction of average
concrete strain at cracking could be prevented in CPC. This behavior
identifies an ability of CPC to reduce the redistribution of CPC whencracking takes place and implies that the stress distribution of concrete incracked portion of CPC should be different from that of RC. Outstanding
performance of CPC is also observable in the post cracking condition atwhich the tension stiffening effect of RC is normally reduced by thedeterioration of bond between reinforcing bar and surrounding concrete.
2.4 Local Bond Distribution of CPC under Tension
As the tension stiffening effect of CPC implies the different bonding
properties of CPC, the strain distribution of rebar embedded in RC and CPC
under uniaxial tension were measured in order to inspect the bonding
properties of CPC (Sahamitmongkol, 2005). CPC show clearly different
strain distribution of reinforcing bar which results in the smaller elongation.
This observed bonding characteristics can be used to explain how tension
stiffening effect is improved in CPC.
2.5 Influence of Internal Damage Condition on the Maximum Crack
Spacing of RC
There have been some studies on the maximum crack spacing of RC.
It was experimentally shown that the cover thickness and the distance
between longitudinal tensile reinforcing bars are the most important factors
influencing the maximum crack spacing (Kakuta, 1970). However, therelationship between maximum crack spacing and cover thickness isdifferent for various types of reinforcing bars. The additional experimental
information was shown by Goto (1980) that the shape and spacing of lug
significantly affects the maximum crack spacing of RC. These studies on
the maximum crack spacing indicate that the maximum crack spacing isshorter when the condition is easier for internal crack to form and propagate
to the surface.

3. EXPERIMENTAL PROGRAM
Based on aforementioned reviews, it is most likely that the longer
crack spacing of CPC is governed by its internal cracking condition. In
order to investigate this internal cracking condition, RC and CPC prisms
with different length, and size of reinforcing bar were produced. Notches
were created in the specimens to control the location of transverse primarycrack at different spacing. By specifying the distance between adjacenttransverse cracks, the maximum crack spacing can be obtainedInternal Damage of Reinforced Concrete and Chemically Prestressed Concrete Under Uniaxial Loads

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experimentally. The specimens were loaded under uniaxial tension and theinternal damage conditions were observed by cutting specimens after
loading.
3.1 Specimens
The RC and CPC prisms with different sizes of reinforcing bar andcross sectional area were produced. The reinforcing bars were located at thecenter of specimens. Steel plates were provided to ensure the chemicalprestressing effect at the ends of all CPC specimens and C-N and D-N. The
holes with a diameter of 4 mm were made at 30 mm on both side of rebar(on the direction of lugs). These holes are provided to allow the injection of
red ink during loading. Table 1 is a list of all specimens and Figure 1 is the
profile of specimens.
Table 1: List of specimens
Name

Type ofSpecimen

Type ofConcrete

Rebar

A-N
A-E
B-N-1
B-N-2
B-E-1
B-E-2
C-N
C-E
D-N
D-E

A
A
B
B
B
B
C
C
D
D

NormalExpansive
NormalNormalExpansive
Expansive
NormalExpansive
NormalExpansive

D29
D29
D29
D29
D29
D29
D19 - 1
D19 - 1
D19 - 2
D19 - 2

Cross
Sectional
Area
200x200 mm2
200x200 mm2
100x100 mm2
100x100 mm2
100x100 mm2
100x100 mm2
100x100 mm2
100x100 mm2
100x100 mm2
100x100 mm2

c/d ratio
3.00
3.00
1.25
1.25
1.25
1.25
2.12
2.12
2.12
2.12

Figure 1: Profile of specimens
3.2 Materials
3.2.1 Concrete
The mix proportions of conventional concrete and expansive concrete usedin this study are given in Table 2.

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Table 2 Mix proportions and compressive strengths
W/(C+E)
s/a
Unit Content (kg/m3)
(%)
(%)
W
C
E
S
NC
50
48
165
330
0
860
EC
50
48
164
268
60
860
Note: NC: normal concrete, EC: expansive concrete

G
956
956

Strength
(MPa)
40.15
33.97

3.2.1 Reinforcing bar
In this experiment, the screw shaped steel bar is used as the reinforcement.
There were three types of reinforcement used in this experiment. The
geometries and yielding strength of reinforcing bar are shown in Figure 2
and Table 3.

Figure 2: Shape of reinforcing bars
Table 3 Dimensions and properties of reinforcing bars
Cross Section

Rebar

Yielding
Strength
(MPa)

Area
2
(mm )

Davg
(mm)

D
(mm)

B
(mm)

Shape of Lug
C
(mm)

P
(mm)

H
(mm)

T
(mm)

D29

390

642.4

28.6

32.1

26.6

27.2

12.0

2.45

11.4

D19 - 1

390

286.5

19.1

21.5

17.5

18.0

8.0

1.75

8.4

D19 - 2

700

286.5

19.1

21.5

17.5

18.0

8.0

1.75

8.4

3.3 Curing, Loading, Measurement, and Observation of Internal
DamageThe specimens were kept under moist curing after the removal offormwork at 24 hours until the loading at 28 days. Before loading the red
ink is injected into the holes inside specimens. The specimens were
subsequently loaded monotonically under direct tension. The strains at 20mm from both side of each notch were measured in lateral direction in orderto detect the occurrence of splitting and opening of splitting cracks. Afterloading, the specimens were cut by diamond-sawed concrete cutter. The
visual observation of internal damage condition was done. The shape ofinternal cracks and general damage conditions were visually compared.

4. EXPERIMENTAL RESULTS
4.1 Maximum Crack Spacing
Because the distance between adjacent notches were varied, the maximum
crack spacing of each specimen can thus be determined as the maximum
crack spacing in which no transverse cracking took place. Table 4 shows the
maximum crack spacing obtained in this experiment. It is clear that that thecrack spacing of CPC is longer than that of RC. The increment of yielding
strength of reinforcing bar from 390 to 700 N/mm2 slightly reduces theInternal Damage of Reinforced Concrete and Chemically Prestressed Concrete Under Uniaxial Loads

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maximum crack spacing. The maximum crack spacing of CPC isapproximately 30% longer than that of RC in this experiment.
Table 4 Maximum Crack Spacing of specimen in series C and D
Specimens
C-N
D-N
C-E
D-E

Maximum Crack Spacing
22 cm
20 cm
28 cm
26 cm

4.2 Splitting Crack
The splitting cracks could be observed from the strain value measured inlateral direction at 20 mm from notches. The occurrence of splitting crack
was attained as the point where a sudden change of strain is observable andopening rate of splitting crack were achieved from the increment of thesestrains.
4.2.1 Occurrence of splitting cracks
The stress of reinforcing bar when the splitting crack took place is displayedin Figure 3. The cover to diameter (c/d) ratio significantly affects theoccurrence of splitting crack. It is easier for splitting cracks to form in thespecimens with thinner cover. In addition, the occurrence of splitting cracksof the shorter cracked portion occurs at higher stress of reinforcing bar. It isalso interesting that the stress of rebar at the occurrence of splitting cracks
can be increased to almost double of that of RC when CPC is employed.

Figure 3: Shape of reinforcing bars

4.2.2 Growth of splitting cracks
The growth of splitting cracks of RC and CPC with c/d ratio of 1.25 isshown in Figure 4. As discussed in previous section, the splitting crack took
place at lower load in RC; however, the splitting crack of RC grew atmoderate rate. In the other hand, although the occurrence of splitting crack
could be observed at higher load in CPC, its growing rate is much faster

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than that of RC. This result indicates that the special attention should be
paid to splitting crack of CPC once it takes place. Providing suitabletransverse reinforcement should be one of the proper countermeasures on
this behavior of CPC.

Figure 4: Opening of splitting cracks of RC and CPC with c/d of 1.25
4.3 Internal Cracking Condition
The internal damage conditions of RC and CPC are shown in Photo 1 andPhoto 2, respectively. As can be easily observed, the additional transverse
cracking was generated between transverse cracks formed at predetermined
notched positions. The bond deterioration area can be observed from thewhite area in the photos. The large bond deterioration area is perceivable atthe location of additional transverse crack.

Photo 1: Internal damage condition of RC with c/d of 1.25

Photo 2: Internal Damage Condition of CPC with c/d of 1.25

Internal Damage of Reinforced Concrete and Chemically Prestressed Concrete Under Uniaxial Loads

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In the case of CPC, the internal cracking could be observed between
predetermined notched locations. However, this crack did not penetrate to
the surface and, as the results, there is no bond deterioration area observed.
Nevertheless, the large deterioration can be observed at predetermined
notched location because of the occurrence of splitting crack. It is, however,important to note here that the condition illustrated by these photos is the
final condition and does not give any information about the process how thisdamage develops. As indicated by the splitting crack in previous section, it
is possible that the bond deterioration of CPC should be very small up to acertain load and increases rapidly afterwards. This behavior implies that
CPC can still perform very well if applied to the suitable range of load.

5. CONCLUSION
CPC shows the notable ability to suppress the propagation of internal cracks
to surface and the occurrence of splitting cracks. However, the special
attention should be paid when CPC is subjected to relatively high load. The
rapid damage can take place if the load is increased beyond a certain level.
Providing transverse reinforcement should be an effective countermeasure
to this limitation of CPC.
REFERENCES
Okamura, H., et al., 1978. Application of Expansive Concrete in Structural
Elements, reprinted from Journal of the Faculty of Engineering, The
University of Tokyo (B), vol.34, no.3
JSCE, 1994. Recommendation for Practical Application of Expansive
Concrete, Concrete Library International, No. 23, pp. 5-9 (inJapanese)
Hosoda, A., 2001. Crack Resistance and Post Cracking Behavior of
Expansive Concrete Based on Microscopic Mechanism andApplication to RC members , Doctoral Dissertation, The University ofTokyo, 2001 (in Japanese)
Sahamitmongkol, R., and Kishi T., 2003. The Effect of Restrained Level on
Cracking Resistance for Chemically Prestressed Reinforced Concrete,
Proceedings of JCI Annual Conference, Vol. 25, No.2, pp.763-768
Sahamitmongkol, R., and Kishi T., 2004. Cracking and Tension-Stiffeningof Chemically Prestressed Concrete under Uniaxial Tension,
Proceedings of JCI Annual Conference, Vol. 26, No.1, pp.237-242
Sahamitmongkol, R., and Kishi T., 2005. Bonding Characteristics of CPC
and RC under Uniaxial Tension, Proceedings of JCI Annual
Conference, Vol. 27, No.1, pp.245-250
Kakuta, Y., 1970. Maximum Crack Width of Reinforced Concrete, Concrete
Journal, Vol.8, No.9, 1-10 (in Japanese)
Goto, Y., and Otsuka, K., 1980. Experimental Studies on Cracks Formed inConcrete around Deformed Tension Bars, JSCE Journal, No.294,
pp.85-100 (in Japanese)146

New Technologies for Urban Safety of Mega Cities in Asia

A DURABILITY DESIGN CONCEPT FOR
CONCRETE STRUCTURES IN THAILAND
SOMNUK TANGTERMSIRIKUL1), JITTBODEE KHUNTHONGKAEW1)
and PITISAN KRAMMART2)
1)
Sirindhorn International Institute of Technology, Thammasat University
2)
Department of Civil Engineering, Rajamangala Institute of Technology

ABSTRACTThis paper reported the concept on durability design for concrete
structures in Thailand. According to the newly revised building design actsby the department of public works and city planning, long-term
performances of structures such as durability must also be considered inaddition to the short term mechanical properties. Concepts for durability
design based on three major deterioration environments i.e. carbonation,
chloride and sulfate environments are proposed as references for therevised building design acts. The concepts of design for carbonation andchloride penetration were based on test results and prediction models
whereas that for sulfate resistance was mainly based on experimental
results. The design concept is applicable for both cement-only and cementfly ash concrete. Various levels of seriousness are specified for each type ofenvironment. For carbonation, the degree of seriousness is set according toconcentration of CO2 and relative humidity of the environment whereas forchloride attack, it is set based on types of sub-environment and distancefrom the seashore. For sulfate attack, the degree of seriousness was set
based upon the sulfate content in the environment as water-soluble sulfate
content. Two different types of sulfate environments i.e. sodium andmagnesium are separated due to different attacking mechanisms. Concrete
mix proportion in terms of water to binder ratio and fly ash percentage, foreach class of fly ash according to Thai standard, can be derived as theoutput of the design. This durability design concept is being processed as apart of the standard specification of the Engineering Institute of Thailand
and the Thai Concrete Association.

1. INTRODUCTION
The design and construction of concrete structures in Thailand havebeen practiced based upon short-term properties such as slump and 28-daycompressive strength (Tangtermsirikul, Kaewkhluab and Kaewmanee,2003). Selection or specification of proper concrete for different types ofsevere environment is also one of the practices which has been ignored. It isevident that the previously mentioned practice can not respond to the current

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needs of service-life or life-cycle design. The practice also created a lot of
problems on low quality structures especially for those located in severe
environments (Tangtermsirikul, 2004).
Realizing this problem, theDepartment of Public Works and City Planning, academically supported by
the Thai Concrete Association and the sub committee on Concrete andMaterials of the Engineering Institute of Thailand, set up a committee tomodify and renew the existing building design acts. Design of concrete
structures is one part of the targeted modification. The new concept will
include long-term properties into the design consideration. Durability is oneof the major items to be considered in the new design acts. As reported by
the first author (Tangtermsirikul, 2004), majority of cases of early
deterioration of concrete structures in Thailand have been due tosubstandard practices in all 4 necessary stages e.g. analysis and design,material selection, construction and maintenance. This design modification
is a part of the efforts to improve quality of concrete structures toward
service-life based practice and is the effort in the stages of design. It is
certainly that the other 3 essential stages must be improved along side withthe design practice. This paper gives the explanation only on a part of thefirst stage (design) by only emphasizing on the durability consideration.

2. DURABILITY DESIGN CONCEPTThe revised design acts will refer to the details given in the codes orstandards which are published by professional organizations likeEngineering Institute of Thailand and Thai Concrete Association, etc. This
causes advantage in a sense that there is no need to frequently modify theacts if the main concept of practice does not change and it is easier andfaster to modify the codes or standards of the professional organizations.
However, these reference codes or standards have to get approval from theCouncil of Engineers which is the legal body taking care of engineering
professional matters of the country.
Since this is the first time of the country to consider durability in thedesign of concrete structures, there are still worries about understanding ofpractical engineers. Therefore, the committee on Concrete and Materials of
the Thai Concrete Association together with the subcommittee on Concreteand Materials of the Engineering Institute of Thailand decided to launch asimple durability design concept at the first step also with the objective to
educate the practical engineers. It is expected that a more complicatedconcept can be launched in the future. For the first simple concept, themain task is to be able to design a good concrete mix proportion and to
specify materials, especially the binders, to fit each severe environment inwhich the structure will be located. Three types of most frequently existing
severe environments, selected for the first durability design codes, arechloride, carbonation and sulfate environments. Since fly ash is currently
popularly used as a cement replacing pozzolan in Thailand, the design also
includes the consideration on fly ash concrete.

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2.1

Design for Carbonation ResistanceIn carbonation environment, the maintenance-free service life isdefined as the service life until steel, nearest to the exposed concrete surface,is depassivated by carbonation. To satisfy the defined maintenance-freeservice life in carbonation environment, the thickness of concrete cover
should be provided not smaller than the depth of carbonation during thedesigned maintenance-free service life.
C ≥ XcB(1)

B

where C is the thickness of concrete cover (mm) and Xc is the depth ofcarbonation (mm)B

B

The carbonation depth can be estimated from
Xc = α1 α2 k t0.5
B

B

B

B

B

B

P

(2)
P

where α1 is the effect of rain subjection which is 1.0 for surfaces which canbe wetted by rain and is 0.95 for surfaces which has no possibility to rainsubjection. α2 is the effect of severity of the environment which can beobtained from Table 1. The severity level of the carbonation environment
can be specified from the average relative humidity and average CO2
concentration of that environment as shown in Figure 1 (Tangtermsirikul
and Khunthongkeaw, 2005). t is the maintenance-free service life (years). k
is the carbonation coefficient which can be derived from
B

B

B

B

B

k = 1.5 kr (w/b)3
B

B

P

B

(3)
P

where w/b is the water to binder ratio and kr is the effect of fly ash on
carbonation coefficient which can be obtained from Figure 2.
B

B

Table 1: Effect of severity of carbonation environment on carbonation depth
Level of severity of carbonation environment
α2
Typical
0.65
Medium0.85
Severe
1.0
B

2.2

B

Design for Sulfate Resistance

It was realized that different types of sulfate cause different
mechanisms of deterioration, i.e. sodium sulfate mainly causes expansion
whereas magnesium sulfate causes conversion and dissolution of calcium
silicate hydrate (Krammart and Tangtermsirikul, 2004). Therefore, different
recommendations are provided for proper mix proportioning of concrete insodium and magnesium sulfates.

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October 2005, Singapore

CO 2 Concentration (ppm)

1000
800

Severe600

Medium

400

Typical

200
0
60

70

80

90

100

Relative(%)
Relativehumidity
humidity(%)

Figure 1 : Level of severity of carbonation environment
Effect of fly ash on
carbonationสัมประสิทธิcoefficient์ผลของเถาลอย

3.00
2.50
2.00
1.50

2ก fly ashเถาลอยCaO
Low

1.00

2ข fly ash
HighเถาลอยCaO

0.50
0

10

20

30

40

50

Fly
ash content (%ofาtotalbinder)รอ ยละการแทนที
่ของเถ
ลอย (%)

Figure 2 : Effect of type and content of fly ash on carbonation coefficient
2.2.1 Sodium Sulfate
Table 2 shows the classification of level of severity of sodium sulfate
environment whereas the recommended conditions for mix proportioning of
sodium sulfate resisting concrete in each severity level are given in Table 3.
Table 2 : Classification of level of severity of sodium sulfate environment
Level ofConcentration of sulfate (SO42-)
severity
In water (ppm)
Soluble sulfate content insoil (% by weight of soil)
Low
Less than 150
Less than 0.1
Medium
150-1,500
0.1-0.2
Severe1,500 –10,000
0.2-2.0
Very severe
Higher than 10,000 Higher than 2.0
B

PB

P

Table 3 : Specification of sodium sulfate resisting concrete
Level of
Recommended binder type
Maximum
severity
w/b
Low
Medium
OPC 2 or OPC5 or OPC 1 with pozzolan 0.50
Severe
OPC5 or OPC 1 with pozzolan
0.45
Very severe OPC 1 with pozzolan or OPC 5 with
0.40
pozzolan

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In case that fly ash is used to improve sodium sulfate resistance, theminimum amount of fly ash, which leads to an equivalent expansion of the
fly ash concrete to that of the concrete using Type 5 cement (sulfate
resisting cement), can be estimated from Figure 3.

Minimum replacement percentage
of fly ash, %50

w/b=0.40
w/b=0.45
w/b=0.50
w/b=0.55

4540

w/b=0.40
w/b=0.45
w/b=0.5035

w/b=0.55

30
25
20
15
2

4

6

8
10
12
14
16
CaO content in fly ash, %

18

20

22

Figure 3 : Minimum fly ash replacement percentage to obtain an equivalent
expansion to that of the Type 5 cement
2.2.2 Magnesium Sulfate
Table 4 shows the classification of level of severity of magnesium
sulfate environment whereas the recommended conditions for mix
proportioning of magnesium sulfate resisting concrete in each severity levelare given in Table 5. In magnesium sulfate environment, the use of
pozzolans worsens the concrete resistance, so pozzolans are notrecommended for the case of magnesium sulfate [Krammart andTangtermsirikul, 2004].
Table 4 : Classification of level of severity of sodium sulfate environment
Level of severity Concentration of sulfate in water (ppm)
Low
Less than 300
Medium
300 – 1,000
Severe1,000 – 3,000
Very severe
Higher than 3,000

Table 5 : Specification of sodium sulfate resisting concrete
Level of
Recommended binder type
Maximuseverity
m w/b
Low
Medium
OPC 1 or OPC 2 or OPC 5
0.50
SevereOPC5
0.45
Very severe OPC 5
0.40

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3. CONCLUSION
According to the revised building design acts in part of concrete
structures, it is the first time in the country that the long-term performanceof concrete especially durability has to be taken into consideration. The
newly revised design acts make reference to codes and standards establishedby professional organization such as Engineering Institute of Thailand andThai Concrete Association. The first durability design code for Thailand isbeing drafted by the two organizations. This paper introduces two examples
of concepts for design of durable concrete in carbonation and sulfate
environment. The concepts also include the design of concrete using fly ash
as a cement replacing material as fly ash is currently popularly used in
Thailand. It is hopefully expected that by the use of this durability designcode, the newly constructed concrete structures in Thailand will have longer
service life and require much less maintenance cost.

REFERENCES
Krammasrt, P. and Tangtermsirikul, S., 2004. Expansion, strength reduction
and weight loss of fly ash concrete n sulfate solution. Asean Journal
on Science and Technology for Development. Vol.21, No.4, 373-390.
Tangtermsirikul, S., Kaewkhluab, T. and Kaewmanee, K., 2003.
Information Acquisition and Structural Health Monitoring of Bridges
in Bangkok. Proceedings of the Second International Symposium on
New Technologies for Urban Safety of Mega Cities in Asia. 30-31
October 2003, Tokyo, Japan, 133-140 (CD-ROM)
Tangtermsirikul, S., 2004. Problems and Future Direction of Concrete
Structures in Thailand : Design, Materials, Construction and
Maintenance. The 3rd International Symposium of New Technologies
for Urban Safety of Mega Cities in Asia. 18-19 October 2004, Agra,
India, 177-184
Tangtermsirikul, S. and Khunthongkeaw, J., 2005. Model for Simulating
Carbonation of Fly Ash Concrete. Proceedings of the International
Workshop on Service Life of Concrete Structures – Concept and
Design. 4 February 2005, Sapporo, Japan, 41-52

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POVERTY AND DISASTER THREAT IN
MEGA CITIES:TEHRAN CASE STUDY, IRAN
Dr. Alireza ANDALIB (PhD Urban Planning; Islamic Azad University,
Science & Research Campus, Tehran, Iran.)E-mail: andalib110@yahoo.com& Dr. Sharif MOTAWEF (PhD Urban Planning; Management and Planning
Organization MPO, Tehran, Iran)E-mail: sm_1332@yahoo.com

ABSTRACT
Rapid population growth in Asia have caused difficulties in most mega cities
that some has exceeded 10 million. The rapid population growth has not
given enough time to urban planners to program for securing safety of thesecities, and has caused many problems. Additionally, lacks of access toresources and population density for urban infrastructures have ended intopoverty, poor infrastructures and resources at the same time. These
problems have been now, the most common characteristics of urban areas
in most mega cities in Asia and Latin America.
Spatial structure in any Asian big city has turned these urban areas tobe severely vulnerable facing disasters, such as earthquakes and floods.
These are because of poverty at all levels in mega cities. Buildings, in thesecases are mainly poorly structured and made of poor quality materials; sothey are harshly vulnerable facing disasters. For the same reason, urban
infrastructures are also vulnerable.
This paper intends to discuss some global experiences in mega cities
on consequences of poverty after a disaster event. It aims to determine somerelationships between poverty and people capacity in disaster response inmega cities. The case study indicates that a relationship between poverty
and natural hazards' results in urban poor areas. In other words, natural
hazards, such as earthquakes can cause disasters in poorly constructedareas and squatters that can not usually seen in any quality structured areas
and wealthy people residential quarters.

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1. INTRODUCTION
Natural hazards hit human settlements can always cause disasters. Areas
affected disasters may be occupied both by rich or poor people. Hazards do
not recognize poor people from wealthy. But those people usually sufferfrom hazards' consequences in a very different way. The wealthy people areseen in urban areas build resistant houses that can stand hazards such as
earthquakes. But poor people can not do the same, so their houses are built
by cheap materials and their structure can not resist hazards. Additionally,
economic situations usually enable wealthy people to have savings, so they
do not lose every thing by each earthquake, which poor people usually do.
Recently researches' findings show that in wealthy countries when an
earthquake event happens, less building's damage and less human deathoccurs than if an earthquake of a similar degree happens in poor countries.
So the main question here is if poverty causes disasters? We know thathazards themselves can not count as disasters unless they cause severdamage and claim lives. So the other question that: does poverty turn ahazard into a disaster?
This paper attempts to examine these subjects, in order to find answers
to such questions. Using many research's results that have been done
recently in Iran and else where, the paper tries to analyze any hypothesized
relations, between poverty and turning hazards into disasters. Research's
findings on poverty Tehran, from one side; and on earthquakes effects, on
the other, have been collected and analyzed in order to examine thehypothesized relations between poverty and disaster effects.

2. THEORETICAL FRAMEWORK
2.1 Main Concepts
Systems usually need to gain their stability and settle to work in stableconditions. But natural hazards such as, earthquakes are generally disturbing
these systems by causing disasters, which affect the ongoing works of thesesystems. When an earthquake event happens in a city, it dose not destroy
buildings only, but also disturbs the entire city life and brake many existing
systems. Thus, to reduce an earthquake effects, building reinforcement is
not the only effort to be done, but reinforcing the other factors such as,
economic and social life systems need to be considered (Motawef, 2004).
Global experiences on natural disasters indicate that in wealthy anddeveloped countries, economic and social welfare systems are alreadyestablished to deal with disaster effects. An earthquake event may severely
disturb local poor community life. Poverty causes poor quality houses
structure and building materials (DPCT, 1978 & Coburn, 1992). Therefore,
any damage-reduction plan should deal with strengthening economy, social
structure, public awareness, and management measures.

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2.2 Research Objectives
The main objective of this paper is to flash light on other systems'
rather than building damage, occurs because of disasters. This paper intends
to project light on poverty.
2.3 Research Methods
Preparing this paper needed an expanded literature review of the mostrecently conducted research projects on two study subjects, particularly in
Iran on Tehran. First, social research in slum and poverty, and the second,studies conducted on disaster and effects in urban areas. Many research
projects have been done recently by Iranian and others, including papers
provided for a national conference recently held by the Municipality of
Tehran. In this paper, analytical works have been done in order to findrelations between poverty and disaster effects in the poorest dwelling areasin the mega city of Tehran. This analysis has been done using the mostrecent analytical techniques.

3. IRAN BACKGROUND: TEHRAN CASE STUDY
3.1 Iran as an Asian Country
Iran, with more than 65 million populations is located on the west of
Asia. It is also located on the Alps-Himalaya Earthquake Belt, between
Turkey and Afghanistan. This was the reason of regular earthquakes,
affecting almost the whole area of the country. Many major earthquakes
have destroyed large parts of urban and rural areas during the last 30 years.
In addition, many large cities in Iran, such as Tehran, Tabriz, Mashhad andShiraz are located on a very earthquake-risk area. Recent earthquakes,
counting, the Tabas 1979, the Manjil 1989, and the Bam 2003 earthquakes
mainly affected small towns and low-population-density rural areas.
However, sever destruction have been caused in these areas, and serious
concern is needed to use new technology to reduce death and damage occur
because of earthquake in Iran.
3.2 Tehran as a Mega City
Tehran, the Iranian Capital, is located on the southern outskirt of theAlborz Mountain Chain, on the Alps-Himalaya Earthquake Belt. The city of
Tehran and its attached smaller human settlements, accommodate more than
10 millions people, on a large expanded area (figure1). It includes the city of
Tehran with nearly 7 million residents, the city of Karaj with more than 1
million residents, and many other towns with more than 3 millions.
Population density is very high in Tehran, including 22 districts. Some ofthese districts, especially district 17; are located on the southern part of
Tehran, occupied by poor people.

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3.3 Tehran: Population and Agglomeration
According to the 1996 population census, the total population of
Tehran for its 22 districts is calculated at 6,742,165. The average population
density of the entire city of Tehran is 110 persons per hectare. The averagedensity of District 10 is 349 person/ha and 347 person/ha in District 17,
where the poor people live. These two districts have the highest population
density values. The density of Districts 1, 2, 3 and 4, which are located innorthern Tehran and occupied by wealthy people, is shown to be between 71
person/ha and 92 person/ha.

Figure (1): Map of Tehran and its 22 districts.

Source: (JICA, 2000)

Building statistics were also prepared by SCI based on 1996 census
data; however, census data only covers residential buildings. For 1996, thetotal number of residential buildings in Tehran is 1,484,138 units.
Apartment houses or connected buildings should be counted as one
residential building unit, from the seismic damage analysis point of view.
The distribution pattern of these buildings shows the characteristics ofTehran's urban growth. Districts having more than 60 % of Steel structures
plus RC structures are Districts 1, 2, 3, 4, 5, 6 and 22, where wealthy people
live. On the contrary, Districts 10, 16 and 17, which are located in southern
Tehran consist of less Steel and RC structures (SCI, 1997).
Districts 10, 16 and 17 have more than 70 % of traditional-type
buildings. Particularly, in District 17, 90% of buildings have less than 3stories (SCI, 1997). According to the book “Tehran – The Jewel on the Silk
Road” (Taher Art & Cultural Institute, 1999), buildings in the older parts of
Tehran (Districts 10, 11, 12, and their surrounding areas) were built before
the 1950’s (TACI, 1999).

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3.4 Poverty in Tehran Urban Areas
Tehran has been highly expanded during its more than 200 year
history. During the 19th century, it was growing fast, as a capital. But during
the Reza Shah Era, (1925-41) a modernization period was started, andmainly concerned building urban and regional infrastructures. The main
work in this regard was the establishment of the railway network of thecountry connecting north to south Iran via the capital Tehran. This wasequal with creating new jobs that attracted rural people to migrate to Tehran.
New squatters were established then (60-70 years a go) by villager migrants
near the railway station in Tehran, forming Districts 15, 16 and 17. Slums
were growing up on the outskirts of Tehran, mainly around the railway
station, near their work places.
At the present time, these districts, especially district 17, are the mostpoor, with highly population and building density of Tehran. All poor
residential areas have remarkable characteristics, such as high population
and building density, poor building quality, and lack of urban
infrastructures. All these characteristics are known with sever vulnerability
to earthquake hazard.

4. NATURAL DISASTER AND EFFECTS IN TEHRAN
4.1 Earthquake Disaster
The Greater Tehran Area is located at the foot slope area of the Alborz
Mountains, which form part of the Alps-Himalayan Organic Zone. This
zone is one of high seismic potential with many peculiar active faults(Berberian, 1983). The urban area of Tehran has been developed on alluvial
layers, accumulated on hard rock through complex geological formations.
According to historical seismic data, Tehran has suffered from several
strong earthquakes with return periods of 150 years (Moinfar, 1994). The
city of Manjil, located 200 km north-west of Tehran, suffered from a strong
earthquake in 1990, which killed approximately 14,000 people (Panah,
1993). Seismologists believe a strong earthquake will strike Tehran in thenear future because the city has not experienced a disastrous earthquake
since 1830. Urban development has been rapidly progressing in Tehran
without the development of proper disaster prevention systems against
potential earthquakes (Tavakoli, 1983). It is urgently necessary to prepare aregional/urban earthquake disaster prevention plan in order to mitigate
possible seismic damages in Tehran (JICA, 2000).
4.2 Expected Earthquake and its Effects
The distribution of the active faults in Iran was investigated since1976. Distribution of active faults in and around the city of Tehran was
originally and systematically compiled in 1983 (Berberian, 1983), and thenin 1998 and 1999 (Berberian, 1999). Based on these reports, the features ofthe main active faults in Tehran can be summarized as follows (figure 2):

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Figure (2): Map of Tehran and its major faults.

Source: (JICA, 2000)

4.2.1 Mosha Fault (MF): The Mosha Fault is one of the fundamental faults ofthe central Alborz Mountains and is situated to the north of Tehran.
4.2.2 North Tehran Fault (NTF): The North Tehran Fault is the mostprominent tectonic structure in the immediate vicinity of the city.
4.2.3 South and North Ray Faults (RF): The South and North Ray Faults are
the most prominent faults in the southern plains in Tehran. Thesefaults are distributed throughout both sides of the Ray depression.
4.3 Different Effects on Different Urban Areas
The Ray Fault Model yields the largest damages. In this case, about
380 thousand inhabitants, or about 6% of the total population will die. The
casualties in District 15 will be vast because of the large number of its
inhabitants. The death ratio in Districts 11 and 12 will be as high as 15 to
20% because there are many vulnerable buildings. The death ratio in thenorthern part of the city, i.e., in Districts 1 to 5 shall only be about 2%. In
case of the NTF Model, the worst case indicates about 130 thousand
fatalities, or about 2% of the total population. The death ratio in the northernpart of the city, in Districts 1 to 5, shall be high, approximately 3%. The
death ratio in the southern part shall be low, approximately 1%. In case of
the Mosha Fault Model, the death ratio does not exceed 0.3 % of the total
population of the city. The casualties in District 12 shall be vast,
approximately 1.7%. This is due to the existence of many vulnerable
buildings of adobe and wood and brick structure, the high damage ratio ofthese buildings and the low rescue ratio. Such a tendency is also observed in
the case of the Floating Model. A ‘full rescue’ case is a case where a
combination of the community rescue, emergency squads and expert
operations is available. In the Ray Fault Model, human casualties are

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estimated to culminate in the southern part of the city. In some census
zones, the number of dead will amount to 100 or more. This area
corresponds to Districts 11 and 12, where vulnerable buildings such as
adobe are prevailing and emergency rescue activities are not effective forthese kinds of structures (JICA. 2000).
4.4 Effects Because of Poverty
In case of the Ray Fault Model, the death ratio in several census zones
in Districts 11 and 12 shall be enormous, 40% or more. In these districts,
building quality because of poverty will cause sever destruction or totalcollapse. In the NTF Model, the high-death ratio area is limited, due tobetter building construction.
Because the Ray Fault Model offers the highest potential earthquake
scenario that would generate the greatest damage to the city of Tehran, poor
areas and squatters which are located on the southern part of Tehran may
receive the highest ever destruction and human death. Most buildings ofDistricts 11, 12, 15, 16 and 17 are with high vulnerability and risk against
earthquakes. Additionally, people live in these districts are from the lower
income-groups that can not do required building reinforcements, or rebuild
their houses according to date building codes. Furthermore, streets in these
districts, especially in Districts 11, 12 and 17 are very narrow, that cancause difficulties for rescue operations after an earthquake. These districts,
also lack urban infrastructure, or have infrastructures that are overcrowded.
In summary, the southern part of the city of Tehran will be severely
damaged in the event of an earthquake caused by fault activity on the SouthRay Fault (BHRC, 1990). One reason for the expected, huge seismic
damage is that the southern part of Tehran is not only located close to an
earthquake source, but also has many buildings that are constructed withtraditional materials such as brick, masonry, wood and steel. Building
structures of this area also seems to be non-resistant to strong earthquakes.
Besides these conditions, the population density of the area is the highest in
Tehran and even one of the highest in the world. According to the 1996
Census Data, a number of its census zones have a population density of over
500 persons per hectare and, sometimes, exceed 700 persons per hectare.
Due to the combination of these physical and social conditions and thegrowth of population, the potential vulnerability against a strong earthquake
seems to be growing every year. District 17 has been designated as the Pilot
Study Area (PSA) in order to identify and collect basic information for the
preparation of necessary measures to mitigate a seismic disaster.
4.5 Case Study in a Poor Area: a Pilot Study Area (PSA)
The PSA is located in the central part of District 17. As of 1996,
population was 32,239 inhabitants, with a population density of 465 persons
per hectare. The total number of buildings in these zones is 4,843 (figure 3).

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Urbanization of this area has been progressing since the 1960, owes tothe concentration of population in Tehran. Before the urbanization took
place, the area had been extensively used as agricultural land. Building
development in this area is mainly targeted for residential use; therefore,
almost all of the buildings in this area were constructed with less than threestories.
Issues and problems for seismic disaster preparedness in the PSA are
described below based on the diagnosis of the PSA from the viewpoint of
mitigating a seismic disaster.
4.5.1 Building Damage
Almost all of the buildings in the PSA will be either heavily damaged or will
totally collapse due to the Ray Fault Earthquake. The damage ratio for thebuildings is estimated at more than 80%, according to the available damage
function data.

Figure (3): Map of PSA in District 17.

Source: (JICA, 2000)

4.5.2 Human Casualties

In the PSA, not only will building damage be high, but also thenumber of human casualties. It is estimated that 3,048 people could die outof the total 32,239 night-time population (1996 Census) of the area. If a
community rescue function and related rescue operation by anotherorganization arrive timely and work effectively, the total number of deaths
will be reduced to 2,151. But narrow streets will cause problems. But thereis less hope because of narrow streets.
4.5.3 Disaster Prevention BaseFor quick and effective response to emergencies such as a seismic
disaster, it is essential to properly equip facilities that will serve as basesthat provide countermeasures for disasters. Presently, in District 17, there is160

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nothing being done to prepare for a seismic disaster or to take necessary
countermeasures.
4.5.4 Community Organization

Community organization plays a significant role not only in first aid
activities during a seismic disaster, but also for collection and disseminationof disaster information to the entire community. However, community
groups have not yet been organized in the PSA. Therefore, theirestablishment on a housing block basis should be, at least, discussed for the
mitigation of a possible disaster. General community participation indisaster mitigation should also be discussed and planned.
4.5.5 Disaster Prevention Awareness

It is necessary to raise the people’s awareness on seismic disasterprevention based on proper dissemination of disaster prevention information
through administrative organizations, school education and mass media. The
main purpose of raising public awareness on seismic disaster prevention is
to minimize human casualties as much as possible.

5. CONCLUSION
In response to the main question of this paper that if poverty causes
disasters? The findings of this research shows that hazards themselves can
not cause disasters unless they cause sever damage and claim lives. But it ispoverty that turns a hazard into a disaster. The research findings show thatin wealthy urban areas in Tehran; when an earthquake event happens, lessbuilding's damage and less human death occurs than if an earthquake of asimilar degree happens in poor areas, such as District 17, south of Tehran.
Also, a clear conclusion indicates that Tehran as a mega city, and its
southern districts, such as District 17 and the PSA, including its surroundingarea, has indicated that the whole city and mainly poor areas have no
defense system against a potential strong earthquake. In the worst casescenario, huge damage is estimated in these areas; therefore, necessary
measures for seismic disaster mitigation, at least to save human lives, must
be prepared as soon as possible. The following items are the main
recommendations to be considered in a planned manner:
1) Most of the southern districts of Tehran are occupied by poor people whocame to live in squatters, and very poor conditions in Tehran, seeking
job during the last 60 years. Their low income level has forced them tolive in poor quality and vulnerable houses against earthquakes. They
should be supported.
2) Urban seismic disaster prevention and a risk management plan must be
prepared by Tehran immediately. It is necessary to clarify the role ofcommunity in disaster prevention.
3) People’s participation and public awareness on seismic disasterprevention should be promoted.

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4) Basic materials explaining earthquake disaster and measures for disastermitigation should be prepared and disseminated properly. School
education for younger generations should also be promoted.
5) Reinforcement of residential buildings must be discussed in depth. Ifbuildings were to be built strong enough to withstand an earthquake,then building damage could easily be minimized. However, economic
conditions dictate use of the most economic and higher cost
performance structures and materials for building construction6) In relation to urban redevelopment, relevant institutional frameworks,
such as tax incentives, low interest housing loans, and bonuses for floor
to area ratio etc., should be formulated to create stronger urban
structures against seismic disaster.

REFRENCES:
BHRC, 1990, Iranian Code for Seismic Resistant Design of Buildings.
Berberian, M. M., Ghoreishi, B., Arajang R awesh, A. Mohajer Ashjai,
1983, Seismotectonic and earthquake fault hazard investigations in the
Tehran region, Geological Survey of Iran, Report No. 56.
Berberian, M., and R. S. Yeats, 1999, Pattern of Historical Earthquake
Rupture in the Iranian Plateau, Bull. Seism. Soc. Am., Vol.89, No.1.
Coburn,A.W., R.J.S. Spence, and A. Pomonis, 1992, Factors Determining
Human Casualty Levels in Earthquakes: Mortality Prediction in
Building Collapse, Proc. 10th. WCEE.
Coburn, A.W. and R.J.S. Spence, 1992, Earthquake Protection, John Wiley.
Disaster Prevention Council of the Tokyo Metropolitan Area, 1978, Reporton the Earthquake Damage Estimation of Central Area in Tokyo.
Japan International Cooperation Agency (JICA) 2000, The Study on
Seismic Micro zoning of the Greater Tehran Area in the Islamic
Republic of Iran: Final Report & Main Report; Pacific Consultants
International; OYO Corporation; November 2000.
Moinfar, A.A., Mahdavian, A. and Maleky, E., 1994, Historical andInstrumental Data Collection of Iran, Iranian cultural fairs institute.
Motawef, Sharif, 2005 "Earthquake, Damage and Reconstruction of Bam";
paper presented in the International Conference on Bam Earthquake,
held by the Housing Foundation of Iran in Bam: May 2005.
Panah et. al. 1993, Case Study 1, Landslide Hazard Zonation Study in
Affected Area by Manjil Earthquake, 1990, Manual for Zonation on
Seismic Geotechnical Hazards, Technical Committee for Earthquake
Geotechnical Engineering, TC4, International Society of Soil
Mechanics and Foundation Engineering,1993.
Statistic Center of Iran (SCI) 1997, Results of The 1996 Population andHousing General Census; SCI, Tehran, Iran.
Taher Art & Cultural Institute (TACI) 1999; “Tehran – The Jewel on the
Silk Road” (Taher Art & Cultural Institute, 1999), Tehran, Iran.
Tavakoli Behrooz, B.and S. Tavakoli, 1983, Estimating the Vulnerability
and Loss Functions of Residential Buildings, Journal of theInternational Society for the Prevention and Mitigation of Natural
Hazards, Vol.7 No.2.

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PLANNING AND DESIGN FOR SECURITY
FANG YEA SAENB Arch, MSIA
Vice President, Security Division
CPG Consultants Pte Ltd, 238B Thomson Road
#15-00 Tower B Novena Square Singapore 307685
fang.yea.saen@cpgcorp.com.sg

ABSTRACT
Acts of terrorism in the last decade have prompted governments andcorporations to respond with urgent security reviews and protective
measures for their infrastructures and buildings in an unprecedented
manner.
The leading example without dispute is the United States.
Countries in this region are also grappling with the issue of terrorism andthe appropriate level of protection to ensure that business and life go on as
usual.
On the one hand, there may be inaction born out of a sense ofhelplessness or apathy. On the other hand, hasty measures may be taken
creating other problems like a fortress environment. There is hence a callfor balance, ie for an agenda where additional security requirements are
met without sacrificing other considerations.
This paper advocates a holistic approach in achieving this balance.
It is also a systematic approach, considering steps like
Security concept plan
Risk assessment – threats, vulnerabilities, asset protection
Master planning for security
Building design for security
Security system, technology and engineering
Security management and business continuity issues.
This paper also stresses the need to work with all stakeholders forthe holistic approach to work.
Because explosions from improvised
explosive devices (IEDs) are such a current and real threat, the security
planning and design process has to deal with this in a pragmatic way inorder for a balanced outcome to happen.
The paper also covers the benefits of the holistic approach tosecurity planning and design and ends with a conclusion that not only is this
holistic approach necessary, but that enhanced security and protective
features will increasingly become part of the building design and design
process from now on.

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1. INTRODUCTION
With the end of the cold war, it was optimistically thought that world peace
would reign.
Unfortunately terrorism and the threat of terrorism areincreasingly seen as part of the modern global city life. Interestingly,
Britain had experienced this to some extent with their earlier bombings by
the IRA and had built up a certain response and resilience to this. Howevertransnational terrorist threats are new to many countries, including the US.
At the same time, the world is seeing greater concentration of people in the
big cities, where economic opportunities and the buzz of urban life draw
people like bees to honey. With such concentration comes vulnerability tolives and safety, something which terrorists recognise.
The power todisrupt life and business through an incident which is magnified by the
publicity of the international media is a potent tool increasingly being
exploited.
Recent acts of terrorism have prompted government with responses fromgreater surveillance, intelligence work to hardening of infrastructure andkey assets. Such calls are percolating down to ‘softer’ buildings likecommercial and civic buildings as terrorists are seen to shift to easier targets.
Governments are also calling upon corporations and owners to view the costof security upgrading not as an extra cost but as a necessary cost of doing
business. Individuals are also asked to report suspicious behaviour andbear with inconvenience as the price to pay for greater security.
However there may be a sense of helplessness born out of lack ofknowledge or a limited budget in a competitive business environment. It
could also be apathy resting on the assumption that attacks will not happen
in one’s backyard or that governments have the direct and full responsibility
to protect citizens against acts of terrorism.
On the other hand, protective measures may be taken hastily, leading toother problems like creating a suffocating and defensive fortressenvironment, witness what is happening in Washington DC and theassociated public debate.
There is hence a call for a balance between security and openness andaccessibility. For what attraction is city living when it begins to feel more
like a prison?
The holistic approach starts with an understanding of what the government
is committed to do and going on to realistically assessing the risks pertinent
to an organization, in a particular country and at a specific period of timeand lastly, considering the range of factors and solutions that relate tosecurity. This is to enable a cost-effective and sustainable strategy to be
implemented to enhance security. The holistic approach will hence become
the critical context for the application of specific protective measures.

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2. THE HOLISTIC APPROACH
2.1

Elements of the holistic approach

What are the elements of this holistic approach? They are Security concept plan
Risk assessment - threats, vulnerability, asset protection
Master planning for security
Building design for security
Security system, technology and engineering
Security management and business continuity issues.
2.2

Security concept plan

The security concept plan is an overall strategy which considers the range offactors, weighs their relative significance, evaluates a panoply of solutions
and proposes an integrated, effective and sustainable plan for security. Itbalances and mediates the different and possible conflicting requirements,
like security versus openness, security versus cost or security versus fire
safety.
For example in prison design, security and normal fire escapeprovisions are contradictory requirements. Such contradictions and theensuring trade-offs and creative solutions to resolve them are true of otherbuilding types. Overall, the security planning and design process seeks todeliver peace of mind, safety and protection of assets.
2.3

Risk assessment

Risk assessment should be a systematic process. It is a key step as it isabout framing the right question even before one searches for the rightanswers. AS/NZS 4360 standard on Risk Management is a good guide andcan be applied to the security planning and design process.
A necessary step in risk assessment is to identify the possible threats jointlywith the stakeholders. One has to remember that threats evolve to elude
new surveillance and protective measures taken.
Hence such risk
assessment will need to be reviewed on a regular basis so that security andprotective measures remain relevant.
With global warming and recent natural disasters, people are also
increasingly concerned over environmental hazards as the impact far
exceeds even terrorist incidents. Though this is not covered in this paper, it
would be good to bear this in mind, especially in locations whereenvironmental hazards become relevant – see Figure 1.

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NaturalInvoluntary

Voluntary

Man-madeearthquake
tsunamivolcanic eruption
cyclonetornadoavalanche
flood
drought
bushfiretransport accidents
industrial explosions
radioactive fallout
air pollution
civil riot
food additives
smoking
mountaineering

Intense

DiffuseFigure 1. Spectrum of environmental hazards (Keith Smith, Environmental
Hazards)
Another consideration in the risk assessment stage is the vulnerabilities of abuilding and an organization. Are there potentially single points of failure,eg power supply to the whole building which is accessible by the public?
Are there other Achilles’ heels? Are key staff located together?
Another consideration is the identification of the organisation’s key assets?
Cash is commonly perceived as assets to be protected.
But from anorganisation’s viewpoint, assets include other things like data, information,
art pieces, money, horses, VIPs, computer systems, even prisoners (forwhose health and safety the prison service is responsible while undercustody), 24x7 capability residing in certain key equipment and key staff,
etc.
To each of these threats and vulnerabilities, consequences of the loss ordamage of the assets and probability of the occurrence can be factored in,giving in an approximate way –Overall risk assessment = threat/vulnerability x consequence x probability.
The next step is the treatment of the risks - see Figure 2. Various options
should be considered and evaluated. This fits very well into the holistic
approach advocated in this paper. Can part of the risk be covered by guard
service? What about insurance? Is the mirror site for a data centre
adequate in covering the risk? Or does the potential bad publicity andsubsequent exposure to further attacks necessitate stronger protective
measures?
This risk treatment process is also a risk allocation process,calling upon different measures to do what they are each best in.

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Figure 2. Risk treatment process chart from AS/NZS 4360
2.4

Master planning for security

Master or site planning for security considers the city or site layout issues
which impact security.
Figure 3 is a typical ‘onion’ security ring concept, providing layers ofdefence to a building and asset with a single access control point. In anarmy camp or prison complex, the two outer layers would be typicallybarbed wire fence with no vegetation in between for unobstructed CCTV
monitoring. The fences would normally be equipped with an FIDS (fence
intrusion detection system). However not all developments need this or can
look like this. In a creative way and going along this holistic approach, one
can consider how other measures can constitute layers of defence. One
layer could be a guard tour circuit, though there will be ‘holes’ because theguard will be moving around. Or a layer could be invisible infra-red beams
which when broken signify an intrusion. The general aim at the masterplanning for security is to create security through deterrence, detection,
delay and a credible response against potential incidents.
At the master or site planning level, it may be necessary to check that viewsof key operations or access by VIPs cannot be easily overlooked bypotential perpetrators who may be planning an attack. Similarly, locationof critical infrastructural facilities like power stations or sub-stations may bedone to avoid vulnerability to attacks which can potentially incapacitate awhole township.

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Outer fence(standoff)

Building

Inner fence(clear zone)

Single access
control point

Figure 3. Example of ‘Onion’ security layers of protection
2.5

Building design for security

Building design for security looks at aspects of the building layout anddesign to create greater security. For example, can zoning be done to groupsimilar functional spaces not only for greater work efficiency but also to
avoid security conflicts?
A popular approach is Crime Prevention Through Environmental Design or
CPTED for short. This looks at low-tech, soft approaches in design tocreating greater security.
For example, can the kitchen of houses bedesigned to overlook a common area, as this ‘natural surveillance’
contributes to security?
In terms of building services, it may be necessary for the sake of security toroute them in such a way that there are no single points of failure, though it
may mean the overall system is less efficient from an engineering viewpoint.
Building owners will increasingly be looking at facilities with more
effective mail room design and entry control facilities, as these are thefrontline checks against illegal access, weapons, contraband goods andpossible IEDs.
Such facilities will increasingly be incorporated in thebuilding designs and workflow patterns.
2.6

Security system, technology and engineering

In a typical situation, a security consultant is engaged when the building
design is decided and he is asked to put in the security systems. In theholistic approach, this is seen as wrong approach as security flaws areembedded in an architectural layout and design and extensive security
systems are then called upon to overcome these. Hence an understandingof security system, technology and engineering should be factored in themaster planning and building layout.

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CCTVs have become a pervasive element. They have proven useful for theauthorities analysing records to apprehend culprits, even if the CCTVs were
not a sufficient deterrent in the first place. While there are still concerns ofprivacy (of Big Brother), terrorism will inadvertently lend greater force for
CCTVs to be accepted as a feature of city life, witness the case in London.
There is a plethora of security systems and new ones are coming out by theweek.
Biometrics, anti-ram bollards, crash barriers, access control,
turnstiles, under-vehicle scanners, x-ray machines, gamma scanners, metal
detectors, etc, are just some examples of technology used in homeland
security. This paper is not going to run through each of these, except tomention the point that there should be an understanding of how the systems
impact the functioning of a building, whether they can be used in asustained manner and how they can be less intrusive.
As metal detectors and x-ray machines become more pervasive, the public
will begin to feel the inconvenience of airport security even for prosaic
access to normal buildings and complexes. Hence there is scope to makemeasures less intrusive. For example, can checks on identity, weapons,
bombs, etc all be done through an all-in security portal? The greatest
challenge will be in places where the public will be in greatest numbers likeshopping centres, checkpoints and mass rapid transit systems.
2.7

Security management and business continuity issues

It is helpful for designers and engineering experts to be familiar with aspectsof security management and business continuity to see how they contributeto security. By doing so and recognising the respective advantages indelivering security, then it would be natural to ask security management andemergency preparedness to cover that part of security where they arestrongest in.
For example, guards can pick up suspicious behaviour
through CCTV or actual sighting, where no CCTV intelligence or analyticalprogramme is able to do so cost-effectively at the moment. Secondly since
it is impossible to prevent an incident from happening by systems andbuilding design, it is critical to get ready emergency preparedness to address
the residual risks.
It has been well documented that in neighbourhoods where windows arebroken but are not quickly repaired, that these attract more broken windows.
But where broken windows and graffiti are quickly addressed, thiscommunicates to potential perpetrators that here is a community where
people care and are willing to take remedial action, possibly even to
apprehend the perpetrators.
Under this topic, one would also attempt to understand guard service andassociated building design implications. For example providing even basic
facilities like toilets in guard house so that the guards need not be absent
from their post for too long and create vulnerable gaps would be somethingthat is consistent with this holistic approach.

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3

STAKEHOLDERS

In planning and design for security, an important consideration is
identifying the key stakeholders and dealing with their concerns. Too often
this process is not thoroughly carried out with the inputs of somestakeholders coming late in a project and becoming difficult toaccommodate. For example, if the security intelligence part is not fully
addressed, then the solution may not have been calibrated to the appropriate
threat level. Or if the customers’ viewpoints are not fully factored in, thenthe security measure may not be user-friendly. Stakeholders can be theproperty owners, the facility managing agent, the guard service company,
the customers, general public, security agency, the government, investors,
etc.
Often the client may be represented by a few parties.
There is one
watching the budget and one directly responsible for the business operations
and yet one more directly responsible for security. Hence not only mustthe interests be identified, but also the possible conflicts. A key thing is
also making the stakeholders see that there are other stakeholders andrequirements in order to prepare them for a balanced outcome with tradeoffs.
4

DEALING WITH BLAST THREATSThis is put as a separate section as it is a key concern in the current security
milieu and will dominate security agenda. For a start, all know that they
do not want to retreat to or create a bunker solution, which a military or law
enforcement facility can do and sometimes do to create a deterrent effect.
A typical military solution like narrow windows is not appropriate in a
civilian building as most users value views and daylight and sense ofconnectedness to the outside environment.

Figure 4. Example of narrow windows from Field Manual FM 3-19.30
Physical Security which may be applicable to military installations but may
not be acceptable in civilian buildings
However when one understands that in most cases, just as in fire fighting
response, the key protection is lives and secondarily property. With thisunderstanding, it becomes more pragmatic to allow glazing to flex and crackwith the blast, absorbing the blast energy but with fragments not flying
beyond a certain distance and hurting people.
GSA has a glazing

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performance condition which helps in calibrating the level of protection at
the façade glazing and allowing protection in a pragmatic way – refer toFigure 5.

Figure 5. Glazing performance condition for blast as given by General
Services Administration (GSA)
In the US, standoffs are typically specified as protection against car bombs.
In critical buildings, visitor parking is even not allowed in basement parking
centres.
Standoffs of 30m are not unusual, enforceable by bollards.
However in urban areas, such compliance is difficult given the limited land
and high land prices.
For example in Singapore, land may cost theequivalent of $9,000 per m2. If the standoff can be reduced, then thesaving in cost of land can be thrown into protective measures like column or
façade strengthening. However this trade-off does not happen, if the client
is not convinced of the threat in the first place, which a systematic risk
assessment can address.
5

BENEFITS OF HOLISTIC APPROACH

In the holistic approach, no single measure is expected to provide thesecurity. For example, if the building design was leaned upon to provide
all the security – then a fortress design is the logical outcome. However if
security is to be contributed by a combination of design, systems, guard
service, law enforcement, citizen vigilance, etc, then a building can afford to
be more open, more accessible, ie create the balance.
The holistic approach would also be more cost-effective, as security systems
and measures will not become white elephants if they go against the natural
workflows of corporations. The holistic approach would also be exploiting
the relative strengths of different measures.
The holistic approach gives the client and the consultants the flexibility andcreativity to deliver security as they have a wider range of options to
consider.

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6

CONCLUSION

Up to now, we have looked at how security planning and design can be andshould be a holistic process. And how judgment calls are made in thisprocess to mediate among the various considerations, so that no single
measure should be asked to carry the burden of security.
This
understanding will enable all stakeholders to agree to trade-offs and to acommon strategy for security.
Whereas current security initiative centres on retrofitting of existingbuildings, it is envisaged that in future, the norm will be for buildings toincorporate enhanced security features as part of the overall building
planning and design process, in recognition that terrorist threats are here to
stay.
“The terrorist is as much concerned with how many are killed as how many
are frightened.” (quote from the Economist)
Lastly, in this holistic equation advocated, the final judgment call will bewith the public who will be asked to bounce back from any security incident,
not to be cowed, but to declare that life will go on and then there will begreater vigilance against future events.

REFERENCES
Australian Standards / New Zealand Standards.
AS/NZS 4360 Risk
Management.
Betts, Curt P., 2005. Guidance for Security Engineering. ASCE 2005, US
Department of Defense
Building and Construction Authority,
Singapore, January 2005.
Enhancing Building Security
Crowe, Timothy D. 2000. Crime Prevention Through Environmental
Design: Applications of Architectural Design and Space Management
Concepts (2nd Edition)
Department of Defense, 8 October 2003. UFC 4-010-01, DoD Minimum
Antiterrorism Standards for Buildings
Department of the Army Headquarters, Washington DC, January 2001.
FM 3-19.30 Physical Security
FEMA, Dec 2003.
FEMA 427 - Primer for Design of Commercial
Buildings to Mitigate Terrorist Attacks
National Security Coordination Centre (Singapore), 2004.
The Fight
Against Terror – Singapore’s National Security Strategy
Smith, Keith, November 2000. Environmental Hazards: Assessing Risk
and Reducing Disaster. Routledge, New York172

New Technologies for Urban Safety of Mega Cities in AsiaDISASTER MITIGATION ASSESSMENT
FOR STORAGE TANK FACILITY
Min-Cheng Teng1 Chien-Mei Lee2 Kuo-Shuh Fan3
Senior Assistant Research, National Sci & Tech. Center for Disaster Reduction, Taipei, Taiwan, Email: jack@ncdr.nat.gov.tw
2
Research Assistant, National Sci & Tech. Center for Disaster Reduction, Ta
ipei, Taiwan, Email: cmlee@ncdr.nat.gov.tw
3
Associate Professor, National Kaohsiung First Univ. of Sci & Tech., Kaohs
iung, Taiwan, Email: ksfan@ccms.nkfust.edu.tw
1

ABSTRACTIn recent years, manufacturing industries in Taiwan develop
vigorously. Otherwise, the chemical process update continually. However,the complicated factors of caused the loss of property and the threat ofenvironmental pollution. Besides, the factory owner the capacity forawareness of industrial safety and accident prevention is weak. For all ofprocess equipments, the storage equipments are one of factors which is easy
to neglect caused storage tank accidents by man-made. In the other hand,
natural disasters such as earthquake and lightning, also be the reason of
accident.
A storage tank without any mitigations strategy typically causes
severe damage and other economic loss, such as by earthquake damage, fire,
exploding pollution of surrounding areas , chemicals to leak , during
disaster occurrence. The main failure mechanisms of tanks are as follows.
(1) Buckling of the shell. (2) Damage to the roof. (3) Differential settlement
or failure of the foundation soils. (4) Fire. (5) Explosion. (6) Contents toleak, etc. The research context to classify storage tank accidents in Taiwan,
fire accident is in 30%, 20% in explosion accident and 20% in chemicalleak release accidents. Moreover, the inappropriate process and lack ofprofession are the main causes of the accident.
In this study, a series of shaking table tests has been conducted toassess the feasibility of seismic base isolation for liquid-filled storage tanks
experimentally for reduction natural disaster. The friction pendulum
bearings (FPS) are considered as the dynamic characteristics of an FPSisolated tank remain unchanged regardless of the storage level.
Effectiveness of FPS for seismic isolation of storage tanks is confirmed. This
research also combines interpretations of the Council of Labor Affairs andNational Fire Agency, Ministry of the Interior regulations, summaries ofstate and local regulatory requirements. This study is designed to assist in
the development of a comprehensive compliance and management programfor oil storage tanks. Moreover, study man-made disaster after discussed
domestic regulation, the research would give the advice about measures of173

October 2005, Singapore

disaster mitigations and emergency response plan that would be thereference for industries in order to develop the capacities of storage tankaccident mitigation.

1. INTRODUCTION
Large storage tanks are vital for industrial purposes and daily life. A
storage tank without any mitigations strategy typically causes severe
damage and other economic loss, such as by earthquake damage, fire,
exploding pollution of surrounding areas, chemical to leak, during disasteroccurrence. The main failure mechanisms of tanks are as follows. (1)Buckling of the shell. (2) Damage to the roof. (3) Differential settlement or
failure of the foundation soils. (4) Fire. (5) Explosion, etc. The vulnerabilityof tanks to ground motion has been demonstrated recently in Chi-Chi
earthquake (1999) of Taiwan, and numerous other major earthquakes
worldwide. For example, The 1964 earthquake in Niigata, Japan caused
extensive damage to two oil refineries；the 1964 Prince William Sound
earthquake in Alaska caused the failure of several oil storage tanks andfires；the 1971 San Fernando earthquake in California led to the failure ofmany water tanks both above-ground and in-ground, and the failure of oil
storage tanks in the 1978 Sendai earthquake of Japan polluted a local
waterway ； On July 17, 2001, an explosion occurred at the Motiva
Enterprises LLC Delaware City Refinery (DCR) in Delaware City,
U.S.A.(CSB,2002). A work crew had been repairing a catwalk above asulfuric acid storage tank farm when a spark from their hot work ignited
flammable vapors in one of the tanks. This tank had holes in its roof andshell due to corrosion. The tank collapsed, and one the contract workers was
killed; eight others were injured. A significant volume of sulfuric acid
(H2SO4) was released to Delaware River, resulting in significant damage toaquatic life. and environment；There was a terrible explosion at the resined
plant in Taoyuan City, Taiwan, on October 7, 1996, with extraordinary or
improper operate procedure of neutralization tank. The tank and plantcollapsed, and nine workers were died; forty eight persons were injured.
Earthquakes may induce substantial hydrodynamic pressures on theshell wall of storage tanks, and the overturning moment caused by thelateral pressures could result in excessive compressive stresses at the bottomof one side of the tank, and hence, dynamic buckling of the shell wall
(Jia:1989, Liu:1989). Damage to storage tanks not only instantly disrupts
essential infrastructure but can also cause fires or environmental
contamination when flammable materials or hazardous chemicals leak.
Although seismic isolation has been recognized as a promisingalternative to protecting structures against earthquakes, engineering researchand practices on seismic isolation of storage tanks remains limited. Unlike
most structures (such as buildings or bridges), the weight of storage tanks
varies in time because of variable liquid storage level, and they may containlow-temperature (e.g. LNG) or corrosive substances. Being made ofstainless steel, FPS bearings are also resistant to chemicals, fires,
temperature extremes, and adverse environmental exposure. Given the174

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above advantages, FPS seismic bearings are better for industrial tankapplications.
Wang, Teng and Chung (2001) devised a hybrid structuralhydrodynamic model and solution algorithm, which permitted simple,
accurate and efficient assessment of the seismic response of rigid cylindricalstorage tanks in the context of seismic isolation. As a further step towards
this study, a series of shaking table tests is conducted using a model tankconsisting of stainless steel and acrylic. The 0.01m thick acrylic shellenables the sloshing response of the liquid to be observed during the tests.
The tank is isolated using four friction pendulum seismic bearings
fabricated by local workshop. The El Centro, Hachinohe and Kobe
earthquakes of various intensities were adopted as inputs for theexperiments and various storage levels of the liquid were considered.
Experimental results show evident reductions in dynamic pressure on theshell wall of the tank consistently while isolated. The effectiveness of thefriction pendulum bearings in the\ protection of storage tanks against
earthquakes was verified. Moreover, numerical simulations carried out
using the hybrid structural-hydrodynamic model previously devised (Wang,
Teng, Chung, 2001) agree very well with the corresponding test results,
indicating adequacy of the analytical model.

2. METHODOLOGY FOR EARTHQUAKE NATURAL DISASTER
2.1

Analytical Modelling
A rigid, circular cylindrical tank defined by a cylindrical coordinate
system, with r, θ and z denoting, respectively the radial, circumferential, andaxial coordinates, is filled with liquid to a storage level H, as illustrated inFig. 1. The liquid with density ρ , is assumed to be incompressible,
irrotational and inviscid. Under horizontal earthquake ground acceleration,&x&g (t ) , in the direction θ = 0 , the velocity potential function, ϕ (r ,θ , z , t ) , ofthe liquid flow within the tank satisfies the Laplace’s equation as∂2ϕ 1 ∂ϕ 1 ∂2ϕ ∂2ϕ+++=0∂r2 r ∂r r2 ∂θ2 ∂ z2

(1)

The solution of Eqn. (1) can be conveniently expressed bysuperpositioning two components as
ϕ ( r , θ , z , t ) = ϕ1 ( r , θ , z , t ) + ϕ 2 ( r , θ , z , t )(2)where ϕ1 is associated with the portion of the liquid that varies insynchronization with the rigid tank, and ϕ 2 is associated with thehydrodynamic motion of the liquid relative to the tank.
The hydrodynamic system (2) can be revised for each mode as ananalogy of a single-degree-of-freedom base-excited spring-mass system as

Disaster Mitigation Assessment for Storage Tank Facility

175

October 2005, Singapore&& (t ) + k D (t ) = −m &x& (t )
mjD
j
j
j
j g

j = 1, K, ∞(3)

where and By considering only the first N modes, the hydrodynamic system
due to ground excitations can be concisely expressed as&& (t ) + K D (t ) = −M 1&x&
Ms D
s
s
g

(4)

where
1 denotes the N × 1 uniform vector with all its entries being 1.
r

θ

H
R

z

&x&g (t )Figure 1: Configuration of the Cylindrical Tank
2.2 Hybrid Structural-hydrodynamic Systems of Base-Isolated Rigid
Tanks

When friction pendulum bearings are installed beneath its base for seismic
isolation, the rigid tank and the liquid it contains will slide together during
earthquakes (Fig.2). The kinetic energy ( T ) and the potential energy ( V ) of
the hybrid structural-hydrodynamic system are defined, respectively, as

[

] [

]

T
1
T = D& + 1( x&b + x& g ) M s D& + 1( x&b + x& g ) + mb ( x&b + x& g ) 2
2

V=

(5)

1 T
1
1 mt
D K s D + mt gRFPS (1 − cos γ ) ≅ D T K s D +xb 2
22
2 R FPS(6)

where xb and x&b are, respectively, the sliding displacement andsliding velocity of the base (relative to the ground); mb is theeffective mass of the tank, including the mass of the tank itself
N

and the equivalent impulsive mass ( m0 )of the liquid; mt = ∑ m j + mb
j =1

is the total mass of the hybrid system; RFPS is the radius ofcurvature of the sliding surface and γ ≅ xb / RFPS is the sliding angle
around the center of curvature as depicted in Fig. 2. Considering

176

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the friction force, f (t ) , between the sliding interfaces of the
bearing as a non-conservative force, the equation of motion of thehybrid system can be derived by applying the Lagrange’s equationas(7)
M&x&(t ) + K x(t ) = −E&x&g (t ) + B f (t )where
 D(t ) M
Ms1
 is the mass is the displacement vector; M =  T sx(t ) = T
1 M s 1 M s 1 + mb  xb (t ) K smatrix; K = 

0


0 
Ms1
 is the
mt g  is the stiffness matrix; E =  T
1
M
1
m
+

s
b

R 

location matrix of the earthquake load, and B =  0  is the location matrix of
1

the friction force.
The hybrid structural-hydrodynamic system (7) is highly nonlinear becauseof friction. A numerical procedure based on the concept of shear balance atthe sliding interfaces (Veletsos:1995, Shivakumar:1995) is developed in thefollowing section to solve this nonlinear dynamic problem.
kN / 2DN

kN / 2D3

k3 / 2mN

k3 / 2m3

k2 / 2D2
m2

k2 / 2
k1 / 2

k1 / 2
m1 D1

mb

xg

xb

Figure 2: Tank Isolated with Friction Pendulum Bearings
2.3 Experiment Model

The cylindrical model tank with a radius (R) of 1.36m, and a height of
2m is illustrated in Figure 3 for side view. The capacity of the model tank is
3 tons as filled up with water. The design was restricted to an ultimate shake
table capacity of 10 tons payload and plan dimensions. The main body ofthe storage tank consists of stainless steel and acrylic. Below the height of
0.8m is stainless steel of 0.003m-thick, and above 0.8m to the top is acrylic
shell of 0.01m- thick. The acrylic shell enables the sloshing response of theDisaster Mitigation Assessment for Storage Tank Facility

177

October 2005, Singapore

liquid to be observed during the tests. The base frame of the tank is welded
together with H-beams (H250*250*9*14) and a steel plate(2m*1.8m*0.01m). The H-beams are reinforced with stiffners. The total
weight of the tank is 0.916 tons when empty. The tank is considered rigid.
Figure 3 shows the model tank that has been readily installed on the shaking
table for testing.
The tank, without seismic isolation, is estimated to have a maximum
base shear of 11.84 kN and a maximum overturning moment of 10.42
kN − m , through preliminary numerical simulations, under the excitation of
El Centro earthquake with its PGA scaled up to 0.7g. The weight of the tankis 0.916 tons as empty and 27.89 kN in full storage (H=1.8m). A safety
factor of 2 is considered in the design.

acrylic
E

FP
stainless steel

Pressure cells

A

Unit: mm

Side View

Figure 3: Storage Tank Model on Shaking Table

3. METHODOLOGY FOR MAN-MADE DISASTER
3.1 Man-Made Disaster Regulations Discussion

As discuss to storage tank safety management must keep theregulations of Council of Labor Affairs, Taiwan R.O.C and National Fire
Agency, Ministry of the Interior. National Fire Protection Association(NFPA) and American Petroleum Institute (API) U.S.A is the most popularfor protected storage tanks ； For example, NFPA 30 - Flammable andCombustible Liquids Code is the industry's most trusted and complete
source for safety rules concerning flammable and combustible liquids. The
purpose of NFPA 30 code shall be to provide reasonable requirements forthe safe storage and handling of flammable and combustible liquids.
Furthermore, the API 650 is the welded steel tanks for oil storage standard
code that is designed to provide the petroleum industry with tanks ofadequate safety and reasonable economy for use in the storage of petroleum,
petroleum products, and other liquid products commonly handled and storedby the various branches of the petroleum industry.
Industrial Technology Research Institute (ITRI) Significant Accident
Data Base was collected the accident cases of storage tank from 1982 to2003(ITRI Web Site). Accident was classified according to cause type, fire178

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

accident has 39 percent accident cases, explosion has 37 percent and leak ofchemical is 24 percent as figure 4 shown.
Figure 5 indicates the fire accident was classified according to cause.
In the Fig 5 unknown, inappropriate operation and inappropriate design had
observably main risk source with storage tank. Moreover, in Figure 6
integrated fire, explosion and leak of chemical accident have the similar
result to Figure 5.
Chemical Leak
24%

Fire
39%

Explosion
37%

Figure 4: Tank accidents were classified according to type1Inappropriate
Environment

1-Electrics
Factors

8-Unknown

2-Natural
Factors

3Inappropriate
Operational
Procedure andNon Expert
Sense
3Inappropriate
DesignFigure 5: Fire accidents were classified according to cause
4%

2%

4%
Inappropriate Operational Procedure and Non
Expert Sense
Unknown
13%

38%
Inappropriate Design
Natural Factors
Inappropriate Environment

15%

Electrics Factors
The Wiring Caught Fire

24%

Figure 6: Integrated fire, explosion and leak of chemical accident wereclassified according to cause

Disaster Mitigation Assessment for Storage Tank Facility

179

October 2005, Singapore

3.2 Emergency Response Planning for Fire Protection

The typical announced flow chart as shown in Figure 7. For
example, National Fire Agency, Ministry of the Interior is the primary
public management organization for disaster rescue.
Executive Yuan
National Disaster Pervention andProtection Commission R.O.C

Ministry of the Interior

Government Information Office
24HRr Media Monitor System

Ministry of Economic Affairs
Council of Agriculture, Executive Yuan
Ministry of Transportation And Communications
Environmental Protection Administration, Executive Yuan

Un-duty Agency in Central
Government

Department of Health, Executive Yuan
Council of Labor Affairs, Executive Yuan
Atomic Energy Council
National Fire Agency, Ministry of the Interior

Fire Department of City (County)
Government ----119

Duty Agencies in City (County)
Government or in Central Government

Un-duty Agencies in City (County)
Government or Un-duty Ministries

The Public

Figure 7: Fire Disaster Announced Flow chart

4. DISCUSSION

Figure 8 indicates the experimental and numerical dynamic pressure
w/ and w/o isolation under El Centro PGA=0.7g. Results are indicated the
dynamic pressure in the storage tank had observably reduction with FPS
isolation. For example, in Figure 8 the peak dynamic pressure without
seismic isolation (broken line) of pressure cell denoted as A is 4.31 kN/m2
and using FPS (solid line) the peak dynamic pressure dropped into 1.66
kN/m2 the reduction ratio has a 61 percent; moreover the dynamic pressureof pressure cell denoted as E the reduction ratio even has a 56 percent.
Summary, another test cases effectiveness of friction pendulum bearings
seismic isolation of the model tank are presented in Table 1.
Experimental

5

Analytical

5

Fixed
Isolated

Fixed
Isolated

P (kN/m2 )0A

P (kN/m2 )

0.926

0

-1,661-3.641-4.307

-5
0

-5

5

10

Time(sec)

180

15

20

0

5

10

15

20

Time(sec)

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Figure 8: Dynamic Pressure Near Bottom of Tank (El Centro Earthquake,
PGA=0.7g, H=1.80m)
Table 2 indicates the percentage seismic effectiveness of peak
dynamic pressure remains constant change when we adjust the earthquake
intensity from 0.34g to 0.7g (H=1.8m) under El Centro earthquake
excitation. In Tab. 2 seismic effectiveness of peak dynamic pressure
gradually rose from 28% to 65%.
Table1: Effects of Isolation to Dynamic pressure
H=1.8mEl Centro PGA=0.7g

P.
Cell

W/o
isolation2(kN/m )A

Hachinohe PGA=1.0g(kN/m2)

Redu
.

(%)

W/o
isolation2(kN/m )

4.31

1.66

61

B

3.99

1.47

C

4.00

D
E

Kobe PGA=1.0g(kN/m2)

Redu
.

(%)

W/o
isolation2(kN/m )

8.29

2.62

68

63

7.72

2.22

1.41

65

7.94

3.81

1.45

62

3.29

1.46

56

Isolation

Isolation(kN/m2)Isolation

Red
.

9.6

2.42

75

71

9.33

2.17

77

2.23

72

9.06

2.16

76

7.80

2.48

68

8.95

2.25

75

6.69

2.22

67

7.01

1.72

75

(%)

Table2:Effects of Earthquake Intensity to Isolation（El Centro）
PGA=0.34g

P.
Cell

W/o
isolation2(kN/m )

A

PGA=0.5g(kN/m2)

Redu
.

(%)

W/o
isolation2(kN/m )

2.53

1.21

52

B

2.34

1.13

C

2.35

D
E

PGA=0.7g(kN/m2)

Redu
.

(%)

W/o
isolation2(kN/m )

4.28

1.69

61

52

3.97

1.59

1.08

54

3.98

2.24

1.18

47

1.93

1.38

28

Isolation

Isolation(kN/m2)Isolation

Red
.

4.31

1.66

61

60

3.99

1.47

63

1.48

63

4.00

1.41

65

3.79

1.49

61

3.81

1.45

62

3.27

1.35

59

3.29

1.46

56

(%)

5. CONCLUSIONS AND RECOMMENDATIONThis study has explored the feasibility of using friction pendulum
bearings for seismic isolation of rigid storage tanks by the scope of natural
disaster. The dynamic analysis of rigid tanks implemented with sliding-type
isolation systems is a highly nonlinear problem due to the presence offrictions. An analytical model for seismically isolated cylindrical storage
tanks has been derived and a solution algorithm developed, to assess theDisaster Mitigation Assessment for Storage Tank Facility

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ICUS Report 11

October 2005, Singapore

structural-hydrodynamic characteristics of such hybrid systems. Based on
the simulation results, it can be concluded that:
1. Seismic isolation of tank using FPS can effectively reduce theimpulsive dynamic pressure of the liquid.
2. Control efficiency increases with earthquake intensity.
3. Numerical simulation closely predicts the test results.
4. Fire, explosion and chemical leak is the main accidents wereclassified according to cause type.
5. Unknown, inappropriate operation and inappropriate design had
main risk source with storage tank fire accident.

REFERENCES

Jia, ZH. and Ketter, RL. Experimental study of “elephant foot budge”
instability of thin-walled metal tanks. Technical Report NCEER-89004, SUNY/Buffalo, New York, 1989.
Liu, WK. and Uras, RA. Transient failure analysis of liquid-filled shells,
part I: theory. Nuclear Engineering and Design. 1989; 117: 107-139.
Liu, WK. and Uras, RA. Transient failure analysis of liquid-filled shells,
part II: applications. Nuclear Engineering and Design. 1989; 117: 141157.
Wang, Y,P., Teng, M,C., and Chung K.W.,“Seismic isolation of rigid
cylindrical tanks using friction pendulum bearings,” Earthquake
Engng.Struct.Dyn.,Vol.30,No.7, 2001,pp. 1083-1099.
Wang, Y.P., Teng, M,C., and Chung K.W., “Experimental Study of Seismic
Isolation of Rigid Cylindrical Tanks Using Friction Pendulum
Bearings,” Proceedings of the Workshop on Diagnosis, Analysis andControl of Vibration and Noise, Shanghai,2001,pp.26-28.
Veletsos, AS. and Shivakumar, P. Hydrodynamic effect in rigid tanks
containing layered liquids. Earthquake Engng Struct. Dyn. 1995; 24,835-860.
Shivakumar, P. and Veletsos, AS. Dynamic response of rigid tanks withinhomogeneous liquids. Earthquake Engng Struct. Dyn. 1995; 24,991-1015.
INVESTIGATION REPORT U.S. CHEMICAL SAFETY AND HAZARDINVESTIGATION BOARD (CSB) REPORT, NO. 2001-05-I-DE,
OCTOBER, 2002.
Industrial Technology Research Institute (ITRI) Significant Accident Data
Base, Web Site：http://w3.itri.org.tw/accident/.

182

New Technologies for Urban Safety of Mega Cities in Asia

SAFETY MANAGEMENT RESEARCH OF
THE COACH ACCIDENT
Min-Cheng Teng1 Shih-Chien Huang2 Kuo-Shuh Fan3
Senior Assistant Research, National Sci & Tech. Center for Disaster Reduction, Taipei, Taiwan, Email: jack@ncdr.nat.gov.tw
2
Research Assistant, National Sci & Tech. Center for Disaster Reduction, Taipei, Taiwan, Email: schuang@ncdr.nat.gov.tw
3
Associate Professor, National Kaohsiung First Univ. of Sci & Tech., Kaohsiung, Taiwan, Email: ksfan@ccms.nkfust.edu.tw
1

ABSTRACT
Coach travel, because of their convenience and mobility, has become
one of the main transportation means on the road for tourism. Safety is theforemost concern and demand for travelers using this mode oftransportation. Numerous major coach-involved traffic accidents worldwide
have resulted in a high number of fatalities and injuries. As demonstrated
recently on October 14, 2003 in Taiwan, a coach accident resulted in 4
deaths and 13 injured. Therefore, the developing of accident analysis andsafety management laws review for coach is imperative in Taiwan. Accident
analysis and safety management are the major topics addressed in thispaper. We apply GIS (Geological Information System) software to build asystem for the coach analysis. In this system, we use space analysis,
property query to sift through the crash/accident data to obtain a coherent
trend pattern for further studies. The purpose of this paper is also to
consider imperfections in correlative laws and frame. GIS-Based Accident
System have four properties to describe the characteristics of a coachaccident: (1) occurred time: about year, month, day; (2) damage: dead,wounded, coach damage; (3) road fragment; (4) results of accident.
The major safety issues discussed in this study are potential for coachaccident as a result of the transportation disaster injuries mitigation.
Assessment of accident investigation, safety recommendation to the
Directorate General of Highway, MOTC in Taiwan. In addition, safety
management research will help to increase the capability of traffic accident
reduction

1. INTRODUCTION
The vigorous development and growth of the Tourism industry in
Taiwan has fueled a growing demand for an efficient method of ferrying
increasing number of passengers from one destination to another. As aresult, the coach bus, because of its high passenger handling capacity, has
become the favored mode of transport throughout the internal highway

183

October 2005, Singapore

routes. However, as a result, this has also led to numerous accidents
involving coach buses resulting in large numbers of dead, wounded andwreckages. According to the Ministry of Communications report, coachtraffic accident cases and number of injured people compared from January
to August 1993 with 1992, both rose by 11.9% and 11.3% respectively.
Over the years, there has been much emphasis placed on studies of traffic
accident disaster early warning and prevention measures conducted fortimes of natural disasters. There has however been a lack of studies for suchmeasures conducted for non nature-related disaster, such as in this case ofcoach-related accidents. Thus, the case analysis of the accident and safety
management of system of taking necessary precautions against coachdisaster and should be strengthened further achieve that end.

2. PRESENT SITUATION DESCRIBING
According to the Department of Statistics, Ministry of Transportation
and Communications database, the vehicle registration of tour buses
increased from 21,598 in 1995 to 26,545 in 2005. That shows a steady
growth of nearly a thousand vehicles annually as Figure 1 indicated.
Tour Bus
30000
25000
20000
Number 15000
10000
5000
0
05
20
04
20
03
20
02
20
01
20
00
20
99
19
98
19
97
19
96
19
95
19

Figure 1: The Vehicle Registration of Tour Bus
According to the Department of Statistics, Ministry of Transportation
and Communications database of May, 2005 (as shown in Tab. 1), thenumber of tour buses that are more than 10 years old exceeds 30%. That
figure exceeds 60% for tour buses more than 5 years old. Older vehicles
typically require more maintenance to keep them in operation amidst ahigher rate of depreciation as well. They may not be inadequate to meet the
rigorous demands of tourists seeking more modern, faster, more efficient,
comfortable and especially safer means of coach transportation. Therefore
the vehicle industry should encourage the vehicle operators to be proactivein adopting a strategy of safety improving, thus promoting higher passenger
traffic safety quality.

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Table1: Vehicle Car Age StatisticalAge(year)
< 1
1～3
3～5
5～7
7 ～10
> 10
Total

Number of Tour Bus
PrivateBusiness
Subtotal
16
206
222
126
3853
3979
129
4348
4477
238
2801
3039
383
5756
6139
1110
7569
8679
2002
24533
26535

Percent(%) Accumulated Percent(%)
0.84
15.00
16.87
11.45
23.14
32.71

0.84
15.83
32.70
44.16
67.29
100.003. METHODOLOGY
A major task in the methodology was helping to formulate a newframework for coach accident data collection, referencing and analysis. The
coach accident data collection and statistical methods used to perform
accident analysis. The method of analysis reporting will rely on the inherent
capabilities of the fundamental software platform used in architecture, theGIS platform. GIS map can not only display traffic accident casualty rates indifferent countries, it can also isolate the figures to coach-related accidents
only and how they compare in dangerous sections of the highway. In
addition, we can also discuss the coach safety management from a
regulation point of view. This paper reviews and summarizes current coachaccident safety management methods in highway adopted by transportation
departments. Furthermore, we can investigate the effectiveness of pastsafety improvement strategies with the newly developed system.
3.1 Comparative Method of LiteratureThis research approach, primarily studies the written historicalinformation of the report that records in order to observe the foundation, forexample: The record file of the organ, survey report, statistical analysis, etc.,
Summary of the content and classification after collecting relevant report,
newspaper and a periodicals, etc.
The information in this text collects will include: (1) Government's
materials; (2) special book; (3) periodical article; (4) an academic
dissertation; (5) others (news report, network information, etc.).
3.2 Data Collection and Analysis
49 coach accidents data were collected from May 5th, 2002 to June
3rd, 2005, which are sourced from the media and newspaper. In May 2005,
the website of Directorate General of Highways, Ministry of Transportation
and Communications (MOTC) in Taiwan has indicated there are potentially
49 coach-dangerous sections on the highway.
Upon the completion of material collection, the total display is
obtained in the GIS platform. An attribute table is then generated, also
performed directly in the GIS platform, and then mapped directly on the

Safety Management Research of the Coach Accident

185

October 2005, Singapore

GIS map to give the coach accident and dangerous section of highway map.
The GIS map can display the accident casualty figures in these different
locations, isolate them further to coach accident-related incidents, andcompare them accordingly.

4. DISCUSSION
4.1 Accident Data Compared with Dangerous Section
The highway coach accident material comprised of 45 cases between
May 5, 2002 and June 3, 2005, which resulted in a total of 52 deaths and617 wounded. These coach accidents caused serious damage as well. The
following serve as examples: a truck crashed into two coaches and one
automobile that caused 5 deaths and 21 wounded in national highway on
November 1, 2002; the coach accident that occurred in Taitung Country on
October 16, 2003, caused 5 deaths and 12 wounded; another coach that wascarrying tour group from Hong Kong, turned over at the mountain area
causing 5 deaths and 32 wounded in October 18, 2004.
Figure 2 shows the accident data compared with dangerous section fordifferent counties. What has to be noticed is 11 locations in Tainan County,
9 locations in Taipei County, 8 locations in Chiayi County for dangerous of
highway. Further analysis of coach accident, the highest numbers ofincidents were in Taipei County (8) and Nantou County (8), followed by
Miaoli County (4).
12

11

10

9
8

8

8

8
Number

6
6
4
4

3

3

2
2

1
00

1
0

1

1
0

1

3

3

2

2
1

11

1
0

0

0

3

2

2

1

1

0

1
0

Ke
elu

ng

Ta CityiTa pei
ip Cite
Ta i C yoyoua unt
n
y
Co
Hs
u
n
i
Hs nch ty
in u C
ch
u ity
M Co
iao unty
Ta l iich Couunnt
Na g Co yntou unty
Yu Co
nl un
in
ty
Ch Co
iay uni C tyTa ountyi
Ta nan
Ka inan Cityohsiu Coun
Pi ng C tyngtu ounngty
Yi Coulan
Hu n C ty
ali ounet
Ta n C yitu ountn
Pe g C yng ou
hu ntyCounty0CountyNumber of Accident
Number of Dangerous Section

Figure2: Number of Coach Accidental Section Compare With Dangerous
Section in Each County
4.2 The Coach Accident and Dangerous Section on GIS Map
The major goal of this paper is the development of a GIS-based
system of highway accident analysis for coach that can provide an insight
into the highway safety and coach travel as well as contributing date,186

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

damage and description of accident at any location. Figure 3 and figure 4
indicate the coach accidental and dangerous sections that were plotted in ageological information system (GIS). Figure 3 shows most of the coach
dangerous sections were in Taipei County, followed by Chiayi County andTainan County. Relatively, figure 4 shows most of coach accidents were in
Taipei County, followed by Nantou County, Miaoli County.

Figure3: The GIS map of dangerous sections in Taiwan

Figure4: The GIS map of coach accidental sections in Taiwan

Safety Management Research of the Coach Accident

187

October 2005, Singapore

The damage of the accidents based on GIS map is as shown in Figure
5. As the diagram indicates from accident damage information transferredfrom the statistical data to the GIS map. The most casualties were in Taipei
County.

160
134

Number of People

140
120

116

100

78

80

64

58

54

60

39

38

40
20

15
12
0
00

14 00

9

9

02 3

0

4

53 00 1

3

12
01 5

K
ee
lu
ng
Ta Ci
Ta ipei tyiTa pei City
oy Co
ua un
n
ty
H Cou
s
H inc nty
sin huch Ci
M u C ty
ia ou
Ta ol
nt
i
y
ic
hu Coun
N g C ntyanto ounY u C tyun oulin
Ch n C ty
ia ounyi
C ty
Ta ounin
Ta a tyni
Pi nan Cit
ng C y
tu ou
ng nt
y
Y Co
ila unH n C tyua
li ou
Ta en C nty
itu ong unt
Co y
un
ty

0

CountyDeath

WoundedFigure5: GIS map of coach accident damage
Directed to highest coach accidental and dangerous sections wasanalysis of Taipei County, Tainan County, Chiayi County, Nantou County,
Miaoli County.
The dangerous and accidental sections of Taipei County are presented
in Figure 6. It must be noted that the dangerous section 5 is near the coachaccidental section 4. In addition to coach accidental section 4, otheraccidents mostly occurred in tourist spots that caused serious damage of up
to 12 deaths and 116 wounded in the past. Comparatively, in the coach
dangerous sections, we should not overlook the sharp turn(s) that is(are)inherent in the mountain region as well.

Figure6: The GIS map of coach dangerous and accidental sections in Taipei
County188

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Figure 7 shows there were 8 coach related accidents in Nantou County
highway that caused 3 deaths and 134 wounded. The location of theaccidents was concentrated on the mountain region road area where 3
incidents had occurred in coach accidental sections 1 to 3, separately.
However, the coach accidental sections 1 to 3 are in the same highway. That
proved this highway was a highest risk area for transportation by coach.
Comparatively, for coach dangerous sections there aren’t any other in
Nantou County.
Figure 8 indicates there are 4 coach transportation related incidents in
Miaoli County highway that caused 9 deaths and 58 wounded of which
three of the incidents occurred on the national freeway. However, thelocation of the coach dangerous section is only in section 1.

Figure7: The GIS map of coach dangerous and accidental sections inNantou County

Figure8: The GIS map of coach dangerous and accidental sections in Miaol
CountySafety Management Research of the Coach Accident

189

October 2005, Singapore

The coach accidental sections were not tallied with dangerous sectionsin these counties. Figure 9 shows the 8 coach dangerous sections were notcorrespond with coach accidental sections in Figure 10 shown 11 coach
dangerous sections, however only one coach accident section in national
freeway in Tainan County.

Figure9: The GIS map of coach dangerous and accidental sections in
Chiayi County

Figure10: The GIS map of coach dangerous and accidental sections in
Tainan County

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Analyzing highway accident data is crucial to understanding safety
trends, designing strategies to combat safety problems, and evaluating
impact on safety measurements. Particularly, the proportion of coachaccident was highest in national freeway (24%) totally 11 out of all 45
coach accident cases. Figure11 shows the coach accident map of national
freeway that caused 11 deaths and 123 wounded and most of the accidents
occurred in the northern part of the Taiwan.

Figure11: The GIS map of coach accident in National Freeway
4.3 Regulations Discussion
As discuss to coach safety management must keep the domestic
regulations of Council of Labor Affairs, Taiwan R.O.C and Ministry ofTransportation and Communications (MOTC). For example, MOTC issued“Directions for the Safety Type Approval and Conformity of Production ofMotor Vehicles”. The vehicle safety type approval shall follow the principleof whole vehicle inspection and testing items, the vehicle type variation andsafety factors, etc., to select proper type and spec. of the whole vehicle forinspection and testing in accordance with the Attachment of Directions. This
research also combines interpretations of the United Nation Economic
Commission for Europe (UN/ECE), Federal Motor Vehicle Safety
Standards in U.S.A. (FMVSS), Safety Regulatuions for Road Vehicle IN
Japan, (SRRV) ； summaries of state and local regulatory requirements
about vehicle inspection and testing items.

Safety Management Research of the Coach Accident

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5. CONCLUSION(1)Implement a common direction for ECE regulations andconsolidating them with the domestic regulations to achieve a worldclass vehicle safety management system.
(2)GIS map can display the differences in accident casualty figures inthe different counties, group them directly by coach accident section
and compared them to dangerous sections of the highway. This GIS
map can provide for reference of government in setting more safety
regulations.
(3)Every county can mark the dangerous road sections with a sign toprovide advanced warning to the coaches. An alternate, safer routecan also be suggested. These measures can prevent many future
accidents from happening .
(4)The proportion of coach accident was highest in national freeway(24%) totally 11 out of all 45 coach accident cases. Therefore, thegovernment can review the characteristics and road environment forthese coach accident road sections, and act accordingly to prevent
more accidents as well.

REFERENCES
Directions for the Safety Type Approval and Conformity of Production ofMotor Vehicles, Ministry of Transportation and Communications,
2004.
Collision of a Greyhound Lines, Inc.Motorcoach and Delcar Trucking Truck
Tractor-SemitrailerLoraine, Texas, Transportation Safety Board(NTSB) Highway Accident Report, NO:PB2002-916201, 2003.
Motorcoach Run-Off-The-Road Accident Tallulah, Louisiana, National
Transportation Safety Board (NTSB) Report, No: PB2005-916201,
2003.
Regulation No 39 of the Economic Commission for Europe of the United
Nations (UN/ECE) —Uniform provisions concerning the approval ofvehicles with regard to the speedometer equipment including its
installation, Official Journal of the European Union, 2003.
Directorate General of Highways, Ministry of Transportation And
Communications, http://www.thb.gov.tw/c_bus/c_bus.htm
Department of Statistics, Ministry of Transportation And Communications,
http://www.motc.gov.tw/hypage.cgi?HYPAGE=stat.asp
Institute of Transportation, Ministry of Transportation And
Communications, http://www.iot.gov.tw
National Police Agency, Ministry of the Interior, http://www.npa.gov.tw/
SearchforNewsof
TVBS-NEWS
Website,http://www.tvbs.com.tw/news/news_search.asp?p=1

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A CASE STUDY OF THE INTRODUCTION
OF DISASTER MANAGEMENT SYSTEMAT ISLAMIC REPUBLIC OF IRAN
Shinya KONDO
Institute of Industrial Science, The University of Tokyo, Japan(Present: Disaster Center and Human Renovation Institution, Kobe, Japan)
kondo@risk-mg.iis.u-tokyo.ac.jp
Kimiro MEGURO
Professor, International Center for Urban Safety,
Institute of Industrial Science, The University of Tokyo, Japanmeguro@iis.u-tokyo.ac.jp

ABSTRACTFor realization of efficient disaster countermeasures, it is important to
prepare an environment in which people can analyze/assess past disaster
responses, sort out potential problems, and discuss countermeasures forthem. Therefore authors proposed a New Style Disaster Management
System for developing this environment.
At Islamic Republic of Iran, people have suffered severe damage due
to many strong earthquakes. For example, over 26 thousand persons were
killed and 30 thousands injured by Bam earthquake 2003. Seismologists
believe a strong earthquake will strike Tehran. According to the damage
estimation, casualty can reach 380 thousands, and over 50 % of building iscollapsed in Greater Tehran City in the worst scenario. As a result, it isnecessary to get lessons from past disaster to shape and pass down them toother people and to create an environment for the implementation ofdisaster countermeasures.
In this study, the authors propose the flowchart of the introduction ofcustomized Disaster Management System and introduce Disaster
Management System to the organization which plans disaster reduction at
Islamic Republic of Iran using this flowchart. At first, the system that people
in charge can analyze/assess and draft/update disaster management manualby themselves was installed at Greater Tehran Gas Company. Then thedisaster information database about disaster response in Bam earthquake
2003 was constructed at Iranian Red Crescent Society.

1. INTRODUCTION
Ideal disaster management measures are conducted in the following
balanced countermeasures: “Disaster Mitigation”, “Preparedness / Disaster
Response” and “Optimum Recovery / Reconstruction Plan” (Figure 1).
“Disaster Mitigation” means efforts to prevent hazard from becoming adisaster. “Preparedness / Disaster Response” means proper measures to193

October 2005, Singapore

prevent the disaster from affecting widely. “Optimum Recovery /Reconstruction Plan” means recovery and reconstruction from disaster
promptly to reduce its effects to a minimum. Comprehensive disastermanagement will not improve without user’s imagination of the realsituation in disaster clearly or the implementation of these three measures.
Same as before, we should prepare the environment people can makedisaster management manual by themselves. The process of making disastermanagement manual consists of 6 stages like Figure 2. First stage is“Imagining real situations in disaster”. Second stage is “Analysis of present
disaster reduction”. Third stage is “Reviewing disaster measures”. Forthstage is “Concretization of disaster measures”. Fifth stage is“Implementation or learning disaster measures”. And the last stage is“Evaluation of method and results of each stage”.
Based on these points, the authors proposed Disaster Management
System which supports people to make disaster management manual as theprocess above. This system consists of several systems, for example, “NewStyle Management Manual” (Kondo and Meguro, 2001) is the basis ofDisaster Management System and supports the stage “Analysis of present
disaster reduction”. This system has three features, “Analysis andAssessment of existing manuals”, “Independent edition by eachpurpose/user”, and “Drafting and Updating of manual”. And “New Style
Information Database” (Kondo and Meguro, 2002) supports the stage“Imagining real situations in disaster”. This database consists of newspaper,
reconnaissance reports, and reports on past disaster. With features,“Analysis and Assessment of existing manuals” and “Independent editionby each purpose/user”, this system can provide information such that people
can imagine real situation in disaster. Moreover, the system can accumulate
and share lessons learned from analyzing information about past disasters.
At Islamic Republic of Iran (Iran), people have suffered severe
damage due to many strong earthquakes. For example, Bam earthquake
2003 killed over 26 thousand persons and injured over 30 thousand persons.
Seismologists believe there is possibility that a strong earthquake will strike
Tehran. According to the damage estimation, casualty distributes 380
thousands, and over 50 % of building will be collapsed in Greater Tehran
City in the worst scenario. Based on these points, it is necessary to getlessons learned at past disaster into shape and pass down them to otherpeople and to create an environment for the implementation of the disastercountermeasures.
In this study, the authors propose the flowchart for introducing
customized Disaster Management System to the organization, and try to
introduce some features of this system to the organization planning disaster
reduction at Islamic Republic of Iran. At first, the system “New StyleManagement Manual” was applied to Greater Tehran Gas Company(GTGC). And “New Style Disaster Information Database” about disaster
response in Bam earthquake 2003 was constructed at Iranian Red CrescentSociety (IRCS).

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Disaster
Mitigation

Disaster Level

RescueEmergency

Preparedness /Disaster Response
Conventional Manual
New Style Manual

Earthquake

RecoveryTime from the Event

Optimum Recovery /Reconstruction Plan
Reconstruction

Figure 1: Difference in the effects of disaster reduction capability
between conventional type and new type of disaster management manual
1. Imagining real situations in disaster

2. Analysis of present
disaster reduction
5. Implementation/ Learning

6. Evaluation

3. Reviewing
disaster measures

4. Concretizationof disaster measures

Figure 2: The process of making disaster management manual
2. OUTLINE OF PROPOSED SYSTEM
2.1

Analysis and Assessment of existing manuals“Analysis and Assessment of existing manuals” makes people tounderstand the relation between each works from indexes set at eachmeasure easier. Therefore it becomes easier to analyze contents of present
manual rationally/objectively from various points of view. Figure 3 presents
an example of analysis and assessment of the disaster management manualof a big city in the Tokyo metropolitan region. The x-axis is “Time to startfrom an event”. The y-axis represents different “Responsible organization”.
The z-axis is “Amount of the work” to be done. From the x-axis, we can see
actions are not well pointed out after 6-24 hours and four days. Also fromthe y-axis, it can be seen that amount of work is not balanced amongorganizations.
2.2

Independent edition by each purpose / user

“Independent edition by each purpose / user” is to pick information of
the latest disaster and to understand the user’s need, directly by accessing

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the manual. Users can choose necessary conditions from indexes set at
previous section “Organization of the Manual” excluding “Work loads”,
picking up necessary items from whole manual, so they can get idea about
their own role, during a disaster. Figure 4 shows the application of thisfeature in the existing government disaster management manual aspresented in Figure 3. This figure shows that how a General Manager,(normally mayor or governor) of an organization can select his own
responsibility just by clicking a button on his position.
Actions are not well balanced(after 6-24 hours and 4 days)

Changes of the actions
in time domain

43

39
33

28
17
11

19
13
3 3

Amount of the work
(No. of articles)
Z

0

33

40
35
30
25

3

6
6

26

1
4

11 8 1

Responsibleorganization

20
15
10

1
2
3
6
12
24
48
72
96
16
8
24
0
33
6
50
4
67
2
99
To 9
ta
l

0
0.
5

5

Y

2 3

Total
WelfareCivil Engineering
Urban Development
General Affairs
Water Supply Management
Fire Fighting
1
18
Citizen Affair
18
General Manager
2
Traffic Management
2
Construction
21
Finance
Education
5
Environment Management
Sewerage Management
3
Health and Medical Facility
Ports and Harbors

50
45

8

3

76

Total amount of business is notbalanced well among organizations

Time from the event (hour)

X

Figure 3: Analysis and Assessment of existing manuals

The edited manual as
Responsible organization = General Manager
Z

Y
43

X

4
3

50

2

45

1
0

0.5

1

3

6

24

Amount of the work
(No. of articles)

No. of articles

33

Transport Planning17
13
Evacuation 11
3 3
Road / Traffic
Housing
Preparedness for Facility
Disaster Relief Law
Supply of Water/Food/Livingware
Medical and Relief

5

0

39
28

6

48

40
35

96 30 999

25
Time from the event (hour)

Service

20
15
10
5

0.

0
5
1
2
3
6
12
24
48
72
96
16
8
24
0
33
6
50
4
67
2
99
To 9
ta
l

0

Content of work can be seen

19
3

76

8

2 3

33

2

3

1
4

Total
WelfareCivil Engineering
Urban Development
General Affairs
Water Supply Management
Fire Fighting
Citizens Affair
6

11 8 1

1

18
18

26

6

General Manager

Traffic Management
2
Construction
21
Finance
Education
5
Environment Management
Sewerage Management
3
Health and Medical Facility
Ports and Harbors

Responsibleorganization

The whole manual

Time from the event (hour)

Figure 4: Independent edition by each purpose / user

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3. OUTLINE OF FLOWCHART TO INTRODUCEIn this study, the authors introduced Disaster Management System tothe organization at Iran followed the flowchart. Figure 5 is the flowchart for
introduction of system to the organization. Content of each work is included
below.
3.1 Checking the length to introduce
For introducing proposed system to the organization, people should
check the length that expert can work on-site. So, the schedule and function
to install can be decided. At GTGC and IRCS, each length that the authors
could work to install is shown in Table 1.
3.2 Grasp of characteristics of the region
People should grasp characteristics of the region, for installingsystem adapting to the organization. At this stage, people studied damage
estimation (JICA, CEST 2000) at Tehran city.
3.3 Setting up project team
People should set up project team with members of the organization
for installing and managing proposed system by themselves. Members ofproject team consist of expert, facilitator, database creator, and interpreter(Farsi to English).
3.4 Grasp of characteristics of the organization
At this stage, people should know structure of the unit of theorganization. So members of the organization were recruited to the project
team. The authors could grasp characteristics of the organization from them.
3.5 Decision the data for database
Project team selected data for making database by database creator. At
GTGC, existent disaster management manual was used. Based on Disaster
Information Database at IRCS, facilitator could ask people who areresponded for Bam earthquake to make database.
3.6 Making database
The authors asked database creator to put 7 indexes in Farsi to eachmeasure, “Responsible organization”, “Service contents”, “Term of
measures (relatively)”, “Time to start and finish measures from an event(absolutely)”, and “Work loads (man x day)”. So it is easy for people toimagine situation after disaster happened. Picture 1 shows the people during
making database at IRCS.

A Case Study of the Introduction of Disaster Management System at Islamic Republic of Iran197

October 2005, Singapore

3.7 Checking the network
Checking the network is very important because proposed system uses
Web application. But network at Iran was poorer than at Japan. Then project
team decided to install proposed system to each PC.
3.8 Installing the system
Expert installed proposed system with a policy decided at pre-step.
Expert installed proposed system as shown Table 2.
3.9 Working out the bugs
After installing the system, project team should find out the bugs ofsystem. They should fix bugs if found. During this time, one bug was found.
Farsi was displayed from left to right (Usually right to left) on screen.
3.10 Evaluation the system
After pre-step, project team asks members of the organization toevaluate installed system. If some problem is pointed out, they feed back tothe system. During this time, they asked boss and several directors at GTGC,
and some researcher to study about disaster response at IRCS. In eachsituation, installed system got high evaluation.
1. Checking the length to introduce
2. Grasp of characteristics of the region
3. Setting up project team
4. Grasp of characteristics of theorganization
User
5. Decision the datafor database
6. Making database

Expert7. Checking the network
8. Installing the system

9. Working out the bugs
10. Evaluation the system

Figure 5: Flowchart for introduction of system

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Table 1: The length to install proposed system.
Organization Date
LengthGTGC
27th , June – 6th , July, 2004
9days
th
th
IRCS
7 , August – 14 , August, 2004 8days

Picture 1: People making database
Table 2: Environment of proposed system.
Function
SoftwareOS
Windows XP
ServerApacheDBMS
MySQL
Server-side Script
PHP
4. RESULT OF INTRODUTION
Figure 6 shows a result of analysis GTGC Disaster Management
Manual. The x-axis is “Responsible Organization”. The y-axis is “Timefrom the event”. The z-axis is “Work loads”. The right side of windowshows name of responsible organization corresponding to the number on thex-axis. From this figure, we can see that all sections will start all works after
1 hour to 2 months from the event. This result shows database creator has ashortage of imagination for disaster situation. So, the environment members
can imagine real situation should be prepared.
Figure 7 shows the example at using Disaster Information Database ofdisaster response of IRCS in Bam earthquake. The x-axis is “Responsible
Organization”. The y-axis is “Time from the event”. The z-axis is “Workloads”. With this system, people can imagine real situation in disaster easier.
Therefore this system prepares environment for members to pick out lessons.

A Case Study of the Introduction of Disaster Management System at Islamic Republic of Iran199

October 2005, Singapore

Analyze /Assess Disaster Manual
Z-axisWork loads

X-axisResponsible
Organization

Display other window

Y-axis Time from the event

Figure 6: Result of analysis GTGC Disaster Management Manual

Ｚ-axisWork loads

X-axisResponsible
Organization
Be Dis 1hr 2hr 3hr 6hr 12h 1da2da 3da 1we 2we1m 2m 3m 6m 1ye2ye 3ye 5ye 10y
for as . s. s. s. rs y ys ys ek ek on ont ont ont ar ar ar ar eas s s rs.
e ters th hs hs hs

Y-axisTime from the event

Figure 7: The example to use Disaster Information Database of disaster
response of IRCS in Bam earthquake
5. CONCLUSION
In this study, the authors proposed the flowchart for introducing
customized Disaster Management System to the organization. Moreover, theauthors tried to introduce some features of this system to the organization
which plan disaster reduction at Islamic Republic of Iran. At first, thesystem “New Style Management Manual” was applied to Greater Tehran
Gas Company (GTGC). “New Style Disaster Information Database” about
disaster response in Bam earthquake 2003 was constructed at Iranian Red

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ICUS Report 11

Crescent Society (IRCS). With this system, these organizations can create
the environment that people can make disaster management manual bythemselves. And they can improve earthquake disaster reduction.

REFERENCES

Kondo, S., Hamada, S., and Meguro, K., 2001, Proposal of New Style
Disaster Manual for Implementation of Efficient Disaster
Countermeasures, 26th JSCE Earthquake Engineering Symposium,
pp.1481-1484.
Meguro, K., 2001, Dynamic Evaluation Model for Large Earthquake
Disaster, Journal of Geography, Vol. 110, No. 6 (979).
Kondo, S., Meguro, K., 2002, Development of New Style Disaster
Information Database for Implementation of Efficient Disaster
Countermeasures, No.4, Journal of Social Safety Science, Institute ofSocial Safety Science, Japan, pp.261-266.
Japan international cooperation Agency (JICA), Center for earthquake andenvironmental studies of Tehran (CEST), and Tehran Municipality,
2000. THE STUDY ON SEISMIC MICROZONING OF THE
GREATER TEHRAN AREA IN THE ISLAMIC REPUBLIC OF IRAN

A Case Study of the Introduction of Disaster Management System at Islamic Republic of Iran201

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202

New Technologies for Urban Safety of Mega Cities in Asia

VULNERABILITY OF COASTAL CITIES OF
ASIA TO RISING SEA LEVEL:A CASE STUDY IN BANGKOK
DUSHMANTA DUTTA
School of Applied Sciences and Engineering,
Monash University, Australia
dushmanta.dutta@sci.monash.edu.au
ABSTRACTThe paper presents the outcomes of a case study conducted to analyze theflood characteristics in Bangkok under sea level rising scenarios. A physically
based distributed hydrological model, which combines surface and river flow, wasadopted to simulate the flood scenarios due to different magnitudes of sea level
rising. The input rainfalls and the upstream boundary conditions of a worst flood
event of 1995 were considered as the baseline for the modeling based on theavailable records of rainfall and water level datasets of the last three decades. The
study was aimed to capture a macro picture of floods to present an overview ofseverity of flood situations under climate change conditions.

1. INTRODUCTION
The 20th century was the warmest the world has seen in 1,800 years.
A warming climate leads to changes in many aspects of climate system andearth environment including precipitation, wind pattern, the frequency andseverity of extreme weather events and rise of sea level. Based on a study of2001, the Intergovernmental Panel on Climate Change (IPCC) has predictedthat the global mean sea level (msl) may rise as much as 88 cm by the endof the 21st century. Approximately 20% of the global population lives
within 30 km of coastal areas and the number is expected to become double
by 2025 (Cohen et al., 1997). The sea level rise will have wide ranging
effects on coastal population and ecosystem, such as saline water intrusion,
erosion of shorelines, amplified intensity and frequency of coastal floodinundation, etc.
The socio-economic impacts of climate change in the coastal cities
of Asia will be enormous due to the rapid urbanization and high population
growth. The combined effects of potential sea level rise and extreme rainfall
events triggered by climate change may lead to catastrophic flood disasters
in many of the coastal cities of Asia, which are located in the low-lying
floodplains of major rivers. So far only a few studies have been conductedin this direction and a very few countries have prepared long-term plans todeal with these problems. It is important to assess the impacts of mean sea
level rise on flooding in coastal cities and prepare long-term plans for risk
management (Dam, 2003).
A study that was conducted to analyze the socio-economic impactsof floods in several large coastal cities of Asia under projected climatic andsocio-economic scenarios using a distributed hydrological model and an203

October 2005, Singapore

agent based land use change model. The paper presents the outcomes of acase study which was conducted to analyze the flood characteristics in
Bangkok under sea level rising scenarios. A physically based distributedhydrological model, which combines surface and river flow, was adopted tosimulate the flood scenarios due to different magnitudes of sea level rising.
Input rainfalls and upstream boundary conditions of a worst flood period
were considered based on the records of the last three decades as thebaseline for modeling. The study was aimed to capture a macro picture offlooding to present an overview of severity of flood situation utilizing
surface elevation of 1km resolution and without going into micro details ofurban topography and drainage.

2. STUDY AREA
Bangkok, the capital city of Thailand, is one of the major cities in Asiaand a regional hub. It is located on the lower flat basin of the Chao Phraya
River, which is originated in the northern most part of Thailand anddischarges to the Gulf of Thailand after flowing approximate 900 km (Fig.
1). The catchment area is 157,925km2, which covers about 30% ofThailand’s land area. The average annual discharge of the Chao Phraya
Basin is about 770 m3/s with a peak of 4,560 m3/s recorded in 1995
(Thammasittirong, 1999).

N

C22

Chao Phraya
Basin

C12
C4

ThailandPom Phrachul

Km

Gulf of Thailand

Figure 1. Location of the study area

Floods, mainly caused by upstream inflow and high intensity rainfalls,
are the most frequent natural disasters in Bangkok. It affects a large numberof populations and causes huge economic damage every year. Due to its low
elevations, ranging from 0m to 4m above msl, tidal effect is prominent in
the Chao Phraya river upto several kilometers inside Bangkok and that
attributes significantly to floods. There are usually two high tides and two
low tides per day in Gulf of Thailand, but these are often asymmetrical withamplitude of 1-2m. The daily variation of tides is normally from -0.5 m to
1.5 m with a peak of 2.5 m recorded in 1995.
3. METHODOLOGY204

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The surface and river components of the IISDHM, a physically based
distributed hydrological model (Jha, et al, 1997, Dutta et al., 2000), wereused for flood inundation simulation. In this model, 1D Saint-Venant’s
equations of continuity and momentum equations are used for river network
flow simulation and 2D form of the equations for surface flow routing. The
exchange of flow between the channel network and flood plains is simulatedusing the floodplain compartment concept (Dutta, et al., 1997).
3.1 Model Setup
The model setup for this case study was done with 1km spatial
resolution and 1hour temporal resolutions. Elevation data was obtained from
HYDRO1K DEM of USGS and landuse data from the USGS global landuse
database. Surface roughness coefficients for different grids were assigned
based on the landuse types. For river network, only the main stream of the
Chao Phraya river was considered with the hydrological gauging station
C22 as the upstream boundary and Pom Phrachul as the downstream
boundary (Figure 1). River cross section data, hourly rainfall data in the 4
gauging stations within the study area, hourly water level data for upstream
and downstream boundary stations were obtained from various local sources
including the Bangkok Metropolitan Administration (BMA), Royal
Irrigation Department (RID) and the Port of Thailand Authority.
3.2 Model Calibration and Verification
The model was calibrated and verified two selected flood events of
1995. The calibrated parameters were Manning’s roughness in the river andrunoff coefficient. Calibration and verification was performed using theobserved water level data for the C12 and C4 water level gauging stations in
the Chao Phraya River (Figure 1). Figures 2 and 3 show the observed hourly
water level data for the upstream and downstream boundary stations and theaverage hourly rainfall in the study area for the period of calibration andverification of the model.
The calibrated value of runoff coefficient was 0.4 and Manning’s
roughness for river was 0.04. Figures 4 and 5 show the comparison ofsimulated and observed water levels at C12 and C4 stations during theperiod of verification. As can be seen from Fig. 4, the simulated water levelagrees well with the observed water levels at C12 for the peak and pattern offlow. However there are some overestimations of the simulated water levelat C4. The simulated maximum surface inundation during the period ofverification for the flood event of 1995 is shown Figure 6. It shows that
surface inundation was highest at the lowest part of the study area.
Inundation height in most of the areas was within 1m, as mentioned inseveral reports on the 1995 floods. However, in absence of any ground
actual flood inundation map, simulated results could not be verified.

Vulnerability of Coastal Cities of Asia to Sea Level Rising: A Case Study in Bangkok

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October 2005, Singapore
Boundary Water Level
3.2

Water Level (m)

2.8
2.4
2.0
1.6
1.2
0.8
0.4
0.0
-0.4
-0.8
0

50

100

Upstream Water Lever

200 Hour150
Dow nstream Water Lever

Figure 2. Input hourly boundary water levels at u/s and d/s (from October 23rd to 31st, 1995)
55.0
50.0
45.0

Rainfall (mm)

40.0
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
1

16

31

46

61

76

91

106

121 136

151 166

181 196Hour

Figure 3. Input hourly average rainfall data (from August 4th to 13th, 1995)

4. IMPACTS OF SEA LEVEL RISING ON FLOODSFor analyzing the impacts of sea level rising on floods in Bangkok, two
scenarios are considered, one for 50cm rising of the highest recorded periodof sea level based on the past 20 years record and another is 100cm rising.
These are close to the highest level of prediction of global average sea level
rise in different SRES Scenarios in IPCC study as shown in Figure 7. This is
close to the scenario of the highest value predicted by IPCC as 88 cm by theend of the 21st century (Watson, 2001). The hourly time series of waterlevel of floods in 1995 is used as upstream boundary condition and hourly
time series of sea level as the downstream boundary condition. The
boundary condition data was selected from 23-31 October 1995, the highest
water level duration recorded in 1995. Hourly rainfall data was taken for thehigher rainfall duration of 1995 floods that is from 4-13 August.
The simulated maximum flood inundation maps for the two selectedscenarios of sea level rising are shown in Figures 8 and 9. The simulated
results show that almost 55% of the study area will be affected by flood ifmean sea level rises by 50 cm and 72% area will be affected if mean sea
level rises by 100 cm. Table 1 shows the possible areas of inundation under
different flood depths as compared to the 1995 floods, which shows that
overall inundation in the study area will be increased by 16% due to 50cm
rise of sea level and 34% due to 100cm rise. Similarly, the inundation
heights will increase significantly in many locations as shown in Figure 10
for the location a (Pak Num) (Figure 9). These results show there will be
serious effects of sea level rising in flooding conditions in Bangkok city andthat will in turn lead to high socio-economic consequences.
Table 1. Flood inundation areas in different scenarios

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Flood
depth in
cm
10-20
21-50
51-100101-150
151-200
201-250251-300
301-350
Total

Simulated flood Area in km2 (in %)Floods in 1995
Sea level rise
Sea level rise 100cm
50cm
987 (29.6)
1025 (30.9)
891 (26.8)
188 (5.6)
593 (17.8)
1,219 (36.6)
37 (1.1)
141 (4.2)
189 (5.7)
37 (1.1)
1 (0.1)43 (1.3)
24 (0.7)
43 (1.3)
9 (0.3)6 (0.2)22 (0.7)
51 (1.5)
0 (0.0)5 (0.2)9 (0.3)0 (0.0)0 (0.0)1 (0.2)
1,279 (38)1,830 (54)2,412 (72)Comparsion of Water Level at C12
1.40
1.20
Water Level (m)

1.00
0.80
0.60
0.40
0.20
0.00
-0.20
-0.40
-0.60
1

11

21

31

41

51

Observated WL

61

71

81

91

101 Hour

Simulated WL

Figure 4. Comparison of simulated and observed water level at station C12

Water Level (m)Comparsion of Water Level at C4
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
-0.20
-0.40
-0.60
-0.80
1

11

21

31

41

Observated WL

51

61

71

81

91

101 Hour

Simulated WL

Figure 5. Comparison of simulated and observed water level at station C4

Figure 6. Simulated maximum flood inundation in 1995

Vulnerability of Coastal Cities of Asia to Sea Level Rising: A Case Study in Bangkok

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October 2005, Singapore
Range in 2100
All SRES envelope including
land-ice uncertainty
Several Models all
SRES envelope
Model average all
SRES envelope

Figure 7. Global average sea level rise (1990-2100) (Church et al, 2001)

Figure 8. Simulated flood inundation map due to sea level rising to 50cm

A

Figure 9. Simulated flood inundation map due to sea level rising to 100cm
Inundation depth at Point A (300 sec)
225
200

Depth (cm)

175
150
125
100
75
50
25
0
82

85

88

Sea L evel ris e 100cm

91

94

97

Sea Level ris e 50cm

100

103

Hour

Flood in 19 95

Figure 10. Comparisons of temporal inundation depth variation at Point A between
simulated floods in 1995 and floods due to sea level rise by 50 cm and 100 cm

5. ASSESSEMENT OF SOCIO ECONOMIC IMPACTS AND
VULNERABILITY
For the assessment of socio-economic impacts of floods, three mainsocio-economic aspects were considered, they were population, buildings
and transportation infrastructure. The existing data and information for three208

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categories for 2000 were collected at the district levels. The spatial
simulation of the future population and urbanization was carried out basedon the IPCC SRES B1 Scenario using the AGENT-LUC model (Rajan andShibazaki, 2000). The maximum population density was designed as
20,000Km-2. The projected urbanization and population of future scenarios
are shown in Figures 11 and 12.

a)

b)

c)

d)

Figure 11. Projected urban area of study area in: a) 2025, b) 2050, c) 2075 and d) 2100

a)

b)

c)

d)

Figure 12. Projected population growth in the study area in: a) 2025, b) 2050, c) 2075 and d)
2100

Flood simulation was carried out by the hydrological model for four
scenarios of mean sea level rise in the high predicted levels by IPCC for
2025, 2050, 2075 and 2100 for socio-economic impact analysis. A set of
qualitative indices were developed for flood impact estimation for the three

Vulnerability of Coastal Cities of Asia to Sea Level Rising: A Case Study in Bangkok

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October 2005, Singapore

selected categories based on the outcomes of a questionnaire survey
conducted among some affected people of the study area in the recent past.
Using these indices, outcomes of flood inundations for the projected meansea level rises and growth of populations, urban buildings and road
networks for the selected years, flood impacts for these three sectors were
estimated.
Table 2 presents the flood impact indices for buildings. The estimatedflood impacts on buildings for the selected years are presented in Table 3. It
is observed that the number of affected of buildings in the ‘less impact’
class increases by 1.5 times in 75 years period from 2025 to 2100. Similarly,
the number of affected of buildings in ‘moderate impact’ class increases by
30% in 75 yrs period from 2025 to 2100. The increase is not only resulted
by the expansion of flood inundation area but also by the growth ofurbanization. The flood impact indices for population and number of flood
affected people under different categories for the selected years arepresented in Tables 4 and 5. Table 5 shows that the number of affected ofpeople in all the three categories will increase significantly during 75 years
period from 2025-2100.
Table 2. Flood impact indices of buildings
Depth offlood (m)< 0.1
0.10-0.60
0.60-1.00
1.00-3.50> 3.50

<1
A
B
B
C
D

Duration of flood (day)1-2 3-4 5-7
>7
A
A
A
A
B
B
B
B
C
C
C
C
C
C
D
D
D
D
D
D

A: No impact, B: Less impact, C: Moderate Impact, D: High Impact, E: Highest Impact

Table 3. Summary of the affected buildings
No. of affected buildings in study area
Impact
Index
2025
2050
2075
2100
Less
1,145,980 1,451,322 1,629,826 1,791,502
Moderate
82,00897,071
105,328
110,577
Table 4. Flood Risk Indices of population
Duration of flood (day)Depth offlood (m)< 1 1-2 3-4 5-7 > 7
< 0.1
A
A
A
A
A
0.10-0.60
B
B
CC
C
0.60-1.00
CC
C
C
D
1.00-3.50
EE
E
E
E> 3.50E
E
E
E
E
A: No impact, B: Less impact, C: Moderate Impact, D: High Impact, E: Highest Impact

The flood impact indices for road and length of affected road lengths inthe study area during the selected years are presented in Tables 6 and 7. It
can be observed that total affected of road in scenario 2100 is much higher
than the total affected road length in 2025 which may be attributed to larger
flood inundation area in 2100 compared to 2025. The flood impact indicesfor railways and affected lengths of railway in the study area are presented
in Tables 8 and 9. It can be observed that total affected lengths of railway in

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future scenarios increases significantly, while the affected railway length
under high impact category remains constant.
Table 5. Summary of the affected population
No. of affected population in study area
Impact
Index
2025
2050
2075
2100
Less
5,720,020 6,804,316 7,632,711 8,969,668
Moderate 134,405
227,777
340,657
446,810Highest293,047
311,898
312,903329,816
Table 6. Flood Risk Indices of road
Duration of flood (day)Depth offlood (m)< 1 1-2 3-4 5-7 > 7
< 0.1
A
A
A
A
A
0.10-0.60
B
B
B
B
B
0.60-1.00
CC
C
C
C
1.00-3.50
CC
C
D
D> 3.50C
C
D
DD
A: No impact, B: Less impact, C: Moderate Impact, D: High Impact, E: Highest Impact

Table 7. Summary of the affected road
Length of affected road in study area
Impact
(m)
Index
2025
2050
2075
2100
Less
569,742 624,118 695,961 837,332
Moderate 65,522 80,041 110,741 133,836
Table 8. Flood Risk Indices of railway
Depth ofDuration of flood (day)flood (m) < 1 1-2 3-4 5-7 > 7
< 0.1
A
A
A
A
A
0.10-0.60
B
B
B
C
C
0.60-1.00
CC
C
D
D
1.00-3.50
DD
D
DD> 3.50
D
D
D
DD
A: No impact, B: Less impact, C: Moderate Impact, D: High Impact, E: Highest Impact

Table 9. Summary of the affected railway
Length of affected railway in study
Impactarea (m)
Index
2025
2050
2075
2100
Less
89,050 95,627 105,913 122,016
Moderate
966
High1,430 1,430
1,430
1,430

6. CONCLUSIONSThe simulated outcomes of the flood model show that almost 55% of the
Bangkok City will be affected by floods if mean sea level rises by 50 cm
and 72% will be affected if mean sea level rises by 100 cm, which arehigher by 16% and 34% respectively as compared to the simulated
inundated areas due to the 1995 floods and that will lead to adverse impacts
on socio-economic sectors. The outcomes of social-economic impacts

Vulnerability of Coastal Cities of Asia to Sea Level Rising: A Case Study in Bangkok

211

October 2005, Singapore

analysis show that number of flood affected buildings and population androad lengths will be rapidly increased due to possible sea level rise from2025 to 2100.
The outcomes present a macro picture of floods and its socio-economic
impacts in the Bangkok City under mean sea level rise scenarios in the 21stCentury. Although the severity of the flood magnitudes simulated by thehydrological model is overestimated to a certain extend due to non-inclusionof the existing structural flood control measures such as the east and west
dyke systems, retaining walls, pumping stations, diversion canals and themicro details of the topography in the modeling, nevertheless, the modeloutcomes present a clear picture of potential risk of severe floods and its
impacts due to the predicted mean sea level rising in the Bangkok city.
Acknowledgement
The authors gratefully acknowledge the financial supports obtained from the
APN Project Grant 2004-CB01-NSY for conducting this study.
References
Cohen, J.E., Small C., Mellinger A., Gallup J. and J. Sachs (1997).
Estimates of Coastal Populations, Science, Vol. 278, pp 1211- 1212.
Dam Jan C. van (2003). Impacts of Climate Change and Climate Variability
on Hydrological Regimes, 1st edition, Cambridge University Press.
Dutta D., Herath S. and Musiake K. (1997). Distributed Hydrological Model
For Flood Inundation Simulation, Annual Journal of HydraulicEngineering, JSCE, Vol. 43, pp 25-30.
Dutta, D., Herath, S. and Musiake, K. (2000). Flood inundation simulation
in a river basin using a physically based distributed hydrologic model.
Hydrological Processes 14: 497-519.
Jha, R., Hearth S. and Musiake K. (1997). Development of IIS Distributed
Hydrological Model (IISDHM) and its application in Chao Phraya
River Basin, Thailand, Annual Journal of Hydraulic Engineering, JSCE,
Vol. 41, pp 227-232.
Rajan, K.S. and Shibazaki, R. (2000). Land Use/Cover Change and Water
Resources – Experiences from AGENT-LUC Model, Proceedings of the
APFRIEND Workshop on Mekong Basin Studies, INCEDE Report 19,
University of Tokyo, Japan, pp. 1-16.
Thammasittirong (1999).Operational Flood Forecasting for Chao Phraya
River Basin, Thesis WM-99-23, AIT, Thailand,
Waston, R.T. (2001). Climate Change 2001, Six conference of Parties to theUnited Nations Framework Convention on Climate Change.

212

New Technologies for Urban Safety of Mega Cities in Asia

SURVEY ON RESIDENTS' ATTITUDES FORRETROFITTING OF EXISTING
VULNERABLE HOUSES
Miho YOSHIMURAInternational Center for Urban Safety Engineering
Institute of Industrial Science, The University of Tokyo, Japanyosimura@iis.u-tokyo.ac.jp
Kimiro MEGURO
International Center for Urban Safety Engineering
Institute of Industrial Science, The University of Tokyo, Japanmeguro@iis.u-tokyo.ac.jp
ABSTRACT
From recent damaging earthquakes, it is clearly found that retrofitting of
low earthquake-resistant houses is the key issue for earthquake disaster
reduction. However, the homeowners possess various reasons not to retrofit
their houses. In this research, a questionnaire survey was conducted tohomeowners in Japan in order to find more effective strategies forpromotion of retrofitting vulnerable houses based on residents' needs. The
main factors that encourage or discourage homeowners to retrofit theirhouses were identified. Moreover, their anxiety for uncertainty of building
strength after retrofitting and the activities of dishonest contractors werealso pointed out. Finally, based on the homeowners' attitudes, somesuggestions were presented to improve the current strategies for promotionof retrofitting vulnerable houses.

1. INTRODUCTION
Even if a very good disaster response system and/or disaster recovery andreconstruction plan is available, it is impossible to reduce earthquake
damage without implementing proper mitigation techniques. The 1995 Kobe
earthquake caused 6,433 dead and 43,792 injured people. It is reported that87% of people were killed in their own homes due to the collapse of thestructure or the falling furniture, as the occurrence time of the earthquake
was early in the morning, 5:46 am. Considering this fact, the only way tosave these lives was to increase the strength of their residences byretrofitting or rebuilding them before the event.
Based on the actual earthquake damage, the structural seismic design code
has been revised several times in Japan. The final (before the Kobe
Earthquake) code revision was done in 1981. The structures that wereconstructed using this code performed well even under the strong groundmotion of the Kobe earthquake as shown in Figure 1. However, there aremany vulnerable ones among the structures constructed before the 1981

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October 2005, Singapore

code revision. According to the Ministry of Land, Infrastructure andTransport Government of Japan, the number of vulnerable timber singlefamily houses are estimated to be 10 million in total 11.5 million houses
constructed before 1981. In spite that these structures need to be retrofitted
before the next big event occurs in order to reduce the earthquake damage,retrofitting activities are not carried out widely especially for private houses.
Some municipalities or local governments have conducted systems topromote retrofitting activities such as, the assistance system, and the lowinterest loan for seismic evaluation or retrofitting of structures. However,
the homeowners possess various reasons not to retrofit their houses.
Unfortunately, so far, there is no municipality in which the retrofitting
activities have been successfully carried out in Japan.
In this research, a questionnaire survey was conducted to homeowners inJapan in order to find more effective strategies for promotion of retrofitting
existing vulnerable houses based on residents' needs. The main factors thatencourage or discourage homeowners to retrofit their houses were identified.
Moreover, their anxiety for retrofitting work was analyzed. Finally, basedon the homeowners' attitudes, some suggestions are discussed to improvethe current strategies for promotion of retrofitting existing vulnerable houses.

After 1981 3.35.3 5.3 11.3

1971-1981 4.9 6.8

Before 1971

38.7

10.7

16.7

20.5

18

Table 1: Estimated number of vulnerable
pre-code houses

36

32.2

22.7

24.9

16.7

0%

20%

40%

60%

Collapse

SevereModerate

Slight18

80%
LittleFigure 1: Damage ratio of pre-code
and current-code structures

Number (Million)
7.9

100%
No damage

Total number
Number of houses
constructed before
1981
Number ofvulnerable houses
constructed before
1981

Houses (including
Timber singleall the construction
family houses
type)
46.9
24.5
17.6

11.5

11.7

10.0

2. OUTLINE OF THE QUESTIONNAIRE SURVEY
A questionnaire survey was conducted for the head Pre-code houses
Current-code housesof a household (or, the spouse of the head of ahousehold) of 30-69 years old who lived in the 105
304
461
1,012
685
owner-occupied house in Tokyo Metropolitan
region, by the internet survey form. Investigation 37
N=2,604
periods were December 17-23, 2004, and it got the
20%
40%
60%
80%
100%
answer of 2,604. The number of respondents was 0%classified by the construction year of their houses-1960
1961-1970
1971-1981.5
1981.6-1989
1990-1999
2000-2004
in Figure 2. The rate of the respondents who live inthe pre-code houses was 17.1%. Considering thatthe rate of pre-code houses is 50.7% according to Figure2: Number of respondents classified
by construction year of their
the national statistics of building stocks, thehousesobserved rate of pre-code houses was smaller than214

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11
100%

100%

108-10
6-8

80%

80%

60-69
50-59
40-49
30-39
(years old)

60%
40%
20%
0%

61-70
-1960
1
2

7181.690-99
2000-04
3
4
5
6
建築年代
81.5
89

N=1,596

60%

4-6
-4
(million
yen)

40%
20%
0%

30-39 40-49

50-59

60-69

N=1,596

Age of respondents

Construction year

Figure4: Number of respondents classified
Figure3: Number of respondents classified byby annual incomes levels
their age and construction years of the houses
the real situation because the survey was done using an internet environment.
The 1,596 respondents who lived in the timber single-family houses wereselected among total 2,604. The relation between the age of these
respondents and the construction year of their houses was shown in Figure 3.
The respondents of 50-59 years old had highest annual incomes as describedin Figure 4.
3. HOMEOWNERS’ WISHES TO RETROFIT THEIR HOUSESFirst, homeowners’ earthquake risk perception was observed. Figure 5 is the
expectations of the earthquake occurrence of the 1995 Kobe Earthquake
level classified by the constructions year of their houses. Any statisticallysignificant difference wasn’t seen in each construction year. Figure 6 showsthe expectations of structural damage to the houses when a great earthquakeof the 1995 Kobe Earthquake level occurred. Homeowners expected severer
damage as their houses became old. More than 50% of homeowners
answered severe damage to their houses in case of the houses constructed
before 1970.
Then, homeowners’ wishes to retrofit their pre-code houses were
investigated by five steps of “I strongly wish, I wish, I don't wish, I neverwish to retrofit my house, I have already retrofitted my house”. Regardlessof the construction year of houses, the rate of homeowners who “strongly
wish or wish” to retrofit their houses was about 35% as shown in figure 7.
100%

100%
80%
Very highHigh
Low
Very low

60%
40%
20%

N=1,5960%-1960 61-70 71- 81.6- 90-99 2000-04
81.5 89

Construction year

Figure5: Expectation of earthquake occurrenceclassified by construction year

80%

Severedamage60%

Moderate
Damage40%

SlightDamage20%

No damage0%-1960 61-70 71- 81.6- 90-99 2000-04
81.5 89

N=1,596

Construction year

Figure6: Expectation of structural damage tothe houses by construction year

Survey on Residents' Attitudes for Retrofitting of Existing Vulnerable Houses215

October 2005, Singapore

100%

100%
I have alreadyretrofitted
I never wish

80%
60%

I don't wish
I wishI strongly
wish

40%
20%
0%
61-70
-1960
1
2

71-81.5
3

I have alreadyretrofitted withremodelingI have alreadyretrofitted
I never wish

80%
60%
40%
20%

N=338

Construction
建築年代year0%-1960 61-70

71-81.5

Construction year

Figure7: Homeowners’ wishes to retrofit
pre-code houses

I don't wish
I wishI strongly
wish
N=338

Figure8: Homeowners’ wishes to retrofit
pre-code houses in case of low
retrofitting cost100%

I have already
Usually, the cost of retrofitting isretrofitted with80%
remarkably reduced (to the 1/2-1/3 price)
remodelingif retrofitting and remodeling is done at theI have already60%
retrofitted
same time, because it doesn’t require the40%
I never wish
cost for restoring the interior. As the next
I don't wish
20%question, we asked whether they wish to
I wishretrofit their houses in case that low- cost0%
I strongly
Very
Very
retrofitting techniques (1/2-1/3 of current
wish
Low
High
low
high
price) are available. Compared with figure
N=338
Expectation of earthquake occurrence
7, the homeowners who wish to retrofit
increased respectively by 9% 17% 13% in Figure9: Relations between homeowners’ expectation ofearthquake occurrence and their wishes toeach construction year. It was confirmed
retrofit pre-code houses
that high cost was one factor that100%
discourages
retrofittingfortheI have alreadyretrofitted with80%
homeowners who changed their attitudes
remodelingin case of low retrofitting cost. On theI have already60%
retrofitted
other hand, the rate of the homeowners
I
never wish
40%
who never wish to retrofit was almostI
don't wish
same between figures 7 and 8. It means
20%
I wishthat these homeowners didn’t wish to
I strongly
0%No
SlightModerate Severe
retrofit due to some reasons except for
wish
damage Damage Damage damage
economical problems.
N=338
Expectation of structural damage to houses
Figure 9 is the relation between
homeowners’ expectation of earthquake
Figure10: Relations between homeowners’ expectation
occurrence and their wishes to retrofit preof structural damage and their wishes tocode houses. As the homeowners
retrofit pre-code houses
recognized high risk of a huge earthquake,their wishes to retrofit increased. The relation between homeowners’
expectation of structural damage in case of a huge earthquake and theirwishes to retrofit pre-code houses was also analyzed in figure 10. It wasobserved that about 50% of homeowners don’t wish to retrofit their precode houses due to some other reasons even if they expect severe damage totheir houses in case of a huge earthquake.

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4. MAIN FOCTORS THAT ENCOURAGE OR DISCOURAGE
HOMEOWNERS TO RETROFIT THEIR HOUSESIn the previous chapter, we observed that various reasons may affect thedecision-making of homeowners to retrofit their pre-code houses. Here,main factors that encourage or discourage homeowners to retrofit the precode houses were discussed. First, various reasons that may affect thedecision-making to retrofit their pre-code houses were shown to respondents
and they answered their attitudes to each reason by three steps of "I strongly
agree, I agree, I don’t agree to the reason". Then, the difference of the rateof "I strongly agree" for each reason was calculated among the homeowners
who consent or oppose to retrofitting in figure 8. Obtained difference isregarded as an index that shows how much each reason affects decisionmaking of retrofitting. If this become plus value, the reason is classified to
be a factor that encourage retrofitting. If it is minus, the reason becomes afactor that discourages retrofitting.
Both factors were described in figures 11 and 12. The main factors thatencourage homeowners to retrofit their houses were identified as the wishes
for saving their families and properties, and the fears of a sudden earthquake.
The biggest factor that influences the homeowners not to decide retrofitting
was their hesitation between retrofitting and rebuilding. The pre-code
houses were built more than 24 years ago. Considering that average lifespanof a timber house in Japan is 26 years, it is reasonable that the decisionmaking between retrofitting and rebuilding become a big problem. Other
negative factors were found as follows: lack of money, fears of being
disturbed, optimism for earthquake disaster, to give off their fighting
attitudes against earthquake disaster and confidence in building strength.
The ratio of confidence in building strength was only 4% among the totalfactors that discourage retrofitting. The respondents had severer economical,
physical, mental problems compared with the problems in perception of
structural damage risk.
We confirmed that the reasons why homeowners don’t wishes to retrofitting
their vulnerable houses are very complex. This fact implies a combinationof the strategies for improving all the factors that discourage retrofitting isnecessary.
今のままでもMy housenever suffer
自宅は地震でstructural壊れない
damageその他
Others14%

4%

I wish to save

家や財産を
my house and
地震から守properties
りたい
40%

A big
近い将来，
earthquake
大きな地震
will
occur
が起こるだ
soonろう17%

I wish to自分や家
save my族の命を地life and震から守り
lives ofmy families
たい29%

Figure11: Main factors that encourage
homeowners to retrofit their houses

I have no地震で死ぬのpower to fightagainst earthquakeは仕方ないdisaster.
9%
I will not have any
difficulties
even if
地震でも何とan earthquake
かなるだろうoccur
12%

Others
その他

補強よりも建てI maywish to rebuild
替えた方が得in stead of
retrofitting
だ

1%

44%

I don’t want to
生活を乱されbe disturbed
by
ると困る
retrofitting
work
13%

I don’t今は金銭的なhave enough money
余裕がない
17%

Figure12: Main factors that discourage
homeowners to retrofit their houses

Survey on Residents' Attitudes for Retrofitting of Existing Vulnerable Houses

217

October 2005, Singapore

5. HOMEOWNERS’ ANXIETY ON RETROFITTING OF THEIRHOUSES
Moreover, the homeowners who wished to retrofit their pre-code houses
were asked about their anxieties on retrofitting work. The rate of thehomeowners who didn’t have any anxieties was around 15% among total
respondents as shown in figure 13. The biggest anxiety was "My house may
suffer structural damage if it is retrofitted". When answers are seen by theage of respondents, the rate of the homeowners who feared it increased up
to about 65% in case of the respondents of 50-59 and 60-69 years old.
Another big anxiety related to technologies was "Seismic diagnosis may not
be trustworthy". In order to lesson these anxieties, developing safer
retrofitting techniques and proving the safety of retrofitted houses tohomeowners through experiments, demonstration, and simulations are very
important.
Several anxieties for the existence of dishonest contractors were also
observed. Many homeowners felt fear such as "The contractor may dounreliable work", "The contractor may charge unreasonable retrofittingcost". These fears were stronger especially in young homeowners as shownin figure 13. On the other hand, these fears were relatively weak in elder
homeowners. Recently in Japan, a lot of crimes that dishonest contractors
deceive elder homeowners into retrofitting their houses at unreasonably
expensive cost were reported. The carelessness for the existence ofdishonest contractors in elder homeowners observed in figure 14 may be
one reason of these crimes. As a result, it was verified that raisinghomeowners’ knowledge regarding retrofitting cost and techniques wasimportant in order to help their distinguishing dishonest contractors.
Constructing a database of retrofitting works including the detail
information such as average costs and characteristics of construction may be
useful for this.
y
I have no anxiety.
My house may suffer structurall
damage if it is retrofitted.
Seismic diagnosis may not
be trustworthy.
The contractor may dounreliable work.
The contractor may charge
unreasonable retrofitting cost.
tyRetrofitting cost may
exceed my budget.

yRetrofitting may disturb
my daily life very much.

<Age ofrespondents>
60-69
50-59
40-49
30-39
0% 10% 20% 30% 40% 50% 60% 70% 80%
N=123

Figure13: Homeowners’ anxieties on retrofitting their houses

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ICUS Report 11

6.

HOMEOWNERS’ ATTITUDES TOWORD INCENTIVESYSTEMS FOR RETROFITTING THEIR HOUSES

Finally, homeowners’ attitudes toward the governmental systems that give
incentives to retrofitting vulnerable houses were discussed. As the incentive
systems, six typical incentive systems were selected. Providing free seismic
diagnosis using simple flowchart, financial assistance to seismic diagnosis
by special engineers, financial assistance to retrofitting work,
recommendation of honest contractors were currently put into practice insome municipalities in Japan. In addition, two newly-proposed systems, “A
system for providing non-financial incentive by retrofitting assurance” and“tax exemption”, were also taken into consideration. “A system forproviding non-financial incentive by retrofitting assurance” is a new idea
proposed by authors for promoting retrofitting. The concept is illustrated infigure 14. Under this system, the government bears a portion of the building
repair and reconstruction expenses if retrofitting is implemented by theowner following the guidelines before an earthquake and in spite of this the
structure is damaged. It has a great merit that the government does not needto prepare huge budget before the disaster compared with the current
financial assistance system. Authors proved from simulations in theprevious researches that the earthquake damage and the governmental costburden after the earthquake can be reduced with this system even if thegovernment provides incentive money described in figure 14.
The rate who answered that each incentive system is effective was shown by
the age of respondents in figure 15. As a result, the homeowners of the 5059 years old thought little of financial assistance to seismic diagnosis andretrofitting, compared with the system for recommendation of honest
contractors and free seismic diagnosis using simple flowchart. They might
not be strongly attracted to financial assistances due to their high income.
On the other hand, the homeowner at the 60-69 years old thought highly of
all the incentive systems except for recommendation of honest contractors.
The reasons for this was analyzed to be their low income, high fear ininsufficient
structural
strength after retrofitting
Before Retrofitting
Earthquake
and carelessness forunreliable contractors as
Incentive Moneyshown in figures 4 and13.
Assistance or
These generation gaps of Low Interest Retrofitting Cost
Loan
Judging Fee Intermediatefavorite
retrofitting
Entity forincentives suggests that
Judgingthestrategies
for
Guarantee
providingsuitable
After Retrofitting
incentives for retrofitting
considering differences Figure14: Concept of a system for providing nonfinancial incentive by retrofitting
in homeowners needs isassurance
very
usefulfor
promoting retrofitting houses.

Survey on Residents' Attitudes for Retrofitting of Existing Vulnerable Houses219

October 2005, Singapore

Free seismic diagnosis using
simple flowchart
耐震診断士の派遣
70%
60%

A system for
耐震補強
providingnon保証
financial incentive
by retrofitting
assurance

Financialassistance to
耐震診断へのseismic diagnosis
補助by special
engineers

50%
40%
30%
20%

Financial
補強へのassistance to３０万円補助retrofitting work

税制優遇
Tax exemption
措置

Recommendationof honest contractors
業者登録
30-39
30歳代

40-49
40歳代

50歳代
50-59

60歳代
60-89

Figure15: Homeowners’ attitudes toward incentive systems
for retrofitting their houses classified by their age
6. CONCLUSION
In this research, a questionnaire survey was conducted to homeowners inJapan in order to find more effective strategies for promotion of retrofittingof existing vulnerable houses based on residents' needs. First, homeowners’
wishes to retrofit their pre-code houses were analyzed considering theirearthquake risk perception, their economical and social situation. Next, themain factors that encourage or discourage homeowners to retrofit theirhouses were identified. Moreover, their anxieties for uncertainty of building
strength after retrofitting and the activities of dishonest contractors werealso pointed out. Finally, homeowners’ attitudes toward the governmental
systems that give incentives to retrofitting vulnerable houses were discussed.
The differences in favorite incentive systems by generations were observed.
As a result, the importance in developing suitable strategies of improving
incentive system considering these differences was suggested.
REFERENCES
Kobe City, 1996. Hanshin-Awaji Earthquake Disaster –Record of Kobe City,
Japan.
The Ministry of Land, Infrastructure and Transport Government of Japan,
2005. A proposal for promoting disaster mitigation countermeasures
for structures. http://www.kenchiku-bosai.or.jp/topics/050610a.pdf,
Japan
YOSHIMURA. M., and MEGURO, K., 2003. Proposal of Retrofitting
Promotion System (RPS) for Low Earthquake-resistant Structures in
Shizuoka Prefecture, Japan, 7th US/Japan Workshop on Urban
Earthquake Hazard Reduction, Hawaii, USA.

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A CASE STUDY IN REHABILITATION OF A
LARGE INDUSTRIAL STRUCTURE
KUMAR NEERAJ JHA* and SUDHIR MISRA#,* Visiting Faculty, Dept of CE, IIT Delhi, New Delhi, India 110 016*,# Associate Professor, Dept of CE, IIT Kanpur Kanpur, India 208 016*knjha@civil.iitd.ac.in #sud@iitk.ac.in

ABSTRACT
Modernization of old industrial structures often needs to beundertaken in urban or semi urban environments, imposing restrictions on
the methods of demolition and construction that can be used, and quite
different methodologies need to be adopted in these cases compared to thoseused in new construction.
This paper describes the rehabilitation of an old industrial shedmeasuring about 66m x 286 m made with brick masonry walls varying
between 500 to 700mm, with a 400mm thick masonry arch slab made withsurki chuna (lime). The shed was replaced with a shell structure resting on
RC columns, with precast prestressed concrete girders and folded roof. The
job required working while the plant was running, which posed a lot ofchallenges and called for specialized design and construction methods, andplanning of all activities to the last detail.
The existing masonry walls were underpinned, and the footings for
new columns were laid. After the columns were raised to the required height,
the concrete girders and folded roof elements were placed in position at aheight greater than the existing roof. The wall elements were also precast.
The existing roof, etc. were then demolished in parts with appropriatearrangements to safeguard the equipment, etc. The challenging work wascompleted using innovative construction methods based on soundengineering practice without damage to equipment or injury to plant
workers.

1. INTRODUCTION
This case study for rehabilitation of an industrial structure carried out
in an urban environment, keeping the plant in operation all the time, refers
to a project located in a small town in the state of Uttar Pradesh in northern
India. The value was of the project to the contractor was INR 96 million,
not including the cost of cement and steel, which were supplied by theowners (at their cost). The project was initially scheduled for completion in
25 months, though it took much longer as additional works were taken up in
the course of the work, and finally completed in March 1999.

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October 2005, Singapore

The basic objective of the project was to modernize the existing
factory building and fully automate the manufacturing unit. It may be notedthat the building had been apparently built more than 150 years ago, andsome of the bricks found during the dismantling bore marking of
manufacture in 1835. The building comprised of different units such as
godowns for tobacco leaf, primary manufacturing and secondary process
departments, shipping department and warehouses. The unit was used for
production of cigarettes (daily production worth INR 30 million) andrequired dust free environment. Thus, the work needed to be executedwithout affecting the production line. The owners had hired an independentarchitectural and structural consultant who provided the basic layout andstructural drawings, and the detailed work was carried out by the contractors.
Though ‘as-existing’ drawings were prepared, changes in structural designand layout were necessitated during the execution of the project, keeping inview the process and plant layout requirements and the existing plant andequipment.

2. EXISTING AND PROPOSEDSTRUCTURE
Figure 1 shows a typical section and planof the old building, which was developing cracks
at several locations. It was made of thick brickwalls with surkhi lime and arch roof slab of total
span 6m. The arches were supported on 300 mm
diameter 25mm thick cast iron columns.
It may be noted that the height of thebuilding was only 3.6m, which could notaccommodate the new equipment to be installed.
Hence the new design envisaged RC column
beam construction with a folded plate roof, withthe roof level raised to 10.2m. The plan of the
new design is given in Figure 2, and it be seenthat the building was planned in 13 grids (1 to 13,@ 22m) in one direction and 4 grids (A to D, @21m) in other direction. At the junction of thesegrids, cast insitu RC columns predominantly of H
shape and square shapes depending on thefunctional requirement were provided.

Fig 1: Plan and sectionof existing building

21 M
22 M

222

Fig 2: Plan of the new design

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Prestressed concrete girders rested on the column in A-D grid direction
supporting the folded roof plates. Precast wall panels were also provided forthe exterior of the building.

3. CHALLENGES IN CONSTRUCTIONSpace constraint
The layout of the new building, prepared in accordance with thepresent day byelaws specified by the local regulating authority, keeping in
mind the need to preserve and if possible increase the floor space available,
led to serious space constraint, e.g. the space between edges of a newcolumn and the face of the old external wall was hardly 50 mm.
Another issue related to constrained space for construction activity
was that the entire area was not handed over to the contractor at once, andhence construction had to be carried out in a phased manner. In fact, certain
areas had to be completed in all respects, and handed back to the owner
before fresh areas could be released. Thus, the construction work started
along the panels ABCD from Grid 8 and proceeded towards Grid 13 in thefirst phase and then moved again from Grid 8 towards Grid 1.
Material Storage and Movement
Since production could not be stopped in situ concrete work was
avoided to the extent possible, and in cases where precasting was not
feasible special arrangements for construction materials and transportationof concrete, etc. had to be made. For example, inside the building, use ofany motorized construction equipment was not permitted due to the likely
effect of emitted gases on the quality of cigarettes produced, and therefore,
concrete and other materials were shifted using horse carts. This also helpedin cases where special precautions had to be taken to protect manual labour,e.g. areas with tobacco dust, etc. where the number of men deployed could
thus be substantially reduced.
SafetySpecial barricades were constructed with locking arrangement aroundfootings of the new RC columns during construction. All workmen and staff
were equipped with personal protective gear such as safety helmets, safety
belts fall arrester, etc. Fire extinguishers were positioned at all vulnerable
points, and welders used asbestos fire clothes to prevent fire related
accidents. An appropriate system was developed to allow operations such as
welding or gas cutting in the plant area, through special permits from thesafety division of the operating plant, and properly visible signs wereerected when the work was in progress.

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October 2005, Singapore

4. CONSTRUCTION SEQUENCE
At peak mobilization, the contractor engaged 36 staff consisting ofmanagers, senior engineers, engineers, supervisors, and foremen and about
450 site workmen. As far as equipment is concerned, gantry cranes ofdifferent capacities such as 5 tonnes, 10 tonnes, and 100 tonnes, launching
girders of about 66m length in two pieces, mobile crane, trailers, prestressing devices, concreting equipments, and equipment for steam curing,were mobilized. In order to arrive at the suitable construction sequences
apart from established practices, of formwork design, precasting, anderection, (e.g. Peurifoy 1964, Harris 1989, Andres and Smith 1998), input
from the owner’s departments were taken into account. Frequent
brainstorming sessions were held with all engineers involved to improve
efficiency of construction.
Underpinning of interior column
First of all a footing for the new column was laid out on the floor. The
supporting schemes for transferring the existing load on to the existing floor,
is outlined in Figure 3, and basically consisted of the following steps: Twosteel beam sections (ISMB 600 or ISMB 300 depending on the loads) wereburied in the floor, such that their top was flush with the existing floor levelso as not to impede production. Two trestles (made with angle section kept
at four corners and braced) were kept on the ISMBs buried earlier. Now
loads from the top beams were transferred to the trestle using appropriate
packing and jack system at the top.

Fig 3: Underpinning arrangement for interior columns
Thus, the load was completely taken off the old columns, which could
be removed, and work for the footings of the new column taken up. The
depth of excavation for the new footings varied between 3m to 3.3 m. Since
the soil was sandy, all sides had to be supported using shoring with the help

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11of planks and steel channel sections. The bottom was then compacted andnew footing was cast in-situ. Reinforcement was tied for columns and firstcolumn lift of 2.4m height (to the bottom of 900mm deep plinth beam
(whose top was flush with the floor level) was cast by leaving dowels forplinth beams. These dowels were coated with cement slurry and wrapped inplastic sheets and finally buried to be taken later for construction.
Subsequently the other two lifts were also cast, to take the columns to aheight just below the existing ceiling level. When it came to fourth lift theexisting roof was carefully punctured at the locations of the new columns,
and columns cast up to the required height (8m from existing floor level).
After holes were made in the existing roof, care was taken to ensure that
dust etc. from the outside did not enter the plant through these holes. Oncethe column casting at one location was complete, the damaged floor in thisarea was repaired and was handed over to client temporarily. This cyclefrom underpinning to temporary handover took about 20 days. It may bementioned, that special care had to be taken to minimize generation of dust
during demolition and construction and the debris from old footings, etc.
were removed and disposed outside the building manually.
Underpinning for exterior column/wall
It may be noted that the new design provided for RC columns andshear walls at some grid locations to take care of earthquake loads, for theexterior columns. At the outset, footings were laid out on the floor andoutside the building. The scheme used for supporting existing loads, is given
in Figure 4. All walls were punctured at floor level and steel beams wereinserted at 2m c/c due to the heavy loads on the columns. Then a notch ofabout 230mm was made along the length of the wall to accommodate
another steel beam perpendicular to the beams laid earlier. It may be notedthat the existing walls were more than 500mm thick. Similarly to the otherside of the wall another notch was cut and a second beam inserted. Packing
wherever required was done. Now, in this configuration, the loads from thewalls were transferred to the beams, which in turn were transferring to thefloor, and the footings of wall and columns of the existing structure could bedismantled. Construction of the new footing, columns and shear walls was
carried out in a manner similar to that outlined for interior columns above,and the cycle time from underpinning to temporary handover was 35 days.

Fig 4: Underpinning arrangement for Exterior columns and wall

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October 2005, Singapore

After 28 days of casting of in-situ columns, these were ready forreceiving precast elements such as Y-girder, folded plates and wall panels.
The precasting details of these elements are given below.
Precasting operations
As mentioned earlier three broad types of elements – girders andfolded plates for the roof, and the wall panels, were precast, and Table 1
gives a brief summary of the operation and a more detailed discussion is
given in the following paragraphs. A casting yard complete with facilities
for steam curing, etc. was setup close to the site, and appropriatearrangements made for transportation and storage of elements.
Table 1: Details of precast elements
Element
Y-girder(20.7mlong)

FoldedplatesWallpanel

Wt (t)
50

Numbers Molds prepared Remarks
52
Six plywood and Normal
curing,timber moulds
prestressingwascarried out at the ageof 28 days after
casting.
15432
Twosteel Steamcuringmouldsadopted4 to 9.55 282
One each of all Normal curing
the types ofnegative mould

Y-girder and wall panels: The Y-girders were cast and prestressed in thecasting yard. The shape of the wall panels was such that the contractor had
to use a negative mould for their casting. Now, for making this mould, angle
frames, brickwork enclosing the waste-fill, and plain concrete was used to
get the desired profile of the wall panel. Once the mould was ready thereinforcements were tied and wall panels were cast. These were water cured
subsequently and shifted to the stacking yard from where they were shiftedagain to the erection location.
Folded plates: A typical crosssection of the folded plates isshown in Figure 5, and it can beseen that, precasting of folded
plates was carried out in twostages. In the first stage after
cleaning the moulds, and tying of
reinforcement for two flaps,
concrete was cast. Now, theseflaps were lifted after 3 hours ofconcreting and aligned as
required. In the second stage thediaphragm and bottom portion of
the folded plates were cast.

226

Fig 5: Folded plate casting

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These elements were then steam cured and shifted from the casting yard to
the stacking yard where they were further water cured for the required
duration.

5. ERECTION AND JOINTING SCHEME
It may be mentioned here that before erection of precast elements,
plinth beams were cast by exposing the dowels left earlier in a phase wisemanner without disrupting the production. The following paragraphs
describe the erection and assembly of the precast elements.
5.1 Y-girders
A typical erection sequence is shown in Figure 6. It may be noted thatwhile the erection work for the girder is being carried out at a level of 8m,
the roof of the existing building can be clearly seen in the photograph.
Temporary brackets were fixed on both sides of the columns already cast
upto their full height. The launching girder was then erected on thesebrackets. The plan was drawn up to cover the entire distance of the grid
ABCD (66m) in a single effort – this was accomplished by erecting thelaunching girder in two pieces of 33m each on either side of the column.

Fig 6: Photographs showing erection of Y-girder

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October 2005, Singapore

After the erection of launching girder, Y-girders kept in the castingyard were lifted from gantry through two lifting nodes. The girder was
shifted to the point when one of its ends reaches the extreme point of thegantry. At this point the load is transferred to the RC column, while making
one node of gantry free and holding the other end of the girder by thesecond node of the gantry. Now the front moving end of the girder is kept
on the trolley provided with the launching girder and the load from girder onto the RC column is released. At this time one end of the Y girder is
supported through one trolley provided with the launching girder and theother end is still supported through the gantry. The girder is pushed further
till the back end of the girder is near the extreme of the gantry. At this time
the back portion of girder is kept on the cast in situ column and the node of
the gantry is released. The back end of the girder is now kept on the second
trolley and loads from column released. The Y girder now rests on both thetrolleys provided with the launching girder. The trolleys are moved till the
Y-girder reaches its exact location, when the trolleys are removed. This
process is repeated for all the grids.
The gap between the end diaphragms of two Y-girders was kept at
about 300mm. A total of 18 numbers (9 numbers on each side of thediaphragm) high tension bolts of 25mm diameter were inserted in the
pockets left in the diaphragm while casting earlier. Reinforcements as per
design were tied in the 300 mm gap portion and concrete was poured.
Finally the pockets were grouted with non shrink grout materials.
5.2 Folded plates
The erection of folded plate elements as shown in Figure 7, wascarried out in two stages. In the first stage, Hilman rollers were fixed to thefolded plate element before loading them on to the trailer, which was hauledFig 7: Erection of folded plate element

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to the erection location. Here, a 955A-LC crane was positioned dependingon the requirement, and the folded plate element was lifted from the trailer
and transferred to the Y girder. In the second stage the folded plate element
was hauled to the precise location, where it was jacked up by about 25mm
to facilitate removal of Hilman rollers. Finally the folded plate element was
lowered on the Y girder. This process was repeated for all the elements. It
may be noticed from Figure 7 that openings have been provided in the roof
elements to provide north lighting. The openings were provided with glass
plates leading to substantial saving in lighting within the building
It may be noted that after erection, there was a gap of about 25 mm
between two folded plate elements. This gap was filled with thermocol,
which also acted as a bottom shuttering, on top of which reinforcements
were laid (10mm dia at 150 centre to centre) and concrete was poured in thedesigned profile. Once the concrete was set the thermocol pieces were
removed and sealants applied from inside in the gap. This helped to seal any
leakage of water from the folded plate joints.
5.3 Wall Panel
Wall panels were shifted from the casting yard to a location near theerection site, and cranes were used to lift them and appropriately align themat a desired location, and the joints were finally grouted.

6. DISMANTLING OF EXISTING ROOFS AND FINAL WORKS
The roof of the old factory (seen in Figure 6) was dismantled in phases
after the roofing of the new structure had been completed as discussed
above, in accordance with a carefully drawn up schedule. As a typicalexample, the dismantling of a typical area (hatched in Figure 1) is briefly
explained here. The area was barricaded first and covered with plastic sheets
all around to prevent dust and debris passing into neighboring areas. The
roof was dismantled using compressors and impact hammers. At this stage,
the ISMB packing and jacks used for transferring the load during
construction (Figure 3) were also removed. In the final stage, the new RC
flooring was laid using the bricks from the dismantling in the base course,which carried a 100mm PCC and 100mm RC layer on top.

7.

CONCLUDING REMARKS

An effort has been made in this paper, to present the challenges ofrenovating an old industrial structure, without shutting down the plant forcivil works. The paper described how use of locally available andappropriate technology can be used to accomplish the task in a time boundand professional manner. The project combined a judicious use of cast insitu
concrete and precast concrete elements, and host of tailor made technologies
such as use of horse driven buggies for concrete transportation,

A Case Study in Rehabilitation of a Large Industrial Structure229

October 2005, Singapore

underpinning arrangement for wall and column, use of launching girders forerecting Y-girder etc.

ACKNOWLEDGEMENT
The authors wish to express their sincere thanks to the staff of thecontracting organization for providing various inputs for this paper. The
support received from Mr. R.N.Gaur, Mr. Ramji, and Mr. H. Chauhan isespecially acknowledged.

REFERENCES
1. Andres, C. K., Smith, R. C. (1998). Principles and Practices of Heavy
Construction. Fifth Edition, Prentice-Hall, Inc.
2. Harris, F. (1989). Modern construction equipment and methods,
Longman Scientific and Technical, England.
3. Peurifoy, R.C. (1964). Formwork for Concrete Structures, McGraw.
Hill Book Company.

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New Technologies for Urban Safety of Mega Cities in Asia

IN-PLANE AND OUT-OF-PLANEBEHAVIOR OF PP-BAND RETROFITTEDMASONRY WALLETTESNAVARATNARAJAH SATHIPARAN
Master Course Student, The University of Tokyo, Japansakthi@risk-mg.iis.u-tokyo.ac.jp
PAOLA MAYORCA
Post Doctoral Fellow, The University of Tokyo, Japanpaola@iis.u-tokyo.ac.jp
NASROLLAHZADEH NESHELI
Post Doctoral Fellow, The University of Tokyo, Japannesheli@iis.u-tokyo.ac.jp
RAMESH GURAGAIN
Master Course student, The University of Tokyo, Japanramesh@risk-mg.iis.u-tokyo.ac.jp
KIMIRO MEGURO
Professor, ICUS, Institute of Industrial Science, The University of Tokyo,
Japanmeguro@iis.u-tokyo.ac.jp

ABSTRACT
Unreinforced masonry is one of the most used construction materials in theworld. It is also unfortunately, the most vulnerable during earthquakes. This
combined with the widespread use of masonry in earthquake prone regionsof the world has resulted in a large number of casualties due to the collapseof this type of structures. Several methods have been proposed to improvestrength, ductility and energy dissipation capability of masonry structures.
However, in developing countries, retrofitting masonry structures should be
economic, should be retrofitting material accessible and should be local
available workmanship used. Also simple construction procedure is needed.
Considering these points, a new retrofitting technique has been proposed
based on the use of polypropylene bands (PP-bands), which are commonly
utilized for packing. This material is available at a very low price even inremote areas of the world.
To evaluate the beneficial effects of the proposed PP-band meshretrofitting method, diagonal compression tests and out-of-plane tests werecarried out on masonry wallettes with and without retrofitting. In diagonalcompression tests, the masonry wallettes were retrofitted with meshes whoseborders were connected with either epoxy or just by overlapping to evaluate
whether the connection type influences the retrofitting performance.
From both tests results, which are highlighted in the paper, it could
be seen that PP-band retrofitted masonry wallettes had larger residual
strength after the first crack in both in-plane and out-of-plane loading. It
was clear that PP-band mesh retrofitting improved the overall stability andductility of the structure.

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October 2005, Singapore

1. INTRODUCTION
In order to verify the suitability of the proposed retrofitting technique, anexperimental program was designed and executed. A real scale model test
makes possible to obtain data similar to real structures. However, it requires
large size testing facilities and large amount research funds, so it is difficult
to execute parametric tests by using full scaled models. Recently, structural
tests of scaled models become well-known as the overall behavior of thesystem can be also understood from scaled model. In this experimental
program ¼ scale model was used to investigate the static and seismic
behavior of masonry walls.
Diagonal compression tests and out-of-plane tests were carried out on
masonry wallettes with and without retrofitting for both burned andunburned bricks to evaluate the beneficial effects of the proposed PP-bandmesh retrofitting method. In addition to these, efficiency of different meshes
orientations was also examined. The test results are reported in this paper.

2. AXIAL TENSILE TEST OF POLYPROPYLENE BANDS
Preliminary testing of the PP-band was carried out to check its
deformational properties and strength. To determine the modulus ofelasticity and ultimate strain, 3 bands were tested under uni-axial tensile test.
The test was carried out under displacement control method. The results areshown in Figure 1. To calculate the stress in the band, its nominal crosssection 15.5×0.6mm2 was used.
All of the bands exhibited a large deformation capacity, with morethan 13% axial strain. The stress-strain curve is fairly bilinear with an initialand residual modulus of elasticity of 3200MPa and 1000MPa, respectively.
Given its large deformation capacity, it is expected that it will contribute toimprove the structure ductility.

Stress(MPa)

200
150
100
50
0
0

0.03

0.06

0.09

0.12

0.15

Axial strain

Figure 1: (a) Polypropylene band used for retrofitting (left)(b) Behavior of PP-band under tension (right)

3. DIAGONAL COMPRESSION TEST232

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To evaluate the beneficial effects of proposed PP-band mesh reinforcement
method, diagonal compression tests were carried out on masonry wallettes
with and without retrofitting for both burned and unburned units. The
wallette dimensions were 292.5×290×50mm3 for burned and 275×275×50
mm3 for unburned unit and consisted of 7 brick row of 3.5 brick each. The
mortar joint thickness was 5mm for both cases. Cement/Water ratios equal
0.14 and 0.33 were used for burned and unburned brick, respectively.
To observe the efficiency of different mesh orientations, two types of
PP-band mesh arrangement were considered.
Type-1: PP-band mesh oriented parallel to the masonry joints.
Type-2: PP-band mesh oriented 45° from the masonry joints.
Both had mesh pitch equal to 40mm. A total of 4 wire connectors
were used to attach the mesh with the masonry.
The specimens were named according to the following convention: AT-O in which A is B: Burned or U: Unburned; T is NR: Non-retrofitted,
RE: Retrofitted by PP-band meshes whose borders were connected withepoxy and wire connectors or RO: Retrofitted by just overlapping of PPband meshes and wire connectors; and O is 1: PP-band mesh oriented
parallel to the masonry joints or 2: PP-band mesh oriented 45° from themasonry joints.
Specimens were tested 28 days after construction under displacement
control. The loading rate was 0.3mm/min and 2mm/min for the nonretrofitted and retrofitted cases, respectively. The retrofitted wallettes wereapplied 50mm vertical displacement. Average measured mechanicalproperties of the masonry at the time of testing are shown in Table 1. Direct
Compression, direct shear and bond tests carried out to obtaining thesecharacteristic properties were similar to that shown in Figure 2.

Figure 2: Layout of specimens used for direct compression, direct shear
and bond test (unit:mm)
Table 1: Mechanical properties of masonry
BurnedUnburned
Brick
brick
Compressive strength (MPa)
21.78
4.45
Shear strength (MPa)
0.075
0.006
Bond strength (MPa)
0.055
0.006
3.1 Behavior of retrofitted masonry

In-plane and Out-of-plane Behavior of PP-band Retrofitted Masonry Wallettes

233October 2005, Singapore

Initially retrofitting was done with PP-band meshes whose borders
were connected with epoxy and wire connectors, in order to evaluate thebeneficial effects of the proposed PP-band mesh reinforcement method. In
the following sections, a brief discussion of diagonal compression test
results of burned and unburned unit specimens is presented.
3.1.1 Behavior of burned brick specimens
Figure 3 shows the non-retrofitted and retrofitted specimens at theend of the test, which corresponded to vertical deformations equal to0.71mm and 50mm, respectively. In the non-retrofitted case, the specimens
split in two pieces after the first diagonal crack occurred and no residual
strength was left. In the retrofitted case, on the other hand, diagonal cracks
appear progressively, each new crack followed by a strength drop. Although
the PP-band mesh influence was not observed before the first cracking, after
it, each strength drop was quickly regained due to the PP-band mesh effect.
Although at the end of the test almost all the mortar joints were cracked, theretrofitted wallettes did not lose stability.

Figure 3: Failure patterns of brick masonry wallettes with and without
retrofitting by PP-band mesh.
Figure 4 shows the diagonal compression strength variation withvertical deformation for the non-retrofitted and retrofitted specimens. In the
non-retrofitted case, the average initial strength was 1.5kN and there was noresidual strength after the first crack. However, in the retrofitted case,although the initial cracking was followed by a sharp drop, at least 50% of
the peak strength remained. Subsequent drops were associated with new
cracks like the one observed at the deformation of 4mm. After this, thestrength was regained by readjusting and packing by PP-band mesh. Whenthe strength exceeded 3.0kN individual PP-bands started to fail. However,this did not reduce considerably strength of the specimen, because stresses
redistributed to other PP-bands. The specimen quickly recovered its strength.
The final strength of the specimen was equal to 3.0kN relatively higher thaninitial strength of 1.5kN.

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Compressive Force (kN)

4.0

3.0

2.0

1.0
B-NR-1
B-RE-1

0.0
0

5

10

15

20

25

30

Vertical Deformation (mm)Figure 4: Force vs. vertical deformation for burned brick masonry wall
specimen with and without retrofitting.
3.1.2 Behavior of unburned brick specimens
Figure 5 shows the diagonal compression strength variation withvertical deformation for the non-retrofitted and retrofitted specimens.

Compressive Force (kN)

2.5

2.0

1.5

1.0

0.5
U-RE-1
U-NR-1

0.0
0

5

10

15

20

25

30

Vertical Deformation (mm)Figure 5: Force vs. vertical deformation for unburned brick masonry wall
specimen with and without retrofitting.
In the non-retrofitted case, the initial strength was 0.89kN and there
was no residual strength after the first crack. In the retrofitted case, although
the initial cracking was followed by a sharp drop, at least 70 % of the peak

In-plane and Out-of-plane Behavior of PP-band Retrofitted Masonry Wallettes

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strength remained. As expected, the initial strength of unburned brickspecimens was relatively lower than that of the burned brick one.
3.2 Efficiency of mesh orientation
Figure 6 compares the diagonal compression strength of retrofitted
masonry wallettes with different mesh orientation:
Type 1 is PP-band mesh oriented parallel to the masonry joints.
Type 2 is PP-band mesh oriented 45° from the masonry joints.
Generally Type 2 mesh provided larger strength than Type 1 mesharrangement. This was expected because the confining effect on themasonry wall is larger in the former case. Cracks become gradually wider as
the vertical deformation increased. In this condition, the reinforcement
oriented perpendicular to the crack. i.e. Type 2 worked under optimum
conditions. The results of B-RE-1 and B-RE-2 were compared; themaximum strength difference was 30% at a vertical deformation of 17 mm.
Although the mesh Type 1 did not fully use the mesh capacity, it improved
the wallette behavior to a degree which can be considered enough for the
purpose of earthquake damage mitigation. In addition to this, the mesh Type
1 is easier to manufacture and install. Therefore, it was selected as theproper solution for retrofitting.
4.0

Compressive Force (kN)Type 23.0

2.0Type 11.0

B-NR-1
B-RE-1
B-RE-2

0.0
0

5

10

15

20

25

30

Vertical Deformation (mm)Figure 6: Comparison between masonry wallettes retrofitted by different
orientation meshes:Type 1 is PP-band mesh oriented parallel to the masonry joints.
Type 2 is PP-band mesh oriented 45° from the masonry joints.
3.3 Effect of mesh edge connection

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Figure 7 shows comparison of the diagonal compression behavior of
retrofitted masonry wallettes with mesh whose borders were connected withepoxy and retrofitted by just overlapping of PP-band meshes for burned
masonry wallettes.
In case of burned masonry wallettes, within the 10mm verticaldeformation, similar performance was observed in both cases. However atlarger vertical deformation, because of PP-band slip was observed along thespecimen borders, compression strength of wallettes without epoxy wasconsiderably reduced. Also it could be observed that close to the connectors
there was almost no mesh slip, ie the connectors could effectively attach twomeshes. On the other hand, the bands located far from the connectors
experienced considerable slip. This was not observed in the meshes
connected with epoxy. As mentioned before for vertical deformation smaller
than 10mm, which corresponds to 15 times the working strain, the behaviorof both edge connections was almost the same.

Compressive Force (kN)

4.0

3.0

2.0

1.0
B-NR-1
B-RE-1
B-RO-1

0.0
0

5

10

15

20

25

30

Vertical Deformation (mm)Figure 7: Behavior of masonry wallettes with mesh edges fully or partiallyconnected

4. OUT-OF-PLANE TEST
Out-of-plane tests were carried out, in order to investigate the PP-band mesheffectiveness in walls exhibiting arching action. The nominal dimensions ofthese walls were 475mm by 235mm; their thickness was 50mm. The PPband mesh edges were partially connected, i.e. no epoxy was utilized. A
total of 6 wire connectors were used to attach the meshes with masonrywallettes. Considering the stability of the specimens, Cement/Water ratios
equal 0.25 and 0.45 were used for burned and unburned brick, respectively.
Bond tests were performed to characterize the engineering propertiesof the material used in the investigation. The average tensile strength of

In-plane and Out-of-plane Behavior of PP-band Retrofitted Masonry Wallettes

237

October 2005, Singapore

burned brick and unburned brick masonry obtained from bond test were0.162MPa and 0.006MPa, respectively.
The specimens were named according to the following convention:
M-T in which M is B: Burned or U: Unburned; T is NR: Non-retrofitted or
RO: Retrofitted by overlapping of PP-band meshes and wire connectors.
Specimens were tested 28 days after construction under displacement
control. The wallettes were simply supported with a 440mm span. Steel rods
were used to support the wallettes at the two ends. The masonry wallettes
were tested under a line load which was applied by a 20mm diameter steel
rod at the mid-span of the wallettes. The loading rate was 0.05mm/min for
the non-retrofitted case. For the retrofitted case, it was also 0.05mm/min for
the first 30mm vertical deflection, and then it was increased to 2mm/min for
the remaining test period. The retrofitted wallettes were applied up to 70mm
vertical displacement. The test setup is shown in Figure 8.

Figure 8: Out-of-plane test setup

Figure 9: Failure patterns of brick masonry wallettes
with and without retrofitting by PP-band mesh.
Figure 9 shows the non-retrofitted and retrofitted masonry wallettes at theend of the test, which corresponded to a mid-span net deformation equal to
2.8mm and 70.0mm, respectively. In the non-retrofitted case, the specimens
split in two pieces just after the first crack occurred at mid-span, and noresidual strength was left. In the retrofitted case, on the other hand, althoughPP-band mesh influence was not observed before the first cracking, after it,
strength was regained progressively due to the PP-band mesh effect.
Figure 10 shows the out-of-plane load variation in terms of net
vertical deformation for the non-retrofitted and retrofitted wallettes in the238

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mid-span. For burned brick, in the non-retrofitted case, the initial strength
was 0.63 kN and there was some residual strength remaining for further
small amount of deformation after the first crack. This behavior wasobserved due interlocking between bricks and also the application of load
under displacement control method. In the retrofitted case, although theinitial cracking was followed by a sharp drop, nearly 45% of the peakstrength remained.
1.4

Out-of-plane Load (kN)

1.2
1.0
B-RE
0.8
0.6

U-RE

0.4
0.2

B-RE
U-RE
B-NR
U-NR

B-NR
U-NR

0.0
0

10

20
30
40
Mid-span Net Deformation (mm)5060Figure 10: Out-of-plane load variation in terms of net vertical deformation
As expected, the initial strength of the burned brick was relatively
higher than that of unburned brick. Even higher cement/water ratio was used
for unburned brick, the poor bonding between mortar and unburned brickled to separation along the brick and mortar. On the other hand, in theburned brick case, failure occurred within the mortar. This behavior highly
influenced the initial strength of the specimens.
After the initial drop in strength, the mesh presence positively
influenced the wallette behavior. Both types of retrofitted brick wallettes
showed similar behavior in strength up to a vertical deformation equal to
8mm. At the point, brick crushing was observed in the unburned brick case.
Due to that, the overall strength of the unburned brick wallettes wasconsiderably smaller than that of burned brick wallettes. There after, if two
types of bricks are compared, almost 40% difference in strength wasobserved.

5. CONCLUSIONSThis paper discusses the results of a series of diagonal compression tests andout-of-plane tests that were carried out using non-retrofitted and retrofitted
wallettes by PP-band meshes.

In-plane and Out-of-plane Behavior of PP-band Retrofitted Masonry Wallettes239

October 2005, Singapore

The diagonal compression tests showed that:(1) When appropriately set, no epoxy failure was observed before 2.9kN.
(2) In the retrofitted case, larger residual strength after the formation of
the first diagonal shear cracks was observed. Furthermore, as
deformation increased, the wallette achieved higher strength than theinitial cracking strength.
(3) Mesh Type 1, in which PP band mesh is oriented parallel to themasonry joints, improved the wallette behavior to a degree which
can be considered enough for the purpose of earthquake damage
mitigation. In addition to this, Type 1 is easier to manufacture andinstall. Therefore, we consider mesh Type 1 is better for retrofitting.
(4) For vertical deformation smaller than 10mm, similar performance
between wallettes, with mesh edges fully and partially connected
was observed.
The out-of-plane tests showed that;(1) In out-of-plane tests, the mesh effect was not observed before thewall cracking. After cracking, the mesh presence positively
influenced the wallette behavior.
(2) The retrofitted wallettes achieved strengths 2 times greater anddeformations 60 times larger than the non-retrofitted wallettes.
(3) Although the overall strength of burned retrofitted wallettes washigher than that of the unburned ones, the ratio maximum
strength/cracking strength in the latter was larger.
Considering the overall performance of the specimens, it can be concluded
that PP-band meshes can effectively increase the seismic capacity ofmasonry houses.

REFERENCE
Sathiparan, N., 2005. Experimental Study of Retrofit of Masonry Buildings
by PP-band Mesh, M.Eng. Dissertation, The University of Tokyo,
Japan.
Mayorca, P., 2003. Strengthening of Unreinforced Masonry Structures inearthquake Prone Regions, Ph.D. Dissertation, The University ofTokyo, Japan.
Galati, N., Tumialan , J.G., Nanni, A., Tegola, A.La., Influence of Arching
Mechanism in Masonry Walls Strengthening with FRP Laminates,
The University of Missouri, Rolla, Italy.
ASTM, E72, 1997. Standard Test Methods of Conducting Strength Tests ofPanels for Building Construction, American Society for Testing andMaterials, Philadelphia, Pa.

240

New Technologies for Urban Safety of Mega Cities in Asia

THE IMPORTANCE OF CURING IN
PREVENTING THE SPALLING-OFF OF
PATCHING REPAIR MATERIALMASANORI ITO1, YOSHITAKA KATO2TAKETO UOMOTO2
1: Research center, Tokyu Construction Co. Ltd,,
2: ICUS, Institute of Industrial Science, Tokyo University
itou.AI9184@tokyu-cnst.co.jp
ABSTRACTThe use of polymer cement mortar (hereafter, PCM) to repair
deteriorated concrete structure has recently become more and more popular,
especially in restoring the damaged cross-section. In this process, thecuring after patching is important for the performance over time of PCM.
This research studied the basic properties, such as compressive strength,bond strength, and carbonation resistance, of repair material applied bywet-spraying process and exposed to drying condition right after its
application. Experimental result shows that the durability of PCM is lessaffected by drying environment than that of common mortar. However, it
was confirmed that microstructure tends to be worsened by drying at theearly age. Therefore, it is important to ensure an appropriate curingcondition right after applying repair material, as long as the long term
performance is concerned.
1. INTRODUCTION
In Japan, the economy grew rapidly in the period 1960～1980. Many
structures, such as buildings, bridges, were built during this period. In thisperiod limited knowledge about durability. As a result, these infrastructures
rapidly deteriorated and appropriate maintenance will be necessary in future.
Figure 1 shows the prediction of future investment in construction field ofJapan. As can be seen in this figure, the maintenance expense will be higher
than that of new investments in the future. The purpose of the maintenanceis to maintain the existing structure in service as long as possible.
350
Investment value(Billion US$)

300
250
200

All investment value after 2002.
The proportion of ratio -1% in the vs. preceding year.
(The Ministry of Land, Infrastructure and Transport white paper ）Disaster recovery
New construction
RenewalM aintenance

150
100
50
0
1950

1960

1970

1980

1990

2000

2010

2020

Figure1: The investment in construction amount in Japan.

241

October 2005, Singapore

Reinforced concrete structures deteriorated by various factors, such ascarbonation, salt attack, alkali-aggregate reaction, etc., need to be repaired
and strengthened. The use of PCM to repair deteriorated concrete structure
has recently become more and more popular, especially in restoring thedamaged cross-section. Technical report of patching recommends the use ofhigh quality PCM for repair. However, satisfactory performance is notalways obtained in field works, because of various environmental effects.
Figure 2 shows the spalling-off of patching repair material due to redeterioration of reinforced beam after repair. In this process, the curing isimportant for the performance of PCM. This research was study about basic
properties, such as compressive strength, bond strength, and carbonation
resistance of repair material applied by wet process and exposed to early
drying condition. The evaluation of these basic properties is carried out
from micro structure point of view.
Patching material

Original
concrete

Figure2: Re-deterioration of concrete bridge

2. Experiment procedure
2.1 Materials and Mix proportions
In this research, two kinds of mortars were tested. One is the PCM,
and the other is normal cement mortar (hereafter NCM). Ordinary portland
cement and crushed sand with particle size smaller than 2.5mm were used.
The polymer is redispersible polymer powders whose components arecopolymer resins such as Vinyl acetate/VeoVa/Acrylic, and physicalproperties are shown in Table 1. Chemical admixtures including Powdery
superplasticizer and antifoaming agent were also used. Table 2 gives themix proportions of PCM and NCM. The polymer to cement ratio for PCM
was 5%, and W/C was 38% for both PCM and NCM. Materials and mix
proportions were decided referring to the commonly-used mixture in actual
patching work. The flowability of the PCM was adjusted so as to obtain a
20mm layer of repair material, when spraying to the wall.

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Table 1: Properties of polymer
Solid
Bulk
Type
Color
Content
density(%)(g/l)
Vinyl acetate/
White
99±1
450±100
VeoVa/Acrylic powder

Particle
size
(%)*
<3%

*: Particle diameter> 315 μm

No

W/C
(%)

NCM
PCM

38.0

Table 2: Mix proportion
SP*
P/C
C
S/C
3
(%)
(kg/m )
(C×%)
0.0
2.0
614
0.08
5.0
1.9

AA**
(C×%)
0.2

*: SP- Superplasticizer, **: AA-Antifoaming agent

2.2 Test Specimen
The mixture was mixed for 5 minutes. PCM specimen was made by
wet-mix spraying. Spraying conditions were as follows: spraying quantity 0.1m3/h, spraying air pressure - 0.7MPa, aperture diameter of the nozzle tip- 8mm. The NCM specimen was made by applying repair material using atrowel.
2.3 Environmental condition
Table 3 gives the environmental conditions of this study. The sealing
condition is to prevent the evaporation of the moisture from the specimen.
The wind velocity, in the windy condition, was set at 2m/sec on the basis of
two data: the wind velocity measurement data in the subway passage andthe average wind velocity data of Tokyo obtained by Meteorological
Agency. The drying condition was set as intermediate one of above
conditions. The sheet was made to be the sealing condition only for first 2
days, and it was exposed in the wind environment afterwards. Evaporation
rate of the water in wind environment were 10 times of dry environment.
Figure 3 shows the experimental setup to simulate the windy condition.
Table 3: Environmental conditions
Condition Content
Room temperature:20℃
Relative Humidity:60%
Seal
Use the vinyl bag
DryWind Velocity: 0.0m/s,
Er*: 0.017kg/m2/hWindy
Wind Velocity: 2.0m/s,
Er*: 0.160kg/m2/h
Sheet
Seal by plastic sheet for
2days → Windy

Test wind tunnel

Electric fan

Test specimen

Figure3: Windy condition*:Er - Evaporation rate

The Importance of Curing in Preventing the Spalling-off of Patching Repair Material243

October 2005, Singapore

2.4 Test Method
2.4.1 Moisture loss quantity test
The effect of different environmental conditions on the quantity of the
moisture loss was examined. The size of the test specimen was exposed as130x130x20mm in spraying/trowel applied each condition immediately.
The measurement of the mass change was carried out by 28days.
2.4.2 Measurement of micro- pore size distribution
After the Moisture loss quantity test specimen was coarsely ground,and a large amount of acetone was added to stop hydration reaction of
cement. The test sample (2.0～5.0mm) was dried by vacuum drying at room
temperature. The micro-pore size distribution was measured using amercury porosimeter (Micromeritiecs Autopore Ⅲ 9400). In addition,
100x100x200mm test specimen was also produced by cutting initial
specimen in order to evaluate to which extent the effect of the environment
has reached form surface.
2.4.3 Compressive strength test
In this study, compressive strength was measured with 20x20x80mm
test specimen. Thought the specimen size is smaller than standard one(40x40x160mm), the result will surely exhibit similar tendency.

2.4.4 Bond strength test
Bond strength measurement was carried out in accordance with JIS A
1171(Test methods for polymer-modified mortar) at 28days. The basic
mortar plate was 70x70x20mm, and test specimen was 40x40x10mm by thespraying/trowel applied on the top.
2.4.5 Accelerated carbonation test
Manufacture methods of this test specimen were as follows: Firstly,
300x300x60mm flat plates produced in the spraying or trowel applied were
exposed to different conditions. At 28-day age, the cores(φ50x60mm) werecollected, and their sides were covered with epoxy resin in order to allow
carbonation just from the surface. Accelerated carbonation conditions wereas follows : CO2 concentration-10%, temperature-20℃，relative humidity60%. After 28days, an alcoholic solution of phenolphthalein was sprayedonto the cut surface of specimens, and the depth of uncolored portion wasmeasured.

3. Test Result

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PCM -Wind
NCM -Wind
PCM -Sheet

3.0

2

Mass reduction rate(kｇ/m )Figure 4 shows the relationship between the time and the mass
reduction. In the sealed condition, the mass change for 28 days was notmeasured. In windy and dry conditions, the moisture began to immediately
evaporate, after it was exposed. First 1day mass reduction was 85% in about
1 month. The mass reduction increases, when the drying condition is severer.
PCM has less on the decreased quantity, compared with NCM. The mass
reduction was little for the case in which specimens were covered by Sheet.
PCM -Dry
NCM -Dry

2.0

1.0

0.0
0.01

0.1

1
Time(day)10

100

Figure4: Result of mass reduction rate

0.003-0.006
0.01-0.05
0.1-1

20

0.006-0.01
0.05-0.1
(μm)
1-

15
10

PCM-Sheet

PCM-Wind

NCM-Wind

PCM-Dry

NCM-Dry0

PCM-Seal

5

NCM-Seal

Proportion of micro-pore diameter(%)

Figure 5 shows the measured result of micro pore size distribution.
When drying condition become severe, the hydration reaction of the cement
is inhibited due to lack of water, and consequently, the micro-pore structure
is coarsened. The gel pore (<0.01mmm) decreases at severer drying
condition (order of drying intensity: sealed Æ dry Æ windy). In all drying
conditions, the volume of gel pore in PCM is larger than that of NCM, whilethe volume of pore greater than 1μm is smaller than that of NCM. It meansthat the PCM is denser than that of NCM. This may be attributed to theexistence of polymer in PCM. The result in this figure also shows that thesame micro structure with sealed condition can be obtained by covering
mortar with plastic sheet during the first two days.

Figure5: Result of measurement of micro- pore size distribution(Effect of the environmental condition)

The Importance of Curing in Preventing the Spalling-off of Patching Repair Material245

October 2005, Singapore

Proportion of micro-pore diameter(%)

Figure 6 - (1) (2) shows also the measurement result of micro-poresize distribution.
This is to confirm the effect of drying at different depth from exposed
surface. From the figure, the PCM was affected by the wind up to about
20mm from the surface. However, NCM received the effect of the wind
deeply, and the micro-pore structure coarsened to 50mm depth from thesurface.
0.003-0.006
0.01-0.05
0.1-1

0.006-0.01
0.05-0.1
1-100 (μm)

20.0

20.0

15.0

15.0

10.0

10.0

5.0

5.0

0.0

0.0
5 15 25 35 50 70 90

5 15 25 35 50 70 90

Distance from surface(mm)Distance from surface(mm)(1)NCM(2)PCM
Figure6: Result of Measurement of micro- pore size distribution(Effect on the depth direction for windy condition)

2

Compressive strength(N/mm )Figure 7 shows the relationship between evaporation rate andcompressive strength.
The compressive strength tends to be lower, at lower evaporation rate.
However, there is no clear difference between PCM and NCM. Similarly,
the strength of PCM covered with plastic sheet just rises slightly.
80

↓Seal

NCM
PCM -Sheet

60

PCM

40

↑Dry

↑Windy

20
0
0.00

0.05

0.10

0.15

0.20

2

Evaporation rate(kg/m /h)

Figure7: Relationship between compressive strength andevaporation velocity

Figure 8 shows the relationship between evaporation rate and the bondstrength.
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4.0

NCM

PCM

PCM-Sheet2

Bond strength(N/mm ）Similar to compressive strength, the bond strength tends to be lower athigher evaporation rate. However, the difference in bond strength is quite
remarkable compared with the result of compressive strength. The use of
PCM helps minimize the loss of bond strength due to windy condition. In
addition, the bond strength of PCM can be almost maintained just bycovering repair material with plastic sheet in two days.

3.0

↓Seal

2.0

↑Dry

1.0

↑Windy

0.0
0.00

0.05

0.10

0.15

0.20

2

Evaporation rate(kg/m /h)

Figure8: Relationship between bond strength andevaporation velocity

Carbonetion depth(mm)Figure 9 shows the relationship between evaporation rate and thecarbonation depth.
In case of NCM, the carbonation depth increases at higher evaporation
rate. However, the progress of the carbonation was suppressed in PCM
compared with NCM in the windy condition. This is the same tendency inthe bond strength (Figure 8). By the use of the polymer, the mortar is dense,
and therefore, it is considered that the penetration of CO2 was suppressed.
20
NCM

PCM

15

↓Dry

10
5

↑Windy
←Seal

0
0.00

0.05

0.10

0.15

0.20

2

Evaporation rate(kg/m /h)

Figure9: Relationship between carbonation depth
and evaporation velocity

4. Conclusions
The patching repair materials may re-deteriorate faster than
anticipated. This may become a serious problem, for future management of

The Importance of Curing in Preventing the Spalling-off of Patching Repair Material247

October 2005, Singapore

infrastructures. The re-deterioration may be caused by macro-cell corrosionand diffusion of chloride, etc. In addition, patching material is directly
affected by the environment, since patching method is carried out without
using formwork.
This research studied the basic properties of repair material applied by
wet process and exposed to early drying condition. The evaluation of thebasic properties carried out from micro structure point of view yielded thefollowing conclusions:
In the environment which receives the rapid drying, the performance
deterioration can be suppressed by the addition of the polymer. The same
micro structure with sealed condition can be obtained by covering mortar
with plastic sheet during the first two days. It is considered that theestablishment of a more efficient maintenance of infrastructures becomes
possible, when the research on the durability of such repairing materials is
advanced.
(Figure 10-12 shows the situation of the patching by the spraying.)

Figure10:
Deteriorated part
Figure11: Spraying situation
Figure12: Situation after patching

REFERENCES
1. Japan Society of Civil Engineers, Standard Specifications for Concrete
Structures – 2005, Materials and construction, 2005. (in Japanese)
2. American Concrete Institute ACI506R-90, Guide to Shotcrete, 1995.
3. American Concrete Institute ACI506.2-95, Specification for shotcrete, 1995.
4. Chandra, S., and Ohama, Y., Polymer in Concrete, CRC Press, Inc., 1994.
5. Ohama, Y., and Sato, Y., “Relation between chemical properties and durabilityof surface layer of polymer cement mortar”, The Society of Materials Science,
Japan, Vol.39, 1990, pp.340-342. (in Japanese)
6. Ito, M., and Uomoto, T., “Evaluation of the spray repair material under windenvironment”, Proceeding of the Japan Concrete Institute, Vol.27, 2005. (inJapanese)

248

New Technologies for Urban Safety of Mega Cities in Asia

ALLOCATION OF LIFE-CYCLE REPAIRING
COST BASED ON PARAMETERUNCERTAINTIES OF DETERIORATION
PREDICTION MODELPAKAWAT SANCHAROEN
Graduate school, Department of Civil Engineering,
The University of Tokyo, Japan
pakawat@iis.u-tokyo.ac.jp
TAKETO UOMOTO
Institute of Industrial Science, The University of Tokyo, Japanuomoto@iis.u-tokyo.ac.jp
ABSTRACT
Repair and maintenance of deteriorated reinforced concrete structure
will become the major task of construction industry in the near future. It isdifficult for a decision maker to evaluate the expected life cycle or annual
R&M cost and select the optimal solutions. Decision makers have to use
many deterioration prediction models to create the R&M program.
Parameters used in those models are decided and assumed to be constantvalues. In reality, there are some uncertainties in those parameters due tomany reasons. This paper proposes the method to determine the expected
probability and cost of R&M by considering parameters uncertainties of theprediction model. From the result, R&M program is able to be planned
based on the expected repair probability as well as required total andannual resources can be allocated. Finally, example of selection of
repairing options is given to illustrate the application of this approach to
optimize the R&M program.

1. INTRODUCTION
The repair and maintenance (R&M) program of the structure is truly theimportant issue in order to maintain structure performance above theacceptable level throughout its service life. In 2002, Japan allocatedapproximately 13.5 trillion yen, which is 21.5% of the total construction
budget, to the repair and maintenance projects. The ratio of maintenancebudget to the overall construction budget is expected to continue increasingin the future because of increasing number of aging structures. In the near
future, R&M will become the major task has to be concerned instead of new
construction project.
Due to the limited resources and budget but large number of aging
structures, R&M program has to be effectively planned. Usually, structure
has to be periodically inspected and evaluated its condition. Decision ofrequired action has to be made based on evaluated condition. One method is249

October 2005, Singapore

using deterioration diagnosis software (Yokosawa et al., 2005) developed toassist a decision making about deterioration mechanism and condition of
structure without opinion of expert. Another method is using prediction of
the deterioration which has to be conducted based on many assumed
parameters to schedule the required actions in the future such as repairing.
However, there are many uncertainties associated with those assumed
parameters used in the prediction model due to many reasons relating sincein the beginning of the construction such as material properties,
workmanship, structural dimensions, and environmental conditions. As aresult, prediction cannot accurately simulate the real condition. Therefore,
the supposed application time of the required actions have to be represented
by the probability distribution instead of the deterministic value.
In this paper, the method to evaluate the expected probability ofrequired R&M at certain time is discussed. Event tree analysis is used tofacilitate the determination of all possible sequences of R&M and their
expected probability during the service life. The ultimate objective of thisstudy is to optimize the life cycle cost of R&M program from many
alternative strategies. Therefore, method to calculate the expected life cycle
cost of R&M is also proposed. Effect of time-value of money is considered
in term of discount rate. Total and annual required resources can beallocated to the specify structure or group of structures based on the
expected cost. Finally, example of selection the optimal repairing method isgiven based on the minimum expected life cycle cost.
2. DETERIORATION PREDICTION MODEL
In this paper, example of structural deterioration due to steel corrosion due
to chloride attack is considered. Fick’s second law is used to predict
chloride diffusion into the concrete as shown in Equation (1). There are 3
uncertainties considered in this prediction model including surface chloride
content, covering depth, and chloride diffusion coefficient. Moreover,uncertainty of the threshold chloride content is also considered in order todetermine the corrosion initiation time. Examples of the results of theirrandom variable parameters observed by other researchers are shown in
Table 1.
x
C ( x, t ) = C s 1 − erf
(1)


D
⋅
t
2
cl


where C(x,t) = chloride content (% by weight of concrete) at depth x(cm) and time t (year), Cs = chloride content at the concrete surface (% byweight of concrete), Dcl = chloride diffusion coefficient (cm2/year)
Monte Carlo simulation (Fishman, 1995), using generated random
numbers and probability statistics sampling of uncertainties variables toprovide approximate solution to a variety of mathematical problems, basedon sample size of 10,000 is used to determine distribution of corrosion
initiation time, when chloride content at steel level exceed the thresholdchloride content, based on those four variables. The simulated result isshown in Fig. 1. For example, probability that corrosion initiation time is 5
years is 0.1390. Corrosion cracking is assumed to occur 10 years after
corrosion was initiated. Then, crack repairing has to be suddenly conducted.

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In the future, uncertainties of prediction of the corrosion cracking time haveto be considered similar to that of prediction of corrosion initiation time.
Table 1: Random variables of model parameters
Variable
Mean
Coefficient of variation
Covering depth, x
3.81 cm0.05
2
Chloride diffusion
1.29 cm /year
0.10
coefficient, Dcl
Surface chloride content, Cs 0.20% by weight0.10
of concrete
Threshold chloride content, 0.025% by weight
0.10
Clim
of concrete
Note: All variables are assumed to have lognormal probability distributions.
0.45
0.4

Probability

0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
1

6

11

16

21

26

31

36

41

46

Time, years

Figure 1: Distribution of corrosion initiation time
3. PROBABILITY DISTRIBUTION OF REPAIRING TIME
Probability distribution of the first repairing time is assumed to be 10 years
after corrosion was initiated as shown in Fig.2. Although, a deterioration
mechanism of repaired structure is different from the original one, it isfirstly assumed that they are the same. Therefore, the distribution ofsubsequent repairing time is same to that of the first repairing time as shownin Fig.2. Except, time is relative time counted after the previous repairing
was conducted instead of finishing of construction. In the future, further
study on deterioration mechanism of repaired structure has to be considered.
Event tree analysis is used to determine all possible repairing events
based on criteria that crack occurred during the service life has to be
repaired. Table 2 shows an example of event tree analysis of possible
repairing events during the service life. Based on relative time scale ofsubsequent repairing, absolute repairing time of each repairing can becalculated. Probability of each possible event is also calculated and shown.
Both of absolute time and probability will be used to calculate the present
value of repairing cost. For example, in the first event, maximum of 3
repairing have to be conducted. All of them are conducted 13 years after the

Allocation of Life-cycle Repairing Cost Based on Parameter Uncertainties of Deterioration Prediction Model251

October 2005, Singapore

previous one. Based on distribution of repairing time, probability ofrepairing time at 13 years is 0.0004. Therefore, probability of the first event
can be calculated as (0.0045¯0.0045¯0.0045). Please be noted that events
that repairing sequence cannot be implemented during the service life are
not considered such as the third repairing is conducted at the year 51st.
0.45
0.4

Probability

0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
1

6

11

16

21

26

31

36

41

46

Time, years

Figure 2: Distribution of repairing time
Table 2: Example of event tree analysis of repairing event
Year
Relative time after theprevious repairingof theEvent probability, Prj,t
last
First
SecondThird
repairrepairrepair repair
13
13
13
39
(0.0045)3 = 9.11¯10-8(0.0045)2(0.1386) =
13
13
14
40
2.81¯10-6
13
13
15
41
7.99¯10-6
13
13
16
42
6.29¯10-6
13
13
17
43
2.42¯10-6
13
13
18
44
4.92¯10-7
⋅
⋅
⋅
⋅
⋅
⋅
⋅
⋅
⋅
⋅
⋅
⋅
⋅
⋅
⋅
19
19
6.00¯10-32020
1.20¯10-3
21
21
4.00¯10-4
Probabilities of repairing ith at time t can be obtained by adding theprobabilities of all events repaired maximum ith time and the absolute yearof last repair is at the time t as shown in Equation (2). For example, there is
only one event that the 3th repairing is conducted at year 39th. Therefore, its
probability is equal to the probability of that event. Results of each repairing
are shown in Figure 3. Finally, summation of probability of all repairingexpected to be conducted at each year calculated by Equation (3) is shownin Figure 4. It should be noted that there is no cost overlapping of different

252

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ICUS Report 11

repairing observed in this example. However, if distribution of repairing
time is wider, overlapping can be observed.
n

Pri ,t = ∑ Pr j ,t
j =1

; if t = t1 + .... + t i(2)nPr ,t = ∑ Pri ,t

(3)

i =1

where Pri,t = probability of repairing ith at time t, Prj,t = probability ofevent j which the last repairing is the ith at time t, Pr,t = probability of all
repairing at time t.
0.45

0.4

0.4

0.35

0.35

0.3

Probability

Probability

0.45

0.25
0.2

0.3
0.25
0.2
0.15

0.15
0.1

0.1

0.05

0.05
0

0
13

18

23

28

33

38

43

12

48

17

22

27

32

37

42

47

Time, years

Time, years

(a)

(b)
0.45
0.4

Probability

0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
12

17

22

27

32

37

42

47

Time, years(c)Figure 3: Expected probability of (a) 1st, (b) 2nd, (c) 3rd repairing
0.45
0.4

First repair

Second repair

Third repair

23

33

43

Probability

0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
13

18

28

38

48

Time, years

Figure 4: Probability of all repairing

Allocation of Life-cycle Repairing Cost Based on Parameter Uncertainties of Deterioration Prediction Model253

October 2005, Singapore

4. EXPECTED REPAIRING COST
The expected repairing cost at each year is calculated based on present value
as shown in Equation (4). The year structure is firstly serviced is assumed as
the base year of discounting.
C ri
E C ri ,t =⋅ p i ,t(4)
(1 + ν ) ti
where E[Cri,t] = expected present value of repair ith at time t, Cri =undiscounted cost of repair ith, ν = discount rate, and pi,t = probability ofrepair ith at time t. It is assumed that undiscounted repairing cost is same forall sequences repairing and equal to 100. Official discount rate, 0.1% (Bankof Japan, 2001), and assumed higher discount rate, 0.5%, are considered.
Figure 5 shows the present value of repairing cost at each year during theservice life of structure. From this result, resources can be annually
allocated to the structure or group of structures based on the expected
probability of repairing to be occurred at the certain year.

[ ]

45

40

First repair

Second repair

Third repair

35
30
25
20
15
10
5

Present value of repairing cost

Present value of repairing cost

45

0

40

First repair

Second repair

Third repair

33

43

35
30
25
20
15
10
5
0

13

18

23

28

33

38

43

48

13

18

23

Time, years

28

38

48

Time, years

(a)

(b)

Figure 5: Present value of annual repairing cost at discount rate (a)0.01%,(b) 0.05%
Cumulative expected life cycle repairing cost of R&M program isshown in Figure 6. Due to the effect of discount rate and the events that are
not considered due to they cannot be implemented during the service life,
total expected life cycle cost is less than the total of assumed total cost of
three repairing, 300. From this result, the total expected life cycle cost of
R&M can be estimated.
350
First repair

300

Second repair

Total expected repairing cost

Total expected repairing cost

350
Third repair

250
200
150
100
50
0

300

First repair

Second repair

Thrid repair

250
200
150
100
50
0

13

18

23

28

33
Time, years

(a)

38

43

48

13

18

23

28

33

38

43

48

Time, years(b)

Figure 6: Present value of cumulative expected repairing cost at discountrate (a) 0.01%, (b) 0.05%

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5. SELECTION OF REPAIRING METHODS
Many structure repairing methods are available in the market with different
cost and performance. Decision makers have to choose the most suitableoption based on an objective and many constrains. This study used
minimum expected life cycle cost as an objective. Assumed performanceand cost of three repairing methods is shown in Table 3. Chloride diffusion
coefficient and coefficient of variation is used to indicate the performance ofrepairing system. Lower chloride diffusion coefficient and low coefficientof variation indicate higher performance and also higher cost. Others
random variables are shown in Table1.

Table 3: Assumed performance and cost of repairing options
Repairing
Mean
Coefficient of variation
Cost
2A
1.29 cm /year
0.10
100
B
0.645 cm2/year
0.10
150
C
1.29 cm2/year
0.05
150
Figure 7 shows expected probability of all repairing at each time ofrepairing B and C. When compared to that of repairing A as shown in
Figure 4, mainly only the first and second repairing has a high probability to
be conducted due to lower chloride diffusion coefficient of repairing B. In
contrast, lower coefficient of variation of the repairing C has small effect on
the expected probability of repairing.
0.45

0.45

0.4

First repair

Second repair

0.4

Third repair

First repair

Second repair

Third repair

0.35

0.3

Probability

Probability

0.35

0.25
0.2
0.15

0.3
0.25
0.2
0.15

0.1

0.1

0.05

0.05

0

0
13

18

23

28

33

Time, years

(a)

38

43

48

13

18

23

28

33

38

43

48

Time, years(b)

Figure 7: Expected probability of all repairing (a) A, (b) B
Comparison of total expected life cycle repairing cost by three options
is shown in Figure 8. It is clearly shown that the higher performance ofrepairing B lower the total repairing cost. In contrast, repairing cost of
option C is the highest. Based on assumed conditions, repairing B is the
optimum method because of the lowest life cycle cost and satisfying
assumed acceptable structural performance during the service life. In the
future, more complete information of assumed variables is required in orderto accurately select the optimum R&M program.

Allocation of Life-cycle Repairing Cost Based on Parameter Uncertainties of Deterioration Prediction Model255

October 2005, Singapore

6. CONCLUSIONS
Methods to evaluate the expected probability of required R&M at each year
during the service life and the present value of expected life cycle R&M
cost of deteriorating structure were presented.
Due to uncertainties of parameters used in the deterioration prediction
model, predicted time to conduct R&M is represented by the probability
distribution instead of deterministic value. Expected cost is calculated basedon obtained expected probability and discount rate. Total and annual
resources can be allocated to structure or group of structure based on
expected total life cycle cost and expected annual cost, respectively.
This approach is a part of the effort to determine the most optimal life
cycle R&M cost for deteriorated reinforced concrete structure. However,further study about acceptable structural performance and database of R&M
are being conducted.

Total expected repairing cost

450
400

Repair A

Repair B

Repair C

350
300
250
200
150
100
50
0
13

18

23

28

33

38

43

48

Time, years

Figure 8: Comparison of total expected repairing cost
REFERENCES
Bank of Japan, 2001. Figures at a Glance. Available online at
http://www.boj.or.jp/en/rate.htm (August/2005)
Enright, M. P., and Frangopol, D. M., 1999. Condition Prediction of
Deteriorating Concrete Bridges Using Bayesian Updating. Journal of
Structural Engineering 125(10), 1118-1125.
Fishman, G. S., 1995. Monte Carlo: concepts, algorithms, and applications.
Springer, New York.
Yokosawa, Y., Sato, T., Kato, Y., and Uomoto, T., 2005. Report on
Tamagawa Bridge Investigations by Using Inspection Software forConcrete Structures. Proceedings of the Annual Convention of Japan
Concrete Institute, Nagoya, Japan.

256

New Technologies for Urban Safety of Mega Cities in Asia

IMPORTANCE OF MAINTENANCE OF
CONCRETE STRUCTURESFOR URBAN SAFETY
TAKETO UOMOTO
ICUS, Institute of Industrial Science, University of Tokyo, Japanuomoto@iis.u-tokyo.ac.jp
ABSTRACTThe maintenance of concrete structures is essential and important tomaintain the safety of urban area. Most of the political, economical andeducational activities are done in urban area. If any accident or hazard
occurs, the effect is tremendous. Concrete structures are durable andpeople easily forget about the durability aspects of concrete structures. It isvery important for both the owners and engineers to recognize how
important it is to maintain concrete structures to keep the people safe inurban area. Before any accident of hazards happens, we should keep eyesto the maintenance of concrete structures. This paper describes what weare doing in Japan to maintain the existing concrete structures.

1. INTRODUCTION
Up till now in Japan, the economic growth was rapid in the period of 1960
～ 1980. More than 100million cubic meters of concrete were used toconstruct the structures such as buildings, bridges, tunnels, dams, etc. tosupport the activities of Japanese people. As a result, these infrastructures
rapidly reached 50 years in service, and due to deterioration of the structures,
maintenance of these structures has become a major interest among theowners and the civil engineers.
On the other hands, population of Japan will reduce from now on
because of fewer babies in a family approximately 1.2 children per one
family. Although high technologies have been developed in recent years, it
is sure that fewer engineers have to take care of the huge amount ofstructures from now on, which has never experienced in the past. Due toreduction in the economical growth, the budget for both construction andmaintenance will be reduced in the future. The maintenance of existing
structures must be done with the following conditions: 1) rapid increasing of
the amount of existing structures reaching to the age of 50 years, 2) lessamount of engineers to maintain the structures, 3) less amount of budget canbe used to maintain the structures. .
Although there are many hazards in each country, concrete structures
are expected to be safe for long period of time. Main hazards for the
structures in Japan are as follows:257

October 2005, Singapore

1) Earthquake and volcanic action2) Landslide and flood3) Typhoons and strong wind4) Fire and Thunder
5) Accidents
6) Terrorism
If the structure is deteriorated before the hazards, the structure mayeasily collapse and difficult to maintain the safety of the people. The
Photograph 1 shows an example of a collapsed pier during Hanshin Awaji
Great Earthquake. As shown in the photo, the pier was deteriorated to large
extent due to alkali aggregate reaction. Concrete is cracked severely and isjust like a bundle of concrete blocks.

Photograph 1: Collapsed reinforced concrete pier affected by alkali
aggregate reaction
In order to keep the safety of urban area, it is important to study andinvestigate not only on hazards but also on durability aspects of existing
structures. Even a small amount of concrete spalling may cause traffic
accidents to large extent as we experienced in Sanyo-Shinkansen in 1999.
Considering these situations now, this paper explains what ishappening now in Japan and how we are dealing with the problems throughresearches and engineering.

2. SITUATION NOW IN JAPANThe Figure 1 shows the estimated amount of concrete consumed inconstruction since 1945. As can be seen from the figure, within 25 years
only 2 billion cubic meters of concrete were used until 1970. After that
more than 8 billion cubic meters of concrete were used within 30 years.
This shows that the existing structures being used for 50 years in service
was less than 10% of the total amount of existing structures at the beginning258

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Amount of concrete（million ｍ3）of the 21st century. One can imagine how the number of old structures used
for more than 50 years will rapidly increase from now on.
Concrete per year

10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
1940

1950

1960

Total amount

1970
Year

1980

1990

2000

Figure 1: Estimated amount of concrete consumption in Japan
The percentage of number of civil structures being already repaired isshown in Figure 2a. The data of the buildings are shown in Figure 2b. The
figure 2a shows that although the reason of repair is not the same, thepercentage of repaired civil structures increases with years in service.
Approximately 50 % of the structures are repaired after being used for about
60 years. The reasons for the repair are mainly due to deterioration or
defects after being used.
R epaired

N ot R epaired

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
-10

11-20 21－30 31－40 41－50 51－60
Years in S urvice

61-

Figure 2a: Percentage of repaired civil structures after being used

Importance of Maintenance on Concrete Structures for Urban Safety259

October 2005, Singapore

Percentage of Repair

Total

Each Year

120
100
80
60
40
20
0
0

10

20

30

40

50

60

70

80

Years in Service

Figure 2b: Percentage of repaired houses and buildings
Compared to civil structures, 50% of houses and buildings arerepaired after 17 years in service. It does not mean that houses andbuildings are not durable. The repair of houses and buildings may be done
because of defects or introduction of new facilities for the benefit of theuser; not always due to deterioration.

3. GENERAL MAINTENANCE METHODS BEING USED UP TILLNOW (Uomoto and Misra, 2001)
The maintenance of concrete structures has been done mostly by the ownersof the structures. In case of public structures, the ministries, etc. maintainthe structure after the structures are completed. For the time being, themethods for the maintenance differ according to the owners of the structures.
Although there are some differences, the main concept of the maintenancecan be summarized as follows:
1) Periodic inspection and evaluation of deterioration degree2) Detailed inspection and decision making
3) Repairing and strengthening of deteriorated structures
For periodic inspections, the inspectors inspect the structures visually,sometimes with the help of binoculars and hammers, once a year or once inseveral years according to the importance and time after the structure iscompleted. The inspectors are mostly trained engineers with experiences.
The detailed inspection is done when the estimated degree of deterioration
exceeds certain limit, or when some new phenomenon is found during theperiodic inspection. The detailed inspection is done by visual inspections
with the aid of non-destructive tests or taking core samples out from theinspected structure. The purpose of the inspection is to decide the cause of
the deterioration and also to evaluate whether repair and/or strengthening isneeded or not.

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To repair or strengthen the existing structures, it is important to designand select sufficient methods and materials. The most popular repair
method for corrosion of steel bars due to carbonation is to eliminate thecarbonated concrete and replace it by new concrete and apply coatings withand without FRP sheets. But in case of steel corrosion due to chlorides fromthe surrounding environment, the highly chloride concentrated portion of
concrete are taken out, anti-corrosive treatment is applied to the surface ofthe bar, and polymer cement mortar is generally used to repair the concrete
before coating the concrete surface.

4. NEW STANDARD SPECIFICATIONS OF JSCE
After the investigations of many deteriorated concrete structures, theimportance of durability was fully recognized by the civil engineers. To
deal with the problem not only JSCE, AIJ, and JCI recommending methods
to deal with the problems but also the Ministries, and other authorities
started to propose practical counter measures to cope with the situation. As aresult, a large amount of researches has been done related to the durabilityof concrete structures including non-destructive inspection methods.
Among these authorities, the Concrete Committee of JSCE, theleading committee in the field of concrete in Japan, has published new“Standard Specifications for Concrete Structures” in the years 2000, 2001
and 2002 to deal with the problems of durability (JSCE, 2000a, 2000b and2001). The concept written in the specifications will surely be adopted byother institutions.
The main proposals of the “Standard Specifications” are the following
two items:
1) Propose a new method to design and construct new concrete
structures that can be used for specified lifetime without large amountof maintenance cost.
2) Propose an effective and economical system to maintain existing
concrete structures with small number of engineers and workers.
To deal with the problems for the items 1) and 2), the following two
Specifications are published: 1) The Standard Specification for Construction
Works of Concrete Structures, Jan. 2000 (JSCE, 2000a) and 2) The
Standard Specification for Maintenance of Concrete Structures, Jan. 2001
(JSCE, 2001). The concepts of the new Standard Specifications are briefly
explained in the following chapters.
4.1 Durability design of concrete structures for new structures
Performance-based durability design was introduced to “Standard
Specification of Concrete Structures” by the Concrete Committee of JSCEin the year 2000 (JSCE, 2000). Although durability of concrete structures
was considered important in the previous specifications, performance-based
design method was not used. The previous specifications described theImportance of Maintenance on Concrete Structures for Urban Safety261

October 2005, Singapore

importance of durability by proposing that the concrete structures are
durable for a long time when specified materials, mixes, covers, etc. areused. But these specifications did not mention about the duration of service
time, etc.
The proposed performance-based new durability design can besummarized as follows:
The concrete structure must be quantitatively checked whether the
structure possesses required performance within the designed period.
1) The degree of deterioration of the structure in service on specified causemust be specified.
2) To maintain the structure above the specified degree of deterioration, therequired performance must be specified.
To examine the performance on durability, a kind of limit state design
scheme was introduced for the durability of concrete structures. The
equation can be written as shown in Equation (1):γ i ⋅ Ad A

≤ 1.0

(1)

lim

Ad: designed performance of the structure at specified time considering thespecified deterioration cause
Alim: limit of the performance of the structure
γi: coefficient of the structure considering the importance, etc.
Generally, deterioration items to be examined are the following items,
but in some cases other causes, such as fatigue loading, must be examined.
1) Corrosion of steel bars due to carbonation of concrete2) Corrosion of steel bars due to chloride penetration into concrete3) Deterioration of concrete due to freezing and thawing4) Deterioration of concrete due to chemical attack5) Deterioration of concrete due to alkali-aggregate reaction
6) Water-tightness of concrete7) Deterioration of concrete due to fire
The Figure 3 shows an example of the calculated result for minimum
cover thickness to prevent carbonation induced corrosion at different yearsof service for OPC concrete and BFSC concrete. As shown in the figure,the cover thickness required changes according to the type of cement to be
used, water-cement ratio of concrete, years of service and exposed condition(wet or dry) of the structure to be constructed. When the structure isdesigned for long period of time, the cover thickness may become too large,
and it is recommended to use other countermeasures such as Epoxy-coated
bars.

262

New Technologies for Urban Safety of Mega Cities in Asia

Concrete cover thickness (cm)887

普通ポルトランドセメント

OPC

Service time
( Years )

66
5

100
100年
75
75年
50
50年
100
100年
75年
75
50年
50
30年
30

44
3

22

乾燥し難い環境，北向きの面など（R=1.0）

Wet Environment

乾燥しやすい環境，南向きの面など（R=1.6）

1

00
40
40

Dry Environment
45

50
50

55

60
60

65

70
70

Water
cement（％）
ratio (%)
水セメント比Concrete cover thickness (cm)

ICUS Report 11

88
Service time
(Years)100
100年

高炉セメントＢ種（スラグ40％）
Blast
Furnace
Slag Cement

7

66

75
75年

5

50
50年
100年
100
75年
75
50年
50
30年
30

44
3

22

Wet environment

乾燥し難い環境，北向きの面など（R=1.0）
乾燥しやすい環境，南向きの面など（R=1.6）

1

Dry environment

00
40
40

45

50
50

55

60
60

65

70
70

Water
cementratio (%)
水セメント比（％）

Figure 3: Calculated results of concrete cover according to JSCE Standard
Specification (JSCE, 2000a)
4.2 Methods of maintenance newly proposed by JSCE (JSCE, 2001)
The methods used in the new Standard Specification are basically thesame as the conventional method. The differences are that the new method
requires to maintain the structure within their required performances
throughout their service life. The principles of the standard are listed below:
1) To maintain a structure, performances required for the structure must be
clearly defined.
2) The performances required for general structures are “safety”,“serviceability”, “hazards to the public”, “aesthetics and landscape” and“durability”.
3) Structures must be maintained according to the designated maintenancecategory by formulating a maintenance program to retain the performances
within the specified tolerances throughout their service life. And the system
for maintenance includes adequate “initial inspection”, “deterioration
prediction”, “inspection”, “assessment/judgment”, “remedial measures”, and“record”.
The details of maintenance works are as follows:(1) Structures must be maintained according to a designated maintenancecategory by formulating a maintenance program to retain the performancewithin the specified tolerances throughout their service life. And
maintenance system includes adequate “initial inspection”, “deterioration
prediction”, “inspection”, “assessment/judgment”, “remedial action”, and“record”.
(2) To maintain a structure, in addition to the assessment and evaluation at
the time of inspection, assessment and evaluation must be made throughout
the service life of the structure based on prediction of deterioration.
(3) To predict the deterioration, required performances of the structure must
be clearly defined, and also the design service life must be made clear.
(4) The records on design, construction, initial inspection, deterioration
prediction, periodical inspection, assessment and/or evaluation, andremedial actions must be kept throughout the service life.

Importance of Maintenance on Concrete Structures for Urban Safety263

October 2005, Singapore

電流量
Ik (mA/cm)
Current
Amperage(mA/cm)One of the difficulties is how to predict the degree of deterioration at
the end of their service life. There are several researches being done topredict the deterioration in numerical manner (JSCE, 2000b). In the
published Standards, several numerical prediction methods are introduced as
references for structures suffering cyclic fatigue loads, carbonation induced
corrosion and chloride induced corrosion. In case of cyclic fatigue, S-N
curves are used to predict the service life. In case of carbonation induced
and chloride induced corrosion of steel bars, diffusion equations for carbon
dioxide and chloride are used to predict the degree of corrosion. Using
these prediction methods, deterioration degree can be estimated to certain
degree. (See Figure 4) But for other deterioration problems, which has notbeen studied numerically, a quantitative model has not been proposed yet.
To deal with the problem, a qualitative method “Grading method” isintroduced in the Standard.
（Temperature:20℃、Crack depth: 7cm）

0.1

Cathode

0.05

Crack

0
-0.05

days
28日
days
91日
days
180日

Anode

-0.1
-0.15

year
1年
years
2年

-0.2
-0.25
0

2

4
6
8
10
モデル端部からの距離(cm)
Distance (cm)12

14

Figure 4: Quantitative prediction of corrosion in marine environment withcracks (Tsukahara et al., 2000)

5. PROBLEMS IN ACTUAL EXISTING STRUCTURES
When a civil engineer is asked by the owner to check the safety of an old
existing structure, one of the largest problems is that there are neither
drawings nor construction records of the structure available. No problem
may occur in case of important facilities, which is maintained with greatcare. But in case of normal structures, the owners do not know theimportance of these documents.
To deal with the problem, NDI is not enough. Fortunately, ourstructures are not too old, and they are mostly designed and constructed by
the method specified by JSCE, AIJ or other associations. Considering these,
the only way is to re-design the structure again using the methodologies
used at the time of construction. Figure 5 shows an example of re-designed
bridge pier constructed about 35 years ago. From the figure, it is mucheasier for a civil engineer to check the safety of the structure under several
hazards. It will become more important for the owners and engineers tokeep these documents throughout the service life of a structure.

264

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

D131201907,300

85 0 65 0
D16

4,500

65 0
4,500

250
D25

1,000 30 0

12 023 0

21@300１

1,300

280 8@200

210

50 280 9@200

18,390CL

9,390
280 16@200280

120@125
15,620120

Figure 5: Re-designed reinforced concrete pier of a bridge (Okazaki, 2005)
6. CONCLUDING REMARKS
Engineering is not always complete, and further research works are needed.
To sustain existing structures, durability of the structure is important. One
good method is to construct durable structures, but for the existing
structures maintenance is the only way to deal with the problem. Althoughconcrete committee of JSCE has set up a good system for maintenance ofexisting concrete structures, there are still many things to be done: not only
researches but also education to the students and engineers about durability
and maintenance. I hope this paper may become a help to the concrete
engineers of the world who are trying to design, construct and maintainconcrete structures.

REFERENCES
JSCE, 2000a. The Standard Specification for Construction Works ofConcrete Structures. (in Japanese)
JSCE, 2000b. References for “The Standard Specification for Construction
Works of Concrete Structures”. (in Japanese)
JSCE, 2001. The Standard Specification for Maintenance of Concrete
Structures. (in Japanese)
Okazaki, S., 2005. Development of monitoring system for RC bridge basedon restoration design method. Thesis submitted to the University ofTokyo for Master of Engineering degree.
Tsukahara, E., Koyama, R., Hoshino, T., and Uomoto T., 2000. Estimation
Method of Corroded Portion of Reinforcing Steel Bar by Natural
Potential Measurement. Non-destructive Testing in Civil Engineering
2000, Elsevier.
Uomoto, T., and Misra S., 2001. Role of Engineers to Improve Quality ofConcrete Structures. Proceedings of EASEC-8, Singapore.

Importance of Maintenance on Concrete Structures for Urban Safety265

October 2005, Singapore

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New Technologies for Urban Safety of Mega Cities in Asia

RECENT SEISMIC LOAD TESTS ON
REINFORCED CONCRETE BEAM-COLUMNJOINTS AT NTU, SINGAPORE
Bing Li and Tso-Chien Pan
Protective Technology Research Centre, School of Civil and Environmental
Engineering, Nanyang Technological University, Singapore
cbli@ntu.edu.sg

ABSTRACT
Current seismic provisions for determining the amount of transverse
reinforcement in beam-column joints vary from one code to another.
Moreover, the seismic provisions in current codes were developed for themost severe earthquake effects. There is a lack of an accepted designed
method for determining the amount of lateral steel in areas of low tomoderate seismicity where the ductility demand may be lower than that inareas of high seismic activity. This paper will provide an overview ofsimulated seismic loads tests conducted on reinforced concrete beamcolumn joint subassemblages at Nanyang Technological University (NTU)
during recent years. Research conducted at NTU is aimed at examining theductility and behaviour of moment-resisting frame with limit ductility inorder to develop detailing guide lines for areas of low to moderate toseismicity.
1. INTRODUCTION
There are a large number of moment resisting frames built for residential
and commercial purposes in Singapore and Malaysia. The current buildingcode used is mainly based on the British Standard: the BS 8110, which has
no provision for seismic loading. Hence, almost all these frames are built
without seismic consideration in design and detailing, for example, no joint
reinforcement in the joint cores. However recent studies have shown that
although Singapore is located in a low seismicity region and there has neverbeen any earthquake damage to the country, the seismic hazard potential in
Singapore should not be ignored. This makes it necessary to study theperformance of these moment resisting frames under possible earthquake
conditions, and as a critical part of such frames, the non-seismically detailed
beam-wide column joints deserve more attention.
This paper provides an overview of simulated seismic loads tests conducted
on reinforced concrete beam-column joint subassemblages at NTU. These
investigations have attempted to gain a better understanding of the generalbehaviour of these joints when subjected to lateral loads.

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2. TESTS ON LIGHTLY REINFORCED BEAM-COLUMN JOINTSSpecimen AL1

Specimen AS1
Column bars
lapped above
floor level
Slab

300

2460
400

A

100

R10@200

A large number of buildings are designed as gravity-load-designed or lightly
reinforced concrete structures in Singapore and Malaysia, therefore, they are
constructed with reinforced concrete moment resisting frames having little
or no transverse reinforcement in the joint zone. Problems have beenencountered when assessing the seismic behaviour of the joints in thesebuildings. This is due mainly to the absence of a theoretical basis forevaluating the joint behaviour that is supported by comprehensive test data.
Modern design codes are also of little assistance for assessing these joints asthey are based on tests of the joints with adequate joint transverse
reinforcement. Quasi-static cyclic loading tests have recently been
conducted on four reinforced concrete beam-column joint subassemblages
with or without a floor slab for examining the influence of regional beamcolumn joints to the overall behaviour of the buildings in low to moderate
seismcity area and providing useful insight s without going into theprinciple of full ductile design (Li, Pan and Pan 2003). Four specimens
designated as AS1, AS2, AL1 and AL2, were built and tested (see Figures 1,2). They were selected from an existent building, which was designed inaccordance with BS 8110. Among these, AL1 and AL2 were represented
connections collected from a weak direction frame and a strong direction
frame, respectively. AS1 and AS2 were the joints with a floor slab.
Reinforcing detailing of AS1 and AS2 were the same as those of AL1 andAL2 with exception that a one-meter width slab and transverse beams wereadded.

R10@200

B

A

B

Transverse beam200

R10@150

R10@1504500

Column bars
lapped above
Specimen AS2
floor level
SlabSpecimen AL2

300

2460
400

A

100

R10@200

Figure 1 Dimensions and reinforcing details of AL1 and AS1

R10@200C

A

C

Transverse beam

R10@150400
4500

R10@150

Figure 2 Dimensions and reinforcing details of AL2 and AS2

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Figure 3 Test set-up
Storey drift ratio
-4%

-3%

-2%

-1%

0%

1%

2%

3%

4%

82

109

80

P y =60.6 kN
Storey shear force (kN)

Experimental

60
40

Initial stiffness
20
0
-109

-82

-55

-27

0

27

55

-20
-40
-60

P y =-60.6 kN-80

Horizontal displacement (mm)Figure 4 Storey shear force versus horizontal displacement for AL1
The storey shear force versus horizontal displacement relationship for AL1
is shown in Figure 4. The theoretical capacity was not reached until the endof the test with the maximum capacity being obtained at a displacement of
37 mm corresponding to a storey drift ratio of 1.4%. Compared with thepredicted yield displacement of AL1, this displacement was much large,
which was about three times that of the first yield displacement of 12.5 mm
predicted through the theoretical approach. The maximum capacities of AL1
were 53 kN in both loading directions. After the loading to a storey drift
ratio of 1.5%, the hysteretic loops pinched significantly due to the severebond deterioration along the beam and column bars as well as the joint
diagonal tension cracking. Consequently, the extensive of joint diagonaltension cracks caused the severe strength and stiffness degradation. At theend of the test, the residual load-carrying capacity of the specimen was
about 37 kN in either loading direction and therefore, the behaviour of thetest specimen was dominated by the response of the most damaged beamcolumn joint. Figure 5 illustrates the storey shear force versus horizontal
displacement relationship for AS1. Also shown are the theoretical capacitiesof the test unit. Solid lines present the theoretical capacities without
consideration of the presence of the slab while dash lines are the theoretical
capacities assuming that all the beam longitudinal bars and slab bars yielded
simultaneously. In other words, it is assumed that slab bars within the whole

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slab width will effectively participate in resisting the lateral loading. The
first yield displacement of AS1 occurred at a displacement of 19.6 mm
corresponding to the storey drift ratio of 0.6% in the positive loading
direction. At this moment, the specimen also reached its theoretical capacity,which occurred earlier than that of a 1% storey drift ratio in the negative
direction. The maximum capacities were obtained at storey drift ratios of
2% and 1.5%, which were 80 kN in the positive and 70 kN in the negative
loading directions indicating that the specimen took over-strength factors at
27% and 11%, respectively. If compared with AL1, the maximum capacities
of AS1 were 51% and 32% higher than those of AL1 in the same loading
directions. It was evident that the participation of a slab enhanced themoment resisting capacity of the specimen, but the slab bars were not fully
effective to resist bending moments and therefore, the specimen didn’t reachthe theoretical capacity with considering the slab effect in both loading
directions. In the first loading cycle to a storey drift ratio of 3.0%, therecorded storey shear force dropped to the theoretical level and thehysteretic loop showed apparent pinching.
Storey drift ratio
-4%

-3%

-2%

-1%

0%

1%

2%

3%

4%

100

P ys = 97.3kN 80

Storey storey force (kN)

Experimental

P y =63.1 kN

60

Initial stiffness

40
20
0

-109

-82

-55

-27

-20

0

27

55

82

109

-40
-60

P y =-63.1 kN-80

P ys = -97.3kN-100

Horizontal displacement (mm)Figure 5 Storey shear force versus horizontal displacement for AS1
Figure 6 illustrates the storey shear force versus horizontal displacement
relationship for AL2. The obtained yield displacement was 21 mmcorresponding to the storey drift ratio of 0.8%. This was about three times
that of the predicted yield displacement of 6.75 mm. At this moment, thespecimen reached its theoretical capacity of 63.9 in either loading direction.
The maximum capacities were obtained at a storey drift ratio of 1.5%,
which were 82 kN in the positive and 75 kN in the negative loading
directions indicating that the specimen took over-strength factors at 28%
and 17%, respectively. From the drift ratio of 1.5%, significant pinching
was observed in the hysteretic loops and, in the repeated cycle, the specimen
started to lose its load-carrying capacity at 11.9% and subsequently, strengthand stiffness degradation was evidently. At the second cycle of the loading
run to a drift ratio of 3.0%, the specimen lost its load-carrying capacity at
20% indicating that the specimen failed at this stage. At the first semi-cycleof a 3.8% storey drift ratio, the load-carrying capacity suddenly dropped to
42 kN and so for the reasons of safety, the test was withheld at this moment.

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Storey drift ratio
-4%

-3%

-2%

-1%

0%

1%

2%

3%

4%

100
80

Storey shear force (kN)

Experimental

P y =63.9 kN

60

Initial stiffness

40
20
0

-109

-82

-55

-27

-20

0

27

55

82

109

-40
-60

P y =-63.9 kN

-80
-100

Horizontal displacment (mm)Figure 6 Storey shear force versus horizontal displacement for AL2
Figure 7 illustrates the storey shear force versus horizontal displacement
relationship for AS2. The first yield displacement was 14 mm;corresponding to a storey drift ratio of 0.6%.This was about two times thatof the predicated yield displacement of 6.54. At this moment, the specimen
reached its theoretical capacity of 66.7 kN in either loading direction. The
maximum capacities were obtained at a storey drift ratio of 2.0%, whichwere 98 kN in the positive and 83 kN in the negative loading directions
indicating that the specimen took over-strength factors at 47% and 24%,
respectively. If compared with AL2, the maximum capacities of AS2 were
19% and 11% higher than those of AL2 in the same loading directions.
Subsequently, AS2 lost its load-carrying capacity progressively until thetheoretical value was reached. Limited pinching was observed after thesecond cycle of a storey drift ratio of 1.5%. After the second cycle of astorey drift ratio of 2.0% up until the end of the test, pinching and stiffness
degradation were obvious.
Storey drift ratio
-4%

-3%

-2%

-1%

0%

1%

2%

3%

4%

120

Storey shear force (kN)

Experimental

90

P y =66.7 kN

P ys =102.7 kN
60

Initial stiffness
30
0
-109

-82

-55

-27

0

27

55

82

109

-30
-60

P y =-66.7 kN

P ys =102.7 kN

-90
-120

Horizontal Displacement (mm)Figure 7 Storey shear force versus horizontal displacement for AS2
As expected, specimens with a slab showed a higher strength thanspecimens without a slab. The presence of a floor slab affects the behaviourof joints in two ways: It increases the flexural capacity of the main beams;
and it imposes torsional moment on the transverse beams that affect the

Recent Seismic Load Tests on Reinforced Concrete Beam-Column Joints at NTU, Singapore

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October 2005, Singapore

confinement of the joint. This phenomenon was observed in load-deflection,
moment-rotation and strain distribution. The measurement of strain
distribution along the longitudinal reinforcement showed that beam
reinforcement of all specimens experienced yield at a ductility level of 1.0.
However, the peak magnitude of beam bar strain of those specimens with aslab was reduced. This could be attributed to the decrease in the curvature
due to the slab participation. The tensile stress of the slab reinforcement
outside the column cores was transferred by means of torsion moment oftransverse beam. Therefore, slab participation could also be verified by thedeveloping of torsional moment. In addition to strength, the stiffness is also
an important measurement of the performance of joints. Excessive shear
deformation in the joints or the loss of anchorage of the beam longitudinal
reinforcement was reflected in the rapid degradation of the stiffness. Whenthe main beam longitudinal reinforcement yielded, the stiffness decreased
rapidly. Up to a drift ratio of 2%, the specimens maintained their initialstiffness; however, beyond the 2% drift ratio, the loss of stiffness variedwith the type of specimen. Those specimens without a slab experienced
significant losses of stiffness. In all specimens, the hysteresis loops became
increasingly pinched after the second loading cycle. This is attributed
mainly to the opening and closing of flexural cracks. Other factor such as
shear deformation of the joint and the slippage of beam and column bars
through the joint also contribute to the loss of stiffness and hence, thepinching of the loops.

3. TESTS ON BEAM-WIDE COLUMN JOINTS
Reinforced concrete structures consisting of wall-like wide column elements
are very common in regions of low to moderate seismicity, and are thepredominant structural system in Singapore and Malaysia. The wide-column
frames are quite stiff in one direction and flexible in the other, and usually
they are designed according to BS 8110 without the consideration of seismic
loading. Beam-column joint regions in such frames are of special interest
because they are usually non-seismically detailed and their joint dimensions
are quite unusual. The lack of seismic reinforcing details is in sharp contrast
to those used in modern seismic design. Therefore, it is of concern that thestrength, ductility, and energy dissipation capacity of these beam-widecolumn joints may not be adequate to sustain earthquake-induced loads dueto the lack of seismic reinforcement details in this type of joints. Proposed
seismic assessment methods and approaches were obtained purely from tests
on normal types of beam-column joints, which differ largely from the beamwide column joints in terms of joint dimensions. Since joint dimensions
have been found to have a great influence on the seismic behaviour ofjoints , the previous findings for normal types of beam-column joints may
not applicable to beam-wide column joints. NTU began a laboratory
investigation of beam-wide column joints in 2000 (Li, Wu and Pan 2002).
Four joint subassemblages have been tested subjected to quasi-static lateralcyclic-loading to determine design details necessary for RC wide column
frames that will resist moderate earthquake without significant loss of272

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strength. Specimens were tested as shown in Figures 8 and 9.

Figure 8 Dimensions and reinforcing details of M1

Figure 9 Dimensions and reinforcing details of M2

Figure 10 Test set-up
The as-built specimen A1 failed at displacement ductility factor µ ∆ of 2 orat story drift ratio of 2.4%, while the modified M1 failed at µ ∆ = 3 or atstory drift ratio of 3.3%. By comparing the storey shear forces of A1 andM1 (see Figure 11), it can be seen that both specimens reached their ideal
horizontal strength in the first cycle with µ ∆ = 2. However, in the second
cycle with µ ∆ = 2, the horizontal strength of A1 dropped significantly, andRecent Seismic Load Tests on Reinforced Concrete Beam-Column Joints at NTU, Singapore

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October 2005, Singapore

the specimen failed at this stage. For M1, the significant drop in horizontal
strength occurred in the second cycle with µ ∆ = 3.

Story shear force versus Storey drift
-2.0%

-1.0%

0

Story shear force versus Storey drift

1.0%

250

2.0%

µ =1

Specimen A1

-3.0%

µ =2

Story shear force (kN)

Story shear force (kN)

0

1.0%

50
0
-50
-100
-150

µ =1

2.0%

µ =2

µ =3

Pi = 162.4 kN

150Theoretical
stiffness

100

-1.0%

Specimen M1

200

Pi=162.4 kN

150

-2.0%

250

200

Theoretical
stiffness

100
50
0
-50
-100
-150

Pi=-162.4kN

Pi = -162.4 kN

-200

-200

µ =2

-250
-80

µ =3

µ =1
-40

0

40

-250
-100

80

-80

µ =2
-60

-40

500

1.0%

2.0%

µ =1

Specimen A2

400-3.0% -2.0%

-1.0%

0

20

1.0%

500

µ =2

40

60

80

100

400

Story shear force (kN)

100
0
-100
-200

3.0%

Pi = 305.6 kN

300

Theoretical stiffness

200

2.0%

µ =1 µ = 2 µ = 3

Specimen M2

Pi = 305.6 kN

300
Story shear force (kN)00

Story shear force versus Storey drift

Story shear force versus Storey drift
-1.0%

-20

Horizontal displacement (mm)Horizontal displacement (mm)

-2.0%

µ =1

Theoretical
stiffness

200
100
0
-100
-200

Figure 11 Story shear force versus horizontal displacement relationship
-300

-300

Pi = -305.6 kN

-400

µ =2

-500

Pi = -305.6 kN

-400

µ =1

-500

µ = 3 µ = 2 µ =1

For specimens A2 and M2, based on test data, the as-built A2 failed at µ ∆ =2 or at story drift ratio of 2.04%, while the modified one M2 failed at µ ∆ = 3
or at story drift ratio of 2.7%. By comparing the storey shear forces of thetwo specimens (see Figure 11), it can be seen that both A2 and M2 reachedtheir ideal horizontal strength in the first cycle with µ ∆ = 2. In the second
cycle with µ ∆ = 2, the horizontal strength of A2 dropped significantly andthe specimen finally failed at this stage. However, M2 did not suffer asignificant drop of horizontal strength until the second cycle of µ ∆ = 3. The
initial stiffness of A1 and M1 obtained from the tests were 4.82 kN/mm and5.4 kN/mm, respectively. That was equal to 38% and 42% of the theoretical
stiffness. The low stiffness was due to the early diagonal cracking within the
joint core region, and the bond deterioration along the beam and column
main bars. The modification of the reinforcing details in M1 did not show
any significant effect on the initial stiffness, because the initial stiffness
depends mainly on the column and beam section properties, which were
kept unchanged for two specimens. The initial stiffness of A2 and M2
obtained from tests were 10.98 kN/mm and 12.44 kN/mm, respectively,
which were equal to 38% and 45% of the theoretical stiffness. The low
stiffness was due to the early diagonal cracking within the joint core region.
The modification of reinforcing details in M2 did not show any obvious
effect upon the initial stiffness, and was also found to have negligible effects
-80

-40

0

40

Horizontal displacement (mm)

274

80

-100

-80

-60

-40

-20

0

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40

60

80

100

Horizontal displacement (mm)New Technologies for Urban Safety of Mega Cities in Asia

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upon the stiffness degradation of the specimens. The stiffness of the two
specimens degraded at about the same rate through the whole test.
For oblong joints A1 and M1, a maximum nominal horizontal shear stress inthe joint core of 0.84 f c' or 0.15 f c' was obtained in the first positive cycleof loading to a displacement ductility factor of 2, and 3, respectively. Whilefor the wall-like column joints A2 and M2, the maximum nominal
horizontal shear stress obtained in the joint core was 0.61 f c' or 0.11 f c' ,which occurred in the first positive cycle of loading to µ ∆ = 2, and 3,
respectively. Based on the experimental results, it was found that the
maximum joint shear stresses occurred in the two oblong joints A1 and M1,
and that the two wall-like column joints A2 and M2, were same. However,M1 and M2 achieved higher ductility levels than A1 and A2. The reason forsuch improvement may be due to the presence of joint transverse
reinforcement in M1 and M2. In A1 and A2, there was no joint transverse
reinforcement provided in the joint core. The joint transverse reinforcementin M1 and M2 helped the joints share a part of the total joint shear force.
Thus it prevented the diagonal compression strut being overloaded at an
earlier ductility stage, and the specimens survived until the higher
displacement ductility levels.
The joint shear deformation was also measured during the testing of A2 andM2. For A2, the joint deformation contributed 10% to 16.5% towards thetotal horizontal displacement, while for M2 joint deformation contributed
13% to 24% towards the total horizontal displacement. The increased
contribution of the joint deformation towards the total horizontal
displacement of M2 could also be attributed to the presence of joint
transverse reinforcement. In M2, the presence of the joint transverse
reinforcement formed a relatively flexible truss mechanism other than therelatively stiff diagonal compression strut. Thus a part of the joint shear
force in M2 was transferred by the relatively flexible truss mechanism rather
than purely by the relatively stiff diagonal compression strut. The relatively
flexible joint core thus allowed the increase of the joint deformation to
occur in M2.
4. SUMMARIESThis paper has summarized simulated seismic loads tests conducted on
reinforced concrete beam-column joint subassemblages at NTU. Based on
experimental studies conducted at NTU, the following conclusions can be
made:
For the lightly RC beam-column joint subassemblages, the maximum
nominal horizontal joint shear stress of the subassemblages exceeded thelimits either required by ACI 318 or NZS 3101 and therefore, the joint
failure mechanism could be expected in the test subassemblages. To fulfill
the reinforcing details for limited ductile frame structures, beam-column
joint must be suitable reinforced to ensure joint shear mechanism. Limited
joint reinforcement can improve the individual joint region. However it isRecent Seismic Load Tests on Reinforced Concrete Beam-Column Joints at NTU, Singapore

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October 2005, Singapore

not enough to improve the overall performance of test specimen and wholebuildings in terms of strength, stiffness and ductility. The presence of a slab
increased both the strength and stiffness of subassemblages. It was also
found that the development of an effective slab width is related to theflexural strength ratio, and the global displacement demand. The transverse
beams were most effective in confining the joint before experiencing
torsional cracks. However once the transverse beams reached their torsional
cracking strength, their ability to confine the joint diminished.
For non-seismically detailed oblong joint and wall-like column joint, themaximum nominal horizontal shear stress in the joint core is 0.15 f c' and0.11 f c' , respectively. Both the joints failed at µ ∆ = 2. While for the two
modified oblong joint and wall-like column joint, which contains 15% and
24% of joint horizontal transverse reinforcement required by NZS 3101,
respectively, the joint shear forces are the same as those of the as-built
specimens. However, due to the presence of the joint transverse
reinforcement, both specimens achieved µ ∆ = 3. And more energy was
dissipated in the modified joints, observed from the hysterisis loops of thespecimens. For wall-like column joints of limited ductility frames having
joint shear stress ratio ( v jh / f c' ) less than 0.15, the column depth is so largethat even when the large diameter beam bars are used, the ratio of beam bar
diameter to column depth can still satisfy the strict requirement given by
NZS 3101. For oblong joints of limited ductility frames having joint shear
stress ratio ( v jh / f c' ) less than 0.2, the improvement of the behaviour of thiskind of joints cannot depend on the restriction of beam bar diameters rather
than increasing the joint transverse reinforcement. A minimum amount ofhorizontal joint reinforcement of Vsh / V jh = 0.35 is sufficient.
REFERENCES
Li B, Wu YM and Pan T-C., 2002, Seismic Behaviour of Non-Seismically
Detailed Interior Beam-Wide Column Joints - Part I: Experimental
Results. ACI Journal, Vol. 99, Nov –Dec 2002.
Li B, Wu YM and Pan T-C., 2003 Seismic Behaviour of Non-Seismically
Detailed Interior Beam-Wide Column Joints - Part II: Discussion andTheoretical Comparisons. ACI Journal Vol.100, Jan–Feb 2003
Li B, Pan T-C and Tan HY.,2002, Earthquake Resistance of Lightly
Reinforced Concrete Interior Beam-Column Joints Including a Floor
Slab – Paper 157, 12th European Conference on Earthquake
Engineering"

276

New Technologies for Urban Safety of Mega Cities in AsiaAPPROXIMATION OF DAMAGE FOR A
REINFORCED CONCRETE COLUMNSUBJECTED TO
INTERMEDIATE RANGE BLAST LOADINGXIN ZHANG AND TSO-CHIEN PAN
Protective Technology Research Centre, School of Civil and Environmental
Engineering, Nanyang Technological University, Singapore
cxzhang@ntu.edu.sg
ABSTRACTThis paper presents response results for a supporting reinforced
concrete (RC) column of a building subjected to an intermediate range,
blast loading. The response results are based on finite element (FE) model,material-level modeling is applied and the material nonlinearity wasconsidered. Anisotropic material model is used for the degradation of
concrete strength. The damage of the column is evaluated for the duration
where the RC column is subjected to the blast load. During the loading
duration, the surface of the column subjected to blast loading is in a state ofcompression as it deforms. As the column springs back, the compression
state of this column surface reverses its stress state to tension, leading tomaterial failure.

1.0 INTRODUCTION
Current security issues emphasize the need of the analysis of residential /commercial buildings under blast loading. The blast effect of an explosion isin the form of a shock wave composed of a high-intensity shock front,
which expands outward from the surface of the explosive into thesurrounding air. As the wave expands, it decays in strength, lengthens induration, and decreases in velocity. When the explosion originates at a large
scaled range and the structure is small compared to the dimension of theblast wave front, the structure will be loaded in a manner that leads to global
deformation, i.e. all the elements provide some degree of resistance to theloading. If the explosion is sufficiently close to the building, the blast
loading on the structural surface will be very uneven. In this case, thestructural response is characterized by local failure of some of the structuralcomponents in the first place and may evolve to the progressive collapse of
the entire building later in a much slower time scale. At an intermediate
scaled range, both global and localized response can be expected. In theevaluation of progressive collapse, the damage of the columns is usually thecontrolling factors. Therefore, it is necessary to estimate the damage ofcolumns subjected to blast loading.

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For a residential/commercial building, the explosion events areusually confined by the city environment, i.e. street width, parking lots, etc.
An intermediate range of 10 m standoff distance of the charge is quite
representatively a conservative estimation for most significant car bombings.
Small explosion events are likely to be closer but less significant. Therefore,
in this paper, a surface explosion of one-ton TNT equivalence at a 10 m
standoff distance is considered for a typical building RC column. The
objective is to understand the building column behavior under this loading
condition.

2.0 THE COLUMN
The dimensions of the column shown in Figure 1 are 1.5 m by 0.5 m,
whereby the wider dimension is exposed to the explosive. In the 10 m
standoff case, its response may be computed by using only half of its
domain due to the symmetry. Therefore, symmetrical boundary conditions
are to be applied on the center vertical plane parallel to the direction of theblast wave propagation. As shown in Figure 1, the left plot shows theelevation of a 5 m high target column with its upper and lower ends fixed.
The fixed-end boundary conditions are as approximated because restraint on
this column provided by other part of the structure may be relatively weak
considering the dimension of the column itself. The right plot shows themeshed half section of the column with symmetrical boundary being appliedon the right hand side border.

Figure 1 FE model of the column

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3.0 MATERIAL-LEVEL MODEL
Concrete is a brittle material, which exhibits distributed damage anddegradation of the mechanical properties with increase loading. The
phenomenological response of plain concrete subject to predominantly
tensile stresses is characterized a rather linear ascending branch of thestress-displacement curve. The linear ascending branch is typically followed
by a progressively decreasing residual strength resulting in the formulationof macro-defects in the form of discrete cracks. When unloaded in the postpeak regime, non-recoverable deformations as well as a degradation of thestiffness of the unloading branch are observed. From a micro-structural
point of view, the degradation progress of the elastic module, commonlyreferred to as damage, is the result of the growth and coalescence of theexisting micro-cracks micro-voids along the interface of the cement paste
and the aggregates. The deterioration process prevents a complete closure of
micro-cracks during unloading. As a consequence, permanent strainsdevelop. On the phenomenological level, this effect is often modeled bymeans of classical plasticity theory. Depending on the level of thehydrostatic stress, a rather gradual transition from highly localized fracture
under tension to distributed micro-structural deterioration leading to a rather
ductile material behavior when subjected to tri-axial compress is observed.
Continuum damage mechanics is concerned with the modeling of
micro-structural degradation processes on a phenomenological level. The
bulk of existing continuum damage approaches is concerned with isotropic
damage evolution, leading to a degradation of Young’s modulus as afunction of a scalar damage parameter by exploiting the notion of effective
stress. In contrast to the assumption of isotropy, the formation of cracks inconcrete induces a directional bias to the material properties. In theformulations based on the concept of micro-plane anisotropic damage isattributed to the reduction of the stress bearing area fraction, associated withthe respective micro-crack orientation.
In the literatures available, there are many constitutive models forconcrete such as Meschke et al (1997), Govindjee et al (1995) and others. In
this study, the concrete model used in the modeling of the building is ananisotropic brittle damage model developed by Govindjee et al (1995). Eachsteel rebar is modeled as a single layer of solid elements. The steel
reinforcement loops are also modeled in the same way. In order to simplify
the modeling, the diameters of the loops were enlarged while the Young’s
modulus of steel is reduced accordingly.

4.0 NUMERICAL RESULTS
The CONWEP loading is applied to the front surface of the column.
The side and back surfaces, which are the surfaces not directly exposed to
the loading front, are considered as free from loading. In this case, thenature of the blast loading may be slightly overestimated.

Approximation of Damage for a RC Column subjected to Intermediate Range Blast Loading279

October 2005, Singapore

The response of the column is then determined for the FE model withthe aid of the analytical software LS-DYNA (2003). The numerical resultsof the column response when subjected to a one-ton explosive at a 10 m
standoff distance are shown in Figure 2. The assumed fixed-end boundary
conditions would lead to induced column reaction forces at the supports
being larger than more flexible boundary conditions. However, the column
damage as determined based on the assumed fixed-end boundary conditions
while being an overestimate, provides engineering conservatism.
In reality, the loss of the supporting capacity of a column may occur in
two stages. The concrete material may first be partly damaged by the blast
loading directly. During the first stage (i.e. loading duration), the column
may still stand although it has been changed in terms of material status andgeometry with some percentage of supporting capacity left. During thesecond stage (i.e. ensuing duration), the gravity loading of the upper storeys
are activated, and the column may experience further material failure fromeither axial compression or column buckling. The second stage isconsidered to be a much slower process compared to the first stage. The
current analysis is concentrated on the first stage of the damage process (i.e.
loading duration).
The evolution process of the damages in the column is shown in
Figure 2. It is one half of the column. The surface with black dots is thesymmetrical plane. These dots are the intersections of the loops with thisplane. The plots in the left side of Figure 2 show the front surface and thesymmetrical plane, while those in the right side of Figure 2 show the backsurface and the symmetrical plane. The color map shows the damage levelof the concrete. It can be seen that the concrete is damaged first in thetensioned part of the column, making an arc-shaped damage zone. As thedeformed column springs back, the compression zone reverses its stressstate to that of tension, and thus becomes damaged. It is noted that thedamage model for the concrete material is directional. The damage in one
direction may not suggest the same level of damage in other directions. A
full damage function has not been currently defined and this requires further
research. Therefore, the assessment of the residual axial load resistantcapacity needs to be further investigated.

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Figure 2 Concrete cracking in the column

Approximation of Damage for a RC Column subjected to Intermediate Range Blast Loading281

October 2005, Singapore

5.0 CONCLUSIONS
The response of a RC column is computed by using aniostropic
concrete model. The damage level is evaluated based on the numericalresults. The blast loading considered is an intermediate range case of a oneton TNT equivalence at a 10 m standoff distance. For the RC column, theboundary conditions are assumed to be fixed at the supports, which provide
engineering conservatism. The focus of the numerical investigation is on thecolumn response during the loading duration. The numerical results showthat during the loading duration, the surface of the column subjected to blast
loading is in a state of compression as it deforms. As the column springs
back, the compression state of this column surface reverses its stress state totension, leading to material failure. Such a local material failure may
compromise the residual axial load capacity, whereby the extent requires
further investigation.

REFERENCES
Govindjee, S., Kay, G.J., and Simo J., 1995. Anisotropic Modeling andnumerical simulation of brittle damage in concrete. International
Journal for Numerical Methods in Engineering 38, 3611-3633.
LS-DYNA manual, 2003. LSTC
Meschke, G., Lackner, R., Mang, A., 1997. An isotropic elastoplastic
damage model for plan concrete. International Journal for Numerical
Methods in Engineering 42, 703-727.
U.S. Department of the Army. 1990. Structures to Resist the Effects ofAccidental Explosions. Army TM 5-1300. Navy NAVFAC P-397,
AFR 88-22. Washington, D.C.: Departments of the Army, Navy, and
Air Force.

282

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SEISMIC MICROZONATION OFSYLHET CITY
MEHEDI AHMED ANSARY AND MD.REZAUL ISLAM
Department of Civil Engg., BUET, Bangladesh
ansary@ce.buet.ac.bd

ABSTRACT
Seismic microzonation maps can play a significant role in mitigating
the consequences of earthquakes. Geographic information system (GIS)
provides an ideal environment for compiling and integrating regional
databases of spatial geologic and geotechnical information for developing
seismic microzonation. The main aim of this study is to develop seismic
microzonation map for Sylhet City based on reflection of ground shaking
and the secondary site attributes such as soil amplification, liquefaction andlandslide.
For microzonation purpose 167 boreholes with SPT data werecollected from different relevant organizations. To verify those data nine
boreholes up to a depth of 30m were carried out. Intensity values obtainedfor different events were calibrated against attenuation laws to check theapplicability for study area. Vibration characteristics at diverse points ofthe study area were estimated by employing one dimensional wave
propagation program SHAKE. The liquefaction resistance factor and theresulting liquefaction potential were estimated by a method suggested by
Seed et al. The program used for landslide hazard analysis is XSTABL,
which is a fully integrated slope stability analysis program, which evaluate
the factor of safety for a layered slope using the simplified Bishop Method.
The quantification of the secondary site effects and the weighting scheme for
combining the various seismic hazards is heuristic, based on judgment andexpert opinion. The final combined hazard is computed as a weighted sumof the various hazards.

1. INTRODUCTION
In accordance with chronological data, northeastern district, mostly,
Sylhet, Mymensingh and Rangpur, experienced earthquakes at regularintervals that have instigated bulky destruction in the earlier period. Seismic
hazard due to local site effects such as soil amplification, liquefaction, andlandslide can be anticipated by combining the available soil parameter datawith the current hazard models or by making use of existing maps showing
estimated levels of these collateral hazards. Regional seismic hazard andrisk analysis is used not only for estimation of potential damage and loss toexisting facilities, but also for planning locations and construction of futurefacilities and for analyzing and comparing the regional effects of various283

October 2005, Singapore

retrofit schemes. The GIS-based analysis is useful to engineers, planners,
emergency personnel, government officials, and anyone else who may beconcerned with the potential consequences of seismic activity in a given
region. The results of a regional seismic hazard and risk analysis are usuallypresented in the form of microzone maps that serve as an effective means ofconveying information from the scientific community to the professional
community of decision makers involved in hazard and risk mitigation.

2.

ADMINISTRATIVECORPORATIONBOUNDARYOF

SYLHET

CITY

Sylhet Municipality was established in 1878. During 1991, area of
Sylhet Municipality was 10.49 sq.km and other urban area was 43.92 sq.km.
Sylhet Municipality had 5 wards until 1991; in 1996 it had 13 wards.
Recently, the Municipality is upgraded to City Corporation with 27 Wards
and 210 Mahallas. Ward map was collected from Sylhet City Corporation
where total area was divided in to 13 wards .The Sylhet City Corporation
authority did not prepare an updated map. So it was decided to prepare an
updated ward map for this study. For this purpose, GPS value of different
fringes site and core sites of the study area were collected. The existing city
corporation map was scanned and converted into digital map. Using this
digital map and 2001 Mauza data as well as consultation with the Sylhet
City Corporation officials, a map containing 27 wards was developed. From
updated map it was found that existing area of municipality is 26.50 km2.
Figure 1 shows the updated ward map of Sylhet City Corporation
24.93°N

6
8
7
4

5
19

9

24.9°N

17

3

1

20
18
16

2

11
10

15

21

12
13

14
22

N

26

24

23

25
24.87°N
27

0

1.5

3

kilometers
91.83°E

91.86°E

91.89°E

91.92°E

Figure 1: Updated ward map of Sylhet City Corporation

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3. REGIONAL TECTONICS
In accordance with Molnar and Tapponnier (1975), for the past 40
million years the Indian subcontinent has been pushing northward against
the Eurasian plate at a rate of 5 cm/year, giving rise to the severest
earthquakes and most diverse land forms. Bilham et al. (2001) has pointed
out that there is high possibility that a large earthquake will occur aroundthe Himalayan region based on the difference between energy
accumulations in this region. There is a seismic gap that is accumulatingstress, and that a large earthquake may occur someday when the stress isrelieved. The major earthquakes that have affected Sylhet since the middleof the last century is presented in Table 1.
Table 1: Some historical earthquakes around Sylhet.
Nameof
Earthquake
1869
Cachar Earthquake
1885
BengalEarthquake
1897 Great Indian
Earthquake

Fault

Magnitude
7.5

EMS
Intensity
VIII

Distance(Km)
92

Focal Depth(Km)
56

TripuraBogura

7.0

V

234

72

Assam

8.1

IX

151

60

1918
Srimangal
Earthquake

SubDauki

7.6

IX

71

14

4. SOIL DATA
Necessary soil data was collected from different relevant sources of
Sylhet City and accumulated in Microsoft Excel. For assessment oflandslide potential Geological Map and Aerial Photograph is essential,
however; these are not available. A total of 167 boreholes with SPT data
were collected from different organizations and used to study site
amplification and soil liquefaction potential characteristics of municipality
area. Among these data, 9 boreholes with SPT-N data up to a depth of 100 ft.
were directly collected by BUET for checking the authenticity of othercollected data. The representative available boring is up to a depth of 50 ft.

5. LANDSLIDE ESTIMATION DATA
The eroded hills are mostly formed by the hill ranges and hillocks(locally called tila) appearing in the north east and south of Greater Sylhet
and surrounding the Sylhet town. These hill ranges attain a low elevationand have a gentle slope. Hillocks are scattered in Sylhet City. Hillocks offringe area have moderate slope and possess nice vegetation, so lessprobable of slope failure. In the core area, tilas possess slopes about rightangles due to rapid urbanization associated with hill cutting. These areas are
more vulnerable to landslide.

Seismic Microzonation of Sylhet City

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October 2005, Singapore

6. ASSESSMENT OF SEISMIC HAZARD
In the regional seismic loss estimation analysis it is considerednecessary to determine the bedrock motion in the region. The most common
method involves the use of an empirical attenuation relationship. These
relationships communicate a given ground motion parameter in a region asfunction of the size and location of an earthquake event. Applying statisticalregression analyses to recorded data, numerous relationships had beendeveloped in the past. Often these relationships are developed with different
functional forms and with different definitions of ground motion,
magnitude, distance, and site conditions. To pick the most apposite
attenuation law for predicting rock motions, 1885 Bengal earthquake, 1897
Great Indian earthquake and 1918 Srimangal earthquake are considered.
The requirements for selecting the attenuation law are as follows:(i)
Applicable to the ground condition of engineering bedrock in thisstudy (Vs=250m/s).
(ii)
Able to explain the observed or analyzed earthquake motion of 1885
Bengal earthquake, 1897 Great Indian Earthquake and 1918
Srimangal earthquake.
In this study, the engineering bedrock is assumed to be the layer atwhich the shear wave velocity (Vs) exceeds 250 m/s, which exist almost 30
m deep from the surface of the study area. In this study, shear wave velocity
is expected by using equation of Tamura and Yamazaki (2002). Distanceversus PGA values for earthquakes is plotted on log-log paper. From
isoseismal maps, the epicentral distances of different locations and theirintensities are found. These intensities are converted into PGA by Trifunac
and Brady (1975) equation (1) and were plotted on preceding figures.
log (PGA) =0.014 + 0.3 (MMI)(1)

From Figure 2, it is found that McGuire (1978) equations follow the
PGA trend of study area. Finally, 1918 Srimangal Earthquake as the
scenario event, PGA value 0.18g at bedrock level for study area wasselected.

7. SITE AMPLIFICATION ANALYSIS
It is well known that the surface ground motion of earthquakes isheavily influenced by the subsurface ground condition, especially in areas
covered by thick sediments. It is important to evaluate the difference insubsurface amplification site by site to know the distribution of earthquake
motion across a wide area. Vibration characteristics at different points of thestudy area were estimated by employing one dimensional wave propagation
program SHAKE. An estimation of the fundamental frequency and the
maximum value of the amplification are obtained at each site. Figure 3
shows the map of fundamental frequencies of Sylhet City. Figure 4 shows
map of amplification at fundamental frequencies of Sylhet City.

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ICUS Report 111000

1918 EQ, M=7.6, h=14 km

2

Acceleration (cm/s )

100

10

1
McGuireJoyner & Boore (1988)
Sadigh et al. (1986)
Boore et al. (1997); Vs=200m/s
Boore et al. (1997); Vs=300m/s
Boore et al. (1997); Vs=400m/s
From Intensity Estimation

0.1

0.01
10

100

1000

Figure 2: Distance versus PGA values based on different
attenuation laws for 1918 Srimangal Earthquake

8. LIQUEFACTION ANALYSIS
The ground water level changes with the season, namely the level is
low in the dry season and high in the rainy season. Based on the data on
ground water level by Bangladesh Water Development Board, thegroundwater distribution in the dry season and the rainy season was

N

Figure 3: Fundamental frequencies at Sylhet City

Seismic Microzonation of Sylhet City

287

October 2005, Singapore

N

Figure 4: Amplification at fundamental frequencies at Sylhet City
estimated. The FL method defines that ground water level to be considered
as less than 10m from the ground surface. The liquefaction resistance factor,
FL, for the top 20 m of soil, and the resulting liquefaction potential, PL forthe 167 sites were estimated. Result of Liquefaction potential was presented
in Figure 5 which shows that 3.35 Km2 area have low and very low
Liquefaction potential, 13.70 Km2 area have moderate liquefaction potential
and 10 Km2 area have high liquefaction potential. More than one thirds(37%) area will be affected rigorously by liquefaction if Srimongal
Earthquake (1918) occurs again with same magnitude and same epicentral
distance.

N

Figure 5: Map showing Microzonation based on liquefaction potential index

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9. LANDSLIDE POTENTIAL ANALYSIS
Most of the recent researches in this field have focused ondetermining the critical level of a given ground motion parameter that will
trigger landslide. The program used for stability analysis is XSTABL, which
is a fully integrated slope stability analysis program. XSTABL performs twodimensional limit equilibrium and analysis to evaluate the factor of safety
for a layered slope using the simplified Bishop Method. Based on the staticFS, the critical acceleration to begin the process of slope failure, ac, iscomputed as
ac =(FS-1) g sinθ
(2)
Where
θ = The slope angle
FS=the factor of safety determined from a static slope stability analysis
g= the acceleration of gravity
These ac values are judged against to the regional estimates of
surface peak ground acceleration to give a prediction for the incidence ofdamaging earthquake-induced landslides in the area. There have been very
few implementations of quantitative landslide hazard models in the GIS
environment instead, a qualitative approach utilizing regional maps showing
relative susceptibility of landslides in various geologic deposits will be used
to depicted earthquake-induced landslide hazard. Figure 6 shows landslide
potential in Sylhet City.

N

Figure 6: Map showing landslide potential in Sylhet City

Seismic Microzonation of Sylhet City

289

October 2005, Singapore

10.

INTEGRATION OF
ENVIRONMENTSITE

EFFECTS

IN

THE

GIS

Every analysis region is different; therefore the quantification of thesecondary site effects and the weighting scheme for combining the various
seismic hazards is heuristic, based on judgment and expert opinion about the
influence of local site conditions in the region and the exactness of theavailable geologic and geotechnical information. However countries like
Japan and the United States have long histories on instrumental seismicity
and numerous models have been projected there to correlate the various
hazard. However that is not the circumstances in Bangladesh. Heuristic
rules for quantification and combination were used which were developedby Stephanie and Kiremidjian (1994).
The bedrock-level ground shaking in the region was ascertained. The
shaking was depicted in terms of peak ground motion values. The regional
distribution of bedrock-level shaking was estimated as 0.18g. Bedrock level
PGA was measured as constant since the study area was relatively small. A
map showing the distribution of the surface-level ground shaking in theregion was developed first, which is, produced just simple multiplication of
the PGA at bedrock level with amplification factor shown in Figure 4.
It is decided that the final combined seismic hazard would bequantified in terms of Modified Marcelli Intensity (MMI). There are several
relationships for converting PGA to MMI. The equation used here isdeveloped by Trifunac and Brady (1975). The following heuristic rules areused to quantify the seismic hazard attributable to liquefaction:
For regions with liquefiable soils with high liquefaction potential
MMILIQ= MMIGS+2
For regions with liquefiable soils with moderate liquefaction potential
MMILIQ= MMIGS+1 and otherwise:
MMILIQ= 0
To quantify the seismic hazard due to landslide (MMILAN), the following
heuristic rules are used. For region designated as “high”
MMILAN = MMIGS +2
For region designated as “moderate”
MMILAN = MMIGS +1 and otherwise
MMILAN = 0
The rules for combining the assorted hazards are based on expert
opinion (after Stephanie and Kiremidjian, 1994) about the comparative
precision of the hazard information and the behavior of the local geology.
For this study, four potential combinations were considered and theirassumed weights are shown in Table 2. The final combined hazard (MMIF)
is computed as a weighted sum of the various hazards. By over-laying theregional maps for each hazard as shown in Figures 3 to 6 in GIS
environment, Sylhet City area is separated into 13 different affected areas.

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Figure 7 shows the regional distribution of the final combined seismic
hazard (MMIF).
Table 2: Quantification rules for seismic hazard (after Stephanie and Kiremidjian, 1994).
Rule Possible hazards
Weighting scheme for Final combined
hazard (MMIF)(a)Ground shaking
MMIF=MMIGS(b)Ground shaking + Liquefaction(c)Ground shaking+ Landslide(d)Ground shaking +Liquefaction+
Landslide

MMIF= .55 MMIGS + .45MMILIQ+. 5
MMIF=. 65 MMIGS + .35MMILAN+. 5
MMIF=. 40 MMIGS + .35 MMILIQ + .25
MMILAN +1

Notes:
1. MMIF= Final Combined Hazard
2. MMIGS= Ground Shaking Hazard
3. MMILIQ=Liquefaction Hazard

N

Figure 7: Map showing regional distribution of combined seismic peakground acceleration in Sylhet City
11.

CONCLUSIONS

Geographic information system is used to carry out regional seismic
microzonation for Sylhet city where reflection of ground shaking and thesecondary site attributes of soil amplification, liquefaction and landslide areincluded. The method to combine the different hazards is based on aweighted average approach. The GIS-based analysis is useful to engineers,planners, emergency personnel, government officials, and anyone else who
may be concerned with the potential consequences of seismic activity in agiven region. The results of this study are presented in the form ofSeismic Microzonation of Sylhet City

291

October 2005, Singapore

microzone maps that serve as an effective means of transferring informationfrom the scientific community to the professional community of decision
makers involved in hazard and risk mitigation.
REFERENCES
Bolt, B. A., 1987. Site-specific study of seismic intensity and ground motion
parameters for proposed Jamuna river bridge, Bangladesh. Report on
Jamuna bridge study.
Boore, D., Joyner, W. and Fumal, T. E., 1997. Equation for estimating
horizontal response spectra and peak acceleration from Western North
American Earthquakes: A summary of recent work. SeismologicalResearch Letter, Volume 68, No. 1, pp. 128-153.
Grunthal, G., 1998. European Macro Seismic Scale. Luxembourg: Cahiers
due Center European de Geodynamics et de Seismology, Volume 15.
McGuire, R., 1978. Seismic ground motion parameters relations. Journal of
Geotechnical Division, ASCE, Volume 104, pp. 461 – 490.
Islam, M. R., 2005. Seismic Loss Estimation for Sylhet City. M.Sc Engg.
Thesis, Dept of Civil Engineering, BUET, Dhaka
Molnar, P. and Tapponier, P., 1975. Cenozoic tectonics of Asia, effects of acontinental collision. Science, Volume 189(8), pp. 419-426.
Oldham, R. D., 1899. Report on the Srimangal Earthquake of 12th June 1918.
Memoir of Geological Survey of India, Volume 29, pp. 1-349.
Rodríguez, C. E., Bommer, J. J. and Chandler, R. J., 1999. Earthquakeinduced landslides: 1980–1997. Soil Dynamics and Earthquake
Engineering, Volume 18, pp. 325–346.
King, S. A. and Kiremidjian, A. S., 1994. Regional Seismic Hazard and
Risk Analysis through Geographic Information System. PhD Thesis,
Stanford University.
Seed, H. B., Idriss, I. M. and Arango, I., 1983. Evaluation of liquefaction
potential using field performance data. Journal of GeotechnicalEngineering Division, ASCE, Volume 109, No. 3, pp. 458-482.
Sharfuddin, M., 2001. Earthquake Hazard Analysis for Bangladesh. M.Sc.
Engg. Thesis, BUET, Dhaka.
Tamura, I. and Yamazaki, F., 2002. Estimation of S-wave velocity based on
geological survey data for K-NET and Yokohama seismometer
network. Journal of Structural Mechanics and Earthquake
Engineering, No. 696, Vol. I-58, 237-248 (in Japanese).
Trifunac, M. D. and Brady, A. G., 1975. A study of the duration of strong
earthquake ground motions. Bulletin of Seismological Society ofAmerica, Volume 65, pp. 581-626.

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New Technologies for Urban Safety of Mega Cities in Asia

DUCTALO- AN ULTRA-HIGH
PERFORMANCE MATERIAL FOR
RESISTANCE TO BLASTSBRIAN CAVILLVSL Australia Pty Ltd, Sydney, NSW, Australia
bcavill@vslsyd .aust.com
ABSTRACTReactive Powder Concrete (RPC) is a cementitious material
consisting of cement, sand, silica fume, silica flour, superplastiser, waterand high strength steel fibres. The material was developed by Bouygues, theparent company of TjSL, and is marketed under the brand name of Ductal°.
Production in Australia commenced in early 2003.
Ductal is almost selfplacing, has a compressive strength of 150-200
MPa and a flexural strength of 30-40 MPa. In structural applications,Ductal is generally used without any passive reinforcement. Very fine highstrength steel fibres are able to withstand secondary tensile stresses .
Prestressing counterbalances the main tensile stresses due to bending.
The durability properties of Ductal and its resistance to aggressive
agents are orders of magnitude better than conventional high performance
concrete . The design life in a marine environment exceeds 500 years.
The unique characteristics of Ductal, including exceptionally highenergy absorption capacity and resistance to ftagmentation, make it an
ideal material for panels and components that may be affected by
explosives, impact or shock loads. The flexural toughness is greater than
200 times that of conventional fibre reinforced concrete. In May 2004 a
total of 7 Ductal panels were tested in two large explosive trials performedat Woomera in South Australia. The panels performed remarkably well,showing extremely high ductility and no fragmentation.
Ductal blast resistant panels have demonstrated very high resistanceto the impact caused by blast produced fragments. In simulated fragment
projectile tests 100mm thick Ductal panels have easily withstood impacts
with energy equivalent to double that produced by mortar fragments.
In June 2005 the first Ductal panels manufactured to provide
resistance to blast were supplied to the Australian Government andinstalled on an Australian Government building in a hazardous
international location .
This paper will give a summary of the properties of Ductal, and provide
details on the blast testing and projectile impact testing carried out on
Ductal panels .

Ductal -An Ultra-High Performance Material for Resistance to Blasts

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October 2005, Singapore
1. PROPERTIES OF DUCTAL FOR DESIGN
Production of Ductal commenced in Australia in January 2003 . The
development and testing of the production mix used were performed at the
University of New South Wales (UNSW), and are reported in detail in
Reference 2.
Table 1 lists the properties of Ductal used in design . Figure l, showsa typical stress-strain response of a compression test with 100mm diameterby 200mm long cylinders and the stress-deflection response for a typicalfour-point flexure test with 100x 100x500mm prisms .
Table I. Design Properties
Property

Standard

Fluidityy

ASTM C230

Compressive strength
Flexural Tension
Modulus of Rupture
Flexural Tension
First cracking
Modulus of Elasticity

AS 1012.9

Heat TreatedDuctal°Between 190 and
250mm after 20 drops
fc .min =160 MPa

AS 1012.11,fcfmin = 24 MPa

AS 1012.11

fct.min = 20 MPa

AS 1012.17

47 GPa< 500 Vt strain after
56 days
0 after heat treatment
2,450 kg/m'

ShrinkageDensity

AS 1012.13

Table 2 . Durability Properties
Ductal U compared to
Durability Indicator
Value
High Performance
Concrete
Total porosity
2-6%
114 to 115 of HPC
Microporosity (>10gm)< 1%
1/10 to 1/30 of HPC
Permeability (air)1150 of HPC
2 .5x10-18 m2
Water absorption< 0.2 kg/m`
1150 of HPC
Chloride ions diffusion
1150 of HPC
0.02x 10-12 m2/s
Electrical resistance (excl.
12to
17 times HPC
1 .13 x 103 kQ.cm
fibre) Electrical resistance
1 .5 to 2 times HPC
137 kQ.cm(incl. fibre)
Abrasion resistance
1 .3
2 to 3 times HPC
coefficient
Fatigue, impact and blast
Far superior to HPC
resistanceHeat treatment consists of curing in steam at a temperature of 90°C
for a period of 48 hours after demoulding . This results in rapid strength gain
and substantially reduced creep, and causes almost all the shrinkage to occur
during the period of the heat treatment. The strength of heat treated Ductal is294

New Technologies for Urban Safety ofMega Cities in Asia

ICUS Report 11
15% greater than non-heat treated, and durability properties are also
improved . The use of heat treatment is optional and depends on theapplication. Table 2 lists the durability properties of Ductal in generalcompared with high performance concrete. The extremely high resistance tothe penetration of aggressive agents, due to the absence of capillaryporosity, corresponds to excellent durability characteristics.

20

0
0

3

5

8

10

Compression strain [10-6 ]

13

0

2

4

6

8

Deflection [mm]Figure 1 : Typical force deformation responseof Ductal ° in compression andflexure (tension)
While the ultra-high strength of Ductal puts it outside the direct
provisions of national design standards, a Design Guide has been preparedby UNSW to be in accordance with the intent of the Australian standards.
This Guide is based on extensive testing in France and at the University of
New South Wales. Details are given in Reference l .
A prestressed beam or slab made from Ductal has between 35-45%of the volume of a conventional prestressed beam or slab . The depth isapproximately the same as a conventional prestressed member in order toproved stiffness for deflection control.
Flexural strength for large span beams and slabs is achieved throughprestressing in combination with the high compressive strength of Ductal .
Short span beams and slabs generally need no reinforcement. Shear strengthis provided by the tensile strength of Ductal . No additional shear
reinforcement is required. The compression stresses due to the prestress add
to the material tensile strength to counter the principal tensile stresses.
Ductal is basically selfplacing. External vibration is used to give thefinal compaction . The plant for the mixing of Ductal in Australia and theforms for the precasting were initially set-up at the University of NSW in
Sydney and were relocated to the VSL factory in Melbourne in January
2 004
Ductal has been used worldwide to manufacture precast elements forvery thin (20mm) fascia panels, sound absorption panels, pedestrian bridges
with spans up to 120m and other innovative architectural and structural
applications .
2. PROTECTIVE PANELS RESEARCH & DEVELOPMENT
Concrete panels (slabs and walls) are very important in protecting
buildings against the extreme loading conditions caused by blast, shock andDuctal - An Ultra-High Performance Material for Resistance to Blasts295

October 2005, Singapore
impact. The high energy absorption capacity of Ductal was known fromstatic strength tests, however the performance of Ductal elements under
severe impulsive loading had not been investigated . The flexural toughness
measured as the area under the flexural stress/strain curve (Figure 1) isgreater than 200 times that of conventional fibre reinforced concrete.
2.1 Blast Testing at Woomera, May 2004
In a joint project between VSL Australia Pty Ltd and the Advanced
Protective Technologies for Engineering Structures (APTES), University of
Melbourne, Ductal panels were tested under extreme explosions at blast
trials performed at Woomera in South Australia in May 2004. The
Woomera trial had two separate blasts equivalent to six (6) tonnes of TNT.
Each detonation consisted of a bare charge of 5 Tonnes of Hexolite RDX/TNT (60 :40) .
A total of seven Ductal panels were tested located at 30m, 40m and
50m from the blast. The panels had a span of 2m and were lm wide, with athickness of 50mm, 75mm and 100mm. Five of the panels contained pretensioning strands and the other two were unreinforced .
The test data and observations showed that the panels performed
remarkably well, with extremely high ductility and no fragmentation. The
stressed panels were able to absorb substantial energy through their ability
to sustain considerable deflection up to span/28 without fracture . The factthat the Ductal panels displayed no fragmentation in any of the tests, even at
fracture, is a major advantage compared to conventional concrete.
Fragmentation poses great danger to both people and infrastructure . Table 3
lists the main observations together with the calculated reflective blastpressures Wca1c) .
Table 3 . Main observations
Panel type
Main observations
D ~ pcalc
Virtually undamaged, no permanentStressed 100mm
30m 2000
deflection, no fragmentation .
Basically undamaged, no
Stressed 100mm
40m 800 permanent deflection, nofragmentation.
Intact, cracked with smallStressed 75mm
40m 800 permanent deflection, nofragmentation.
Intact, shallow crack, no permanentStressed 50mm
50m 420
deflection, no fragmentation .
Unreinforced 50mm 50m 420 Fractured, no fragmentation
Stressed 75mm
30m 2000 Fractured, no fragmentation
Unreinforced
40m 800 Fractured no fragmentation
l00mm
The series of photos in Figure 2 show ; a typical 2 x Im panel being
installed into a concrete test frame; the test panels before a blast; one of thetwo blasts ; the crater caused by a blast and two of the panels after being
subjected to extreme blast loading.

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The IOOmm thick stressed panel at D = 30m after the blast is shownin Figure 2 bottom left. The panel had deflected inwards 50mm, thenoutwards 37mm and come to rest with no permanent deflection. The panel
was basically undamaged. The 50mm thick stressed panel at D = 50m after
the blast, also shown in Figure 2 (bottom right), withstood significant
deflection and had no permanent deflection. The panel was basically intact,and had a shallow crack on the front face .

Installing panels into concrete
framesPanels ready for blast

Blast, equivalent to 6t of TNT

Crater caused by the blast

IOOmm panel at D=30m after the
SOmm panel at D=50m after the
blast; undamaged
blast, shallow crack, no spalling or
The blast resulted in an average
fragmentationreflected impulse at the panel
surface of 3771 kPa.msec with areflected pressure of 1513 kPa.
Figure 2 : Protective panel tests, Woomera 2004

Ductal -An Ultra-High Performance Material for Resistance to Blasts297

October 2005, Singapore
2.2 Constitutive Model for Ductal at High Loading Rates
The response of concrete to very high strain rates need to be known
in order to properly design structures subjected to blast or impact effects. At
these high strain rates, the strength of concrete can increase significantly.
The response for Ductal was determined by a series of impact tests carriedout using the Split Hopkinson Pressure bar (SHPB) setup on large-diameter
test cylinders. A range of loading rates and hydrostatic pressures were used .
Fig. 3 shows the stress-strain curves at different strain rates of 50mm
diameter RPC (Ductal) cylinders. It can be seen that the compressive
strength increases up to 1 .5 times at the strain rate of about 267.4/sec . This
corresponds to a strength Dynamic Increase Factor (DIF) of 1 .5 . Table 4summarises the test results of 3 RPC specimens. It was found that RPC isless rate sensitive compared to both NSC and HSC (Ngo 2005).

a
N
N
d
L

N

0.002

0.001

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0.02

StrainFig. 3 - Stress-strain curves ofRPC (Ductal) at
different strain-rates

04

=

was
Static
Test
RPC-1
RPC-2
RPC-3

-

-

159 .8

-

11 .6
16
20

80.7
187 .3267.4

187.2
226 .1240 .9

1 .17
1 .41
1 .5

Table 4
Dynamic Compressive Strength ofRPC (Ductal)
Based on the results of the experimental program using the Hopkinson Bar
apparatus and through a rigorous calibration process, a new strain-rate
dependent constitutive model has been proposed for concrete under dynamic

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load. The model can take into account the strain-rate effect by incorporating
multiplying factors for increases in the peak stress and strain at peakstrength . This model is applicable to concrete strengths varying from 32
MPa to 160MPa with a strain rate up to 300 s-1 . A detailed report is given in
Reference 4.
The results of the trials demonstrated the suitability of Ductal for
blast resistance and confirmed the design methods. The uniquecharacteristics of Ductal, including exceptionally high energy absorption
capacity and resistance to fragmentation, make it an ideal material for panels
and components that may be affected by explosives, impact or shock loads.
2 .3 Fragment Impact Simulation Tests
On June 9, 2005, two 100mm thick Ductal blast resistant panel
pieces were subjected to simulated fragment projectile (SFP) loading. Tests
were carried out at a NATA approved projectile testing lab in Melbourne.
Test pieces were sourced from the production of high-performance blast
resistant Ductal panels . The pieces had a thickness of 100mm and were
reinforced with high strength steel strands. They were cut from a single
larger panel . In accordance with Australian Standard AS 2343 (1997), alltest pieces had a plan dimension of 420 x 420mm.
During production of the project panels, Ductal cylinders and prism
were tested and strength results of approximately 170 MPa in compression
and 30 MPa in tension (flexural) recorded.
Testing procedure followed AS 2343 and consisted of firing
projectiles at the target piece with an intended speed. Each test piece wasmounted in a frame and a witness (paper) card was placed behind it torecord fragmentation impacts. The test was considered to be passed if nofragment penetrated through the witness card .
Two types of steel projectiles were used, 50 caliber (13mm
diameter) and 20mm diameter . The projectiles were fired at the test panelswith different target speeds . The projectiles are shown in Figure 4 .

13mm diaFigure 420mm dia

50 caliber SFP and 20mm SFP, before and after impact

The tests were the first of their type to be undertaken using Ductal highperformance blast protection panels . The results of these simulated fragment
projectile tests show that a specifically designed 100mm thick Ductal blast
resistant panel will withstand a 50 caliber SFP at speeds up to 1164m/s and20mm SFP up to 821 m/s without fragmentation on the non-impact side.
The test pieces after impact are shown in Figure 5 and the details are given
in Table 5.

Ductal -An Ultra-High Performance Material for Resistance to Blasts299

October 2005, Singapore

Panel 1, with impacts from SO
Panel 2, with impact from 20mm
caliber SFP at 715 m/s and 1164
SFP at 821 m/s. The crater has am/s.
depth of25mm
Figure S : Test pieces after impact

Panel 1
50 Caliber
SFP at 715 m/s
Panel 1
50 Caliber
SFP at 1164 m/s
Panel 220mm
SFP at 821 m/s

Table 5 . Observations- SFP did not cause spalling of the panel on the nonimpact face
- No micro cracking observed behind impact
Panel passed impact test successfully- SFP did not cause spalling of the panel on the nonimpact facem Micro cracking observed behind impact
m Impact crater larger diameter and depth than in shot 1
Panel passed impact test successfully- SFP did not cause spalling of the panel on the nonimpact facem Cracking observed behind impact but no spalling
Panel passed impact test successfully

In comparison with standard mortar fragments the results compare
favourably with impact data for 81mm Mortar, general purpose (GP) andUS 4.2 inch Mortar fragments. The impact of the projectiles that caused no
spalling on the non-impact face and repelled the fragment (20mm at
821m/s), are at least a magnitude of almost two greater than the impact data
for the mortars. Refer to Table 6. The results clearly show the effectivenessof Ductal panels of 100mm thickness, against mortar and similar blast
produced fragments .

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Table 6 : Projectile (SFP)

Projectile
81 mm mortar
US 4.2 inchmortar
81 mm GPmortar
50 caliber SFP
20mm SFP

Weight
grams
grams
1 .9
30

Velocityfee /s
m/s
6338
1932

Impact Energy
f .lbs
k
2675
3 .63

96

6 .2

5551

1692

6703

9.10

435

28 .2

9091

2772

7887

10 .69

207
830

13 .4
53 .8

3815
2693

1164
821

6693
13363

9.07
18 .12

2.4 Close Charge Tests
In July 2005 two Ductal panels were tested with close charges of
TNT. All the panels had a plan dimension of 1 m x I m. One panel was
100mm thick and the other was 150mm thick.
The panels were
manufactured at the VSL Ductal factory in Melbourne. The tests were
performed at a laboratory in England .
All panels were reinforced with high strength steel strands. The
100mm panel was subjected to a 3kg blast at l .Om and the 150mm thickpanel had a 3kg blast at 0.5m from the face of the panel.
The two panels performed very well under the very severe loadingwith only minor hairline cracks appearing on the back face .
2.5 Ballistic Tests
In September 2005 three 100mm thick Ductal panels were tested forresistance to attack by NATO standard 7.62/9.3g full metal case bullets.
The tests were performed in accordance with AS/NZS 2343 : 1997.
All panels easily passed the test and achieved an R2 rating
3. FIRST PROJECT
Panels for the first structure to utilise Ductal to provide resistance toblasts were manufactured in March/April 2005 at the VSL plant in
Melbourne. The client was the Department of Foreign Affairs and Trade of
the Australian Government .
The panels are up to 4.5m long x 2 .Om wide x 100mm thick. They
are being used to provide blast resistance to an existing building in a very
hazardous international location . The panels were installed on site in July .
Photos of the panels prior to shipment from the VSL factory are
shown in Figure 6. Photos of the installed panels are not available forpublication due to security reasons.

Ductal -An Ultra-High Performance Material for Resistance to Blasts301

October 2005, Singapore

Precast Ductar blast resistant
The panels are typically 3.4m long
panels at the factory in Melbourne,
x 2.Om wide x IOOmm thick.
prior to shipment to site.
Figure 6
4. CONCLUSIONS
Ductal is a unique material. The ultra high strength enables structuraland architectural products to be lighter, thinner and stronger thanconventional . The extremely high durability gives it a design life inaggressive environments that can be measured in hundreds of years.
The exceptionally high energy absorption capacity and resistance tofragmentation, make it an ideal material for panels and components that may
be affected by explosives, impact or shock loads.
The tests have confirmed that Ductal is a very effective material for
blast resistance. Panels can be much thinner than those made fromconventional concrete, and the risk of injury or damage caused by concrete
debris is eliminated or minimised .
REFERENCES
I.Gilbert, N. Gowripalan and B . Cavill, "On the Design of Precast,
Prestressed Reactive Powder Concrete (Ductaf) Girders", Austroads
4th Bridge Conference, Adelaide, November 2000.
N. Gowripalan, R.Watters, I. Gilbert and B .Cavill, "Reactive Powder
Concrete (Ductal") for Precast Structural Concrete - Research andDevelopment in Australia", 21st Biennial Conference of the CIA,
Brisbane, July 2003.
B. Cavill and G.Chirgwin, "The World's First RPC (Ductal") Road Bridgeat Shepherds Creek, NSW", Austroads 5th Bridge Conference,
Hobart, May 2004.
T. Ngo, P . Mendis, N. Lam and B. Cavill, "Performance of Ultra-High
Strength Concrete Panels subjected to Blast Loading", The 2005
Science,EngineeringandTechnology
Summit,Canberra, July 2005

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OPTIMAL ASEISMIC PERFORMANCE OF
BUILDINGS WITH FRICTION DAMPERSSANJAYA KUMAR PATRO and RAVI SINHA
Department of Civil Engineering
Indian Institute of Technology Bombay, India
sanjay@civil.iitb.ac.in, rsinha@civil.iitb.ac.in

ABSTRACTFriction-based passive energy dissipation devices (or dampers) are
known to be very effective for controlling the seismic response of multistory
buildings. These devices can be used for the design of new buildings as wellas to retrofit existing buildings. The locations and properties of friction
devices are typically decided based on numerical modeling wherein thesliding friction is modeled with Coulomb friction having a constantcoefficient of friction. However, the basic laws for sliding materials andexperimental investigations show strongly non-linear relationship between
friction and sliding velocity, which includes stiction and Stribeck effects.
These effects may be significant and can not be ignored while simulating theseismic response of structures with friction-based dampers.
This paper analytically investigates the optimal seismic performanceof frame buildings with friction-based energy dissipation devices. Nonlinear
response-history analysis has been carried out considering realistic sliding
friction models. The performance has been evaluated using several different
response parameters. Different performance indices have been used toevaluate the performance of the building due to different earthquake groundmotions. The results show that the conventional approach may significantly
overestimate the performance of friction dampers. It is also concluded that
optimal design of dampers can only be carried out using comprehensive
friction models.
1. INTRODUCTION
In recent years, significant efforts have been undertaken to develop the useof energy dissipation or supplemental damping for aseismic design ofbuildings. A number of these devices have been installed in buildings
throughout world (Constantinou et al., 1998). The presence of the energy
dissipation devices can dissipate a significant proportion of the input seismicenergy during building motion, thereby reducing the energy that needs to bedissipated by the structure through inelastic deformations. Among theenergy dissipation devices, friction devices have proved to be very efficient303

October 2005, Singapore

in dissipating larger amount of energy than the other methods that involve
yielding of steel plates, viscoelastic materials and viscous materials.
The dependence of friction coefficient on slip velocity, normal load,and history of motion has received considerable attention in the recent past(Armstrong-Helouvry, 1991; Feeny et al., 1998; and Berger, 2002). Theseand other investigations show that the coefficient of friction at stick stage ishigher than the coefficient of friction at sliding stage, which leads to stickslip and Stribeck effect or other unstable oscillations in the response
behavior of structures. However, the prevalent practice to determine thelocation of friction devices and the optimal slip load within building frame
are based on Coulomb friction model. The stiction and Stribeck effects maylead to significant changes in their design parameters.
In this paper, the response of generalized MDOF frame building withfriction device when subjected to various earthquake excitations has been
considered. The paper discusses the following aspects: (i) Performanceindices considering different response parameters, (ii) Optimal slip-loadcorresponding to each performance index, and (iii) Importance of stick-slip
and Stribeck effects.
2. DRY FRICTION MODELS
The following two models have been considered in the investigation of
response behavior of frame structure with friction device (Fig. 1), where F isthe friction force and u& is the relative velocity.
F

F
Fs
Fd

Fd

u&

(a)

u&

(b)

Figure 1: Dry friction models
2.1 Coulomb Friction Model (Model FM1)
This is the most frequently used model, proposed over 200 years ago
and is represented in Fig. 1(a). In this model, the coefficient of friction
remains constant and the friction force is expressed as
F = µ FN sgn(u& )

304

(1)

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where FN is the normal load (controllable prestressing force) on the sliding
surface, F is the frictional resistance that is same for both stick and sliding
stages, µ is the coefficient of sliding friction, u& is relative sliding velocity,and sgn( u& ) is the signum function that assumes a value of +1 for positive
sliding velocity and –1 for negative sliding velocity.
2.2 Comprehensive Friction Model (Model FM2)
It has been observed through various experimental studies that friction
force does not remain constant throughout the sliding phase. The frictional
resistance on dry surface, modeled with reference to experimental andtheoretical investigation by Wang and Shieh, (1991) shows that the friction
force during sliding, F, obeys the following exponential law:
 u&  
F =  Fd + ( Fs − Fd ) exp  −  sgn(u& )

&
u
s



F =µ Fdd N
F = µ Fss N

(2)The empirical parameter u& s is known as Stribeck velocity. The Stribeck
velocity depends on response memory (history of response), material
properties and surface finish.
Friction Device
ud3(t)

uf3(t)Beam

Beam(Slotted plate
welded tocenter line ofbeam soffit)(Section ofslot bolted
connection)

uf2(t)
ud2(t)
uf1(t)
ud1(t)
Brace
u&&g

Free Framea) Example Structureb) Details of Energy
Dissipator

Figure 2: Schematic diagram of three-story frame structure with friction
dissipater (Levy et al. (2001))
3. MATHEMATICAL FORMULATION
The mathematical formulation of multi-degree-of-freedom (MDOF) braced
frame structure with friction slider on the top of chevron brace system
shown in Fig. 2 has been presented below. The dynamic model of the

Optimal Aseismic Performance of Buildings with Friction Dampers

305October 2005, Singapore

structure is considered as a symmetric two dimensional (2-D) shear
building. In this formulation structure without brace is denoted as free frame
structure (subscript f) and brace along with device is denoted as dissipatersystem (subscript d). Two lumped mass models, one for free frame structure
and another with dissipater system represent the dynamic behavior of thestructure. Two degrees-of-freedom per floor, corresponding to the horizontal
displacement of the floor mass in the direction of excitation and thedissipater system, respectively, have been shown in Fig. 2(a). The sliding
plate of the dissipater system is welded to the centerline of beam soffit in thevertical plane as shown in Fig. 2(b). The sliding plate having slotted holes issandwiched between two clamping plates. Clamping plates are connected tothe sliding plate through prestressing bolts. The prestressing bolts fixed in
the slotted holes provide normal force to the sliding system, and thearrangement ensures that the normal force is relatively independent of thebeam loads.
The motion of the structure consists of two phases: (1) non-sliding or
stick phase when the stick frictional resistance ( Fst ) between structure anddevice is not overcome, and (2) sliding or slip phase in which sliding
frictional resistance ( Fsl ) opposite to the relative velocity between floor anddissipater activates. This will activate when the relative motion across thesliding surface takes place. The overall response consists of a series of nonsliding and sliding phases on each story. Through the entire solution
process, the equations of motion are split in two subsets with sub-indexes st(stick phase/ non-sliding phase) and sl (sliding phase). The number of active
degree of freedom ranges between Nf (number of floors) and Nf + Nd
(number of floors + number of dissipaters). If the total number of nonsliding floors are called nst and total number of sliding floors nsl, thus at any
instant Nf = nst+nsl. If the dissipaters are placed on all the floors, the total
degrees of freedom will be 2Nf. The generalized governing equation of
motion in matrix form for 2Nf degree of freedom can be given as:&& st + sl + Cu& st + sl + Ku st + sl = −Mru&&g − F f + sl
Mu

(3)&& f , st = u&& d , st , u& f , st = u& d , st , and u f , st − u d , st = constant
u

(4)

where

and the matrices are given as:
C f + C d 2 Cd 3 K f + K d 2 K d 3 M f 0 
,
=
M=
K


,
, C = TT
Md 
Cd 1 
K d 1 0 (Cd 3 )(K d 3 )(5)
u f , st + sl r f + F f + sl u st + sl = , r =  , F =  , r f = 1, rd = 1
u d , st + sl −F f + sl rd 
in which

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 cd 1 0 0 
 cd 2 0 0 − cd 2 0 
0






Cd 1 =  0 O 0  , Cd 2 = 0 cdNd 0  , Cd 3 =  0 0 − cdNd  , 0 0 cdN 
0 0
0 0
0 
0 
d 



(6)
 kd 1 0 kd 2 0 0 − kd 2 0 
0 
0






K d 1 = 0 O 0  , K d 2 = 0 kdNd 0  , K d 3 =  0 0 − kdNd 0 0 kdN 
0 0
0 0
0 
0 
d 



In the above equations, M f , C f , and K f are the Nf ×Nf mass, damping
and stiffness matrices of the free frame structure excluding the bracing
members, M d , Cd 1 , Cd 2 , Cd 3 , K d 1 , K d 2 and K d 3 are Nd ×Nd mass,
damping and stiffness matrices of the dissipaters, r is the force influence
vector of structure with dissipater, and u&&g is the ground acceleration. M d is
Nd ×Nd diagonal mass matrix of dissipaters. The degrees of freedom are therelative horizontal displacement of the each floors ( u f ) and relative
horizontal displacement of each dissipater ( ud ) with respect to the base. The
over dots represent derivative with respect to time.
In Eq. (3) stick or non-sliding phase ensures that the friction forces
satisfy the equation,

Ff ,st < Fst(7)where,
Ff ,st = M f ,st u f ,st + sl + M f ,st r f u&&g + (C f ,st + Cd 2,st )u& f ,st + sl
+Cd 3,st u& d ,st + sl + ( K f ,st + K d 2,st )u f ,st + sl + K d 3,st u d ,st + sl

(8)

and Ff ,st is the unbalanced frictional resistance vector at stick stage. Whenthe inequality in the above Eq. (7) is not satisfied for any dissipater, thatdissipater enters into the sliding phase. Then subscript sl activates in thecorresponding sliding degree-of-freedom at the floor level.
The maximum frictional resistance at stick stage ( Fst ) and frictional
resistance at sliding stage ( Fsl ) for different friction models are given in Eq.
(1) and Eq. (2). The direction of sliding is governed by the signum function
and can be expressed as:sgn( u& f − u& d ) = −Ff ,st ,max
Ff ,st ,max

(9)

Before the application of base excitation, the structure is at rest.
Therefore, the response of the structure always starts in stick phase. This
phase of response continues until the unbalanced frictional resistance

Optimal Aseismic Performance of Buildings with Friction Dampers

307October 2005, Singapore

exceeds the maximum frictional resistance at stick stage at the corresponding degree of freedom level. It is important to note that the degrees of
freedom nst and nsl belonging to the sticking and sliding conditions at eachfloor vary continuously through the motion. When the relative sliding
velocity ( u& f − u& d ) during motion becomes zero or changes its sign, then the
structure may enter to stick phase/non-sliding phase corresponding to thatdissipater level. It may reverse its direction of sliding or have a momentary
halt and continue in the same direction. The status of motion duringtransition phase can be evaluated by checking the validity of Eq. (7) andthen solving the appropriate equations of stick (subscript st) or sliding(subscript sl) during the next time-step.

4. PERFORMANCE INDICES
The response of a MDOF building includes a large number of
response quantities. In order to evaluate the optimal performance of thebuildings with energy dissipaters, the three indices given below have evaluated. The maximum response from all floors has been considered for theirevaluation. The response quantities are normalized with respect to thecorresponding maximum response of the free frame and the braced frame
for the same base excitation. The index value close to zero indicatesexcellent performance of the energy dissipater while values close to 1
indicate ineffectiveness of the system.
(i) Drift and acceleration ratio (DAR): This ratio has been defined as(Moreschi, 2000),

 Max. storey drift of str with device Max story drift of free or (braced) frame 1 (10)DARF or ( DARB) = Max. Abs. Acc. of str with device2
 + Max. Abs. Acc. of free or (braced) frame It is noted that this information gives equal weight to the deformation andacceleration related responses. If required then different weights can also be
assigned.
(ii) Base shear ratio (BSR): This ratio has been defined as
BSRF or ( BSRB) =Max shear of the frame str with dissipator(11)
Max base shear of the free or (braced) frame str(iii) Relative performance index (RPI): This ratio has been defined as(Filiatrault and Cherry, 1990),
RPIF or ( RPIB) =

308


SEA
SEM
1
+


2  ASEF or ( ASEB) SEMF or ( SEMB ) (12)

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ICUS Report 11

where SEA = strain energy area, is the area under the strain-energy time
history for the system with dissipaters, ASEF = strain energy area for freeframe structure, ASEB = strain energy area for braced frame structure,
SEM = maximum strain energy for the system with dissipaters, SEMF =maximum strain energy for the free frame, and SEMB = maximum strainenergy for the braced frame. If RPIF or RPIB is close to 1, then the response
corresponds to the behaviour of a free or braced frame structure,
respectively. If RPIF or RPIB < 1, the response of the system with
dissipaters is smaller than the response of free or braced frame structure.
5. BEHAVIOR OF EXAMPLE BUILDING
5.1 Description of example structure

A three story steel frame (Fig. 2(a)) structure with friction-based
supplemental system has been considered for evaluating the optimal
performance. The structural damping ratios of free-frame and of the brace
are taken as 2% and 0%, respectively. The structure has the following
properties (Levy et al. 2001):
Story mass: m f 1 = m f 2 = m f 3 = 200.4 kg ,Story stiffness: k f 1 = k f 2 = k f 3 = 11946.6 N/m ,Dissipater mass: md 1 = md 2 = md 3 = 0.1kg ,Dissipater stiffness: kd 1 = 80623.0 N/m, kd 2 = 64192.0 N/m,
kd 3 = 37234.0 N/m .
The coefficient of friction has been considered for steel on steel slider(slideaway) in accordance with Bilkay and Anlagan (2004). Based to theirinvestigation the following friction parameters have considered: Minimum
coefficient of sliding friction (sliding stage, µd ) = 0.16, Maximum coefficient of sliding friction (stick stage, µs ) = 0.29, and Stribeck velocity vs =0.025 m/s.
In this investigation, the time-history responses of the example
structure have been evaluated for an ensemble of nine earthquake records(Patro, 2005). The ground motions chosen in this study cover a wide varietyof earthquakes having different peak ground accelerations (PGA), frequency
content and duration. Three time histories have been selected for each ofsoft soil (FSR), alluvium soil (FMR) and hard soil (LHR).
5.2 Optimum prestressing force

The performance indices discussed above have been evaluated for theselected ensemble of time history. The performance indices have beennormalized with the maximum corresponding response of free frame (Fig.
3(a-c)) and braced frame structure (Fig. 3(d-f)), respectively. It can beobserved that selection of optimal response varies from index to index.

Optimal Aseismic Performance of Buildings with Friction Dampers309

October 2005, Singapore

However, depending upon the relationship between the different
performance functions, the optimal design for one performance objective
may also be reasonably near optimal for other performance indices.
Optimum structural performance has been found for a prestressing
force of 1500-2500 N if the RPIF/RPIB is to be minimized, and 500-1000 N
if the DARF/DARB is to be minimized when the comprehensive friction
model (Model FM2) is used. The performance indices for prestressing force
FN = 767 N , which corresponds to optimal DARF/DARB response, is also
shown in Fig. 3. It can be observed that other than LHR2 and LHR3 baseexcitations, the prestressing force FN = 767 N gives near-optimal response
for other base excitations with reference to free-frame structure. Similarly
other than FSR1 and LHR3 base excitations, the prestressing force of
FN = 767 N effectively reduces the response for other base excitations withreference to braced frame structure. It has also been observed that other thanfew ground records optimal performance indices closely match with theindices corresponding to predicted optimum prestressing force (767 N). This
indicates that robust design of structures can be carried out by considering asingle performance index only.
5.3 Base shear response

The typical time-history response of base shear of example structure
subjected to FMR3 base excitation is shown in Fig. 4. This responses areshown for free frame, braced frame, structure with dissipater modeled using
Coulomb friction model (Model FM1), and structure with dissipatermodeled using comprehensive friction model (Model FM2). As expected,
significant reduction of base shear can be observed for structure with
dissipaters when compared to free frame and braced frame structures. The
results also clearly show that when the dissipater is modeled using Model
FM2, the response has significant high-frequency components, which are
not captured when using Model FM1. This illustrates the importance ofincluding stiction and Stribeck effects in the friction model. It is also seenthat the use of Model FM1 predicts lower maximum base shear compared tothe use of Model FM2, indicating the possibility of over-estimating theeffectiveness of the dissipaters when only simple friction model is used.
6. DISCUSSIONS AND CONCLUSIONSThe paper discusses the importance of realistic friction model for optimal
aseismic design of buildings with friction dampers. It is seen that the
breakaway and Stribeck effects may significantly influence the performanceof the building. It is also found that optimal aseismic design may be feasible
by only considering the Drift and Acceleration Ratio index for determining
the optimal prestressing force.
Based on the investigations presented in this paper, the following
main conclusions can be drawn:

310

New Technologies for Urban Safety of Mega Cities in Asia

(d)

BSRB

0.75
0.50

(e)

0.25
0.00
2.0
1.5
1.0
0.5
0.0
-0.5

(f)

FS
R
FS 1
R
FS 2
R
FM 3
R
FM 1
R
FM 2
R
LH 3
R
LH 1
R
LH 2
R
3

RPIB

FS
R
FS 1
R
FS 2
R
FM 3
R
FM 1
R
FM 2
R
LH 3
R
LH 1
R
LH 2
R
3

FS
R
FS 1
R
FS 2
R
FM 3
R
FM 1
R
FM 2
R
LH 3
R
LH 1
R
LH 2
R
3
FS
R
FS 1
R
FS 2
R
FM 3
R
FM 1
R
FM 2
R
LH 3
R
LH 1
R
LH 2
R
3

RPIF

0.75
0.50 (c)
0.25
0.00
-0.25
-0.50

2.0
1.5
1.0
0.5
0.0

FS
R
FS 1
R
FS 2
R
FM 3
R
FM 1
R
FM 2
R
LH 3
R
LH 1
R
LH 2
R
3

DARB

DARF

2.0
1.5 (b)
1.0
0.5
0.0

Based on Optimal Indices
Based on FN = 767 N

FS
R
FS 1
R
FS 2
R
FM 3
R
FM 1
R
FM 2
R
LH 3
R
LH 1
R
LH 2
R
3

2.0
1.5 (a)
1.0
0.5
0.0

BSRF

ICUS Report 11

Figure 3: Optimal performance indices considering comprehensive friction
model (Model FM2) subjected to ensembles of ground motions

1. Most structures with friction-based energy dissipation systems aredesigned based on Coulomb friction; however behavior of actual friction
is more complex and includes stiction and Stribeck effect. The
consideration of these effects results in much higher structure response.
2. Optimal prestressing force is closely related to the characteristics ofground motion and the performance index of interest. However, Driftand Acceleration Ratio index can be used for near-optimal design of thestructure.
REFERENCES

Armstrong-Helouvry, B., 1991. Control of machines with friction. Kluwer
Academic Publishers, Boston.
Berger, E. J., 2002. Friction modeling for dynamic system simulation.
Applied Mechanics Review 55, 535-577.
Bilkay, O., and Anlagan, O., 2004. Computer simulation of stick-slip
motion in machine tool slideways. Tribology International 37, 347351.
Constantinou, M. C., Soong, T. T., and Dargush G. F., 1998. Passive energy
dissipation systems for structural design and retrofit, MCEER Report,
University at Buffalo, Buffalo, NY.
Feeny, B., Guran, A., Hinrichs, N., and Popp, K., 1998. A historical review
on dry friction and stick-slip phenomena. Applied Mechanics Review
51, 321-341.
Filiatrault, A., and Cherry, S., 1990. Seismic design spectra for frictiondamped structures. ASCE Journal of Structural Engineering 116,
1334-1355.

Optimal Aseismic Performance of Buildings with Friction Dampers

311

BASE SHEAR (N)October 2005, Singapore

600
300
0
-300
-600

Free Frame

600
300
0
-300
-600

Model FM1

600
300
0
-300
-600

Model FM2

6000

646.50 N

433.49 N

529.85 N

0

2

4

6

8

10

12

14

16

18

20

22

6

8

10

12

14

16

18

20

22

24

Braced Frame

3000
0
-3000

4407.42 N

-6000
0

2

4

24

TIME (S)Figure 4: Base shear time-history response of example structure subjected
to Landers (1992) ground motion (FMR3) for optimal prestressing force of
767 N (PGA = 0.283g)

Levy, R., Marianchik, E., Rutenberg, A., and Segal, F., 2001. A simple
approach to the seismic design of friction damped braced medium-riseframes. Engineering Strucures 23, 250-259.
Moreschi, L. M., 2000. Seismic design of energy dissipation systems for
optimal structural performance, Ph.D. Thesis, Virginia Polytechnic
Institute and State University, Blacksburg, Virginia.
Patro, S. K., 2005. Presynopsis Seminar Report, Indian Institute ofTechnology Bombay, India.
Wang, J. H., and Shieh, W. L., 1991. The influence of a variable friction
coefficient on the dynamic behavior of a blade with a friction damper.
Journal of Sound and Vibration 149, 137-145.

312

New Technologies for Urban Safety of Mega Cities in Asia

NUMERICAL INVESTIGATION OF
STRUCTURAL RESPONSE TO ABOVEGROUND EXPLOSIONS
Y. LU 1*, Z. WANG 2
1
Protective Technology Research Centre, Nanyang Technological
University, Singapore
2School of Mechatronic Engineering, Beijing Institute ofTechnology, Beijing, China*
Email: cylu@ntu.edu.sg

ABSTRACTIn this study the response of building structures to above-ground
explosion is investigated using coupled numerical analysis. The emphasis isplaced on the response characteristics, looking into the concentration of
localized damage and the global structural dynamic response, rather thanthe detailed damage processes. The computational domain encompasses thesurrounding air and soil medium, thus allowing also for an evaluation of thesignificance of the explosion-induced ground motion in the overall
structural effects. A multi-storey reinforced concrete frame is used as an
example to illustrate the general structural effects. Results show that undera typical above-ground explosion scenario, the critical structural damage isdominated by air pressure, whereas the ground shock could induce
additional vibration but its structural effect is relatively insignificant. The
distribution of structural damage appears to be governed by member level
effects, especially on the front side of the structure.

1. INTRODUCTION
When assessing the threat of explosion on a building structure, it isnecessary to evaluate the structural effects of the blast loading. As a matterof fact, the response of building structures to nearby explosions iscomplicated by the drastic spatial and time variation of the blast loads.
Therefore, a clear understanding of the response characteristics is required
before any simplified approach may be adopted. For this purpose, coupled
numerical simulation is deemed to be an appropriate tool.
The present study adopts the fully coupled numerical simulation
approach so that the interactions between layers of different nature involvedin the processes can be better preserved. The computational domain
encompasses the structure, the surrounding air, the charge, as well as asufficient layer of soil medium so that the explosion-induced groundvibration effect can also be included for evaluation. The focus is placed on
the distinctive characteristics of the structural effects under nearby above-313

October 2005, Singapore

ground explosions, looking into the relative importance of localized damage
and the global dynamic response in the structural behaviour. Besides, thesignificance of the above-ground explosion induced ground vibration in the
structural response will also be examined and discussed. The models for theconstituent materials are carefully selected and validated, and a newly
developed three-phase soil model for high dynamic loading is employed. As
an example, a generic multi-storey reinforced concrete frame is selected toillustrate the characteristics of the structural effects and the dominantmechanisms governing the damage to the structural system.

2. COUPLED MODEL AND MATERIAL DESCRIPTIONS
A general configuration of building structures subjected to an aboveground explosion is depicted in Figure 1, in which the structure, air, soil
medium and the charge are represented respectively using the corresponding
material models. The algorithm of coupling the computational fluid
dynamics and computational structural dynamics is adopted to facilitate theinteraction between the air shock wave, the structure, and the ground.

Structure

Air

ChargeGround surface

Soil

Figure 1: Schematic of a generic coupled model
For the modeling of concrete, the RHT model (Riedel et al., 1999) is
adopted. The RHT model contains many features that are necessary todescribe a brittle material, namely pressure hardening, strain hardening,strain rate hardening, third invariant dependence for compressive and tensile
meridians, and cumulative damage (strain softening). As shown in Figure 2,
the material model uses three strength surfaces: an elastic limit surface, afailure surface and a remaining strength surface for the crushed material.
The failure surface Y is defined as
Y fail = YTXC ( p ) ⋅ R3(θ ) ⋅ FRATE (ε& )(1)*
FRATE (ε& ) ) N ] , f c = compressive strength, A =where YTXC = f c [ A( p * − p spall

failure surface constant, N = failure surface exponent, p * = pressure314

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

fc*
p spallp* ( f t / f c )FRATE (ε& )R3 (θ ) defines the third invariant dependency of the model as a function of

the second and third stress invariants and a meridian ratio.
The elastic limit surface is scaled from the failure surface,
Yelastic = Y fail ⋅ Felastic ⋅ FCAP ( p )(2)where Felastic = ratio of the elastic strength to failure strength, FCAP ( p ) is afunction that limits the elastic deviatoric stresses under hydrostatic
compression, and it varies in the range of (0,1). Linear hardening is usedprior to the peak load. For the residual strength,*
Yresidual= B * p*M

(3)where B = residual failure surface constant, M = residual failure surface
exponent.
Y
Uniaxial Compression

Uniaxial Tension

Failure Surface
fc
Elastic Limit SurfaceftCompressive
Elastic Strength

TensileElastic
Strength

Residual Surface

P

Figure 2: RHT Concrete strength model
The damage in concrete is accumulated via

D=∑

∆ε pl

ε

failurep,*
ε pfailure = D1 ( p * − p spall) D2 ≥ ε minf(4)

where D1 and D2 = damage constants, ε min= minimum strain to reachffailure. The post-damage failure surface is then interpolated via***
Y fracture= (1 − D)Y failure+ DYresidual(5)

For the reinforcing steel, the John-Cook model (Meyes, 1994) is
adopted.
For an appropriate modeling of the behaviour of soil under severe
explosion loading, a numerical three-phase soil model developed recently
by the authors (Wang et al., 2004) is adopted in the full coupled analysis in

Numerical Investigation of Structural Response to Above-Ground Explosions

315

October 2005, Singapore

this study. This model extends from a classical concept (Henrych, 1975) in
describing the soil as an assemblage of solid particles that form a skeleton
with their voids filled by water and air. The model formulation can beroughly divided into two main parts; the equation of state and the strength
model. Satisfying the continuity requirements, it follows∆ V ∆ Vw ∆ Vg ∆ Vs
=
+
+
V0
V0
V0
V0

(6)

where V = volume of a soil element, V0 = initial total volume of the element,
Vw = volume of water, Vg and Vs = volumes of air and soil particles,
respectively.
The pressure load causes deformation in each phase, as well as
friction between the solid particles and deformation of the bond between thesolid particles. The friction force and the force due to the bond are allexerted on the solid phase. Satisfying the equilibrium leads to anincremental form of the equation of state for the multi-phase soil, in which
the contributions from the constituent phases can be obtained from their
independent equations of state or stress-strain relationship.
To include the effect of hydrostatic stress on the shearing resistanceof the soil, the modified von Mises’ yield criterion (Drucker and Prager,
1952) is adopted, as follows,f = J 2 − α I1 − k = 0(7)where α and k = material constants related to the frictional and cohesivestrengths of the material, respectively; I 1 , J 2 = first and deviatoric stressinvariant, respectively. This yield function is further modified to take into
account the strain rate, as
ε& eff(8)
f = J 2 − (α I 1 − k )(1 + β ln
)=0
ε& 0

where ε&0 = reference effective strain rate, β = slope of the strength against
the logarithm of strain rate curve, ε&eff = effective strain rate.

The Jones-Wilkens-Lee (JWL) equation of state (Lee et al., 1968) is
adopted to model the pressure generated by the expansion of the detonation
product of the chemical explosive in the simulation, as follows

⎛
⎛
ω ⎞
ω ⎞
ωe
⎟⎟ exp(−r1v) + C 2 ⎜⎜1 −⎟⎟ exp(−r2 v) +P = C1 ⎜⎜1 −v⎝ R1v ⎠
⎝ R2 v ⎠(9)where v = specific volume, e = specific energy. C1 , R1 , C 2 , R2 , ω areconstants.

316

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

3. NUMERICAL ANALYSIS AND DISCUSSION OF RESULTS
3.1 General
For the analysis to characterize the structural effects from an aboveground explosion, a generic multi-storey reinforced concrete frame ischosen. The frame has a total above-ground height of 20 m (six storeys), a
total width of 10m, and a basement height of 3m (1 storey). The reinforced
concrete beam and columns are assumed to have a uniform cross-sectional
depth of 400mm. The concrete has the following properties: compressive
strength = 30 MPa, tensile strength = 3 MPa, Young’s modulus = 26 GPa. A
gross reinforcement volumetric ratio of 2% is assumed. The reinforcing
steel has yield strength of 460 MPa.

Figure 3: Computed blast wave propagation
The explosion scenario is designed such that both local and entire
structural system response can be represented to allow for a comprehensive
evaluation of the response characteristics. Thus, a charge of 1000 kg TNT(equivalent) is selected, representing a major incident. The stand-off
distance is 30m measuring from the front face of the structure, giving ascaled standoff distance equal to 3m/kg1/3. Based on the associated analysis,
a nearer standoff distance would generally result in more concentrated local
damage. The detonation centre is assumed to be 1m above the groundsurface. The numerical calculation is carried out using hydrocode Autodyn(Autodyn 1997) with necessary user defined subroutines.
Figure 3 depicts the contours of the pressure at two time instants.
These graphs show clearly the propagation of the shock wave in air as wellas in the soil. The incident and reflected waves can also be clearly observed.
3.2 Air blast load and stress wave in soil
Figure 4 shows the blast overpressure on the front face of thestructure. As expected, the peak overpressure tends to decrease gradually athigher positions on the front face. At the same time, the arrival time of theshock front gradually delays as the height increases. The shape of thepressure curves and main pulse duration do not exhibit sensible difference
among different target points.

Numerical Investigation of Structural Response to Above-Ground Explosions

317

Overpressure /MPa

October 2005, Singapore

Overpressure /MPa

0.8

Target 55

0.6
0.4
0.2
0.0
0

100

200

300

0.6

Target 57

0.4
0.2
0.0
0

400

100

Storey 1-mid height

300

400

Floor level 1
0.4

0.6

Target 59
0.4
0.2
0.0
0

100

200

300

400

Overpressure /MPa

Overpressure /MPa

200

Time /ms

Time /ms

Target 64

0.3
0.2
0.1
0.0
0

100

200

300

Time /ms

Time /ms

Floor level 2

Roof level

400

Figure 4: Blast pressure load on the front face of structure
In order to measure the stress wave in the soil, several target points
are arranged inside the soil. Typical recorded soil pressure curves areplotted in Figure 5. As can be seen, the pressure in the soil also attenuates
rapidly with the increase of the distance from the charge location. Near the
charge the pressure exhibits extremely high value. In fact, as can be seenfrom the contours shown in Figure 3, a half-spherical crater of radius about
2m is created beneath the point of detonation.

Target 47

Pressure /MPa

Pressure /MPa

40
30
20
10
0
0

10

20

30

40

1.2
1.0
0.8
0.6
0.4
0.2
0.0
-0.2

Target 50

0

50

20

40

60

80

100

Time /ms

Time /ms

Target 52

Pressure /MPa

Pressure /MPa

0.25
0.25
0.20
0.15
0.10
0.05
0.00
-0.05
0

50

100

Time /ms

150

200

Target 53

0.20
0.15
0.10
0.05
0.00
0

50

100

150

200

Time /ms

Figure 5: Stress wave propagation inside soil

3.3 Structural responses
Figure 6 shows the damage contours of the entire structure. Severe
damage is observed to occur mainly in the elements on the front face of the318

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

structure, due apparently to the strike of direct air shock wave. The
remaining part of the structure exhibit more or less a uniform distribution ofdamage among different elements and it is generally minor. This indicatesthat the global dynamic response plays a relatively insignificant role ascompared to the direct shock effect on the front face of the structure.
20 (m)
17

Floor level
Mid-column

14
11
8
5
2

100

(mm)

50

0

-1

-50

-4

Figure 6: Damage contours and front face displacement profile
The damage to the front face elements shows a distinctive pattern.
Within each storey, the severest damage is concentrated at both ends of theelement on the outer side and around the middle portion on the inner side.
For the particular example structure herein, the first storey column
experiences disproportionately severer damage than columns in otherstoreys on the front face, due apparently to the relatively weaker resistanceof the column because of its longer length, as well as the relatively higher
loading at the first storey level.
To further illustrate the dynamic response of the structural system,
the vibration histories at target points all over the structure are recorded.
Figure 7 plots the horizontal velocity histories at typical target points. The
highest velocity of about 6 m/s occurs at the first storey column on the front
face (target 5), followed by the second storey column (about 1.7m/s, attarget 8). The maximum velocity at the joint locations is generally on alower order of about 0.5m/s, including that at the interior joints (e.g., target
21).

Numerical Investigation of Structural Response to Above-Ground Explosions

319

6
5
4
3
2
1
0

Target 5

0

100

200

300

R-Velocity /m/s

R-Velocity /m/s

October 2005, Singapore

0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6

Target 7

0

400

100

Target 8

R-Velocity /m/s

R-Velocity /m/s

2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
0

100

200

300

0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
0

400

R-Velocity /m/s

R-Velocity /m/s

Target 14

0.2
0.0
-0.2
-0.4
100

400

100

200

200

300

400

Time /ms

0.4

0

300

Target 9

Time /ms

0.6200

Time /ms

Time /ms

300

400

Time /ms

0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6

Target 21

0

100

200

300

400

Time /ms

Figure 7: Horizontal velocity time histories at targets on structure
The displacement profile of the front face elements is also shown in
Figure 6. The concentration of damage in the first storey column, as well as
the significant element (column) level responses within each storey as
evidenced in the damage contours is clearly observed. On the contrary, theglobal response as represented by the drifts at the floor (or joint) locations isrelatively insignificant. In fact, the maximum relative drift between adjacent
floors is no more than 10mm, or 0.3~0.4% of the respective storey height.
3.4 Significance of ground shock effect
The response of the structure described above is the results of a
combined effect of the air shock wave and the ground vibration. In order toshed light on the extent to which the explosion induced ground vibration
affects the damage and vibration response of the structure, two additional
analyses are performed using the coupled model for separate air
overpressure and ground vibration effects, respectively. In the analysis forthe air overpressure effect only, an artificial rigid barrier is placed in front of
the basement in the soil to block the propagation of the stress wave in thesoil towards the structure base. Likewise, for the other case a rigid barrier isplaced in front of the main structure to block the propagation of the air
shock wave towards the structure so that only the ground vibration iseffective.
Figure 8 shows a comparison of the damage contours for the
structure separately under the air shock wave and ground shock effect. It can
be clearly observed that the damage of the structure is almost entirely

320

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

attributable to the air shock wave effect, while the damage due to the groundvibration effect is practically negligible. The above trend is also evident
from the comparison of the velocity responses at typical target points (notshown here). While the velocity response of the frame appears to be almost
identical under combined loading or air shock only, the velocity response
under the ground vibration alone is generally of one order of magnitude
lower.

Damage under air shock

Damage under ground vibration

Figure 8: Damage due to separate air blast or ground vibration

4. CONCLUSIONS
Based on the analysis using coupled numerical model, the following
conclusions may be drawn concerning the characteristics of a multi-storey
frame structure subjected to a typical above-ground explosion: 1) The
damage to the building frame primarily occurs in the elements on the front
face, due to the effect of the direct air shock wave. The global dynamic
response of the system is relatively insignificant concerning the structural
damage. 2) For the typical explosion scenario under consideration, thestructural damage and the critical vibration responses appear to be
dominated by the air shock loading, while the explosion-induced groundvibration effects are limited to a certain degree of additional vibrations. 3) Itshould be mentioned that the present study concerns the direct blast effect.
Once the residual state of the structure from the direct blast load isdetermined, the analysis of the post-blast process can proceed using asuitable analysis means.

REFERENCES
AUTODYN Theory Manual, 1997, revision 3.0, Century Dynamics, San
Ramon, California.
Drucker, D.C., and Prager, W., 1952. Soil Mechanics and Plastic Analysis
or Limit Design. Q. Appl. Math 10(2), 157-164.
Henrych, J., 1979. The Dynamics of Explosions and Its Use. Elsevier,
Amsterdam.

Numerical Investigation of Structural Response to Above-Ground Explosions

321

October 2005, Singapore

Lee, E. L., Hornig, H. C., Kury, J. W., 1968. Adiabatic expansion of highexplosive detonation products. UCRL-50422, Lawrence Radiation
Laboratory, University of California.
Meyers, M. A., 1994. Dynamic Behavior of Materials. John wiley & sons,
New York.
Riedel, W., Thoma, K., and Hiermaier, S., 1999. Numerical analysis using a
new macroscopic concrete model for hydrocodes. Proceedings of 9th
International Symposium on Interaction of the Effects of Munitions
with Structures, Berlin, Germany, 315-322.
Wang, Z., Hao, H. and Lu, Y., 2004. The three-phase soil model for
simulating stress wave propagation due to blast loading. International
Journal for Numerical and Analytical Methods in Geomechanics 28,
33-56.
Wang, Z., Lu, Y., Hao, H. and Chong, K., 2004. A full coupled numericalanalysis approach for buried structures subjected to subsurface blast.
Computers and Structures 83(4-5), 339-356.

322

New Technologies for Urban Safety of Mega Cities in Asia

EXPERIMENTAL STUDY ON
SEISMIC BEHAVIOR AND CRACK PATTERN
OF CONCRETE BLOCK INFILLED RC FRAMESYOSHIAKI NAKANOInstitute of Industrial Science, The University of Tokyo, Tokyo, Japaniisnak@iis.u-tokyo.ac.jp
HO CHOI
Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
choiho@iis.u-tokyo.ac.jp

ABSTRACTIn this study, concrete block infilled reinforced concrete frames forschool buildings in Korea are tested under cyclic loadings, and a simplified
model is proposed to investigate the relationship between residual crack
widths in concrete block wall and frame’s residual deformations. Although
the measured crack widths in concrete block walls are much smaller than
the residual deformations, a simplified model proposed in this paper
considering flexural and shear deformation distribution of columns canrationally reproduce the measured crack widths. The relationship between
crack widths in concrete block wall and frame’s residual deformations isfurther investigated and their ratio is found to lie approximately in therange of 0.2 to 0.3. This result implies that the residual deformation of frames
can be estimated form crack widths in concrete block wall.

1. INTRODUCTION
After an earthquake, the major concerns to damaged buildings are
their safety/risk to aftershocks, quantitative damage assessment to evaluate
their residual seismic capacity and to identify necessary actions on thedamaged buildings. Post-event damage evaluation is therefore essential for
quick recovery of damaged communities as well as pre-event seismic
evaluation and strengthening of vulnerable buildings. Few investigations on
unreinforced masonry walls, however, have been made to quantitatively
identify their damage level and criteria to judge necessary actions for theircontinued use, repair and rehabilitation although their damage has been
often found in the past damaging earthquakes.
In this study, concrete block (CB) infilled RC frames for schoolbuildings in Korea, where CB walls are typically unreinforced, areexperimentally investigated to develop pre- and post-earthquake seismic
evaluation method. In the tests, full-scale, one-bay, single-story specimens
having different axial loads in columns and different opening configurations
in walls are tested under cyclic loadings, and the contribution of CB walls to323

October 2005, Singapore

overall behaviors is examined. Furthermore, crack patterns and widths inwalls and frames which may be of great significance for post-event damage
assessment are carefully observed, and the measured results in CB wall arecompared to those estimated by a simplified model proposed in this paper.

2. OUTLINE OF EXPERIMENT
2.1 Test Specimen
Figure 1 shows a standard design for Korean school buildings in the
1980s (The Ministry of Construction and Transportation, 2002). As can befound in this figure, CB walls are commonly used as partition walls or
exterior walls in Korean school buildings. In this study, 4 specimens
representing a first or fourth story of 4 story RC school buildings are tested
under cyclic loadings. They are infilled wall type 1 (IW1) assuming a firststory, infilled wall type 2 (IW2) assuming a fourth story, and wing wall type(WW) and partial height wall type (PW) both having an opening in the wall.
The axial force applied in each column is 720 kN (4 N/mm2) for specimens
IW1, WW, and PW while 180 kN (1 N/mm2) for IW2.
The design details of specimen IW1 are shown in Figure 2. Since
seismic design provisions for buildings were introduced in 1988 in Korea,
the model structures studied herein are not designed to seismic loads.
Therefore, they have (1) large spacing of hoops (300 mm) and (2) 90-degree
hooks at both ends of hoops as shown in the figure. Specimens IW1, WW,

Figure 1: Standard design of Korean school buildings in the 1980s andspecimen configuration

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and PW have the identical re-bar arrangement in columns but different wallarrangement, while IW2 has fewer re-bars than other 3 specimens. Concrete
block units are laid in the RC frame after concrete is hardened.
2.2 Test Setup and Test Program
Figure 3 and Photo 1 show the elevation view of the loading system.
Cyclic lateral loads are applied to each specimen through a loading beamtightly fastened to the specimen. Figure 4 shows the loading history, wherea peak drift angle R is defined as “lateral deformation (δp) / column height(=2,400 mm)”. As shown in the figure, peak drift angles of 0.1, 0.2, .0.4,
0.67, 1.0, and 2.0% are planned and 2.5 cycles for each peak drift are
imposed to eliminate one-sided progressive failure (unsymmetric failure
pattern in positive or negative loadings). It should also be noted that 0.4%
loading is imposed after 1.0% to investigate the effect of small amplitude
loading after large deformation (i.e., aftershocks). After severe damage isfound, the specimen is pushed over to collapse. A constant axial load of
1,440 kN (720 kN for each column) is applied to specimens IW1, WW and
PW while 360 kN (180 kN for each) to specimen IW2.

Figure 2: Detail of specimen (IW1)

Figure 3: Test setup

Photo 1: General view of test setup

Experimental Study on Seismic Behavior and Crack Pattern of Concrete Block Infilled RC Frames325

Target displacement (mm)October 2005, Singapore

60
40
20
0
-20
-40
-60

0.1

0.2

0.4

0.67

1.0

0.4

2.0

Peak drift angle, R (%)

Figure 4: Loading history

3. CRACK WIDTHS AND RESPONSE OF SPECIMENS
3.1 Measurement of Crack Width
Cracks in members after an earthquake are visible and essential
evidence of damage that can be found at the building site, and they often
provide valuable information regarding the response that the building has
experienced and its residual capacity. To investigate the relationshipbetween crack width and residual capacity, crack widths in RC columns andCB walls are carefully measured at peak loads and unloaded stages. Figure 5
shows the measurement points in columns and walls made in this study.
The widths of flexural and shear cracks observed at the top andbottom of each column are visually measured with crack scales. Since crack
widths are not necessarily uniform along the crack, its major width which isdeemed to be largest along a crack is measured. It should also be noted thatthe width perpendicular to the crack is measured.

Figure 5: Schematic illustration of crack pattern and measured points

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All visible cracks in the head joints found in stair-stepped diagonal
cracks running through the CB wall are also measured to record the lateraldislocation of CB units (see Figure 5(a)) while several cracks in the bed
joints of one continued crack are measured to investigate a rotational
behavior of wall (see Figure 5(b)). In the following sections, crack widths
measured in the head joints of CB walls of specimens IW1 and IW2 areinvestigated to understand the relationship between observed cracks andframe’s behavior.
3.2 Residual Crack Width in CB Wall
The residual deformation (δ0 ), total residual crack width (Σ maxW0)
measured in CB wall, and their ratio [Σ maxW0 / δ0] at unloaded stages after
each first cycle in the positive domain are plotted for specimens IW1 andIW2 with respect to the peak drift angle in Figure 6. In this figure, maxW0 isdefined as the maximum residual crack width, as is shown (a) in Figure 5, inthe head joints of a continued stair-stepped diagonal crack. When the CB
wall has more than one major stair-stepped diagonal crack, maxW0 can befound along each continued crack and the sum of maxW0 ( = ΣmaxW0) is thencalculated. The ratio [Σ maxW0 / δ0] of specimen IW1 differs from that of
IW2 over the peak drift angle R smaller than 0.2% and larger than 1.5%.
The results can be attributed to the following observations.
(1) The ratio tends to be dependent on crack inspectors especially when the
deformation is small (i.e., R ≤ 0.2%) since the observed crack widths arearound 0.1mm which would be the limit for visual inspections. The
calculated ratio is therefore sensitive to the measurement error and may
not be consistent in the small drift range along different specimens.
(2) The crack widths in CB wall significantly increases after R = 1.4% in
IW1 due to extensive shear cracks in columns, while IW2 performs welleven in such a large deformation. The ratio is therefore higher in IW1
than in IW2.
It should also be noted that the ratio [Σ maxW0 / δ0] is approximately inthe range of 0.2 to 0.3 over the peak drift angle larger than 0.2 % and muchsmaller than 1.0. The reason can be found in the following section.
20

20

0.5

16

12
8

δ0

0.2

4

0.4

0.8

0.3

1.2

12

0.3

ΣmaxW0 / δ0

8

0.2
δ0

ΣmaxW0

0.1

4

1.6

0.0
2.0

0
0.0

Peak drift angle, R (%)

0.4

ΣmaxW0

0.4

0.8

1.2

ΣmaxW0 / δ0

Shear cracks
extensively
widened(R =1.4%)

ΣmaxW0 , δ0 (mm)0.4
ΣmaxW0 / δ0

ΣmaxW0 / δ0

ΣmaxW0 , δ0 (mm)

16

0
0.0

0.5
[IW2]

[IW1]

0.1

1.6

0.0
2.0

Peak drift angle, R (%)

Figure 6: δ0 , Σ maxW0 and [Σ maxW0 / δ0] (CB wall) vs. peak drift angle R

Experimental Study on Seismic Behavior and Crack Pattern of Concrete Block Infilled RC Frames327

October 2005, Singapore

3.3 Estimation of Measured Crack Width in CB Wall by Simplified Model(1) General assumptions
In order to investigate the crack development mechanism and to
estimate the crack width in CB wall, the following assumptions are made.
1) The residual deformation (δ0) of frame can be approximated by the sumof residual flexural deformation (δf0) and residual shear deformation (δs0)
of column as shown in Figures 7(a) and (b). (i.e., δ0 = δf0 + δs0)2) Cracks in head joints of CB wall result from the discrepancy of
deformation distribution along its height in each column.
If each column has an identical anti-symmetrical flexural deformationand distribution as shown in Figure 7(a), no discrepancy should be found in
the CB wall’s clear span length l0i along column height (i.e., l01 ≈ l02 ≈ l03).
Since a similar flexural deformation distribution is observed in each column
during tests, no major cracks due to flexural deformation are expected.
The shear deformation distribution along its height in each column,
however, is not obviously identical as shown in Figure 7(b), since thedeformation due to shear cracks concentrates on the bottom of compression
column and the top of tensile column resulting from a compressive strut
action as can be found in specimens IW1 and IW2 (see Figure 8). This may
cause the discrepancy of lateral deformation distribution in CB wall along(a) Flexural deformation(b) Shear deformation
Figure 7: Deformation of column and CB wall(a) IW1(b) IW2
Figure 8: Cracks in RC columns and CB wall at the 1st cyclewith peak drift angle of +1.0%

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column height (i.e., l01′ ≠ l02′ ≠ l03′). The maximum discrepancy, which may
be simply expressed by the residual shear deformation (δs0) as shown in
Figure 7(b), then needs to be consistent with crack widths in head joints
resulting in high correlation between the residual shear deformation (δs0)
and total crack width in CB wall (Σ maxW0).
Bearing in mind that the flexural deformation may highly contribute tothe overall deformation of long columns but that the flexural deformation,
as is described earlier, may not cause major cracks in head joints, the ratio[Σ maxW0 / δ0] can be expected to be small as demonstrated in Figure 6.
Based on studies by Maeda et al.(2000), AIJ Guidelines define therelationship between residual crack width and residual deformation for RC
members (AIJ, 2004). However, few researches on the relationship for RC
frames and/or CB wall infilled frames have been yet made to date. It istherefore of great interest and significance to investigate the applicability ofanalogous relationship to CB wall infilled frames. In the subsequentdiscussions, a simplified model considering the discrepancy of flexural andshear deformation distribution is proposed to estimate the crack width in CB
wall, and the correlation between measured and estimated results is discussed.
(2) Crack width due to flexural deformation
Figure 9 shows the outline of the simplified model studied herein. The
flexural deformation, tδf and cδf , of each column can be approximated using
the average total flexural crack width at the top and bottom of column asshown in equations (1) and (2) (AIJ, 2004), where “t ” and “c” denote“tension side” and “compression side”, respectively. The maximum
discrepancy between two columns due to flexural deformation distribution,
which causes minor cracks in head joints as discussed earlier, is assumed
herein to develop in the mid-height of column (h0 / 2) as shown in equation (3).

(a) Flexural deformation(b) Shear deformation
Figure 9: Simplified model of column and CB wallt

δ f =t R f ⋅ h0 =1  Σ tW f ,T +Σ tW f , B  ⋅ h0⋅D − x 2
(1)

δ f = c R f ⋅ h0 =1  Σ cW f ,T + Σ cW f , B  ⋅ h0⋅D − x 
2


(2)

c

 Σ cW f , B −Σ tW f , B  h0 ⋅
Σ maxW f = 
D−x

 2

Experimental Study on Seismic Behavior and Crack Pattern of Concrete Block Infilled RC Frames

(3)

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October 2005, Singapore

where,t δf , c δft Rf , c Rf

ΣtWf,T , ΣtWf,B
ΣcWf,T , ΣcWf,BD
xh0
ΣmaxWf: flexural deformation of tension and compression side column,
respectively (see Figure 9(a)): flexural rotation angle of tension and compression side column,
respectively (see Figure 9(a)): total flexural crack width of top and bottom in tension column,
respectively (measured): total flexural crack width of top and bottom in compression
column, respectively (measured): column depth (=450 mm): distance from extreme compression fiber to neutral axis
( 0.2 D (= 90 mm) is assumed herein ): column clear height (= 2,400 mm): total crack width in CB wall due to the discrepancy of flexural
deformation distribution(3) Crack width due to shear deformation
The shear deformation, tδs and cδs , of two RC columns can beapproximated based on the measured total shear crack width of each column
as shown in equations (4) and (5) (AIJ, 2004). The total crack width in CB
wall due to different shear deformation distribution between tension andcompression side column can be estimated using the average total shear crack
width as shown in equation (6).

δ s =Σ tWs ⋅ cos θc δ s =Σ cWs ⋅ cos θc δ s +t δ s tΣ maxWs =2=(Σ cWs +ΣtWs ) ⋅ cosθ 
2




(4)
(5)

(6)

where,t δs , c δs

ΣtWs , ΣcWs

θ
ΣmaxWs: shear deformation of tension and compression side column,
respectively (see Figure 9(b)): total shear crack width of tension and compression side column,
respectively (measured): angle between shear crack and vertical direction of column(45-degree angle is assumed herein): total crack width in CB wall due to the shear deformation
distribution(4) Total crack width in CB wall

As shown in equation (7), the total crack width in CB wall, Σ maxW,
can be calculated using crack widths defined in equations (3) and (6).
∑ maxW =∑ maxW f +∑ maxWs Σ cW f , B −Σ tW f , B  h0 (Σ cWs + Σ tWs ) ⋅ cos θ ⋅ +
(7)
= 
2
D−x

 2
Figure 10 shows the residual deformation δ0 and δf0 with respect to thepeak drift angle, where δf0 is assumed to be the average of tδf and cδf at

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unloaded stages derived from equations (1) and (2). Since major wide
cracks are selectively measured after 1.0 % drift, δf0 is plotted up to 1.0 %.
As is anticipated in 3.3 (1), δf0 mainly contributes to the overall residual
deformation δ0. It is also interesting to point out that the ratio of crack
widths Σ maxWf0 to δf0 is relatively small, which is consistent with the results
shown in Figure 6. This is mainly because the flexural deformation
distribution along their height of two boundary columns does not differ
much (i.e., l01 ≈ l02 ≈ l03) and therefore leads to minor cracks in head joints.
Figure 11 shows the estimated crack widths in CB wall at unloaded
stages obtained from equation (7) together with measured results. The
estimated results (shown in circle : -○-) slightly overestimate the measured
results (shown in square : -□-) since all cracks developed in CB wall are
not perfectly measured during tests. The estimated results, however,generally compare well with the measured results and the proposed model
shown in Figure 9 successfully explains the crack development mechanismof CB wall studied herein. This result implies that the residual deformation δ0
of frames as well as RC members can be estimated from crack widths Σ maxW0
5

5

1.0

2

ΣmaxWf 0 / δf 0

1

0.4

0.8

1.2

1.6

2
1

0.0
2.0

0
0.0

0.8

Major wide cracks 0.6
of columns are
selectively measured
0.4

3

0.2

δf 0

ΣmaxWf 0 / δf 0

0.4

0.8

1.2

ΣmaxWf 0 / δf 0

0.6
Major wide cracks
of columns are
selectively measured 0.4

δ0 , δf 0 (mm)

δ0 , δf 0 (mm)

3

δ0

4

0.8

δf 0

ΣmaxWf 0 / δf 0

δ0

4

0
0.0

1.0
[IW2]

[IW1]

0.2

1.6

0.0
2.0

Peak drift angle, R (%)

Peak drift angle, R (%)

Figure 10: δ0 , δ f0 and [Σ maxWf0 / δf0] vs. peak drift angle R
0.6

0.6
[IW2]

0.5

0.5

0.4

0.4

0.3
0.2

Major wide cracks of columns
are selectively measured

0.1
0.0
0.0

0.8

1.2

1.6

Peak drift angle, R (%)

Major wide cracks of columns
are selectively measured

0.3
0.2
0.1

measured (cf. Figure 6)
estimated by simplified model

0.4

ΣmaxW0 / δ0

ΣmaxW0 / δ0

[IW1]

2.0

0.0
0.0

measured (cf. Figure 6)
estimated by simplified model

0.4

0.8

1.2

1.6

2.0

Peak drift angle, R (%)

Figure 11: [Σ maxW0 / δ0] vs. peak drift angle R (in positive loading)Experimental Study on Seismic Behavior and Crack Pattern of Concrete Block Infilled RC Frames331

October 2005, Singapore

observed in CB wall based on the ratio [Σ maxW0 / δ0]. The residual seismic
capacity, therefore, could be evaluated through previously estimated δ0 if
the typical hysteretic characteristics of CB wall infilled frame are given.

4. CONCLUSIONS

Concrete block (CB) infilled RC frames for school buildings in Korea
are tested under cyclic loadings, and a simplified model is proposed toinvestigate the relationship between residual crack widths in CB wall andresidual deformation. The results can be summarized as follows.
(1) The measured ratio [Σ maxW0 / δ0] for specimens IW1 and IW2 lies
approximately in the range of 0.2 to 0.3 before the specimen extensively
fails in shear.
(2) Although the ratio above is much smaller than 1.0, a simplified model
proposed in this paper considering flexural and shear deformation
distribution of columns can rationally reproduce the measured results.
(3) The results described above imply that the residual deformation δ0 offrames can be estimated from crack widths Σ maxW0 observed in CB wall
based on the ratio [Σ maxW0 / δ0]. The residual seismic capacity, therefore,
could be evaluated through previously estimated δ0 if the typicalhysteretic characteristics of CB wall infilled frame are given.

ACKNOWLEDGMENT

The research reported herein was performed in cooperation withProfessor Waon-Ho Yi of the Kwangwoon University and Dr. Sang-Hoon
Oh of RIST (Research Institute of Industrial Science and Technology) in
Korea. The authors express their deepest gratitude to all these supports
without which the test could not be accomplished.

REFERENCES

The Ministry of Construction and Transportation, 2002. A study on theseismic evaluation and retrofit of low-rise RC buildings in Korea. pp.
113-155.
Masaki Maeda, Masahiro Bunno and Masayuki Nagata, 2000. A study on
the damage level estimation of RC buildings based on residual seismic
capacity of members. Proceedings of the Japan Concrete Institute,Vol. 22, No. 3, pp. 1447-1452.
AIJ(Architectural Institute of Japan), 2004. Guidelines for performance
evaluation of earthquake resistant reinforced concrete buildings(Draft) pp. 155-161.

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SIMPLIFIED METHODOLOGY FORDAMAGE ASSESSMENT OF 2-STOREY RC
FRAME SUBJECTED TO EXPLOSIONINDUCED GROUND MOTIONS (EIGMS)CHEE LEONG LIM AND TSO-CHIEN PAN
Protective Technology Research Centre, School of Civil and Environmental
Engineering, Nanyang Technological University, Singapore
cheeleong@ntu.edu.sg
ABSTRACT
Explosion-induced ground motions (EIGMs) have large amplitudes
and high frequency contents, occurring within a short duration. EIGM
characteristics can be segmented into two parts: the major shock duration(Phase 1) and the ensuing duration (Phase 2). When subjected to EIGMs,
the structure experiences small structural deformations and large induced
shear forces during the loading duration (Phase 1). After the loading
duration, larger structural displacements are experienced in Phase 2. Dueto the high frequency contents of EIGMs, the response analysis of Phase 1
requires a sufficient number of elements, in order to capture the local mode
response. In the case of a multi-storey reinforced concrete (RC) frame, thecomputational effort would be large. In this paper, a simplified damage
assessment method is proposed, whereby the damage assessment of multistorey RC frame can be approximated by this simplified methodology. Thismethodology is for approximating the damage assessment of a multi-storey
RC frame during Phase 1, by performing the damage assessment of a basecolumn of the RC frame with simplified fixed-fixed boundary conditions.
Also, this simplified methodology considers the strength enhancement due tostrain rate effects. The damage assessment results of the simplified
structural-level model of the simplified fixed-fixed column were determined.
The results from the simplified methodology were compared with the resultsfrom a material-level model of a 2-storey RC frame. It is shown that theboth results are comparable and that the simplified methodology may beable to approximate the damage of a multi-storey RC frame during thePhase 1 response, when subjected to an EIGM.

1.0 INTRODUCTION
Growing populations, industrial development and commercial development
has pushed closer the supply and the demand of land. Thus, ongoing
defence strategies of each country, underground space has been developed
for ammunition storage. These underground ammunition storages pose athreat to structures in the vicinity of an accidental or intentional333

October 2005, Singapore

detonation. When there is such a detonation, explosions-induced groundmotions (EIGMs) are generated. These ground motions propagate throughthe soil or rock medium and may cause damage to the structures above andaround the detonation source. The difference between earthquakes and
EIGMs lies in their magnitudes, durations and predominant frequencies.
EIGMs occur within shorter durations (in the order of microseconds) thanearthquakes and so their frequency content is also higher than earthquakes(Lu et al, 2001; Pan et al, 2004). The acceleration amplitudes of EIGMs canbe in the range of 80 to 150 g, which is larger than earthquakes (Lu et al,
2001; Pan et al, 2004).
Structural response to EIGMs can be segmented into two parts: themajor shock duration (Phase 1) and the ensuing duration (Phase 2). It was
shown that the high frequency nature of an EIGM led to a large shear force
with small structural displacement during Phase 1, followed by significant
structural displacement during Phase 2 (Pan et al, 2004). Thus, for areinforced concrete (RC) structure designed for resistance to EIGM. it
should possess toughness for the large induced shear forces during Phase 1;
it should however also possess ductility for Phase 2 response where thestructural displacements are significantly larger. Other researchers have
performed numerical analyses of multi-storey RC frames subjected tosimulated EIGMs. For a 2-storey RC frame, Lu et al (2001) noted that themass of the second-storey filtered significant amounts of high-frequency
input of energy as the stress waves propagate along the column, during
Phase 1 response. This is because the presence of concentrated masses canact as frequency filters by blocking high-frequency components of waves.
Thus, the masses reduce the inertia action of EIGMs on upper storey levels
during Phase 1 response.
Frames have global mode(s) associated with the floor(s) where themass is lumped. There are also local modes associated with the degrees of
freedom at intermediate points accounting for the distributed masses ofbeams, columns and slabs. When frames are subjected to high-frequency
ground motions, the local modes display significant response (Lu et al,
2001; Pan et al, 2004). Thus, in the response analysis of frames subjected to
EIGMs, inclusion of the higher-frequency local modes within the analyticalmodel leads to a significant increase in computational effort.
It has been hypothesized that the strength of a material increases withthe strain rate (Malvern, 1951). For concrete and steel reinforcement bars,
the hypothesized strength-enhancement effect due to higher strain rates has
been demonstrated (CEB, 1993; Malvar, 1998). The strength-enhancement
due to strain rate effects is normally shown as a dynamic increase factor(DIF), which is a ratio of the dynamic strength to the static strength. For thispaper, the damage assessment shall consider the strength-enhancement due
to strain rate effects.
For a material-level model of a 2-storey RC frame, the damage
assessment of the RC frame to a simulated EIGM was determined (Pan et al,2004). Figure 1 shows the 2-storey RC frame. The dimensions for the RC

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column are 300 mm × 230 mm × 3,300 mm. For this RC column, the steel
reinforcement is as follows: 6 longitudinal steel bars of 19 mm diameter and
10 mm diameter double-legged lateral ties at 100 mm spacing. The
following concrete properties are assumed: concrete unit weight = 24
kN/m3; concrete compressive strength = 30 MPa; concrete elastic modulus =26 GPa. For the steel reinforcing bars, the following properties are assumed:
steel yield strength = 410 Mpa and steel elastic modulus = 200 GPa. Figure
2 shows the acceleration time history of the simulated EIGM. The groundshock is a simulated EIGM at 50 m from the source of detonation whereby
the explosion is 250 ton of TNT with a loading density of 10 kg/m3. The
horizontal component of the simulated EIGM at 50 m from source, has thefollowing properties: peak ground acceleration (PGA) = 123 g; peak ground
velocity (PGV) = 0.91 m/s; and a dominant frequency band between 95 Hz
and 260 Hz (Zhou et al 2002; Pan et al, 2004). Figure 3 shows the damage
assessment results based on the material-level model of the 2-storey RC
frame (Pan et al, 2004). A parametric study was undertaken whereby afamily of EIGMs was generated by scaling the PGA, PGV and dominantfrequency. The scaled EIGMs were used as the input ground motions for thematerial-based model of the 2-storey RC frame. Representative PGAs and
PGVs were taken as the mean of the horizontal PGA and mean of thehorizontal PGVs, respectively. Also, the principal frequency wasdetermined as the average of the two frequencies corresponding to theacceleration Fourier spectra, at half of the peak spectral acceleration. Figure
3 shows the types of failure mechanisms that were considered for thedamage assessment, in terms of PGV and PGA of the EIGM, which would
result in each failure mechanism. The two failure mechanisms consideredwere diagonal shear failure and flexural failure. However, the damage
results were not analyzed for the chronology of flexural and shear failure(region B in Figure 3). For the material-based model of the 2-storey RC
frame, there was no explicit consideration of the strength-enhancement due
to strain rate effects.
In this paper, a simplified methodology is proposed as an
approximation for the damage assessment of a multi-storey RC frame,during the Phase 1 response. The simplification in this methodology
involves performing the damage assessment based on a structural-level
model of a single column, representative of the base column of a multistorey RC frame. The boundary conditions of the single column are
assumed to be fixed at the top and bottom (fixed-fixed). The reason for sucha simplification is due to how the mass of the second storey level has beenshown to filter the propagation of the stress waves during Phase 1 response.
Also, the strength-enhancement due to strain rate effects is explicitly
considered in this simplified methodology. This simplified methodology isapplied on the 2-storey frame used by Pan et al (2004) and the damage
assessment results are compared with those obtained by the material-basedmodeling of the same 2-storey RC frame. The purpose is to compare thedamage assessment obtained based on a structural-level model of a fixedfixed column, with those obtained by the more refined material-based modelof a 2-storey RC frame (Pan et. a., 2004). If the damage assessment resultsfrom the two types of model be comparable, the simplified methodology

Simplified Methodology for Damage Assessment of 2-Storey RC Frame Subjected to EIGMS

335

October 2005, 2005

with its gross assumptions may serve as an approximation for the damage
assessment of multi-storey RC frames subjected to EIGMs, with a much
reduced computational effort.
230
30
3000

300

300

300

3300

300

6 bars of
19 mm dia

Clear cover25
Beam and column
5000
cross-section
Figure 1: 2-Storey RC frame
150(g) 100

Maximum = 123 g
Mean PGA about 113 g

50
0
-50
-100
-150

Minimum = -103 g

0.00

0.05

t (s)
0.10

0.15

0.20

0.25

Figure 2: Simulated EIGM at 50 m from explosion(Zhou et al, 2002; Pan et al, 2004)
PGV (m/s)

10.0

B
C

A
1.0
No failure
0.1
1

10

100
1000
principal frequency (Hz)
A: flexural failure; B: flexural failure and shear failure; C: shear failure

Figure 3: Failure mechanisms determined by material-based modelof 2-Storey RC frame

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2.0 PROPOSED DAMAGE ASSESSMENT FOR PHASE 1
For the proposed simplified methodology, the following failure
mechanisms are considered: (a) direct shear failure defined as when the
induced shear force exceeding the direct shear failure strength capacity; (b)diagonal shear failure defined as when the induced shear force exceeding
the diagonal shear strength capacity; and (c) flexural failure defined as when
the induced bending moment exceeding the yielding moment, of the RC
section. For the direct shear failure and diagonal shear failure, the strength
enhancement effect due to strain rate effect is considered by using the DIF
formulation by CEB (1993). For the direct shear strength capacity, thepredictive equation by K&C (1973) is used. For the diagonal shear strength
capacity, the predictive equation by Priestley et al (1994) is used. However,no strength-enhancement due to strain rate effects was considered for the
flexural failure. This exception is because flexural responses normally occur
at lower frequency ranges than shear responses.
For the column subjected to EIGM, the shear characteristic (i.e. thedistinction between a diagonal shear behavior and a direct shear behavior
experienced by the column), is determined based on the research by Li andJones (2000). Li and Jones (2000) made a distinction between theoccurrence of a direct shear and diagonal shear behavior, which was
described in the extent of the formation of a shear hinge. Shear hinge occurs
when there is a dominant zone of shear deformation. For a rectangularcross-section, the extent to the formation of shear hinges is recast as adimensionless parameter, as follows (Equation 1):
Direct shear: M (QH) ≤ 0.433(1a)Diagonal shear: M (QH) > 0.433(1b)where M is the induced bending moment; Q is the induced shear force; andH is the thickness of the beam.
For the response during Phase 1, a strength-based damage index is
proposed. The proposed damage index is designed for a toughness test.
Thus, no attempts shall be made to add the independent contributions to thedamage from the effects of shear force and bending moment. That is, thedamage index shall be taken as the maximum of two ratios, each of which is
the ratio of the induced shear force or bending moment to the respective
strength capacity. For an instant in time t, the propose damage index for
Phase 1 is as follows:
 Q M 
(2)
Damage Index = Max , Qc M c 
where Q and M are the induced shear force and induced bending moment attime t, respectively; Mc = currently taken as the yielding moment capacity
without strength-enhancement effect; Qc = shear strength capacity including
strength-enhancement effect adopting formulations by K&C (1973) andPriestley et al (1994), where the choice of shear strength capacity to be used

Simplified Methodology for Damage Assessment of 2-Storey RC Frame Subjected to EIGMS

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October 2005, 2005

depend on the behavior as defined by Equation 1. When the proposed
damage index exceeds one, failure is deemed to have occurred.
Furthermore, the base column of the 2-storey RC frame (Figure 1) was
represented as a structural-level model. The based column was modeledwith fixed boundary conditions at the top and bottom supports. Also, thebase column was discretized as 19 finite, Timoshenko beam-column
elements. The modal frequencies of the column ranged from the first modal
frequency of 89 Hz to as high as 1.7 MHz for higher modes. The numericalanalysis adopted for the response analysis of Phase 1, was elastic. Similar tothe scaling of the EIGMs adopted by Pan et al (2004), a family of horizontal
EIGMs was generated by scaling the simulated EIGM as shown in Figure 2.
Here, the vertical ground motion of the EIGM was not considered.

3.0 DAMAGE ASSESSMENT USING SIMPLIFIEDMETHODOLOGY
The damage assessment results from the parametric study of using
many scaled EIGMs are consolidated and presented in a similar manner asthat of Figure 3. The damage assessment results from the proposed arecompared to those obtained from the material-based model of the 2-storey
RC frame.
The parametric study results for the damage assessment of the fixedfixed column are shown in Figure 4. From Figure 4, the following
observations can be made:
The general trends presented in both damage assessment methods
show that when the PPV of an EIGM is larger than 2 m/s, as theprincipal frequency is increased, there will be a transition fromflexural failure to shear failure.
However, a distinction is made between diagonal shear failure anddirect shear failure when using the proposed damage assessment
method.
For EIGMs of a given PPV, a high principal frequency is required for
direct shear failure as compared.
It can be seen that the damage assessment using a fixed-fixed column
can produce a similar map of failure modes for a multi-storey RC
frame. The lower bound of failure modes, which represents the
EIGMs that do not cause failure, is similar by both damage assessment
methods. However, the proposed simplified method required lesscomputational effort than that by Pan et al (2004).
It has been shown that the proposed simplified method produced
similar failure maps of a 2-storey RC frame as compared to those produced
by Pan et al (2004). Furthermore, the simplified method made a distinction
between diagonal shear failure and flexural failure when subjected to certain
EIGMs. Lastly, the proposed simplified method requires less computational
effort than that the damage assessment method by Pan et al (2004).

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ICUS Report 11____________________PPV (m/s)
10.0

C2
A
1.0

C1
No failure

0.1
1

10

100

1000

10000

Principal frequency (Hz)diagonal shear failure

A: Flexural failure only;

direct shear failure

moment yielding

C1: Diagonal shear failure C2: Direct shear failure

Figure 4: Failure modes determined by fixed-fixed column

4.0 CONCLUSION
A damage assessment for the shear force in Phase 1 was proposed forstructures subjected to EIGM. This proposed damage assessment consideredstrength-enhancement due to strain rate effects. Also, the proposed method
allows one to perform a toughness test of the structure during Phase 1.
A simplification was proposed for the damage assessment of RC
frames when subjected to EIGMs. The simplification involves studying thedamage on the base column where large forces are induced during Phase 1.
This proposed simplification and the associated damage assessment of thebase column were based on structural-level modeling of the base column,
with fixed boundary conditions at the top and bottom. The damage resultsfrom the simplified structural-level model of a fixed-fixed column weresimilar with those obtained from a material-level model. The simplified
method although with its gross assumptions, has its merits in that it provides
an approximation of the damage, with less computational effort.

REFERENCE
Lu, Y., Hao, H., Ma, G.W., and Zhou, Y.X., 2001. Simulation of structural
response under high-frequency ground excitation, Earthquake
Engineering and Structural Dynamics, Vol 30, 307-325.
Pan T.-C., Dhakal R.P., and Lim C.L., 2004. Damage assessment ofreinforced concrete building frames subjected to explosion induced
ground motions, Final Report, PTRC-CSE/LEO/98.02, Protective
Technology Research Centre, School of Civil and Environmental
Engineering. Singapore: Nanyang Technological University.
Wu C., Lu Y., and Hao H., 2002. Parametric calculations of underground
explosion induced stress wave propagation and ground shockprediction, Technical Report, PTRC-CSE/DSTA/2000.02, Protective

Simplified Methodology for Damage Assessment of 2-Storey RC Frame Subjected to EIGMS

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October 2005, 2005

Technology Research Centre, School of Civil and Environmental
Engineering, Singapore: Nanyang Technological University.
Malvern, L.E., 1951. The propagation of longitudinal waves of plastic
deformation in a bar of material exhibiting a strain-rate effect. Journalof Applied Mechanics, Transactions of ASME, Vol 18, 203–208.
Comité Euro-International du Béton (CEB), 1993. CEB-FIP Model Code
1990, Redwood Books, Trowbridge, Wiltshire, UK.
Malvar, L.J., 1998. Review of static and dynamic properties of steel
reinforcing bars. ACI Materials Journal 95, 609-616.
Karagozian, and Case (K&C), 1973. Construction Joint Test Program. Final
Report to Space and Missile Systems Organization, Norton AFB,
Contract F04701-72-C-0358, Glendale, CA.
Priestley M.N.J., Verma R., and Xiao Y., 1994. Seismic shear strength ofreinforced concrete columns. Journal of Structural Engineering,
ASCE, Vol 120, 2310-2329.
Li, Q.M., and Jones, N., 2000. Formation of a shear localization in structuralelements under transverse dynamic loads. International Journal of
Solids and Structures, Vol 37, 6683-6704.

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EFFECTS OF EXTERIOR CLADDINGPANELS ON RESPONSES OF MULTISTOREY RC FRAME STRUCTURES TODISTANT EXPLOSIONS
Haicheng Rong, Bing Li and Tso-Chien Pan
Protective Technology Research Centre, School of Civil and Environmental
Engineering, Nanyang Technological University, Singapore
cbli@ntu.edu.sg
ABSTRACT
Responses of multi-storey reinforced concrete frame structures withand without exterior cladding panels subjected to blast loadings fromdistant intense surface explosions are studied with the program ABAQUS.
The finite element models involved are then verified by comparing thenumerically results of a reinforced concrete beam and slab under blast
loadings with available experimental data. Analytical results indicate that
due to the variation of the blast forces received, the dynamic responses aremuch more severe for the frame structure with exterior cladding panels thanthe one without exterior wall panels under the same blast condition. The
whole dynamic response process of the frame structure with exterior
cladding panels can be approximately divided into two stages with thelocalized responses of the blast-loaded members critical in the initial stage
and with the increase in time, the structural global response dominant at alater stage.
1. INTRODUCTION
The behaviour of civilian reinforced concrete structures under blast
conditions has become of a major concern to structural engineers due to therecent surge in explosive events worldwide. After the trigger of a blast, a
blast wave including a high-pressure shock front is formed which expands
outward from the centre of detonation. As the blast wave strikes a building,the analysis of overpressure and drag force of the blast wave load on the
structure, the interaction between which is extremely complicated. However,considering the relative distance of the detonation centre with the target
structure as well as the size of the structure itself, two classes of blast wavestructure interaction can be generally identified as shown in Figure 1. The
first one is the interaction of a blast wave produced by the detonation of asmaller charge loading a target structure at a short standoff distance, which
is typical for most terrorist attacks such as car bombings. The second one is
the interaction of a blast wave on a relatively distant structure as might bepresent due to an accidental severe surface explosion of petroleum refineries,
chemical plants and ammunition storage areas, or nuclear devices ofsubstantial yields.

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Blast wave

Blast wave

Figure 1 Two classes of blast wave-structure interaction
The profiles of blast loadings on the structure tend to be different withinthese two classes of blast wave-structure interaction. In the first class, theblast pressures are produced locally to individual structural members andthe members are likely to be loaded sequentially. By comparison, in thesecond class of blast wave-structure interaction, the target structure isengulfed due to the diffraction of the blast wave and a normal squashingforce will be applied to every exposed surface. Many explosion tests andnumerical analyses have been carried out on the behaviours of structures in
the first class of blast wave-structure interaction where the blast pressures
are applied locally to individual structural members resulting in thepossibility of an excessive local failure of several critical structuralmembers and further the progressive collapse noticeable in a non-redundant
structure. However little research has been devoted to behaviours of civilian
structures and their possible failure mechanisms in the second class of blast
wave-structure interaction and the available literature is also very limited.
This paper aims to study the structural behaviours in the second class of
blast wave-structure interaction especially for multi-storey reinforced
concrete frame structures which are mostly common to the civilianbuildings. The findings from this study are used to reach conclusions andrecommendations in the blast resistant design concerning explosive safety
for civilian reinforced concrete frame structures.
2. BLAST LOADINGS
Determination of the exact blast loadings of a distant explosion on the front,
top and the sides, and the rear faces of the closed target is almost unrealistic
considering the complicated process of the interaction of the blast wave withthe concerned target. In order to reduce the complex problem of blast
loadings to reasonable terms, a computational procedure is recommended in
TM5-855-1 (1986) based on two assumptions that (a) the target is generally
rectangular in shape, and (b) the object being loaded is in the region of theMach reflection. These two assumptions are rational for the derivation of
the blast loadings on rectangular targets in a relatively large standoff blast
environment. The simplified loading configurations on various faces areshown in Figure 2 whose parameter can be calculated with the equations
listed in TM5-855-1 for a closed rectangular aboveground target, i.e. acolumn, a beam, or a closed structure.

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P or
0

t2

t1

S

Top face loads

Pr

f

b

e

d

D

d'
D'
Hs

Blast wave

P tc
0

L

tof

t r tcoFront face loads

W s /2

Ws

L

Blast wave

P ob
0 t3

t4

t5

Rear face loads

Figure 2 Blast loadings on a simply closed rectangular target
The computation of the blast loadings on a frame structure is relatively more
complicated than that plotted in Figure 2 since the whole structure could not
be arbitrarily taken as a closed rectangular target. The loading profiles
applied to the frame structure are dependent on the out-of-plane strength andstiffness of exterior cladding panels due to the direct action of blast loadingson them, as well as their connection with the frame members of beams andcolumns. In this study, two extreme cases are considered that
• The exterior cladding panels are constructed with the material ofreinforced concrete with significant strength and stiffness.
• there is no exterior cladding panels for the frame structure (bareframe structure);
In the case of frame structure with exterior cladding panels made ofreinforced concrete, the cladding panels possess the significant out-of-plane
strength, stiffness and strong connection with other frame members. As theblast wave hits the outer surfaces of the structure (outer surfaces of exterior
cladding panels, exterior beams and columns), the blast wave can not go
into the building and the blast loadings on the cladding panels would betransferred to the primary frames in terms of reaction forces. Thesetransferred reaction forces together with the blast loadings acting directly on
the outer surfaces of the exterior beams and columns will produce dynamic
responses of the structure. Therefore, it is reasonable to treat the whole
structure as a closed target, based on which the blast forces upon the front,
roof and rear faces are computed.
As for the second case, the blast wave front would enter the building
producing a high pressure on the rear faces of the columns. Figure 2 can not
be directly used for computing the blast loadings on a bare frame structuresince the whole structure can not be taken as a closed rectangular target.
However, the shock wave front in the distant surface explosion condition isessentially parallel to the front faces of the blast-loaded columns. By taking
each column as a closed rectangular target, the blast forces on the front andrear faces of the columns could be evaluated according to Figure 2 where
the parameters ( L , Ws and H s ) are equal to those of each column. The blast
loadings on both side faces of each column are identical as well as on the
top and bottom surfaces of each slab leading to a zero resultant force due toEffects of Exterior Cladding Panels on Responses of Multi-storey RC Frame Structures to Distant
Explosions343

October 2005, Singapore

the blast wave approximates to a planar wave, and therefore they are nottaken into account in the analysis
In addition to blast overpressure effects, intense surface explosions produce
ground shocks as results of the directly induced ground motion propagating
through the soil or rock, which might affect structural responses. Howeverconsidering the fact that the target to be studied is located at a large standoff
distance relative to the source of explosion, the magnitude of the groundshock has been greatly diminished and the arrival time of the shocks to thestructures is different from that of blast wave. Therefore the direct groundshocks are ignored in this analysis.
3. DESIGN OF THE TARGET FRAME STRUCTURE
To study the dynamic behaviours of frame structures under the distant blast
conditions, a three-dimensional six-storey reinforced concrete frame
structure is designed according to BS 8110. The loads involved in the design
include the dead loads (5.0 kPa), the super imposed dead loads (1.0 kPa),
the live loads (4.0 kPa), and the wind loads calculated in accordance with
the BS 6399 code by taking the wind speed to be 30 m/sec. The layout of
the structure and the reinforcement details of structural members are shownin Figure 3.
A blast wave produced by the detonations equivalent to a 50 ton TNT at the
ground level with a standoff distance of 100 m is considered in the study. In
these blast conditions where the standoff distance is significantly larger than
the size of the target structure, the blast wave can be reasonably modeledwith a planar wave as displayed in Figure 3. The wave engulfs the whole
structure producing blast pressures on exposed surfaces of the structure
uniformly distributed not only along the width of the structure but also
along the height. Due to the symmetry of both the configuration of the target
structure and the blast pressure distributions on it, a three-dimensional subframe including a planar frame and half of adjacent components is modelled
to simulate the whole structural dynamic responses.
Two numerical examples are performed for the six-storey frame structure inorder to incorporate the effects of exterior cladding panels on the structural
blast responses. In the first example, the exterior cladding panels are
assumed made of reinforced concrete with sufficiently out-of-plane strengthand stiffness to prevent the blast waves from entering the building, therefore
the modelling of the structural responses have to include the exterior
cladding panels (whose reinforcement arrangements are found in Figure 3c),
together with the floor slabs, beams and columns. In the second example,
the structure is built without exterior cladding panels. As discussed
previously, the frame structure in such a situation can be assumed to be abare frame against the blast loadings, accordingly only the beams, columns
and floor slabs are modelled for the numerical simulations.

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Blast wave

4500

6000

4500

6000

Blast wave

6000
18000

22200

Analytical
3D sub-frame

6000

6000

3300 3300 3300 3300

ICUS Report 11

6000

6000

18000

Figure 3 Details of the target six-storey frame structure

4. FINITE ELEMENT MODELSThe three-dimensional six-storey sub-frame structures are modelled to performthe numerical simulations of the structural dynamic responses under theconcerned blast conditions by utilizing the program ABAQUS (2004). The
finite element models consist of the structural modelling, material modelling of
concrete and reinforcement, the analysis steps and loads, and the integration
methods.

4.1 Structural modelling
Two types of structural members are included in the sub-frames, namely theframe members composed of beams and columns, and the planar members
including exterior cladding panels and floor slabs. In order to obtain moreaccurate simulations of the structural responses in blast conditions, threedimensional continuum solid elements should be employed in modelling thesestructural members. However it involves considerably greater computational
efforts due to the complicated nonlinear behaviours of the concrete andreinforcement as well as the extremely large size of the finite element model.
For simplicity, Timoshenko beam elements for modelling frame beams andcolumns, together with shell elements for exterior cladding panels and floorslabs are adopted. Reinforcement in the concrete modelled by means of rebars,
which are one-dimensional strain theory elements (rods) defined singly orembedded in oriented surfaces. Each rebar is placed at its corresponding
location for the beam elements while the layers of rebar are defined for theshell elements with the needed data-input of rebar’s area, location, and thespace length.

4.2 Material modelling
The dynamic responses of reinforced concrete structures under blast conditions
are dependent on the material properties of the concrete and reinforcement. To
obtain valid numerical simulations of the dynamic responses of the structures,the accurate modelling of the material properties becomes essential. In thefinite element analysis, the material behaviours of the concrete, reinforcing bars
and the bondages between them should be taken into account. It is presumed
that the bars are perfectly bonded with concrete. Although it will impose someerrors, it is the only practical solution for the numerical simulations of the
responses of reinforced concrete structural systems, considering theunmanageable size of the computational work and the lack of reliable data on
this topic in blast environments. The stiffness used in the analysis for unloaded

Effects of Exterior Cladding Panels on Responses of Multi-storey RC Frame Structures to Distant
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concrete in tension and compression is also given in Figure 4. When thecracked concrete is unloaded, the secant unloading modulus is utilized as
stiffness so that the strain across the crack is reduced linearly to zero as thestress approaches zero. If the load is removed at some point after inelasticstraining has occurred for the concrete in compression, the unloading response
is softer than the initial elastic response, but this effect is ignored in this model.
Thus initial elastic stiffness is used when the concrete in compression is
unloaded.

Figure 4 Concrete modelling
The von-Mises yield criterion is used to describe the constitutive behaviour of
the reinforcement. The stress-strain relationship of reinforcement is modelledwith an elasto-plastic curve. The strain hardening of reinforcement is notconsidered in this analysis since it is hard to define under the blast conditions in
the case of lacking enough experimental data. The ultimate strain value is often
not reported in current literatures due to the difficulty of determining exactly
when the peak stress occurs as well as the confusion between ultimate strain
and rupture strain. In order to consider the fact that under higher loading rates
both concrete and reinforcement exhibit increased strengths, a dynamic
increase factor (DIF), the ratio of the dynamic to static strength, is employed inthis analysis. The expressions by Malvar and Crawford (1998) are utilized
which are derived from a literature review of the extensive test data about theeffects of strain rate on the strength of concrete and reinforcement. To integrate
the DIF expressions into the analysis, the user subroutine USDFLD is usedwhich allows the user to define the field variable at a material point as afunction of any of available material point quantities. Thus by taking the strain
rate as a field variable, the strain rate-dependent material properties can be
introduced in the analysis.

4.3 Application of loads and analysis procedure
In the simulation of the structural blast responses, two steps of analyses arecarried out according to different loading stages. Before the occurrence of an
explosion, the service loads have been already imposed on the structure. The
intensity and distribution of the stresses and strains induced by the service loads
will influence the structural behaviours under blast conditions. Thus nonlinear
static analysis is performed priorly for the three-dimensional sub-frame
structure under service loads. The loads involved in this step include the live
loads, the dead loads and the super imposed dead loads. The second step is the
dynamic response simulation of frame structures loaded by blast pressures
where the nonlinear dynamic analysis is performed. The functions of blast

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pressures on the structures which are necessary in this step are discussed for thebare frame structure and the frame with exterior cladding panels, respectively,
as follows.
500

Blast forces on different faces

400

Pressure (kPa)

Front wall

Blast wave

300

200

Top slab
Rear wall

100

0
0

25

50

75

100

125

150

Time (ms)
B

A

C

D

Figure 5 Blast loadings on the frame structure with exterior cladding
panels500

Blast force on columns at Axis A

Pressure (kPa)

400

Blast wave

300

200
Front face
100
Rear face
0
0

10

20

30

40

50

60

Time (ms)A

400

Blast force on columns at Axis B

B

C

350

Blast force on columns at Axis C

D

Blast force on columns at Axis D
300

350

300
250

300

200
150

Front face

100
50

10

20

30

200
150
Front face
100

200
150
Front face
100
50

50

Rear face

Rear face00Pressure (kPa)

Pressure (kPa)

Pressure (kPa)

250
250

40

Time (ms)

50

60

70

Rear face
0

0
0

10

20

30

40

50

60

70

80

90

0

10

20

Time (ms)

30

40

50

60

70

80

90 100 110

Time (ms)Figure 6 Blast loadings on the bare frame structure
For the frame structure with reinforced concrete exterior cladding panels, by
taking the whole structure as a closed rectangular target, the blast force
functions on the front, top and rear surfaces are evaluated as demonstrated in
Figure 5. In this case, while the reflected pressure dominates in the blast
loadings on the front cladding panels, the blast pressures composed of theincident overpressure and dynamic pressure dominate on the top and rearsurface. As for as the bare frame structure, the planar wave enters the structureloading each exposed columns, thus by taking each column as a closed
rectangular target, the functions of blast forces on its front and rear faces are
obtained and the results under the blast condition mentioned above are shownin Figure 6 where the shadow area stands for the net blast pressure on eachcolumn.

5. VERIFICATION OF FINITE ELEMENT MODELS
The verification of the finite element models as mentioned above is carried out
by implementing it into the analysis of a simply supported beam subjected

Effects of Exterior Cladding Panels on Responses of Multi-storey RC Frame Structures to Distant
Explosions347

October 2005, Singapore

to blast loadings tested by Seabold (1967) and a square slab, clamped andlongitudinally restrained along all edges exposed to uniform lateralpressure tested by Keennan (1969). The computed and experimental results
for the beam and the slab are compared in Figure 7. It can be seen that theanalytical results agree well with the experimental response. Therefore thenumerical model has the ability to simulate the failure process of concrete
and reinforcement, which are thus integrated into the nonlinear analysis of
the blast-loaded six-storey frame structure.
12

25
20
15

Numerical analysis
Experimental results

10
5

0.0

10
8
6
4

Numerical analysis
Experimental results

2

Strain at mid-span of beam

Deflection at center of slab (mm)Mid-span deflection of beam (mm)300-5.0x10-4-1.0x10-3-1.5x10-3-2.0x10

0

5

10

15

20

25

0

30

1

2

3

4

5

6

7

8

-3

-2.5x10

-3

-3

-3

Strain1.0x10-4

5.0x10

0.0
0

2

4

6

8

-4

10

Time (ms)-5.0x10

Support reaction (N)Tensile steel-numerical analysis
Tensile steel-experimental-3

1.5x102.5x105

2.0x105

1.5x105

1.0x105

5.0x104

Numerical analysis
Experimental results-3-1.0x10-3-1.5x10

8

10

12

14

Top compressive strain-numericalanalysis of concrete at beam mid-span
Top compressive strain-experimental
analysis of concrete at beam mid-span

3.0

Compressive steel-numerical analysis
Compressive steel-experimental

0.0
0

5

10

15

Time (ms)20

25

Velocity at mid-span of beam

2.5x10-3

6Time (ms)Time (ms)

2.0x104Time (ms)

0

0

2

2.5

Numerical analysis
Experimental results

2.0
1.5
1.0
0.5
0.0
-0.5

0

5

10

15

20

25

30

Time (ms)

-1.0
-1.5
-2.0

Figure 7 Comparison of experimental data with analytical results

6. NUMERICAL EXAMPLES
6.1 Example I ⎯ Frame structure with exterior cladding panels
A more detailed description of the structure responses and its damage
propagation with time are shown in Figure 8. A flexural plastic hinge isassumed to initiate when the longitudinal tensile reinforcement first yields ata point along the beam element and the hinge will continue to spread over acontinuous portion of the beam. Thus the occurrence time of the hingecorresponds with the first appearance of plastic strain of reinforcement
whose variation with time can be found from the numerical analysis in
ABAQUS (2004). It is obvious that the structural responses can be divided
into two responses stages. The difference between the time of forming thisdamage mechanism on the front columns and top-storey beams is caused by
the difference of the time when the peak blast pressures acting on them isreached. As for the other frame members, almost no plastic deformation ispresent.
At a later stage, the structural dynamic response is in a mode where theglobal response of the structural system as a whole dominates; hence the
distribution of damage as well as its propagation with time is in a different
manner with those at the initial stage. As shown in Figure 8, plastic hinges
are formed firstly on both end sections of the first-storey columns at a time348

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of about 60 ms as the inter-storey drift within this storey increases. Later,
damage spreads upward with more plastic hinges successively formed on
those connected cross sections around the joints located in the first andsecond floor levels. Since the plastic hinges formed at this stage are causedby large global sideway responses, they appear only at the end sections ofstructural members.

B

A

C

D

B

A

C

B

A

D

MIDR= 0.12%
MIDR= 0.67%( t = 15 ms)( t = 40 ms)
Initial stage

C

D

A

MIDR= 1.20%( t = 60 ms)

B

C

D

B

A

MIDR= 2.13%( t = 100ms)
Later stageC

D

MIDR= 2.88%(t = 180 ms)

Figure 8 Plastic hinge propagation with time (Example I)

6.2 Example II ⎯ Bare frame structure
The numerical simulation results of the energy responses for the six-storey
bare frame structure under the concerned blast condition are presented in
Figure 10. It can be seen that due to the absence of the exterior cladding
panels, this bare frame will experience a much slighter dynamic responses
when compared with the first case study. Therefore much less damage is
induced as shown in Figure 9 where only a small magnitude of 1.0 kNm ofplastic energy appears on the floor slabs. As for the frame members(columns and beams) there is no plastic deformation on them.

800

0.03

600

Within the whole structure
Within the floor slabs
Within the beams and columns

400

200

0.02
0.01
0.00

0
0.1

0.2

0.3

Time (s)

0.4

0.5

5
4

t=0.031st=0.051s
t=0.084s
t=0.145st=0.181st=0.198st=0.267s

3
2

1

0.0
-0.01

0.0

First storey
Second storey
Third storey
Forth storey
Fifth storey
Sixth storey

Storey level

0.04

Storey drifts (m)Plastic strain energy (Nm)

6

1000

0.1

0.2

0.3

Time (s)

0.4

0.5

0.6

0.7
0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.6

-0.02

Storey drifts (m)Figure 9 Responses of bare frame structure (Example II)

The responses of structural storey drift demonstrate that the maximum interstorey drift, which happens to the second-storey level, is only about 9.5 mm
equivalent to a MIDR of 0.21%. The MIDRs within other storey levels are
smaller than this value and thus there is no global damage to the structure
under this blast condition. In addition, from the storey drift contours at
different time stations shown in Figure 9, it is obvious that the maximum
storey drift occurs firstly at the first storey whereas with the lengthening oftime it will move upwardly to the second storey and third storey until it ispresent on the top storey in sequence. Thus a transverse wave is formed in
the frame structure.

Effects of Exterior Cladding Panels on Responses of Multi-storey RC Frame Structures to Distant
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7. SUMMARIES

Based on the analytical results, the following conclusions can be drawn
regarding dynamic responses and damage distributions of a six-storey
reinforced concrete frame structure with or without exterior cladding panels
under distant blast conditions:
1. The responses of the frame structure with reinforced concrete
exterior wall panels can be approximately divided into two stages;
localized responses of the blast-loaded members are critical in theinitial response stage while the global responses of the structural
system dominate at a later stage. In addition, the flexural responses
play a more important role in the plastic deformation of frame beams
and columns in comparison to their respective shear responses.
2. In the identical blast situation, the existence of reinforced concrete
exterior cladding panels produces more severe dynamic responses
than those of the bare frame structure. Due to the diffraction of theblast waves around the columns, reflected pressure will quickly
reduce to zero for the bare frame structure and only the drag forces
associated with the dynamic pressure are critical in the net blast
loadings on the structure. However the exterior cladding panels
cause the structure to be loaded with reflected blast pressure,
overpressure, and dynamic pressure, thus the blast forces received by
the frame structure with cladding panels are much greater. To
dissipate the work produced by such a large blast force, some plastic
deformation would appear to the structure producing damage tosome extent as expected in the numerical studies.
REFERENCES

TM 5-855-1.,1999 Fundamental of protective design for conventional
weapons. United States Department of the Army, Washington D. C.
ABAQUS. 2004 ABAQUS/Standard user’s manual. HKS, Inc.
Malvar L.J. and Crawford J.E. 1998 Dynamic increase factors for concrete.
Twenty-Eighth DDESB Seminar, Orlando, FL. 1998.
Malvar L.J. and Crawford J.E.,1998 Dynamic increase factors for steel
reinforcing bar. Twenty-Eighth DDESB Seminar, Orlando, FL.
Seabold R. H., 1967 Dynamic shear strength of reinforced concrete beams,
part II. Naval Civil Engineering Laboratory, Port Hueneme, California.
Keenan, W. A.,1969 Strength and behaviour of restrained reinforced
concrete slabs under static and dynamic loadings, Technical Report
R-621, Y-F008-08-02-123, DASA-RSS3318, Naval Civil Engineering
Laboratory, California.

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EARTHQUAKE RESISTANTCONSTRUCTION IN THE URBAN AREAS
OF ANDHRA PRADESH (INDIA): PRESENTPRACTICES AND IMMEDIATEREQUIREMENTS
SHYAM SUNDER REDDY T.1 AND RAMANCHARLA PRADEEP KUMAR2
1. Ph.D. Student, Computer Aided Structural Engineering, International Institute ofInformation Technology Hyderabad, Hyderabad – 500 019, India.
2. Assistant. Professor, Earthquake Engineering Research Centre, International Instituteof Information Technology Hyderabad, Hyderabad – 500 019, INDIA
e-mail: ramancharla@iiit.ac.in

ABSTRACT
According to seismic Zone map of India given in IS 1893-2002(Criteria for earthquake resistant design of structure), 34% of Andhra
Pradesh (AP) falls in zone III which is having the possibility of earthquakes
up to intensity VII (MSK) or more. Active zones in the state are the Eastern
Ghat belt and Godavari Valley. Recorded seismic history of AP shows thatthe state has experienced earthquake of magnitude up to 5.7 on the Richterscale i.e., Vizianagaram (M5.5 1917, Ongole (M5.4, 1967) andBadrachalam (M5.7 1969). Though not much of damage occurred due tothese events, the earthquake in Killari (M6.3 1993) brought to the forefront
the possibility of high risk to urban areas of AP, where building
construction activity is growing at phenomenal rate. And also according toIS 1893-2002 the state is in the proximity of zone III areas of Maharastra,
Orissa, Tamilnadu and Karnataka apart from being near to Andaman &Nicobar Islands which fall in zone V.
Major urban centers of the state with mushrooming apartments andcommercial complexes are Hyderabad (Zone II) with population over 6.0
million, Visakapatnam (zone II) with population of over 2.0 million andVijayawada (zone III) with population over 1.8 million. Other important
towns which fall in zone III are Tirupati, Nellore and Cuddapah. As there isgreat demand for parking in urban areas, existing building bylaws allow
stilt and upper floors to be used as parking. Also the existing practice isextension of building all around on cantilevers beyond the column line,
supporting upper floors on floating columns. Such practices lead to serious
consequences in the event earthquake. However the existing rules do nothave any methodology to check the plan and structural design/detailingwhile approving building permission. Authors study the existing
construction practices in major cities of AP considering seismic hazard
levels and suggest necessary changes in building bylaws, planning
regulations, structural design/detailing and construction practices.

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October 2005, Singapore

1. EARTHQUAKE SCENARIO OF URBAN AREAS IN ANDHRA
PRADESH
1.1 Earthquake concerns of the state
Andhra Pradesh, one of the major states of INDIA is located incentral part of Peninsular Indian Shield. Though Peninsular Region
considered to be stable has been experiencing major damaging Earthquakes
for the last few decades. As the Indian plate hitting against the mass of theEurasian plate, which is situated in the north, inter plate movement
occurring in weak planes along existing faults in peninsular region lead toearthquakes. The recent Lathur Earthquake of 1993 and Jabalpur earthquakeof 1997 have proven that the faults in peninsular region are active andcausing earthquakes.
The other major concern for Andhra Pradesh is its long coast line along
Indian Ocean (Bay of Bengal) which has very active faults. The recent
Tsunami which hit south Indian coastal areas and southeast Asia caused due
to earthquake of magnitude 8.9 in Indonesia (26 December 2004) and thefollowing earthquake in Andaman and Nicobar Islands brings out theinterface activity of Indian plate and Burma plate.
1.2 Active Faults in AP
The main tectonically active zones in the state are Eastern Ghat belt
and Godavary river valley. The Gundlakamma Fault which extends in a
NW-SE direction front near Ongole on the coast running inland for about
100km and kaddam Fault which runs in parts on northern Andhra Pradesh
are known active faults. Several minor faults zones also exist near
Hyderabad, Chitoor, Venukonda, Vizianagaram and Vishakapatnam.
However it must be noted that proximity to fault does not imply higher
hazard. Factors such as subsurface geology and the construction practices
define the level of hazard.
1.3 Significant Earthquakes
Vizianagaram earthquake of 1917 (M 5.5), Ongole earthquake of 1967
(M 5.4) connected with Eastern Ghat and Badrachalam earthquake of 13
April 1969 (M 5.7 and Intensity VII) connected to Godavary valley are thesignificant earthquakes recorded. Most of the other recorded earthquakes inthe state are of small category. Ongole town with population of 1.5 lakh has
14 number of recorded earthquakes in the last 200 years out of which 12 isrecorded between 1950 to 2000 period. The largest recorded magnitude wasM5.4 in 1967.
1.4 Growing Urban Centres and recorded earthquakes.
As per the 2001 census the AP state has a population of 75.73
million in which 27.08% are living in urban areas. There are total of 210
towns in which 98 towns are having population of more than 50,000 andhalf of them have a population of one lakh and above. The major fast

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growing urban agglomeration areas in the state are covered under Urban
Development Authorities jurisdiction. Each of the Urban Development
Authorities has Municipalities and Grampanchayats within. Table 1 lists
Urban Development Authorities in the state
Table 1: Urban Development Authorities in the state
Sl.
No
1
2

3
4
5

Authority
Hyderabad Urban Development
Authority (HUDA)
Vijayawada Guntur Mangalagir
and Tenali Urban Development
Authority(VGTMUDA)
Vishkapatanam Urban
Development Authority(VUDA)
Thirupati Urban Development
Authority(TUDA)
Kakatiya Urban Development
Authority(KUDA)

Area
(km2)
1864

Population(million)
6.5

Seismic
zone
II

1550

1.8

III

1721

2.1

II

848

0.75

III

663

0.6

II

All the Above Development Authority Areas are developing very fast and as
the land prices are constantly increasing, people are opting more forapartments. Due to high demand of parking areas in residential andcommercial areas, multilevel parking floors area proposed above groundlevel which acts like soft floors. This trend is more in HUDA area followed
by VUDA, VGTM and TUDA. Apart from the above urban areas, manyother towns in AP are adopting soft floor multi storied structures.
Many of the towns in the state have number of recorded earthquakes in thelast 200 years (records available from 1800 onwards). However the majorurban centers having more than 2 earthquake incidents in the last 200 years
are Hyderabad, Visakapatnam, Guntur, Nellore, Vizianagaram, Ongole,
Kothagudam, Badrachalam and Venukonda.

1.5 Seismic Hazard Zones
As per IS 1893-2002, India is divided into four seismic zones i.e., zone II
to zone V (see figure 1). The state of Andhra Pradesh lies in seismic zones II
and III. Major towns/districts in zone III are Vijayawada, Guntur, Nellore,
Warngal, Rajamundry, Chitoor, Badrachalam, Ongole Cudappah, Kakinada,
and Khammam (see figure 2). It may be seen from the map that many urban
areas are falling in zone III. Almost 11 districts of the state are partially offully in zone III. Districts that lie in the Godavari and Krishna river valleys,
including the Godavari-Krishna delta region lie in Zone II. The city ofHyderabad lies in Zone II. Figure 3 shows the earthquake occurrences in thestate of AP. From the figure, it can be seen that the seismicity of Ongole
region is high compared to other areas.

Earthquake Resistant Constructions in Urban Areas of Andhra Pradesh (India)353

October 2005, Singapore

Figure 2: Zone map of AP

Figure 1: Seismic zone map of India

Figure 3: Seismicity of Andhra Pradesh
2: PRESENT CONSTRUCTION SCENARIO IN ANDHRA PRADESH
2.1 Apartment Buildings all around
Apartments and commercial complexes of more than 3 floors havebecome a common place in all big and small towns in the state. Due toconvenience of use and driving advantage, the parking floor is build as stilt
floor at ground level without any walls. The concept of apartmentcomplexes was initially started in 1980 in Hyderabad as an affordable
alternative solution by Andhra Pradesh Housing Board (APHB). Due tohigh demand for such housing units called flats, private builders started
building the complexes and by 1990, the city of Hyderabad has changed its
skyline with apartment buildings everywhere. Slowly the other cities
Vishakhapatnam, Vijayawada and Tirupathi followed. The culture ofapartments has spread to other cities like Kakinada, Guntur, Khammum,

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Tanuku, Miryalaguda, Warangal etc. Today in 2005 one can find Apartmentcomplexes of 3 to five floors in all district centers and in many small towns.
Ten acres and above apartment Towns can be seen in and around
Hyderabad with individual blocks of ten floors and above having two or
more parking floors above ground. As land prices are continuously raising,apartment complexes of twenty floors and above are being planned and APState Govt has already proposed new building rules to accommodate suchbuildings.
2.2 Need for stilt parking floors (soft floor)
All the apartment complexes built initially by APHB had no covered
parking provision. However, the entire scene of construction changed andparking floor became an essential need. As people started liking parking at
ground level, stilt parking became a standard and government changed its
building rules. Figure 4 and 5 shows typical open ground storey buildings inHyderabad and Vijayawada. As per the existing building rules, forcomplexes proposed in less than 1000 m2 only stilt floor is allowed. No
brick walls are allowed in parking floors. Stilt floors act as soft floors
causing heavy damages during earthquake (see figure 6) unless they aredesigned with utmost care.

Figure 4: Parking floors

Figure 5: Open ground storey

2.3 Cantilever Projections and floating columns
To maximize built up area while keeping set backs intact, the mostingenious method adopted by the builder is to project the building on
cantilever up to 2.5 to 3 m from first floor. Most of the times, theprojected area is covered into rooms and floating columns are raised fromfirst floor. Cantilevers and floating columns would create an adverse stressin the structure and lead to collapse.
Figures 7 shows typical cantilever projections adopted in a building
constructed recently. Figure 8 shows the floating columns being
constructed in a structure.

Earthquake Resistant Constructions in Urban Areas of Andhra Pradesh (India)355

October 2005, Singapore

Figure 6: Collapse of open ground storey structure during Bhuj
Earthquake

Figure 7: Cantilever beams of 2.5 m

Figure 8: Floating columns raised
from first floor on both sides

2.4 Code provisions and practices in construction detailing:
Indian Standard codes published by Bureau of Indian standards arevery comprehensive and they are being revised regularly. The mostimportant codes governing RC structure design and ductile detailing for the
structural safety and durability of buildings are the following.
a) IS 456:2000 Code of Practice for Plain and Reinforced Concrete.
b) IS 1893 (Part 1):2002 Criteria for Earthquake Design of Structures,
general provisions and Buildings.
c) IS 13920:1993 Ductile Detailing of Reinforced Concrete Structures
Subjected to Seismic forces- Code of Practice.
d) IS 4326: 1993 Earthquake Resistant Design and Construction of
Buildings – Code of Practicee) SP- 34: 1987 Handbook on Concrete Reinforcement and Detailing,
BIS

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ICUS Report 11

Apart from the above there are number of other important IS Codes forstructural safety, such as Pile Foundations, Retaining Walls, Steel Structures,
Loading, , Material Testing, Fire safety etc.
The most important ductile detailing and other reinforcement provisions in
the codes are hardly enforced in the present construction practices in thestate. The following are the important wrong Practices which need
immediate attention by all concerned in the industry.
•

Development Length which is most important for reinforcement toattain its strength is the most neglected in execution. Top andBottom reinforcement at ends in beams are hardly provided with therequired development length.

•

Proper Placement of Steel is most important for strength anddurability which is hardly taken care on sites. Steel cover in slab for
cranked top steel is never maintained properly and most of the times it
is moved down below neutral axis while concreting.

•Transfers Reinforcement in Columns, Special Confining stirrups(in Columns, Joints and Foundations), Spacing of Hoops in Beams
and hook bends in stirrups are grossly neglected•

Verticality of the Column in each floor and from floor to floor isinvariably not maintained.

•

Concrete Preparation, Column Marking in each floor, Curing and
Shuttering are other important Contraction activities where known
errors are always continued.

•

Important Detailing Provisions of the Codes IS 1392:1993, SP 34(S&T):1987 which are neglected are illustrated in images 3.1 to 3.7.

Figure 9: Detailing provisions in IS 13920

Earthquake Resistant Constructions in Urban Areas of Andhra Pradesh (India)357

October 2005, Singapore

Figure 10: Detailing provision of column in IS 13920
3. BUILDING RULES AND URBAN PLANNING ISSUES
3.1 Building Control Rules
Municipal Administration and Urban Development (MAUD)
department of the state government brings out Govt. Go’s concerned withmunicipalities and all towns. The present building rules are governed by thefollowing important G.Os.
a) G.O. Ms. No 423 and M.A. dated: 31st July 1998: This G.O specifies
permissible F.A.R (Floor Area Ratio) and set back rules for various
land uses and road widths. It also specifies other building
requirements such as parking, common areas, permissible balcony
projections and other special regulations.
b) G.O.Ms.No.483, M.A. dated 29th august 1998: This G.O specifies
certain relaxations to building and zoning regulations it also gives
extra F.A.R for road widening cases.

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ICUS Report 11c) G.O.Ms.No 528, M.A dated 25th September 1998: This G.O
specifies land development/layout regulations.
d) G.O.Ms.No 541, M.A dated 17th November 2000: This G.O
specifies procedure for obtaining permission and fixes construction
responsibilities.
3.2 Government and Public Concern for the Rules.
Apart from the above G.Os, there are number of other relevant G.Os,
acts and policies that govern building industry in the state. Urban Land
Ceiling Act, Tourism policy, Industrial policy, land acquisition act,
Regularization act, special G.Os. And also court judgments do control thebuilding process.
In all the above G.Os an attempt is made to regulate building constructions
with reference to architectural and planning issues. However, there are no
special regulations for safety of the buildings against earthquakes. Neither
the master plan nor the zonal development plan of any city/region in thestate has any proposals to safeguard buildings against earthquakes. It would
be of great help if land use and planning proposals incorporate the regional
seismic demands and safeguards.
As the profit is the prime motto of a builder, he finds a number of ingenious
methods to circumvent the rules. As he employees the professionals whose
prime concern is to serve the client, they also some time become
instrumental in building for the worst.
However after the Bhuj Earthquake of 2001, there is a positive change
among all to improve the safety of the buildings. AP state Govt Revenue
and Relief Department has prepared a manual of “Earthquake Contingency
Plan “in 2002 which attempts to identify the vulnerable urban and regional
areas of different districts and proposes an auction plan for earthquake
preparedness and immediate rescue/relief measures. Though the attempt isvery much appreciable, no concrete steps are proposed in terms of building
construction regulations.
Government of India, Ministry of Home Affairs through its National
Disaster Management Division has constituted an expert committee which
prepared a report in September 2004 proposing Model Building Bye - Laws,
amendments to Town and Country Planning Act and Zoning Regulations forhazard safety. The Recommendations of the committee are widely
circulated to all concerned state and central government deportments andother professional institutions for discussions and opinions. The attempt byCentral Government is very much appreciated and the recommendations
proposed are more of legislative in nature.

Earthquake Resistant Constructions in Urban Areas of Andhra Pradesh (India)359

October 2005, Singapore

4. CONCLUSIONS
During discussions with state Govt. officers in municipality andother planning departments it is found that they are equally concernedwith the earthquake safety but they are not well equipped with theknowledge and the required technical, political and administrative support
is lacking. Apart from the officers, Builders, Architects, Engineers andTown Planners have to acquire the subject knowledge of earthquake
forces and methodology to build earthquake resistant buildings. Without
the active support of all people involved with construction, no Govt. rules
can be successfully implemented. Hence Awareness among all sections of
the society should be cultivated to mitigate earthquake risk.
As there are well defined building Bylaws for architectural and planning
controls, there should be well defined regulatory controls for Building
Construction. Though IS codes are very comprehensive, a mechanism isrequired for strict practicing of the same by all sections. While Preparing
Master plan and Zonal Development Plan for any urban
area,
comprehensive hazard mitigation plan and its effective implementation
methodology should be given due importance.
Government should bring out rules so as to encourage basement and cellar(below ground) parking floors. In case parking is provided at stilt floor, it
should have sufficient lateral rigidity and the same should be ensured byproviding RC/brick walls. The existing structures in all urban areas should
be examined and strengthening measures should be taken up wherever
required.
REFERENCES
P.R.Reddy and G K.Chandrakala, 2004, Sesmicity in around Ongole,
Andhra Pradesh- an appraisal. J. Ind. Geophysics. Union (April 2004)
vol 8 No2 143-146.
Chndra, U., 1977, Earthquakes of Peninsular India _ A Seismotectonic
study, Bulletin of the Seismological Society of America, Vol67 No51387-1413.
IS 1893 (Part 1): 2002 Indian Standard Criteria for Earthquake Resistant
Design of Structures Part 1 General Provisions and Buildings (Fifth
Revision).
IS 13920:1993 Ductile Detailing of Reinforced Concrete Structures
Subjected to Seismic forces- Code of Practice.
SP- 34: 1987 Handbook on Concrete Reinforcement and Detailing, BIS

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DYNAMIC RESPONSE OFSTEEL BAR IN RC UNDER BLAST LOAD
HUAN SHI1, JIANG GUOPING1,TAN XIANGQIAN1, LIU ZHIHANG1, HUANG FENGLEI2
1 Earthquake Engineering Research Center, Guangzhu University, China.
E-mail: huanshi@gzhu.edu.cn
2 National Key Laboratory of Explosion Science, Beijing Institute ofTechnology, China.

Abstract
For evaluation and designing the blast resistant capability ofimportant buildings, there is need to make investigation for dynamic
response of steel bar in reinforced concrete (RC) under blast shock wave
load. In this paper, the dynamic response of several reinforcing steel bar inRC, excited by some given shock wave, is theoretically analyzed andnumerically simulated to investigate its movement and the damage evolution
processes. It has been found in the research that: When loaded by alongitudinal shock wave, the steel bar can be brought a longitudinal relative
movement in RC, and a crash zone formed around the steel bar at the sametime; When loaded by a transverse shock wave, some local breaks areformed between the steel bar and concrete; The thickness and thelongitudinal length of the damage zone above-mentioned are determined by
the strength and the acting time of shock wave respectively.
1. INTRODUCTION
Blast is a calamity phenomena which has terribly strong destruction. It
can be classified into physical, chemical and nuclear blast. In view of blast
befallen frequently in nature, industry and our daily life, and which is amain attack way for the war and terrorism, the probability for the importantbuilding attacked by a blast is bigger than which fall across an intensity
earthquake. The effection of blast shock wave on buildings is different fromseismic in mechanics. Blast shock wave is provided with high peak pressure,short acting time, great strain rate and rapid transmit velocity .Concrete is
widely used in civil buildings and ground or underground works. Recently,
the constitutive relationship of reinforced concrete (RC) has been widely
researched by many scientists, such as, Johnson-Cook’s model for thefracture damage of RC[1], Ottosen’s model engaged to describe the shockloading process of RC[2], Chen’s continuum damage model for dynamic
characteristics of RC[3], The modified continuum damage model[4] and thebeam-particle model in two dimension[5] is used to research the failure
process of a steel bar perforating into a RC panel.

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October 2005, Singapore

For evaluation and designing the blast resistant capability of importantbuildings, there is need to make investigation for dynamic response of steel
bar in reinforced concrete (RC) under blast shock wave load. In this paper,the dynamic response of several reinforcing steel bar in RC, excited bysome given shock wave, is theoretically analyzed and numerically simulated
to investigate its movement and the damage evolution processes.
2. THEORY ANALYSIS
One-dimensional (1-D) shock wave theory is used to analyze the typemodel (see Fig.1 and Fig.2). When steel flyer with certain thickness
impacts targets at high velocity, a 1-D plane shock wave travels along target
and steel flyer respectively, the following formulas are satisfied:
Pf = ρof (-Df – W)(Uf – W)
(1)
Pt = ρotDtU t(2)
Where P is pressure, ρo is initial density, D is shock wave velocity, W issteel flyer velocity, U is particle velocity, subscript f is for steel flyer and t
for target. The shock compressional relations are
Df ＝ Cof + λf Uf
Dt ＝ Cot + λt U t
The boundary condition is Pf = Pt and Uf = Ut = U.
From above equations we obtain

(3)
(4)

(5)
U = [ B + ( B2 + 4AC )1/2] / 2A
Where A = aλt +λf , B = (λf – 1)W – aCot – Cof ,C = Cof W + W2, a = ρot / ρof .
Material parameters are[6]ρof = 7.85(103kg/m3), Cof = 3.574(103m/s), λf = 1.920;
ρot = 2.60(103kg/m3), Cot = 3.50(103m/s), λt = 1.43.

Fig.:1 Longitudinal impact
Fig.2: Transverse impact
1. steel flyer, 2. concrete, 3. steel bar
The pressure and velocity of concrete and steel bar for longitudinal
impact are listed in Table 1, where subscript s is for steel bar and c is forconcrete, P ＝ Ps – Pc, U ＝ Uc – Us. On account of transition area
between the steel bar and concrete, the actual differential pressure Pa isless than the theoretical one P. When Pa less than the static friction
resistance, there is no relative motion occurred(seen in Table 1,*). The
critical pressure against static friction resistance Pcr is about 0.55 GPa[7].

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Table 1:Pressure and velocity of concrete and steel bar
for longitudinal impact.
0.05 0.10 0.20 0.30 0.40 0.60 0.80 1.00

W(103m/s)

Ps(GPa)0.711 1.44 2.96 4.55 6.21 9.77 13.6 17.8
Pc(GPa)0.351 0.713 1.49 2.30 3.19 5.11 7.26 9.66
P(GPa)
0.360 0.727 1.47 2.25 3.02 4.66 6.34 8.14
Us(103m/s)
0.025 0.05 0.10 0.15 0.20 0.30 0.40 0.50
3
Uc(10 m/s)
0.038 0.076 0.154 0.231 0.311 0.471 0.634 0.800
U(103m/s)*
0.026 0.054 0.081 0.111 0.171 0.234 0.300
For transverse impact, during shock wave transmission(see Fig.2),
steel bar and concrete move equidirectionally, after the shock wave removed,
the restoring displacement of steel bar is more than the concrete, so a voidband between the steel bar and concrete is formed (seen in Fig.3).

Fig.3: Void band between steel and concrete
3. NUMERICAL ANALYSIS
Dynamic finite element code ANSYS 970/LS–DYNA is used to makenumerical analysis for the above mentioned problem. Holmquist’sconstitutive model [2] is used for concrete subjected to large strains, highstrain rates and high pressure. The equivalent strength is expressed as afunction of the pressure, strain rate, and damage. The pressure is expressed
as a function of the volumetric strain and includes the effect of permanent
crushing. The damage is accumulated as a function of the plastic volumetricstrain, equivalent plastic strain and pressure. The material model type 3 isused for steel bar. This model is suited to model isotropic and kinematic
hardening plasticity with the option of including rate effects.
Fig. 4 shows the calculation model, where 1 is steel flyer, 2 is concrete,
3 is steel bar. Four examples are simulated:

1
3

2
Fig. 4: Calculation model

Dynamic Response of Steel Bar In RC Under Blast Load363

October 2005, Singapore(1) The thickness of steel flyer is 15cm. Its impact velocity is 0.04
(103m/s). The results are show in Fig.5 and Fig.6. In this case, therelative motion between the steel bar and concrete is not found.
400

P(Mpa)

P(Mpa)

400

200

200

0

0

0

5
T(µs)

10

0

15

5

10

15

T(µs)

Fig. 5: Pressure curves in steel bar(left) and concrete(right)

0.004
U(CM/µs)

U(CM/µs)

0.004

0.002

0.000

0.002

0.000
0

5

T(µs)

10

0

15

5

10

15

T(µs)

Fig.6: Particle velocity curves in steel bar(left)and concrete(right)(2) The thickness of steel flyer is 15cm. Its impact velocity is0.30(103m/s). The results are show in Fig.7 and Fig.8. In this case, therelative motion between the steel bar and concrete can be seen in
Fig.11.
3000
2500

2000

2000

1500

1500

P(Mpa)

P(Mpa)

2500

1000
500
0

1000
500

0

5
T(µs)

0

10

0

5

10

T(µs)

Fig. 7: Pressure curves in steel bar(left) and concrete(right)
0.04
U(CM/µs)

U(CM/µs)

0.04

0.02

0.02

0.00
0.00

0

5

10
T(µs)

15

0

5

10

15

T(µs)

Fig.8: Particle velocity curves in steel bar(left)and concrete(right)

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ICUS Report 11(3) The thickness of steel flyer is 9 cm. Its impact velocity is0.30(103m/s).The results are show in Fig.9 and Fig.10. In this case, therelative motion between the steel bar and concrete can be seen in
Fig.12.

1000

1000

P(Mpa)

P(Mpa)

1500

500

500

0

0
0

5

0

10

5

T(µs)

10

T(µs)

Fig. 9: Pressure curves in steel bar(left) and concrete(right)

0.02

U(CM/µs)

U(CM/µs)

0.02

0.01

0.00

0.01

0.00

0

5

0

10

5

10

T(µs)

T(µs)

Fig.10: Particle velocity curves in steel bar(left)and concrete(right)

f(mm)

4
2
0

0

5

T(µs)

10

15

Fig. 11: Relative displacement curves for 15cm steel flyer

f(mm)

4

2

0

0

5

T(µs)

10

15

Fig. 12: Relative displacement curves for 9 cm steel flyer(4) Fig. 13 is a transverse impact model. The thickness of steel flyer
is 5 cm . Its impact velocity is 0.40 (103m/s). A void band under
the steel bar can be seen in Fig. 14.

Dynamic Response of Steel Bar In RC Under Blast Load

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132Fig. 13: Transverse impact model.
1. steel flyer, 2. concrete, 3. steel bar

Fig. 14: A void band under the steel bar

1. DISCUSSION(1) When loaded by a longitudinal shock wave, the steel bar can be broughta longitudinal relative movement in RC, and a crash zone formed
around the steel bar at the same time;(2) If the actual differential pressure △Pa between the steel bar andconcrete is less than the critical pressure which against static friction
resistance △Pcr, there is no relative motion occurred;(3) The values obtained from one-dimensional theoretical analysis is morethan that from numerical calculation;(4) The longer is the shock loading time, the larger is the relative motion
between the steel bar and concrete;(5) When loaded by a transverse shock wave, some local breaks are formed
between the steel bar and concrete;(6) The thickness and the longitudinal length of the damage zone abovementioned are determined by the strength and the acting time of shock
wave respectively.

2. REFERENCES(1) Cao J. Z., Zhou S. R., Li E. Z., 1998. Effect of constitutive relation ofmaterial in numerical computation. Acta Armamentarii , 19, 69-72.
(2) Holmquist T. J., 1992. A computational constitutive model for concrete

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ICUS Report 11

to large strain, high strain rate, and high pressure. 14th International
Symposium Ballistics, 591-600.
(3) Chen E. P., 1994. Simulation of concrete perforation based on acontinuum damage model, DE95000544.
(4) Wu H. J., Huang F. L., Jin Q. K., Zhang Q. M., 2003. Numericalsimulation on perforation of reinforced concrete targets. Explosion andShock Waves 23, 545-550.
(5) Zhang D. H., Zhu F. S., Xing J. B., 2005. Application of beam-particle
model to the problem of concrete penetration. Explosion and ShockWaves 25, 85-89.
(6) Yuen S. R., Zhang B. P., 1979. Explosion and Its Action. China Industry
Press.
(7) Li H. L., Han F., 2004. Computation method of shaped-charge jetpenetrating concrete targets. Progress in Safety Science and Technology,
Vol. 4, Science Press, Beijing/New York, 2894-2900.

Dynamic Response of Steel Bar In RC Under Blast Load367

October 2005, Singapore

368

New Technologies for Urban Safety of Mega Cities in Asia

STATISTICAL STUDY OF
LETHALITY RATE FROM ACCIDENTAL
BUILDING FAILURE
X. GU 1, Y. LU 1*, S. GONG 1
and Y. ZHOU 2
1
Protective Technology Research Centre,
Nanyang Technological University, Singapore
2
Defence Science and Technology Agency, Singapore*
Email address: cylu@ntu.edu.sg

ABSTRACTThis study has been conducted in association with the investigation
into building failure due to underground explosion induced ground shocks.
Previous numerical and experimental studies have shown that strong
ground motions induced by large-scale underground explosions have thepotential to damage nearby surface buildings. As a probable consequence ofsevere building damage, especially collapse, the lethality of building
occupants is a critical concern for the authorities and the designers.
Therefore, the prediction of the possible lethality for building collapse due
to ground shocks is required. An important element in the lethality
prediction model is a model for the lethality rate in case a building failure
occurs. This article summarizes a statistical study in attempt to provide apreliminary probabilistic model for the lethality rate. Because direct
evidence of building failure due to blast-induced ground shock is almost
none, this study collected cases where rather brittle building failure took
place. Such data are relevant because the building failure due to explosive
ground shocks is deemed to be of basically a brittle nature. The work
presented in this paper includes the description of the database, theclassification of the collected data and the preliminary statistical analysis.
Subsequently, preliminary probabilistic models for the lethality rate forcertain categories of building structures are proposed.

1. INTRODUCTION
Previous numerical and experimental studies have shown that strong
ground motions induced by large-scale underground explosions could resultin damage to nearby surface buildings. As a probable consequence of severebuilding damage, especially collapse, the lethality of building occupants canpose a huge negative impact on the society. Therefore, the prediction ofoccupants’ lethality in case of collapse becomes essential while considering
the building safety issues and thus, a risk based lethality model is required.
One of the essential information required in the lethality model topredict the lethality at collapse is the expected lethality rate which can be369

October 2005, Singapore

defined as the ratio of death toll over the total number of building occupantspresent at the time of the incident. Some previous researches have suggested
various lethality rates at building collapse ranging from 10~50% (Kummer2004). These values are all proposed in deterministic terms. As a matter offact, the lethality rate largely depends on the damage state and otheruncertain factors concerning the integrity of the structure, in addition to
those well defined parameters such as the structure type, the number ofstories, and the building’s function. In other words, there exist large
uncertainties in the prediction of lethality due to building collapse.
Therefore, a probabilistic lethality rate is considered more appropriate inview of the various uncertainties involved.
In this paper, a simple risk based lethality model to predict theoccupants’ lethality at building collapse is introduced briefly first. Then, thecollection of lethality data and the organization of the database are described.
Finally, a probabilistic model for the lethality rate is proposed based on a
statistical analysis.
2. THE LETHALITY MODEL
There are a lot of models proposed for the prediction of earthquake
casualties. Coburn & Spence (1992) used a four-level injury severity model
associated with building collapse. Murkami (1992) proposed an event treemodel that includes fatalities caused by building collapse. Recently, theUSA Earthquake Loss Estimation Methodology by HAZUS (2003)
established an earthquake casualty model using an event tree. Similarly, theevent tree concept is applied in the present study. However, due to the factthat the probability of being killed in buildings with low-to-moderate
damage is marginal, only the situation where the building is completely
damaged and collapsed is considered in the current event tree. Furthermore,
only the lethality (not including injury) is concerned here. The simplified
event tree is shown in Figure 1.

GroundmotionPCollapse Ground shock

Completely damaged
and Collapse

PLethal Collapse

OccupantskilledFigure 1 Lethality event tree
According to AC/258 (2002), the Lethality due to an unexpectedunderground explosion event, PLethal Event , is defined as the conditional
probability of a personz “being instantaneously killed or mortally injured”
orz “receiving injury which pose an immediate life threatening
condition if not treated adequately and expeditiously”

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if present in a building when hit by the ground shock from an undesired
explosion event.
Consequently, from Figure 1, we have
PLethal Event ≈ PLethal Collapse ⋅ PCollapse Ground _ Shock(1)

where, PLethal Collapse is the probability of a person falling into theaforementioned lethal situation if present in a building when an undesired
collapse event occurs. PCollapse Ground _ Shock is the probability of collapse of abuilding being hit by an undesired explosion event.
The exact value of PLethal Collapse is very difficult to evaluate because theincident, Individual Lethality at Collapse, can never be repeated in a samemanner. According to Bernoulli Theorem, the frequency of occurrence of anevent converges to the corresponding probability in case of the experimentbeing repeated for a large number of times. Practically, PLethal Collapse can beapproximated by the Lethality Rate at Collapse, expressed as R Lethal Collapse ,which can be estimated from experience from cases where the number of
inhabitants being killed in the collapsed building has been recorded.
Moreover, to estimate the probable death toll, the Lethality Rate of
inhabitants in a building when hit by an undesired explosion event,
R Lethal Event , is required. In this stage, PLethal Event is used to approximate
R Lethal Event as:
R Lethal Event ≈ PLethal Event(2)

N Lethal = R Lethal Event ⋅ E(3)Then we have:where N Lethal is the expected number of lethalities and E is the Exposure
expressing the average amount of people expected to be continuously
present.
Extracted from a survey of building collapse accidents, R Lethal Collapse isa percentage (rate) of the number of killed over the number of all inhabitants
in a collapsed building. It must be aware that in practice, the lethality rate ofan undesired building collapse can never be predicted exactly due to thesignificant uncertainties involved, such as the random distribution of
inhabitants within the building and the random collapse modes. Therefore, aprobabilistic lethality rate is considered reasonable to describe thisrandomness. In the following sections, the efforts which have been made toestablish a database of lethality rate at building collapse and to evaluate theprobabilistic lethality rate are introduced.

Statistical study of lethality rate from accidental building failure371

October 2005, Singapore

3. THE DATABASE
So far, no report on lethality due to underground explosion inducedbuilding collapse has been found from the literature survey conducted by theauthors. However, numerous incidents where people are killed by sudden
and brittle building collapse due to earthquakes, weather disasters, poor
designs and constructions, improper renovations, and so on are reported
extensively. On the other hand, according to the previous studies on thecharacteristics of structural response under blast induced ground shocks (Luet al. 2001; Ma et al. 2002), it is deemed reasonable to assume that the likely
mode of collapse of buildings under strong ground shocks would be
generally brittle. Based on this consideration, all those past incidents where
sudden and brittle failure of structures occurred, regardless the various
structural types, building functions, number of stories, damage states andtime of collapse, are pulled together to build up a database concerning thelethality rate due to sudden building collapse. In lieu of more direct
information, the statistical results extracted from these cases may be applied
to predict the lethality due to building collapse induced by blast induced
ground shocks.
It should be mentioned that the definition of collapse of a building
structure sometimes can be subjective, especially if the structure does not
physically crumble. Considering the fact that the actual physical state of acollapsing structure can never be predicted with certainty as it is by itself aprobabilistic matter, the present study adopts the definition of collapse as astate where the structure apparently have lost its integrity or overall stability,
which may be signified by large permanent displacements in conjunction
with falling structural parts. The variety of actual collapse scenarios
satisfying the above definition manifests as a probabilistic phenomenon.
This treatment allows the lethality statistics thus derived to be applicable inan analytical procedure involving predicted “collapse” of the building
structures.
For cases where only a section of a building structure collapsed while
the remaining part apparently remained intact, only the lethality to thepersons being present at that collapsed section is considered. This isconsistent with the above definition of building collapse.
Most of the reported cases are from newspapers or news websites.
The text is usually not precise enough regarding the number of occupants,
death toll, structure type and mode of collapse. Despite of these limitations,
it is possible to extract directly or indirectly the necessary lethality
information for a lot of cases. So far, a total number of 94 individual
building collapse cases from all over the world are collected to form thecurrent database. This database contains the following types of information:yTime and place, when and where the collapse occurs.
The time of collapse is essential information to determine thenumber of occupants according to the building’s function.
y
The probable causes of the collapse.
In many cases, the probable causes of the collapse pointed out by
authority or police are reported. This information can provide someclues about the mode of collapse and damage state.

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ICUS Report 11

y

y

y
y

The general information of the collapsed building, including thebuilding’s function, structure type, number of stories, and thedamage state.
This information can help establish a general picture of the accident.
If available, the photograph of the collapsed building is also
attached. The building’s function, structure type and number ofstories are also important criteria for data classification.
The number of occupants, injury and death.
This is the most essential information regarding the lethality rate.
This study focuses on the death toll rather than the number of
injury. For a single event, several sources have been traced toverify the number of occupants and death toll.
Photographs from the site, if available. Some of the pictures areshown in Figure 2 to illustrate some typical modes of collapse.
Other information including the details of probable causes of thecollapse.

Several typical cases from the database are tabulated in Table 1 toillustrate how the database is organized and how one case significantly
differs from the others.
Strictly speaking, the collected raw data should be properly classified
before a statistical analysis is performed. The possible classification criteria
may include the structure type, the number of stories, the building’s function,
the situation of building before collapse, the cause of collapse, the time ofcollapse, and the damage state. Restricted by the limited number of thecollected cases, it is not feasible to perform such a detailed classification.
Nevertheless, based on the limited sample space, a preliminary
categorization according to structural types within the database was carriedout to establish a rough statistical picture of the collapse induced lethality
rate. Other important classification criteria, such as number of stories, will
be incorporated in the data processing when the sample space becomes big
enough.

a) Total collapse
Sampoong Department Store, Korea,
1995. (by Chosun.com)b) Partial collapse
A garage in construction, LA, USA,2003. (by Richard Korman for ENR)c) Floor collapse
A commercial building, Jerusalem,
Israel, 2001. (AP Photo)d) Roof collapse
An indoor swimming poor, Moscow,
Russia, 2004. (AP Photo)

Figure 2 Photographs of some collapsed buildings

Statistical study of lethality rate from accidental building failure373

October 2005, Singapore

Four main structure types are identified from the database as RC(reinforced concrete), BMC (brick, masonry & concrete), BM (brick &masonry), and TM (timber & masonry). Steel structure is not included because
few cases of steel structures have been found during the data survey. The first
three structural types covers the majority of current buildings and facilities inurban area and thus the lethality rate data of these three categories are combined
to illustrate a general statistical property of the lethality due to collapse ofengineered structures.
Table 1 Typical cases from the database
Incident Description
No.

StoreyDamagestate

Total Injured Dead Lethality

Seoul
South
Korea

Overweight Departme
and poor D/C nt StoreRC

5Completecollapse

141
1

910

501

35.5%

Singapore

Poor D/C

RC

6+1

Completecollapse

50

17

33

66%

Residential & Brick &commercial Concrete

4+3Completecollapse

59

22

37

62.7%

Brick &
Concrete

5Completecollapse

9

7

2

22.2%

185

46

19

10.3%

36

12

6

16.7%

(47)

41

6

12.8%

Place

RC-09

29-061995

17:50

RC-20

15-031986

11:25

BMC05

03-081998

night

Bandra,
India

BMC07

21-021999

night

Beirut,Lebanon

BM-40
TB-01

04-061959
21-082002
11-051927

6:00
23:10
night

Casualty

Type

Time

BM-01

Building
NatureDate

YingdeChina
Moscow
RussiaSouth
Dallas,USA

Cause

Illegally
added 3stories
Structural
damageduring theconflict
Rainstorm
Gas
explosion
Gasleakage
explosion

Hotel

Residential

Residential
Residential
Residential

Brick &
masonry
Brick &
masonry
Timber &
brick

1-2
5
2

Completecollapse
Completecollapse
Completecollapse

4. STATISTICAL ANALYSIS
Due to the large uncertainty involved, it is reasonable to predict thecollapse-induced lethality in a probabilistic manner. For this purpose, astatistical analysis on the classified database is performed. According to theresults from the statistical analysis in Table 2, the lethality rate due to building
collapse shows a significant uncertainty as expected. It is found that theprobabilistic properties of category RC, BMC and BM are quite similar. Due toprevalence of these three structure types in modern urban area, the probabilistic
property of their combination is also evaluated as a general representative of
urban buildings. The category TM is treated separately as this structure type islesser used in modern urban area.
From Table 2, it can be found that category RC, BMC and BM all have anumber of samples around 26, which is significantly more than 17, the numberof samples in category TM. This also reflects the dominance of the first threestructure types. The mean values and COVs of category RC, BMC and BM
differ from each other slightly. Normal and Beta distribution are found suitableto describe the probabilistic distribution of the corresponding lethality ratios.
The data from the combination of these three categories, representing the main
structure types in modern urban area, has a mean value and COV of 0.371 and374

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

0.547, respectively. This mean value is within the range reported by some otherstudies (Kummer 2004). Assuming a normal distribution and a probability of
being exceeded of 5%, the corresponding lethality rate due to collapse of amodern urban building, i.e. PLethal Collapse , is 0.705. If the value ofPCollapse Ground _ Shock and E is known, say 10% and 100 for instance, PLethal Event and

N Lethal are equal to 0.0705 and 7 respectively, with a probability of being
exceeded of 5% from Equation 1~3. The mean N Lethal would be 3.7 ≅ 4 in thiscase. For the purpose of illustration, the fitted Beta distribution is plotted in
Figure 3, along with the corresponding histogram.

8

6
5
4
3
2
1
0

Observed

Theoretical

Frequency

Frequency

Table 2 Summary of statistics of lethality rate
Category
No. of samples Mean
Cov
Distributions
RC
24
0.376
0.539 Normal, Beta
BMC
26
0.395
0.562 Normal, Beta
BM
27
0.343
0.545 Normal, Beta
RC+BMC+BM77
0.371
0.547 Normal, Beta
TM
17
0.249
1.055 Lognormal

Observed
Theoretical

6
4
2
0

0~10

0~10

20~30 40~50 60~70 80~90

Percentage lethality

Percentage lethalitya) Category RC (24 samples)
Observed
Theoretical

6b) Category BMC (26 samples)20

4

Observed
Theoretical

15

Frequency

Frequency

820~30 40~50 60~70 80~90

10

2
0
0~10

20~30 40~50 60~70 80~90
Percentage lethality

5
0
0~10

20~30 40~50 60~70 80~90
Percentage lethalityc) Category BM (27 samples)d) RC+BMC+BM (77 samples)

Figure 3 Lethality histograms and fitted Beta distributions

Statistical study of lethality rate from accidental building failure375

October 2005, Singapore

The effect of number of stories on the lethality rate has also been studied.
The classification of number of stories applied in this study is generally
consistent with that of HAZUS (2003), which are listed as follows:y Low-rise: 1~3 storiesy Mid-rise: 4~7 stories
y High-rise: 8+ stories

No. of stories

No. of stories

Table 3 Effects of number of stories on lethality rates
1~3
4~7
8+
Categories
No. of Mean No. of Mean No. ofMeansamples value samples value samples value
RC
8
0.303
10
0.403
6
0.43
BMC
10
0.311
14
0.479
2
0.225
BM
26
0.342
1
0.364
0
RC+BMC+BM
44
0.328
25
0.444
8
0.379
TM
17
0.249
0
0
-

8+
4~7
1~3
0

20

40

60

Percentage lethality

4~7
1~3
0

20

40

60

Percentage lethalitya) Category RC
No. of stories

8+b) Category BMC

8+
4~7
1~3
0

20

40

60

Percentage lethalityc) RC+BMC+BM
Figure 4 The effect of number of stories on lethality rate

The mean values of the lethality rates are calculated for different groupsof buildings in terms of the number of stories and they are shown in Table 3.

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ICUS Report 11

For category RC, there is a general increasing trend of mean lethality rate as thenumber of stories increases. For categories BMC and BM with much fewer
samples of more than 8 stories, the mean lethality rate corresponding to 4~7
stories is also larger than that of 1~3 stories. The result from the combination of
categories RC, BMC and BM is similar to categories BMC and BM. Based onthese observations, a preliminarily conclusion may be drawn that the lethality
rate increases with the increase of the number of building stories. Thisobservation echoes the finding from a previous study (Kummer 2004) based ona relative small number of samples. Further data expansion is required topossibly enhance the observation. The effect of number of stories on lethality
rate is also illustrated in Figure 4 for categories RC and BMC.

5. CONCLUDING REMARKSThis paper introduces the establishment of a database on the lethality rate
due to sudden and brittle building collapse, and the subsequent statistical study
on the results. A total number of 94 incidents of sudden building collapse havebeen collected to form the database. By statistical analysis on the processed
data, a probabilistic model of the lethality rate due to sudden building collapse
is proposed. It is found that the probabilistic properties of categories RC, BMC
and BM are close to each other. These three structure types actually cover a
majority of the building structures in a modern urban area. Therefore, they are
combined to represent the main structure types in modern urban area. The meanvalue and COV of lethality rate at building collapse for the combined category
are found to be 0.371 and 0.547, respectively.
The dependence of the lethality rate upon the number of building stories
has also been examined based on the available database. It can be generally
concluded that the mean value of lethality rate at building collapse increases as
the number of stories increases.
REFERENCES
AC/258 (UGSWG) NO (ST) IWP 06-2002, 2002. Lethality Model for Building
Inhabitants Exposed to Ground Shock from Accidental Explosions in
Underground Ammunition Magazines, First draft. Norwegian Defence
Estates Agency, Norway.
Coburn A. W. and Spence R. J. S., 1992. Factors Determining Human Casualty
Levels in Earthquakes: Mortality Prediction in Building Collapse.
Proceeding of 10th WCEE, Madrid, Spain, 5989~5994.
HAZUS, 2003. Multi-Hazard Loss Estimation Methodology: Earthquake Model.
Technical Manual. National Institute of Building Sciences, Washington
DC.

Statistical study of lethality rate from accidental building failure377

October 2005, Singapore

Kummer Peter O., 2004. Lethality/Injury as a Result of Building Collapse, Update dated November 2004 to NATO AC/326 SG 5-UG Storage CustodianGroup. Bienz, Kummer & Partner Ltd, Zollikerberg, Switzerland.
Lu, Y., Hao H. and Ma, G.W., 2002. Experimental investigation of structural
response to generalized ground shock excitation. Experimental Mechanics
42(3), 261-271.
Ma, G.W., Hao, H., Lu, Y., and Zhou, Y.X., 2002. Distributed structural
damage generated by high-frequency ground motion. Journal of StructuralEngineering, ASCE, 128(3), 390-399
Murkami H. O., 1992. A Simulation Model to Estimate Human Loss for
Occupants of Collapsed buildings in an Earthquake. Proceeding of 10
WCEE, Madrid, Spain, pp. 5969~5974.

378

New Technologies for Urban Safety of Mega Cities in Asia

SAFETY EVALUATION METHODOLOGYFOR BUILDING CONTENTS SUBJECTEDTO EARTHQUAKE LOADINGYUTAKA NAKAMURA(1), MIKA KANEKO(2),HIROSHI KAMBARA(3) and KAZUO TAMURA(4)Institute of Technology, Shimizu Corporation
4-17, Echujima 3-chome, Koto-ku, Tokyo 135-8530, Japanemail address: (1) yutaka.nakamura@shimz.co.jp, (2) mika@shimz.co.jp,(3) kambara@shimz.co.jp, (4) tamkaz@shimz.co.jp


ABSTRACTAn indoor safety evaluation methodology for buildings subjected toearthquake shaking has been developed that takes into account the risks ofoverturning or sliding of furniture and other building contents and damageof nonstructural elements. The safety evaluation methodology consists ofthree main estimation components: an approximate evaluation of the
maximum responses of a building subjected to earthquake shaking,estimation of the risks of overturning and sliding of furniture and othercontents, and estimation of the significant stages of damage of nonstructuralelements. The paper introduces each of the three estimation methods andexamples of indoor safety evaluations are shown to demonstrate the validityof the developed method.

1. INTRODUCTION
Overturning or sliding of furniture and other building contents anddamage of nonstructural elements due to earthquake shaking may injurebuilding occupants even when the building structural frame does not suffer
severe damage. Overturned furniture and damaged nonstructural elements
may also become obstacles to evacuation and relief activities following anearthquake. In the study presented here, an indoor safety evaluation method
for buildings subjected to earthquake shaking has been developed that takes
into account the above-mentioned risks. The flow of the indoor safety
evaluation is shown in Figure 1. The developed evaluation methodology
consists of the following three main components: (1) an approximate
evaluation of the maximum responses of a building subjected to earthquake
shaking, (2) estimation of the risks of overturning and sliding of furnitureand other contents, and (3) estimation of the significant stages of damage ofnonstructural elements. New relationships have been developed that allow
the maximum acceleration, velocity and interstory drift of each story of abuilding to be estimated using only the story number and the PGA (peakground acceleration) and PGV (peak ground velocity) of the earthquake.

379

October 2005, Singapore
Based upon the estimated maximum responses, the risks of overturning andsliding of specified pieces of furniture and the damage of specified
nonstructural elements can be estimated and classified into four levels. The
paper introduces each of the three estimation methods and provides
examples of indoor safety evaluations to demonstrate the validity of thedeveloped method.
















Figure 1: The flow of the indoor safety evaluation

2. DEVELOPED ESTIMATION COMPONENTS
2.1

Approximate evaluation of the maximum responses of a building

New relationships have been developed that allow approximate
evaluation of the maximum response of a building to be estimated using
only the story number and the PGA and PGV of the earthquake. Since a
conventional response analysis requires an analytical model of a building
and the time history record or the response spectrum of the earthquake, it ishard for non-engineers to obtain these data and carry out the proper
simulation analyses. The developed relationships can be used without
expertise, and provide approximate maximum responses with reasonableaccuracy for the estimation of the risks of overturning and sliding of
furniture and the estimation of the significant stages of damage ofnonstructural elements.
A significant number of time-history response analyses have been
carried out for the standard building models shown in Table 1 for 1,027
collected earthquake records, the PGA of which are normalized to380

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11100cm/sec2. Figure 2 shows the average maximum responses, R (maximum
floor acceleration [Acc], velocity [Vel], or story displacement [Dis]) of a 20story RC building for the same range of earthquake PGA/PGV values. The
figure indicates that R (=Acc, Vel, or Dis) varies considerably with
PGA/PGV even for the same normalized PGA (=100cm/sec2) and that theevaluations of R should consider the effect of PGA/PGV of the input
earthquake.
Table 1: Standard building models
RC structure
Steel structure
Story number
N = 5,10,15,25,30,40,50
The natural period of 1st mode
T=0.07N
T=0.10Nst
The damping factor of 1 mode
h=3%
h=2%
Damping factors for higher modes frequency proportional
Floor mass
uniform distribution
Story stiffness
trapezoidal distribution
stiffness ratio of 1st/top story=3.0
PGA/PGV<3 [53]PGA/PGV=3-5 [95]
PGA/PGV=5-7 [131]PGA/PGV=7-10 [187]

PGA/PGV=10-15 [253]
PGA/PGV=15-20 [166]
PGA/PGV=20-25 [77]
PGA/PGV=25-30 [65]20

15

Story number


20
20

15
15

10
10

5
5

0
0
350
0
 0 50 100 150 200 250 300
2
Acceleration (cm/s )


10

5

20 40 60 80 100 120

0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Velocity (cm/s)

Story displacement (cm)Figure 2: Average maximum responses of a 20-story RC building










Figure 3: Simplified story-wise distributions of maximum responses

Safety Evaluation Methodology for Building Contents Subjected to Earthquake Loading381

October 2005, SingaporeThe story-wise distribution of R (=Acc, Vel, or Dis) can be simplified
to a piecewise-linear shape represented by two straight lines as shown in
Figure 3. The relationships between PGA/PGV and RH, M, L, R at the top [H],middle [M] and 1st floor [L], for a RC building with N=10, 30, 50 stories areshown in Figure 4. RH, M, L can be expressed by the following formula:R H ,M ,L =da( PGA /PGV ) + b( PGA /PGV ) + c2 f ( N )  PGA(1)g
f (N) =
eN + fwhere f(N) is a correction function for the story number, and a, b, c, d, e, f
and g are coefficients to be determined based on the results of response
analyses such as that shown in Figure 4. Table 2 shows the coefficients for
R (=Acc, Vel, or Dis) of RC and steel structures.
N=10

N=30

N=10

150

N=30

N=50

VelH

AccH

250

Velocity (cm/s)

Acceleration (cm/s2)

300

N=50

200
150

100

50

100
50
0

10

20

30

40

0

50

0

10

N=10

N=30

N=50

AccM

150

30

50

10

20

30

N=10

120

40

40

0

50

N=30

0

10

20

30

N=50

N=10

50

20

40

50

N=50

20

0

10

20

30

PGA/PGV

N=50

DisM

1

0.5

0

10

20

30

40

50

N=10

2

N=30

40

N=50

DisL

30

0

50

PGA/PGV

10

20

40

N=30

1.5

0

Story displacement (cm)

60

40

30

Vel

80

30

10
N=10

2

50

40

PGA/PGV

0

L

Velocity (cm/s)

Acceleration (cm/s2)

40

N=30

Acc

20

0

PGA/PGV

100

10

0.05

N=50

60

L

0

0.1

PGA/PGV

20

0

0.15

50

VelM

PGA/PGV

0

40

N=30

80

100

0

N=10

100

Velocity (cm/s)

Acceleration (cm/s2)

200

20

N=50

DisH

PGA/PGVPGA/PGV

N=30

0.2

Story displacement (cm)

0

N=10

0.25
Story displacement (cm)

 350

50

1.5

Thin lines indicate
developed formulasin all charts.

1

0.5

0

0

10

20

30

40

50

PGA/PGV

Figure 4: The relationships between PGA/PGV and the average maximum
responses at the top, middle and 1st floors for N=10, 30, 50 of a RC building

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Table 2: Coefficients in equation (1) for RC and steel structure buildings
a
b
c
d
e
f
g
RH, M, L
1
(1)
1
(1)
0
(0)
1
(1)
1
(1)
1
(1)
1
(1)
1
(1)
1
(1)

AccH
AccM
AccL
VelH
VelM
VelL
DisH
DisM
DisL

7
(14)
47
(54)
0
(0)
4
(3)
9
(2)
62
(34)
13
(14)
8
(10)
8
(10)

161
(125)
478
(262)
1
(1)
47
(29)
48
(30)
65
(60)
223
(124)
49
(22)
49
(22)

493
(526)
1037
(820)
1
(1)
55
(52)
43
(32)
74
(49)
0.5
(0.7)
0.8
(1.3)
0.8
(1.3)

1
(1)
1
(1)
0
(0)
0
(1)
0
(1)
0
(0)
1
(1)
0
(0)
0
(0)

15
(5)
15
(5)
1
(1)
1
(105)
1
(105)
1
(1)
10
(5)
1
(1)
1
(1)

45
(35)
45
(35)
1
(1)
1
(135)
1
(135)
1
(1)
40
(35)
1
(1)
1
(1)

N.B. Numbers inside parentheses are for steel structure.

2.2

Estimation of risks of overturning and sliding of furniture

The risks of overturning of furniture and other building contents, QOT,
can be estimated by the overturning ratios given by (Kaneko, 2003)

QOT = ln Acc f  A
  
A


F f  Fb    lnVel f  V



V

F f > Fb(2)

where Accf (cm/s2) and Velf (cm/s) are the maximum response accelerationand velocity of the floor,  is the probability distribution function of anormal distribution with mean and standard deviation of A or V, and A or
V, respectively, Ff (Hz) is the equivalent frequency of the floor and Fb (Hz)is the boundary frequency determined by the depth B (cm) and the height H(cm) of a piece of furniture. Ff and Fb are given by

Ff =

Acc f
,
2  Vel f

Fb =

15.6
H (1+ B H )

1.5

(3)

In equation (2),  is the slide-resistant coefficient which ranges from 0 to 1
and is determined by considering the ratio B/H and the coefficient of friction
μ between the floor and furniture. Table 3 shows A, A, V, V and  for

Safety Evaluation Methodology for Building Contents Subjected to Earthquake Loading383

October 2005, Singapore
categorized conditions in terms of the furniture and floor types. Figure 5
shows the relationship between Accf or Velf and QOT of each type offurniture on Floor B in Table 3. QOT is classified into four levels as shownin Figure 5.

Table 3: A, A, V, V and  in equation (1) for categorized conditionsFf  Fb
Ff > Fb
type

H1
H2
L1
L2

heightoffurnitureLean
againstwall?

A

H  150cm

no
yes
no
yes

5.70
6.11
6.34
6.75

90cm <
H < 150cm

A
0.34
0.44

V
4.06
4.47
4.63
5.04

V

Floor
A:
μ=0.2
~0.4

Floor
B:
μ=0.4
~0.6

Floor
C:
μ>0.6

0.45

0.8

1.0

1.0

0.63

0.3

0.8

1.0

Figure 5: The relationships between the maximum floor responses, Accf and
Velf and the overturning ratios, QOT

The risks of sliding of furniture and other building contents, QSD, canbe determined by the two indices, namely the probability of sliding, PS, andthe sliding distance, Ds. PS is given by 1- , and Ds (cm) is estimated by thefollowing formula (Kaneko et al., 1999):
1.56

μg 
0.3
0.5
(4)
Ds = 0.02  μ  F f Vel f 

F
2

f 
where g denotes the acceleration of gravity. Figure 6 shows the relationshipbetween Velf and Ds for three floor types and a roller cabinet with μ=0.05.
QSD is classified into four levels according to the values of PS and Ds as
shown in Figure 7.

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Sliding distance [cm]100
Roller cabinet

50
Floor A
B
C
0
0

50

100

150

Floor veleocity [cm/s]
Figure 6: The relationship between
floor velocity and sliding distance

2.3

Figure 7: Risks of sliding determinedby probability of sliding and sliding
distance

Estimation of damage of nonstructural elements

Earthquake-resistant capabilities of nonstructural elements are
categorized into four classes based on the various published documents ofearthquake simulator tests as shown in Table 4. In Table 4, damage ofnonstructural elements such as outer and inner walls in classes A, B and C isassumed to be caused by the story drift angle, while damage to ceilingelements in class D is assumed to be caused by the story drift angle andresponse acceleration. Figure 8 shows fragility characteristics, namely,
relationships between the story drift angle and damage level of nonstructuralelements in classes A, B and C where damage levels are classified into fourlevels (Kaneko et al., 2005).

Table 4: Classification of earthquake-resistant capabilities of nonstructuralelements
Earthq.Damage is
Examples of Nonstructural elements
Class resistantcaused bycapability
ALC panel in general, curtain wallAHigh
framed partition wall, window glass
ALC panel with inserted steel bar,story drift angle
B
Mediumdirect-adhered partition wall
tiled wall on RC surface,C
Low
mortared wallstory drift angleDceiling& response acc.
N.B. ALC= Autoclaved Lightweight aerated Concrete

Safety Evaluation Methodology for Building Contents Subjected to Earthquake Loading385

October 2005, SingaporeFigure 8: Relationships between story drift angle and damage level ofnonstructural elements

3. VERIFICATIONThe overturning ratios of furniture in a 14-story condominium due tothe 2005 West Off Fukuoka Earthquake (March 20, 2005) are estimated by
the developed evaluation method and compared to the actual overturning
ratios surveyed by questionnaires. Maximum floor responses, Accf and Velf,of every story are estimated by the developed maximum evaluation
formulas with the observed PGA and PGV at the nearest observation point.
Figure 9 shows the range of overturning ratios of furniture corresponding to
the top, middle and low-story floors along with the results of the survey.
The estimated overturning ratios agree well with the observed results, which
demonstrates the validity of the developed method.

Figure 9: Estimated overturning ratios of furniture with the results ofquestionnaire survey

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Estimated damage levels of selected nonstructural elements due to the
Niigata Chuetsu Earthquake (October 26, 2004) are compared to actual
observed damage to demonstrate the validity of the developed method. The
average maximum story drift angles of a supposed three-story steel building
is estimated by the developed maximum evaluation formulas for theobserved PGA and PGV in each of the chosen cities in Niigata prefecture.
Damage levels of window glass (in class A), ALC panel with inserted steelbar (in class B), tiled wall and mortared wall (in class C) in Nagaoka,
Tokamachi, and Ojiya-city are estimated from the estimated responses ofthe supposed building and the fragility characteristics of the elements
specified in Figure 8. Figure 10 shows the estimated damage level of eachelement in each city along with the comments of observed damage. The
estimated damage levels agree well with the actual observed damage, which
demonstrates the validity of the developed method.

Figure 10: Estimated damage level of four elements in the three cities alongwith the comments of observed damage

4. CONCLUSIONS
An indoor safety evaluation methodology for buildings subjected toearthquake shaking has been developed that takes into account the risks ofoverturning or sliding of furniture and other building contents and damageof nonstructural elements. The safety evaluation methodology consists ofthree main estimation components: an approximate evaluation of the

Safety Evaluation Methodology for Building Contents Subjected to Earthquake Loading387

October 2005, Singapore
maximum responses of a building subjected to earthquake shaking,estimation of the risks of overturning and sliding of furniture and othercontents, and estimation of the significant stages of damage of nonstructuralelements.
The developed response evaluation formulae can estimate themaximum acceleration, velocity and story drift of each story of a buildingby using only the story number and the PGA and PGV of the earthquake.
Based upon the estimated maximum responses, the risks of overturning andsliding of specified pieces of furniture and the damage of specified
nonstructural elements can be estimated and classified into four levels.
Estimated damage levels of selected nonstructural elements due to the
Niigata Chuetsu Earthquake were compared to the actual observed damage
to demonstrate the validity of the developed method.

REFERENCES
Kaneko, M., 2003. Proposal of simple estimation method for overturning
ratios of furniture during earthquakes, Summaries. 2003 Meetings of
the Architectural Institute of Japan, 61-62. (in Japanese) .
Kaneko, M., Hayashi, Y., and Tamura, K., 1999. Evaluation of sliding
displacement of furniture during earthquake: By using revised formula
to estimate sliding displacement of furniture. Summaries. 1999
Meetings of the Architectural Institute of Japan, 537-538. (inJapanese).
Kaneko, M., Kambara, H., and Tamura, K., 2005. Seismic performance of
non-structural elements based on results of seismic resistant tests. AIJ
Journal of Technology and Design, No. 21, 39-44. (in Japanese).

ACKNOWLEDGEMENT
The study here has been carried out as part of ‘Research project on
great earthquake disaster mitigation in big cities’ by the Japanese Ministryof Education, Culture, Sports, Science and Technology, and entrusted by
National Research Institute for Earth Science and Disaster Prevention.

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SAFETY EVALUATION OF SUBMERGEDTUNNEL AGAINST BLAST LOAD
MA GUOWEI*, Nanyang Technological University, Singapore
AN XINMEI, Xi’an Jiaotong University, China
LI YONGSHENG, Tongji University, China
cgwma@ntu.edu.sg

ABSTRACT
Submerged tunnel is extremely vulnerable to internal explosion. The
design code usually does not take into consideration the blast load effect oroversimplifies the blast load as a constant pressure on the internal walls oftunnel. In the present study, numerical simulation of a submerged tunnel
system under blast load caused by high explosive (HE) detonation ispresented. The problem is studied by using LS-DYNA, an explicit, 3-D
dynamic, nonlinear finite element program. The tunnel damage by different
intensity of the blast load is simulated. The pressure- and velocity-time
histories of several key points around the donor tunnel are compared. The
result is helpful for relative authorities to apply necessary protection
measures for submerged tunnel against blast load.

1. INTRODUCTION
Submerged tunnel has been widely used in the recent years.
Submerged tunnel can be used in rivers or waterways when it is possible toplace the tunnel in the riverbed or seabed. A submerged tunnel may consistof several prefabricated tunnel elements, which are floated to the site;
installed one by one; and connected to one another under water in a trenchthat has been pre-dredged. As construction proceeds, the tunnel is backfilled.
The completed tunnel is usually covered with a protective layer over theroof. The history of submerged tunnel practice began in 1910, with theconstruction of a two-track railroad tunnel across the Detroit River between
the United States and Canada (Saveur and Grantz, 1993). After that, fewer
than 100 railroad or highway tunnels have been designed worldwide overthe past century. The catalog of totally 91 submerged tunnel projects arepresented by Grantz (1993). Two basic techniques have been evolved: thesteel shell method (commonly used in USA) and the concrete box method(used in Europe) (Hakkaart, 1993). More recently, these techniques havemerged in the Far East, Hong Kong and Japan.
The resistance of the submerged tunnel against blast load is an
important component of the entire structure’s safety. Blast load, as one of
the accidental loads should be taken into account in the submerged tunnel
design. A recent example is a tunnel in Belgium, located near an industrial
area, which has been designed for an internal explosion pressure of 0.4 MPa

389

October 2005, Singapore(Grantz, 1993). A constant blast pressure is applied on the walls of thetunnel, which, however, may oversimplify explosion induced blast load.
Since, the experimental studies with respect to this approach can be very
expensive and time-consuming, numerical modeling and simulation of
explosion inside a submerged tunnel can play an important role tounderstand the capability of such tunnels against blast load. A case study byconsidering a submerged reinforced concrete tunnel is presented in thepresent paper. The tunnel damage by different intensity of the blast load issimulated. The pressure- and velocity-time histories at different locations on
the tunnel wall are compared.
2. ANALYTICAL MODEL
2.1

Description of the Problem

The case study considers a submerged tunnel segment with a length of
40 m along the tunnel axis. The internal explosion occurs at the center of theconsidered segment. Due to symmetry, only half of the tunnel segment (20m) is simulated. The bottom of the tunnel is fixed, which assumes that it issit on the seabed. The cross section of the considered submerged tunnel isshown in Fig 1, which is made of reinforced concrete and integrated withthree parallel tunnels. The two side-tunnels are used for main incoming andoutcoming traffic lines and the center-tunnel is designed as an operational
service tunnel. Points 1-4 are selected at the center of the bottom, top, left,
and right walls, respectively, in the donor tunnel of an accidental explosion.
Points 5-6 are at the floor 3 meters away from point 1. Load on the walls
and damage of the tunnel is simulated by using LSDYNA (LSTC, 2003).
2
4

3
5

1

6

Figure 1: Schematic view of the cross-section of the tunnel
The effect of the water is simplified as a hydrostatic pressure on theexternal walls of the tunnel. The water-tunnel interaction, however, is notconsidered. Assuming the water depth above the top of the tunnel is 10 m.
Then, the hydrostatic pressure on the top of the tunnel is 1000×9.8×10＝
0.098 MPa, the pressure on the two sides of the tunnel is 1000×9.8×(10+9.55/2)＝0.145 MPa, the hydrostatic pressure on the bottom of thetunnel is 0 since it is assumed to be fixed. The hydrostatic pressure is first
applied onto the tunnel until convergence. Blast load is subsequently appliedon the inner walls of the donor tunnel.
2.2

Material Model“Pseudo Tensor Concrete Model”, which is one of most robustmaterial models available for the analysis of concrete structures, is adopted.

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This model decouples the volumetric and deviatoric responses; viz. thestress tensor is separated into hydrostatic tensor and deviatoric stress tensor.
The hydrostatic tensor changes the concrete volume and the deviatoric one
conjugates the distortion or shape deformation. For the hydrostatic tensor,
the tabulated compaction equation of state is used and it is linear in internalenergy. Pressure variable is defined by
p = C (ε V ) + γT (ε V ) E(1)
in the loading phase, where E is the internal energy per volume, γ is the ratioof the specific heats, εv is the volumetric strain and given by the natural
logarithm of the relative volume.
σ max
Yield

σ failed
Pressure
Figure 2: Two-curve concrete strength modelTwo curves with respect to the hydrostatic pressure are used tocharacterize the strength of concrete, which is shown in Fig. 2. The upper
curve describes the maximum yield strength of concrete which is defined byp(2)
σ max = a 0 +a1 + a 2 p
the lower curve gives the failure strength which is defined byp(3)
σ failed = a 0 f +a1 f + a 2 pthen, the function σyield which limits the deviatoric stresses is defined as alinear combination of the above described parameters
σ yield = σ failed + η(σ max − σ failed )(4)

where p is the resulted hydrostatic pressure, η is a constant. η = 0.309 issuggested in the LSDYNA manual (LSTC, 2003) for concrete. The yieldsurface is mitigating from and σmax to σfailed.
The effect of reinforcement is simulated by a mixture model. In thismodel, a reinforcement fraction, fr, is defined along with properties of thereinforcement material. The bulk modulus, shear modulus, and yieldstrength are then calculated form a simple mixture rule, e.g., for the bulk
modulus,K = (1 − f r ) K c + f r K r(5)
where Kc and Kr are the bulk modulus for concrete and the reinforcement
material, respectively.
The strain rate effect on the strength of the material is considered by
employing a strain rate multiplier. For the mixture model, the strain rate
multipliers are obtained from concrete and the reinforcement respectively.
Lu and Xu (2004) have given a theoretical model for concrete dynamic
strength change with strain rate based on continuum fracture mechanics andSafety Evaluation of Submerged Floating Tunnel Against Blast Load391

October 2005, Singapore

experimental data. The strain rate effect is incorporated by a rateenhancement factor defined as
3a1 f c' r f + a 2 f c' r f2
rc =(6)
3a 0 a1 + (1 + a 0 a 2 ) f c' r f
where rc is the rate enhancement factor at fixed pressure, rf is the rateenhancement factor for the uniaxial strength, fc’ is the quasi-static
compressive strength, and ai are parameters defining the maximum stress.
The reinforcement dynamic strength change with strain rate is obtained
from the equation given by Liu and Owen (1986):
 ε& 
σd(7)= λ log 10  d  + 1σs ε& s 
where σd and σs are the dynamic and static yield strength; εd and εs are thecorresponding strain rate, λ is 0.03, εs is 0.01 for steel.
3. NUMERICAL RESULTS AND DISCUSSIONSThe numerical simulation of the considered submerged tunnel againstinternal blast load is then simulated. The key parameters, such as the weightof charge (W), vertical distance between the charge and the bottom of thetunnel (DV), horizontal distance between the charge and the floor center (DH)are investigated. The damage zone is represented as the area where theplastic strain is above 0.01, shown as red color in the following figures.
3.1

Weight of the Charge (W)Three cases, i.e. W=100 kg, W=200 kg, W=500 kg are simulated. The
damage zone of these three cases is shown in Figure 3. The internal blast
induced damage mainly concentrates on the bottom of the tunnel. With theincrease of the charge weight, the damage zone is extended to the joint andthe ceiling of the tunnel. The ceiling and exterior wall damage may result indisastrous water flood in the tunnel.

(a) W=100 kg(b) W=200 kg(c) W=500 kg
Figure 3: Damage zone with different charge weight
The pressure-time histories of Points 1-4 for these three cases areplotted in Figure 4. It can be seen that the blast-induced pressure is an
impulsive load, with a very high peak but a short duration. The peakpressure increases with the charge weight. The peak pressure at point 1 is ashigh as 145 MPa, which is much higher than those of other points. The
simplified uniformly distributed pressure (for example 0.4 MPa) in

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submerged tunnel design cannot represent properly the intensity as well as
the distribution of the blast load.

(a) Pt. 1(b) Pt. 2(c) Pt. 3(d) Pt. 4
Figure 4: Pressure (MPa) time (s) history of Pt. 1-4 for three cases: W=100kg (dash line), W=200 kg (solid line), W=500 kg (dot line)
Since PPV (peak particle velocity) is one of the efficient criteria fordamage, the velocity time history at points 1-4 for three cases are shown in
Figure 5. It is shown again that the PPV increases sharply with the increaseof the charge weight and the distribution is significantly uneven.

(a) Pt. 1(b) Pt. 2(c) Pt. 3(d) Pt. 4
Figure 5: Velocity (m/s) time (s) histories of Pt. 1-4 for three cases: W=100kg (dash line), W=200 kg (solid line),W=500 kg (dot line)
3.2

Vertical Distance between the Charge and Floor ((DV)

Three cases, i.e. DV=0.1 m, DV=0.5 m, DV=1.5 m are studied toinvestigate the influence of DV. The damage zone is shown in Figure 6.
When DV is relatively small (0.1 m), the damage zone is concentrated in asmall area right below the charge. When DV increases to 0.5 m, the damage

Safety Evaluation of Submerged Floating Tunnel Against Blast Load393

October 2005, Singapore

zone becomes larger. When the charge is far from the bottom (DV=1.5m),
the damage zone at the bottom decreases, while the damage at the ceilingexterior wall conner increases.
Pressure-time histories of Pt.1-4 for the three cases are plotted in
Figure 7. The maximum peak pressure appears at the bottom of the tunnel
and their values are 320 MPa, 144 MPa, 78.3 MPa. The peak pressure ofPt.1 decreases dramatically with the increase of DV, while the peak pressureof other three points increases with DV.
Velocity-time histories of Pt.1-4 for three cases are plotted in Figure 8.
The maximum velocities appears at the bottom of the tunnel and their values
are 98.6 m/s, 88.2 m/s, 7.05m/s respectively for three cases: DV=0.1m,
DV=0.5m, DV=1.5m. The velocity at the bottom decreased dramatically with
the increase of DV, while there is only a little increase for the velocities ofother places. The damage zone is mainly concentrated at the bottom.

(a) DV=0.1 m(b) DV=0.5 m(c) DV=1.5 m
Figure 6: Damage zone in tunnel for three cases(a) Pt. 1(b) Pt. 2(c) Pt. 3(d) Pt. 4
Figure 7: Pressure (MPa) time (s) histories of Pt.1-4 for three cases:
DV=0.1 m (dot line), DV=0.5 m (solid line), DV=1.5 m (dash line)

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ICUS Report 11(a) Pt. 1(b) Pt. 2(c) Pt. 3(d) Pt. 4
Figure 8: Velocity (m/s) time (s) histories of Pt. 1-4 for three cases:
DV=0.1m (dot line), DV=0.5m (solid line), DV=1.5m (dash line)
Horizontal Distance between the Charge and Floor Center (DH)Three cases, i.e. DH=-3 m (‘-’ means to the left from the center), DH=0m, and DH=+3 m (‘+’ means to the right) are studied here. The damage zone
corresponding to these three cases are shown in Figure 9. The damage isagain mainly concentrated on the floor. When DH=±3 m, the damage in the
nearby walls becomes more serious.
3.3(a) DH=-3m(b) DH=0m(c) DH=+3m
Figure 9: Damage zone in tunnel for three cases
The pressure-time histories of Pt.1 (or 5, 6) –4 are plotted in Figure 10.
The maximum peak pressure occurs at the point right below the charge,
which is about 150MPa, which is much higher than those of the other threepoints.

(a) Pt. 1 (5, 6)(b) Pt. 2(c) Pt. 3(d) Pt. 4
Figure 10: Pressure (MPa) time (s) histories of Pt.1 (or 5, 6) –4 for threecases: DH=-3m (dash line), DH=0m (solid line), DH=+3m (dot line)

Safety Evaluation of Submerged Floating Tunnel Against Blast Load395

October 2005, Singapore

Velocity time histories of Pt.1 (or 5, 6) –4 are plotted in Figure 11.
The distribution of the velocity around the donor tunnel is again not uniform.
The explosion location significantly affects the blast load distribution.

(a) Pt. 1 (5, 6)(b) Pt. 2(c) Pt. 3(d) Pt. 4
Figure 11: Velocity (m/s) time (s) histories of Pt.1(or 5, 6)-4 for three cases:
DH=-3m (dash line), DH=0m (solid line), DH=+3m (dot line)
4. CONCLUSIONSIn the present paper, numerical simulations of a submerged reinforced
concrete tunnel against internal blast load have been carried out. Parametricstudies with respect to three key parameters are performed. The tunnel
damage induced by different intensity of explosion is simulated. The
pressure-and velocity-time histories around the donor tunnel are compared.
From this study, following conclusions can be drawn.
(1) Blast-induced damage in a submerged tunnel is mainly concentrated on
the floor but it may spread to ceiling and exterior/interior walls if the
explosion is relatively intensive. Under a scale with the equivalent TNT
explosive less than 500 kg, the donor tunnel undergoes a certain degreeof ceiling damage which may results in disastrous water flood in thedonor tunnel. The two parallel tunnels, however, are relative safe
without severe damage at the ceiling and the exterior wall.
(2) Blast-induced pressure is an impulsive load, the peak pressure can be as
high as a few hundred MPa but the duration is within a few
milliseconds, which is very different from a constant pressure.
Maximum peak pressure occurs at the floor bottom of the tunnel, and it
is much higher than those of other points. It is oversimplified that theinternal blast load is considered as a constant pressure acting on the
inner walls of the tunnel.
(3) It is suggested that the blast load induced by accidental/artificial
explosion should be carefully considered in the submerged tunnel
design. To prevent severe damage of the submerged tunnel, proper
protection measures are required.

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REFERENCES

Grantz W.C., 1993. Chapter 5: Catalog of immersed tunnels, Tunneling andUnderground Space Technology, Vol. 8, No. 2: 175-263.
Hakkaart CH. J. A., 1993. Chapter 6: Submerged floating tunnels,
Tunneling and Underground Space Technology, Vol. 8, No.2: 265285.
Liu G.Q. and Owen D.R.J., 1986. Ultimate load behavior of reinforced
concrete plates and shells under dynamic transient loading.
International Journal for Numerical Methods in Engineering, Vol. 22,
189-208.
LSTC, 2003. LS-DYNA Keyword user’s manual, Version 970, Livermore
Software Technology Corporation, Livermore, CA.
Lu Y. and Xu K., 2004. Modeling of dynamic behavior of concretematerials under blast loading, International Journal of Solids andStructures, Vol. 41, 131-143.
Lu Y. Xu K. and Lim H.S., 2003. Numerical simulation of concrete breakup under explosive loading, Design and Analysis of Protective
Structures against Impact/Impulsive/Shock Loads, pp. 278-286.
Saveur J. and Grantz W. C., 1993. Chapter 2: Structural design of immersed
tunnels, Tunneling and Underground Space Technology, Vol. 8, No.
2: 123-139.
U.S. Department of the Army, 1986. Fundamentals of Protective Design forConventional Weapons, Technical Manual 5-855-1.

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New Technologies for Urban Safety of Mega Cities in Asia

FULL-SCALE TESTS OF BLAST DOORSFOR PROTECTION AGAINST EXPLOSION
TAT-SENG LOK and CHEE-HIONG LIM
Protective Technology Research Centre
c/o School of Civil and Environmental Engineering
Nanyang Technological University, Singapore 639798
ctslok@ntu.edu.sg

ABSTRACTThis paper highlights blast doors – these are used to resist the effectsof air-blast only – and how these components are tested in full-scale
explosion tests. Further, such blast doors may be vulnerable to the effects offire and fragments. So, secondary tests must be conducted to comply withregulatory authorities. This paper outlines two full-scale explosion tests toassess a number of production blast doors. Testing methodology is
described to provide better understanding of the procedure and expectation.
Performance of each tested blast door is assessed and survivability is
discussed. Detailed outline of the blast doors is presented so that theperformance can be compared by designers/engineers who may haveconducted similar tests elsewhere.

1.

INTRODUCTION

An explosion (e.g. caused by the detonation of high explosives) isessentially a rapid chemical reaction. The consequence of which is therelease of a vast quantity of energy in the form of blast wave. Other byproducts include heat energy, other gases and traces of unburned products.
The most important and damaging component of conventional explosives isthe blast wave. If appropriate instrumentation were positioned perpendicular
to and facing the detonating source, then a pressure-time history would berecorded. The characteristic of the pressure-time history is a rapid rise inpressure of several bars above atmospheric pressure with a subsequent
decay occurring over a short duration, perhaps in the order of a few
milliseconds. Thereafter, a negative phase (suction) occurs. This
characteristic exposes the violent nature of a chemical process.
Such hazards are often associated with acts of terrorism in mega cities andbuilt-up urban areas but there are other sources of explosions that have
similar effects and consequences. For example, explosions derived from arapid burning process of oil-based products (petroleum refining facility),
confined gas (offshore natural gas) and coal/powdery dust (flour, cement
and pharmaceutical products).

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October 2005, Singapore

Pressure generated from an explosion impinges on every object in the pathof the expanding gas. The behaviour of the shock front and the effects of
explosions are well documented [Baker, 1973; Mays and Smith, 1995].
Thus, engineers need to be aware that the blast loading will cause buildings
to deflect, and the response is governed by the flexural stiffness of the
combined beam/column joint action and in-filled components. Therefore, itis essential for engineers to design structures or components with due care.
In the past, small-scale tests [Lok and Xiao, 1999] were designed to obtainblast parameters. However, studies showed that size effect has a significant
influence on pressure readings and material response. So, full-scale tests[Gould and Higgs, 2000] were considered important, especially in validating
blast-resistant glazing, doors and blast valves in buildings and infrastructure
systems to ensure that designs are responding to the specific stimulus.
This paper outlines a programme of research and development of blast doors
at the Protective Technology Research Centre. As part of the study, fullscale field trials were conducted. Two explosion tests were designed toinvestigate the performance and response of a number of production blastresistant doors. The tests were conducted at two separate locations inAustralia. A number of secondary studies were also designed to determine
the response of “seating” door arrangement. Details of the set-up, types ofdoors and observation of the performance are presented.

2.

FULL-SCALE TEST USING SMALL CHARGE WEIGHT

2.1

Sandwich blast doors

Most blast doors are constructed using a sandwich form. This systempromises high strength to weight and high stiffness to weight ratios
compared with other structural sections. Sandwich construction ischaracterised by two flat sheets with a core separating but firmly attached tothe sheets, and sandwich blast doors have been used extensively inimportant buildings and military facilities.
In this test, five different sandwich blast-resistant doors were subjected
to an explosion from the detonation of 100 kg of high explosives. Details of
the blast doors are summarised in Table 1 and the sandwich doors are shownin Figures 1 to 4.
Figures 1 and 2 are single leaf doors while Figures 3 and 4 areregarded as double-leaf doors. The arrangement of the double-leaf door
shown in Figure 3 may be regarded as two single-leaf doors. The doors were
installed into standard steel frames with its attendant silicon rubber sealaround the perimeter of the rebate. These doors, together with the frame,
were manufactured in a high-precision factory and transported to the testsite in Australia.

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No.
1

2
3

4

5

Table 1: Description of blast doors.
Door ID
Description
Door #1 Single leaf door – fabricated with horizontal aluminium
truss-core [Lok and Cheng, 2000] sections. Core sections
span horizontally across the width and door is wrapped in
0.8mm thick mild steel facing sheet.
Door #2 Identical construction as Door #1
Door #3 Large single-leaf “C” core door – fabricated entirely frommild steel sections. Channel sections use as core, spanvertically across the height.
Door #4 Double-leaf blast channel-core door – each leaf measures
1075mm wide by 2600mm high. Central mullion built
into frame. Doors are effectively single-leaf blast doors.
Channel core spans vertically.
Door #5 Fabricated exactly as Door #4 but without a central
mullion – vertical edge of one door is stiffened and acts
as the “central mullion”. Channel sections as core, spanvertically across the height.

Figure 1: Door #1

Figure 2: Door #3

Figure 3: Door #4

Figure 4: Door #5

Full Scale Tests of Blast Doors for Protection against Explosions

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October 2005, Singapore

2.2 Test site arrangement
To obtain the designed pressure from the explosion, each door was
arranged at the perimeter of circles as shown in Figure 5(a). Five heavily
reinforced concrete “open” supports were designed to accommodate theframe/door set. The distance (range) of each door was obtained byestimating the incident and reflected overpressures from the detonation of
the 100 kg bare TNT equivalent charge. Estimated overpressures are shownin Table 2. The test was conducted at the Proof and Experimental
Establishment in South Australia.
Blast waves flow around rigid objects at relatively high speed. So,
depending on the shape of the rigid object, turbulence and eddys form at theleading edge of objects. These flows could interfere with the front and rearface of an open support structure. To prevent the engulfing blast wave from
affecting the response, a 25mm thick steel plate was installed at the rear of
the supports. This plate was sandwiched between the concrete opening and astack of four pendine concrete blocks – Figure 5(b).
#2#1Charge
#3

R2

#5

R5

#4

Door
No.
(1)
#1
#2
#3
#4
#5
2.3

RC support

Range

R4

(a) Plan view of site

Steel plate
Concrete

1.5 m

R3ChargeR1

Blast(b) Elevation of support arrangement
Figure 5: Test arrangement and target layout

Table 2: Estimated and recorded peak blast overpressures
Range Estimated overpressure Measured overpressure
(kPa)
(kPa)
(R)
Incident
Reflected
Incident
Reflected
(2)
(3)
(4)
(5)
(6)
10.0 m241
851--140612.3 m
150
461
--491
17.9 m
70
178
81
227
17.9 m
70
178
81
302
17.9 m
70
178
81
---

Explosion testing

Pressure transducers and accelerometers were installed on thereinforced concrete frames and blast doors. One additional pressuretransducer was installed to record the side-on free-field incident

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overpressure. The data was recorded on personal computers linked byground cables 300 metres from the site. Figure 6 shows the set-up of the 100
kg of bare PE4 (TNT equivalent) charge prior to detonation. Three hundredand sixty-five sticks of PE4 were arranged in a circle. A single booster witha detonation cord was placed in the middle of the pack.

Door #4
1.5m

Figure 6: Arrangement of explosives and relative position of target
2.4 Test Results and performance of blast doors
Free Field Pressure.

100Kg. 5-JUN-2001.

14

DAT2, CH1.

81 kPa

12

11.8

10

8

Pressure (psi)After the detonation, blast
overpressures were successfullyrecorded on all the instrumentation.
The recorded incident overpressure
at 17.9 m from the charge is shownin Fig. 7. This recorded incident
overpressure was used to check theaccuracy of the estimated pressuretime data (70 kPa).

6

4

2

0

-2

-4
-20

-10

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

Time (mSeconds)

Figure 7: Pressure-time history

The estimated peak free-field overpressure shown in Table 2
underestimated this recorded value by about 14%. Measured normally peakreflected overpressure at Door #1 was 65% higher than the estimateddesigned pressure. This blast door was positioned closest to the explosive
source. At this distance, it would require about 165kg of TNT (equivalent)
to yield the same overpressure of 1406 kPa over 11.2 millisecond duration.
Generally, the measured overpressures are of a similar trend as
designed values. Although the hinges, shear pins, facing sheet and internal
aluminium truss-core units of Door #1 were not damaged, the locking
system was torn from the panel. However, the facing sheet was undamaged.
This door was positioned closest to the source of the explosion. The
measured normally peak reflected overpressure was over 14 bars; which
was 65% above the designed overpressure. Figures 8 to 11 show the posttest front view of blast doors #2, #3, #4 (with central mullion) and #5
respectively. All the doors survived the test and the silicon rubber seals
around the frame rebate were also intact.

Full Scale Tests of Blast Doors for Protection against Explosions403

October 2005, Singapore

3.

Figure 8: Door #2

Figure 9: Door #3

Figure 10: Door #4

Figure 11: Door #5

FULL-SCALE TEST USING LARGE CHARGE WEIGHT

From the previous test, the merits of a “composite” sandwich blast
door fabricated from a special extruded hollow aluminium truss-core section
were demonstrated. However, the cost of the truss-core aluminium extrusion
was high. Consequently, an investigation was undertaken to consider analternative core-section for the sandwich door with similar strength/stiffness
characteristics. An aluminium hollow rectangular core section was selected
because this section was generally available. A similar lightweight sandwich
blast door panel consisting of steel facing sheets with aluminium hollow
rectangular sections as the core was derived. Altogether, five blast doors
were fabricated and tested in this second trial, consisting of:• 3 number lightweight housing shelter blast doors (herein identified as
Door #6, Door #7 and Door #8).
• 1 number all-steel blast/ballistic-resistant ammunition storage sliding
door (Door #9).

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1 number all-steel internal “unseated” blast- and fire-resistant doors(Door #10).

The five blast doors were tested at the Woomera Protected Area inSouth Australia. To reinforce understanding of structural behaviour of the
sandwich system, numerical analyses of these door subjected to the
explosive loading was also conducted. The results of the numerical study
provided information on the response history and performance of a numberof preliminary designs. In the numerical analyses, material non-linearity was
included to account for the high-intensity explosive loading.
3.1

Fabrication of blast doors #6, #7 and #8

Three single-leaf doors were fabricated in an identical manner usingaluminium rectangular core sections and wrapped with thin mild steel facing
sheets. Short lengths (approximate widths of the door opening) of therectangular section were cut to form the dimension of the door width. Thinsteel facing sheets were then glued to the core sections. Various fixtures (e.g.
locks, hinges, shear pins) were installed prior to sealing. Overall dimensionsof the three doors were 1000mm wide by 2152mm high. The core units
were 2.0mm thick extruded aluminium hollow rectangular sections.
Thickness of the facing sheets varies with the distance from the centre of thecharge. The thicknesses were 1.0mm, 1.5mm and 3.0mm for the doors
furthest to the closest point measured from ground zero respectively. Threelarge reinforced concrete “box” frames with reinforced masonry side/backwalls were constructed to house the door. A standard steel door frame wascast in-situ during concreting.
3.2

Details of blast doors #9 and Door #10

Details of two other all-steel blast doors are shown in Figures 12 and13. In both these doors, a number of glazing component was also tested. For
Door #9, three glazing units were built into the reinforced concrete box
structure. A single cavity vision panel was installed in Door #10.

(b) Set-up at test site(a) Outline for construction
Figure 12 (Door #9) – All-steel sliding blast door (ammo storage)

Full Scale Tests of Blast Doors for Protection against Explosions405

October 2005, Singapore(b) Set-up at test site(a) Outline for construction
Figure 13 (Door #10) – All-steel internal “unseated” blast door
Instrumentation of all the blast doors was completed and checked onsite. All the five blast doors were subjected to a single detonation from a 5tonne TNT (equivalent) explosion. The door targets were positioned asshown in Figure 14 to accept the designed air-blast loading. Computed
overpressures and positive phase duration were calculated and shown in
Table 3. Once the targets were checked, the area was evacuated and all
personnel were requested to clear the site until after the detonation. Figure
15 shows an aerial view of the detonation. The fireball was observed at 6km from ground zero.
72 metres
51 metres
Reinforced soil wall barrier

34 metres
Door #8

Door #6
Door #7
Door #9

Door #10Three blast doors (Doors #6, Door #7 and Door #8)
Sliding door plus glazing (Door #9)
Internal “unseated” glazed door (Door #10)

Figure 14: Test site layout of blast door targets

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Table 3: Estimated pressure-time values
Normally peak+ve phase
Pressure
Distancereflected
durationloading on(m)overpressure (bars)(milliseconds)
Door #6 & #9
34
10.75
29
Door #751
3.36
60
Door #8 & #10
72
1.45
107

Door targets

Figure 15: Aerial view of fireball following the detonation
3.3

Results of test

All the blast doors survived the explosion. However, rippling of thefacing sheets was clearly observed on Door #6, #7 and #8. Details of therecorded maximum air-blast overpressures and durations are shown in Table
4. It can be seen that all recorded peak reflected overpressures are lower
than the estimated blast overpressures shown in Table 4.
Table 4: Recorded peak overpressure and duration
Normally peak+ve phase
Pressure
Distancereflected
durationloading on(m)overpressure (bars)(milliseconds)
4.17
25
Door #6 & #9
34
1.82
45
Door #751
1.03
50
Door #8 & #10
72
Although the blast doors were designed to sustain the initial higher
estimated peak overpressure, damage was observed to be excessive forDoors #6 and #7. This is due to a number of reasons but the most likely
reason was that the doors were improperly fabricated and not manufactured
to specification. Due to time constraints, many issues were not resolved

Full Scale Tests of Blast Doors for Protection against Explosions407

October 2005, Singapore

before the doors were transported to and installed in Australia. De-bondingof the surface sheet from the aluminium core was noticeable prior to the test.

4.

CONCLUSION

The performance of production blast doors subjected to two full-scale
explosion tests has been investigated. Despite the high costs, full-scale blast
tests are necessary to identify design faults and to inspire confidence ofusers. No amount of computer analyses can substitute a full-scale test or the
response of the shear pin/locking system. The cost to lives and investment
confidence would be higher if faults were not identified or corrected prior to
installation of such components in buildings and important facilities inmajor cities and urban areas. The tests provide a significant learning
opportunity to better understand the mechanics of real situations in an
explosive environment.

5.

ACKNOWLEDGEMENT

The authors wish to acknowledge the financial and other forms ofassistance provided by the Defence Science and Technology Agency,
Protective Technology Research Centre (NTU), Major Warren Smith and Mr
John Carley (from the Proof and Experimental Establishment), Mr Craig
Hoing (Chief UK Scientist, Ministry of Defence) and Major Keith Parker(Woomera Protected Area).

REFERENCES
Baker, W.E., 1973. Explosions in air. University of Texas Press, Austin andLondon.
Gould, M.J.A, and Higgs, Q., 2000. UK/Australian 40t donor/acceptor trial
housing damage and quantity-distance assessment. Proc 16th Int.
Symp. on Military Aspects of Blast and Shock, Keble College, Oxford,
Sept, 201-216.
Lok, T.S. and Xiao, J.R., 1999. Steel fibre reinforced concrete panels
exposed to air blast loading. Proc ICE Structs & Bldgs, Vol 134, Nov,
319-331.
Lok, T.S. and Cheng, Q.H., 2000. Free vibration of clamped orthotropic
sandwich panel. Jour of Sound and Vibration, Academic Press, Vol
229, No 2, Jan, 311-327.
Mays, G.C. and Smith, P.D. (Ed.), 1995. Blast effects on buildings – designof buildings to optimize resistance to blast loading. Thomas Telford,
London, UK.

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New Technologies for Urban Safety of Mega Cities in Asia

STUDY ON OPTIMUM DESIGN METHODFOR PLEASANT OUTDOOR THERMALENVIRONMENT USING GENETIC
ALGORITHMS (GA) AND COUPLEDSIMULATION OF CONVECTION,RADIATION AND CONDUCTION
HONG CHEN, RYOZO OOKA, SHINSUKE KATO
Institute of Industrial Science, University of Tokyo,
4-6-1 Komaba Meguro-ku, Tokyo, Japanchenhong@iis.u-tokyo.ac.jp

ABSTRACT
A lot of research has recently been conducted into improving outdoor
thermal environments in summer. In this paper, (1) an optimum design
method with Genetic Algorithm (GA) and coupled simulation of convection,
radiation and conduction for comfortable outdoor thermal environments isdeveloped; (2) in order to examine the validity of the proposed optimum
design system, apartment block space in an urban area is set as an analysis
target and the optimum arrangement of trees is analysed for pleasant outdoor
thermal environment design. For the optimum arrangement of trees, twocases which are different in target area are examined to clarify the effect ofdifferent target areas (all open space or pedestrian road) on optimization. As
a result, the optimum arrangements of trees are given using GA andsimulation, and the validity of the optimum design method is confirmed.
1. INTRODUCTION
In recent years, with increasing urbanization, the heat island phenomenon
has become significant and a deterioration in the outdoor environment as a resultof heat islands and similar phenomena has become a serious problem. In an
attempt to improve the outdoor thermal environment in summer, a lot of research
has taken place in the fields of urban planning, architectural design, andenvironmental engineering. The relief effect on the outdoor thermal environmentof the arrangement of planting has attracted attention from the point of view ofpromoting latent-heat evaporation and solar shading (Hagishima et. al., 1999,
Yoshida et. al., 2000). However, most of these researches have been concernedwith the development of an evaluation method to measure the effect of thesetechniques on the outdoor thermal environment. An optimum design method forthe outdoor thermal environment has not yet been developed sufficiently.
Although appropriate planting arrangements become very importantfactors in designing a comfortable outdoor thermal environment, thesearrangements are actually often made empirically, from the varying standpoints409

October 2005, Singapore

of conventional planning concepts or landscape design. There is almost no
example of research into the optimum design method for a pleasant outdoor
thermal environment. On the other hand, for the designer, it would be very useful
to develop an optimum design method. However, in order to determine which
design is actually "the optimum", it would be necessary to examine the effect ofall possible designs. In this case, the potential number of cases to be examinedbecomes almost impossibly large. Researches into the optimum design method,which sets out to maximise the evaluation function value used as a design target,
have reached an early stage in the fields of structural and architectural design(Mitsui et. al., 1994, Okamoto et. al., 1993, Aoki, et. al., 1996) and, recently,
researches in optimum design have also been introduced for designing airconditioning in the environmental engineering field (Kim et. al., 2001). A similar
approach is possible for outdoor thermal environmental design. In the present
situation, when an improvement of the outdoor thermal environment in summer
is urgently required, an optimum design method concerned with the arrangementof planting so as to improve the outdoor thermal environment needs to be
developed. However, it could be considered that one of the reasons that these
optimizations have never been handled as an engineering problem hitherto is thatthe engineering design method has not been sufficiently developed. In thisresearch, an optimum design method for planting arrangements to improve theoutdoor thermal environment in summer is proposed as the 1st step of research
into the outdoor optimum design method. In future, a multiple-object optimum
design method incorporating other factors will be examined.
In this research, the authors concentrate on human thermal comfort in an
outdoor space; an optimum design method using a coupled simulation of
convection, radiation and conduction is examined in connection with planting
arrangements for a pleasant outdoor thermal environment. Genetic algorithms(GA) (Kitano et. al., 1993) are used for an inquiry into the optimum solution.
2. OPTIMUM DESIGN SYSTEM
2.1

Composition of Optimum Design System and Optimum Inquiry
using Genetic Algorithms

Figure 1 shows a flow-chart of the optimum design system for theoutdoor thermal environment using Genetic Algorithm (GA) and coupledsimulation of convection, radiation and conduction. This optimum design system
is composed of the following three parts: (1) Optimization problem set up by thedesigner. (2) Numerical analysis of the outdoor thermal environment using(1) Setting of Problem
Design Objective(2) Numerical Analysis

Feedback
on design
parameter

Input Data

Change of Design Parameter

Design parameter
Method of Optimum Design
Evaluation Method and Standard
Value for Optimum Design

Designer
設計者(3) Evaluation and Control

The design target is not filled

Numerical Analysis of Outdoor
Thermal Environment using
Coupled Simulation
The spatial distribution of Wind
Velocity, Air Temperature,
Humidity and MRT are Obtained.

Outdoor Thermal
Environment Evaluation
Optimum
Evaluation
Value

The design target is filled

Optimum Design

Figure 1 The Composition of the Optimum Design System

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coupled simulation of convection and radiation. (3) Evaluation of the optimum
solution candidate and control of the optimum inquiry process by GA. Here, inthe first part, the design objective and the design element for the optimum design
are determined. The optimum design methods, the method for quantifying theoutdoor thermal environment and the standard value for selecting the optimum
solution candidate are also determined at this stage. In the second part, the spatial
distribution of wind velocity, air temperature, humidity and MRT (Mean
Radiation Temperature) of a candidate are calculated and the spatial distributionof the optimum evaluation value is calculated from the above results. (In thisresearch, the SET*, New Standard Effective Temperature, which is thecomprehensive index of human thermal comfort (Gagge et. al., 1986), isemployed.) In the third part, it checks whether the optimum evaluation value ofthe optimum solution candidate computed in the second part corresponds withthe standard value for selecting the optimum solution candidate determined in thefirst part. When the outdoor thermal environment does not satisfy the design
objective, the combination of design variables is changed, and the optimum
inquiry is advanced by feeding back this combination of design variables to thesecond part. Eventually, when the evaluation values of the outdoor thermal
environment satisfy the design objective, the feedback is ended at the second part.
The value of the design parameter at this time becomes the optimum value.
In this research, theSimple GA
numerical analysis method of
outdoor thermal environment
Population
which the authors developed is：Individual
used in the second part (Chen et.
：Migrational., 2004).
Individual
In the third part, thegenetic algorithm (GA) is used
to select optimum solution
Islandcandidates and control theMulti-island model
optimum inquiry process. In thisFigure 2 The Concept of Multi-Island
research, a more efficient
Genetic Algorithm
Genetic Algorithm called a
The First Step Optimum Inquiry"Multi-island
Genetic
Simple Analysis
Condition Setup
Algorithm" is used in thisBuilding
Radiation
CFD
Trees
research (Tanese et. al., 1989).
(steady)(large mesh)•••
Figure 2 shows the concept ofmulti-island genetic algorithm.
Standard vaule for
Optimum Design Inquiry
optimum evaluation
using GAThe method is a distributed(1)
genetic algorithm. The feature of
Individual who has high fitness
this method is that the population
Standard vaule for
optimum evaluationin one generation is divided into
case1
case2
•••
(2)
several sub-populations, and thegenetic operations are performed
Design parameter
Fitness
Fitness•••
independently in each subcombination of
1
2
optimum
population. The exchange of
Detailed Analysis
individual is
Radiation (unsteady)considered as
individual information that is
CFD (turbulent flow)
optimum design
called "migration" is generated
The Second Step Optimum Inquiry
periodicallybetweensubFigure 3 Two-step Typepopulations.
Optimum Design Method

Study on Optimum Design Method for Pleasant Outdoor Thermal Environment Using Genetic Algorithms···411

October 2005, Singapore

2.2 Two-step type optimum design method
If the detailed coupled simulation of convection, radiation and conduction is
performed on all the individuals in the optimum inquiry process described in theforegoing paragraph, the calculation load becomes huge and is unsuitable for apractical design process. Thus, a two-step type optimum design method is used in thisresearch. The two-step type optimum design method is divided into a 1st step inquiry
where high-ranking individuals are extracted with a fairly rough calculation and a 2nd
step inquiry where the optimum individual is chosen by more detailed analysis fromamong the group of highest-ranking individuals identified in the 1st step inquiry.
Figure 3 shows the flow chart of the two-step type optimum design method.
(1) 1st step inquiry:
The radiation analysis is performed under steady state conditions. The
laminar and isothermal CFD simulation is performed with coarse meshes.
From among all the optimum solution candidates, the individual for which
the evaluation value exceeds the optimum evaluation standard value
becomes the candidate for the 2nd stage inquiry.
(2) 2nd step inquiry:
The detailed coupled simulation of convection and radiation is performed on
the candidate for the 2nd step inquiry. The spatial distribution of air temperature,
wind velocity, relative humidity, and MRT are calculated, and the objectivefunction is calculated. In this step, the radiation analysis is performed under
unsteady state conditions, and the CFD simulation is performed with small meshes.
(3) Among the candidates analyzed in the 2nd step inquiry, the candidate
which has the highest fitness is regarded as the optimum individual, and the design
parameter combination of this individual is considered as the optimum design.
3. APPLICATIONS OF THE OPTIMUM DESIGN SYSTEM ON
OUTDOOR THERMAL ENVIRONMENTAL DESIGN
3.1 Design Objective
This research sets the optimization problem of the outdoor thermal
environment with the optimum arrangement of trees in summer as its design
objective. In concrete terms, it investigates the optimum arrangement oftrees, where the spatial integration of the spatial distribution of the objectivefunction described later is to be maximized.
3.2 Analysis Target
Figure 4 shows the building block model. The block is composed of thesame shaped buildings (20m(L) ×20m(W) ×30m(H)). 15:00 on July 23rd istargeted as the date for analysis. The sun’s altitude is 45.1º, the wind direction issouth, the wind velocity is 3.0m/s at a height of 74.6m, and the air temperatureand relative humidity are set at 31.6ºC and 58%. In addition, the number of thetrees is fixed at eight in this model. The tree height and tree crown diameter are
assumed to be 7m and 5m respectively. In this research, the tree model developedby Yoshida et al. (Yoshida et. al., 2000) is employed for coupled simulation.
3.3 Design Parameter
The position of the tree in the analysis domain is assumed to be a design

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Sun’s altitude 45.1°
N
W
S

E

83.2°

wind

22

26

21

25

20

24

19

23

13 14 15 16 17 18
7 8 9 10 11 12Road(concrete)

20.0
5.0 5.0

Building(concrete)
Trees arrangement domain(concrete)

1

10.0

wind

Unit：m

40.0

30.0m

40.0

5.0 5.0

20.0

5.0 5.0

Figure 4 Analysis Target

2 3

4

5

6

5m
5m

Allotment of a Mesh Number
Trees Number
The Position of Trees(Mesh Number)（continue）

Coding

1
3

2
7

3
12

5
13

6
15

7
17

（continue）

8
23

Figure 5 Chromosome’s Describing Methodparameter in this research. In practical terms, the number of the mesh inwhich a tree is positioned among the possible 26 meshes in the analysis
domain is assumed to be a design parameter.
3.4 Objective Function
The evaluation of optimization proceeds by the following method. A
comparison is performed between the spatial distribution of SET* in thebasic case where there are no trees and in the case where eight trees havebeen arranged. The improvement level of the outdoor thermal environment
with the arrangement of trees is evaluated by the decrease in the value of
SET*. The objective function (the fitness) is defined by the following
equation:

Ftotal = ∑ { B j − D j }（1）where, Ftotal is the objective function (fitness), Bj is the value of SET* atpoint j in the basic case, and Dj is the value of SET* at point j in the casewhere trees are arranged. In this research, the optimum arrangement of treesthat has the maximum value of spatial integration of objective function in
the outdoor thermal environment is set as a design objective.
3.5 GA Parameter and Chromosome Description Method
Table 1 shows the GA parameter used in this research. The size of
sub-population is 10, the number of islands is 6, and the population size is 10
×6=60. The number of generations is 12, and the total number of individuals
analysed in the inquiry process becomes 60×12=720. The selection used themethod of tournament selection, which repeatedly selects the individual withthe highest fitness from two or more individuals chosen at random. The rateof a tournament is set as 0.4. The crossover is simple crossover, the rate ofcrossover is 1.0, and the rate of mutation is 0.02. In addition, the rate of
migration and the interval of migration are set at 0.5 and 2 respectively.
Figure 5 shows the chromosome description method. The arrangement
problem of trees is becomes the problem of which eight cells should be selectedfrom the 26 cells available for the positioning of trees in the two dimensional
plan. One tree is assumed to be a "Unit", and "Tree number" is set respectively.
The chromosome is set to a sign row that describes the position of each tree inthe row (using the mesh number defined in Figure 5). Usually, the chromosome
is described with a binary mark, and a "0" or "1" is written at the appropriate

Study on Optimum Design Method for Pleasant Outdoor Thermal Environment Using Genetic Algorithms···413

October 2005, Singapore
Table 1 GA Parameters
Size of Sub-Population
10
Number of Islands
6
Population Size
60 (10×6)
Number of Generations
12
Total Individual Size
720 (60×12)
Rate of Migration
0.5
Interval of Migration
2
Rate of Tournament
0.4
Rate of Crossover
1.0
Rate of Mutation
0.02

Table 2 Analysis Case
Case 1-0 Basic case (trees are not arranged)
The whole outdoor domain isCase 1-1 targeted (The horizontal plane at
1.5m height in the analysis domain).
The road area (human activity
domain) is targeted (The horizontal
Case 1-2
plane at 1.5m height in thepedestrian road).

locus. In this research, the chromosome is defined by each mesh number beingchanged into a binary mark that is written in the corresponding locus.
3.6 Analysis case
Table 2 shows analysis case. In order to clarify the effect of different
target areas (all open space or pedestrian road) for the optimization, the following
3 cases are analysed. (1) case1-0 is the basic case, inwhich trees are not arranged.
(2) case1-1 deals with an entirely open space. In other words, it is evaluated using
the sum total of SET* at each point (at 1.5m height) throughout the whole openarea. (3) case1-2 applies only to the domain for human activities. Namely, it isevaluated using the sum total of SET* at 1.5m height on the pedestrian road.
3.7 Analysis Procedure
In this research, the analysis procedure shown in Figure 2 is used.
The laminar and isothermal CFD analysis is performed with coarse meshes
in the 1st step inquiry. In this step, the spatial distribution of air temperatureand relative humidity are assumed to be constant throughout the wholeanalysis space. Among all of the individuals, ten candidates are selected forthe 2nd step inquiry. Moreover, the spatial distribution of SET* for the basic
case is calculated respectively in two step inquiries and is adopted as thestandard value for optimum evaluation at each stage.
4. ANALYTICAL RESULTS AND CONSIDERATIONS
4.1 1st Step Inquiry
Figures 6 and 7 show the optimum inquiry processes of cases1-1 and 12 with GA in the 1st step inquiry. The horizontal axis represents the Run
Counter of the optimum inquiry process, and the vertical axis is the objectivefunction (SUMSET). As a trend, we can see that the objective function of theindividual becomes higher with the optimum inquiry process.
The results of optimum inquiry (up to 5th highest rank) in cases1-1 and 1-2
are shown in Figures 8 and 9. The sun azimuth of Tokyo is west-south-west at
3:00PM on July 23rd and the surface temperature of the building on the west andsouth sides becomes high. In order to reduce MRT (Mean Radiant Temperature) inboth cases, there is a tendency for trees to be arranged on the west and south sidesof the building because the sun is located in a south and west direction in theafternoon. The trees are arranged in a rather scattered fashion in the case1-1 that
deals with the whole open area. But in contrast to case1-1, in case1-2 that pays
attention only to the road area the trees are gathered near the pedestrian road.

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4.2 2nd Step Inquiry
The 2nd step inquiry is performed for ten individuals chosen by 1st stepinquiry in cases1-1 and 1-2. The optimum individuals chosen by the detailed
coupled simulation of convection, radiation, and conduction are shown by thepatterns of tree arrangement surrounded by a dotted line in Figures 8 and 9. The
thermal environment of the optimum design for cases1-1 and 1-2 are shown in

Figure 6 case1-1 The Optimum
Inquiry Process

The First

Figure 7 case1-2 The Optimum
Inquiry Process

The Second

The Third

The Fourth
The Fifth
Figure 8 case1-1 The Results of Optimum Inquiry in 1st Step (up to 5th high rank)

The First

The Second

The Third

The Fourth
The Fifth
Figure 9 case1-2 The Results of Optimum Inquiry in 1st Step (up to 5th high rank)

Study on Optimum Design Method for Pleasant Outdoor Thermal Environment Using Genetic Algorithms···415

October 2005, Singapore

Figure 10 and 11. Considering the average value within the analysis domain, theair temperature of case1-1 is about 0.5˚C higher than that of case1-2, and alongwith a higher air temperature, the relative humidity of case1-1 is lower by about
3% than that of case1-2. The wind-velocity scalar value of case1-1 is higher by
about 0.04m/s, and MRT of case1-1 is lower by about 0.5˚C, than those of case12. The average value of SET* at 1.5m height in the whole open area and the roadis shown in table 3. Compared with the basic case, SET* decreases in both case11 and case1-2, and the outdoor thermal environment relief effect from thearrangement of trees is recognized. Moreover, in case1-1, although average
SET* for the whole open area is lower than that of case1-2, average SET* in theroad area becomes higher. It is apparent that the difference in target domain has
had a significant influence on the result of the optimum inquiry.
In order to reduce MRT, although it might be expected that all trees would
be arranged on the south and western sides of a building in the optimum individual,some trees (No. 25 of case1-1, No. 3, 4 and 25 of case1-2) are in fact arranged on
the eastern and northern sides of the building in both cases. This is considered
to be for the following two reasons. For example, the individual in whichtrees are arranged like the third place in the 1st step inquiry of case1-2 issimilar to two optimum individuals in case1-1 and case1-2. (1) In case1-1, theauthors consider the whole open area for the objective function. Although
MRT becomes a little higher in the optimum individual (individual of the 4thplace in the 1st step inquiry) in case1-1, a circulation flow occurred in thebuilding canyon space because trees are concentrated on the southwest cornerin the building canyon, and wind velocity is increased in the building canyon
in the optimum individual in case1-1. Moreover, although the tree in No.25
mesh does not shade direct solar radiation, MRT is decreased in theneighboring area of the tree because reflected solar radiation and long wave
radiation from the wall are shaded. Therefore, SET* of the individual in the
4th place in the 1st step inquiry becomes low, and this becomes the optimum
individual for the 2nd step inquiry. (2) In case1-2, the authors pay attention to
the pedestrian road area in the analysis domain for the objective function.
Since the sun azimuth at analysis time is in the west-south-west, the road area
does not become shaded if trees are arranged in the western and southernsides as in the 2nd place of case1-2 in 1st step inquiry. Moreover, in case1-2,
MRT for this optimum individual at the road becomes lower compare withthe 3rd place individual in the 1st step inquiry because the reflected radiationand long wave radiation from the neighboring wall are shaded by the trees
with mesh numbers 3, 4, and 25. Therefore, the 2nd place individual in the 1st
step inquiry becomes the optimum design for case1-2 in the 2nd step inquiry
confined to the road area.
5. CONCLUSIONS AND REMARKS(1)
The optimum design method for the optimum arrangement ofbuildings and trees with GA and coupled simulation of convection, radiationand conduction for the design on outdoor thermal environment is developed.
(2)
In considering the optimum arrangement of trees, two cases which
are different in target area (all open space or pedestrian road) are analysed.
Compared with case1-0 (the basic case), the relief effect of trees on the outdoor

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30.
0.4
0.2

69

31

0.2
0.4

30

30

66

30.

63

60

63
66

(1) Wind Velocity Vectors(2) Air temperatureand Scalar Value (0.39m/s)(29.6°C)50(3) Relative Humidity(62.9%)

42

38

36
40

25
20

30

30

34

40

34
36

35

20
20

25
22

(4) MRT(5) SET*(35.9°C)(34.32°C)
Figure 10 case1-1 The Thermal Environment of the Optimum Design (at 1.5m height)(The Horizontal distribution of Physical Quantities in Optimum Evaluation Domain)(The value in parentheses is an average value)
29.5
0.4
0.2

75

27.5

0.2
0.4

29.5

28

63

28.5

(2) Air temperature(29.1°C)

50

38

32

35
30

35 30

34

34

20
45

(3) Relative Humidity(65.9%)

42

25

66

66

29

(1) Wind Velocity Vectors
and Scalar Value (0.35m/s)

69 72

69
72

36

34

32
22

(4) MRT(5) SET*(36.4°C)(34.71°C)
Figure 11 case1-2 The Thermal Environment of the Optimum Design (at 1.5m height)(The Horizontal distribution of Physical Quantities in Optimum Evaluation Domain)(The value in parentheses is an average value)

Study on Optimum Design Method for Pleasant Outdoor Thermal Environment Using Genetic Algorithms···417

October 2005, Singapore

outdoor thermal environment is seen from the results of case1-1 and case1-2.
In addition, although the average value of SET* in the all open area incase1-2 is higher by about 0.4˚C than that in case1-1, the value in pedestrianroad in case1-2 is lower by about 0.2˚C than that in case1-1. Thus, theoptimization of outdoor thermal environment is achieved in accordance withdifferent target areas, and therefore it is considered that the validity of this
proposed method for the optimum design can be seen.
(2)
A lot of researchers have proposed countermeasures for heat island
phenomena in order to realize a healthier outdoor thermal environment. In thiscontext, it is considered that the results of the optimum inquiry method for tree
arrangements will be useful in the practical design stage of an urban environment.

REFERENCES
Aoki, Y., Muraoka, N., 1996. A method of the facility location by Genetic
Algorithm, J. Archit. Plann. Environ. Eng., AIJ, No.484, 129-135 (inJapanese)
Chen, H., Ooka, R., Harayama, H., Kato, S., Li, X., 2004. Study on outdoor
thermal environment of apartment block in Shenzhen, China withcoupled simulation of convection, radiation and conduction, Energy
and Buildings, pp. 1247-1258
Gagge, A.P., Stolwijk, J.A.J., Nishi, Y., 1986. A Standard Predictive index
of human respons to the thermal environment, AHSRAE Transactions,92(1), 709-731
Hagishima, A., Katayama, T., Hayashi, T., Tanimoto, J., 1999. Numericalanalysis on cooling effect of a row of trees in an urban canyon, Part2
Prediction of thermal comfort on streetwith roadside trees, J. Archit.
Plann. Environ. Eng., AIJ, No.525, 83-90 (in Japanese)
Kim, T., Kato, S., Murakami, S., 2001. Two Step Optimal Design Method of
Indoor Thermal Environment based on CFD Simulation and Genetic
Algorithm, Annual Technical Meeting of Architectural Institute ofJapan (D) (2001) 771-772 (in Japanese)
Kitano, H., 1993. Genetic Algorithm 1, Industrial books Ltd. (in Japanese)
Kato, M., Launder, B.E., The modeling of turbulent flow around stationary
and vibrating square cylinders, Prep. of 9th Symp. on Turbulent shear
flow (1993) 10-4-1-6
Mitsui, K., Tomita, K., Tosaka, N., 1994. Application of genetic algorithm
in structural form analysis, Annual Technical Meeting ofArchitectural Institute of Japan (B) (1994) 1211-1212 (in Japanese)
Okamoto, H., Hatori, M., 1993. Application of neural network on the
optimum arrangement including nonlinear evaluation function,
Annual Technical Meeting of Architectural Institute of Japan (E)(1993) 773-774 (in Japanese)
Tanese, R., 1989. Distributed genetic algorithms, Proc.3rd ICGA, pp. 434–439.
Yoshida, S., Ooka, R., Mochida, A., Tominaga, Y., Murakami, S., 2000.
Study on Effect of Greening On Outdoor Thermal Environment Using
Three Dimensional Plant Canopy Model, J. Archit. Plann. Environ.
Eng., AIJ, No.536, 87-94 (in Japanese)418

New Technologies for Urban Safety of Mega Cities in Asia

PREDICTION OF POLLUTANTDISPERSION CAUSED BY AUTOMOTIVEEXHAUST- A COMPARISON BETWEEN FIELDMEASUREMENTS AND WIND TUNNELDATA Takeaki Watanabe1, Shinsuke Kato2, Ryozo Ooka3,
Takeo Takahashi4 and Ryohei Kono1
1
University of Tokyo, Japan2, 3, 4
Institute of Industrial Science, University of Tokyo, Japanwtakeaki@iis.u-tokyo.ac.jp

ABSTRACTThis study aims to contribute to the development of traffic measuresthat result in less pollution by predicting the distribution of pollutant
concentrations caused by automotive exhaust around an intersection in an
urban area. An example of the traffic measures is the traffic lights control
to reduce the frequency of stop and go at intersections. The study consists ofa wind tunnel experiments and field measurements. The studied area iscentered on the Ikegami-Shinmachi intersection in Kawasaki-shi, situated in
an industrial region in the vicinity of Tokyo. The wind tunnel experiments
consist of diffusion tests using point and line sources of tracer gas, and thefield measurements include diffusion tests using a point source of tracer gas
and measurements of carbon monoxide (CO) and nitrogen monoxide (NO)concentrations. The results of the wind tunnel experiments using point andline sources were also in good agreement with the field measurements. The
results indicate that the experimental data obtained in this study is highly
reliable in verifying predictions based on computational fluid dynamics.
1. INTRODUCTION
Air pollution from automotive exhaust along major highways has
recently been recognized as a problem in large cities. Such pollution ischaracterized by pollutant concentrations that are several times higher along
the highways than in the background urban area. The problem isexacerbated by poor air passage associated with dense use of city space. In
order to resolve this problem, precise information on pollutant distribution isrequired.
This study aims to contribute to the development of traffic measuresthat result in less pollution by predicting the distribution of pollutant
concentrations caused by automotive exhaust around an intersection in an419

October 2005, Singapore

urban area. An example of the traffic measures is the traffic lights control.
Reducing the frequency of stop and go means reducing pollutant generation.
The study consists of a wind tunnel experiments and field measurements.
The wind tunnel experiments consist of diffusion tests using point and line
sources of tracer gas, and the field measurements include diffusion tests
using a point source of tracer gas and measurements of carbon monoxide(CO) and nitrogen monoxide (NO) concentrations. The results obtained by
the two approaches are then compared. Similar comparative studies werepreviously performed by Kennedy [1977] and Bachlin [1991].
2. STUDIED AREA
The studied area, shown in Figure 1, is centered on the IkegamiShinmachi intersection in Kawasaki-shi, situated in an industrial region in
the vicinity of Tokyo. This area is known to have the worst air pollution
from automotive exhaust in Japan. A local highway runs in a southwestnortheast direction through the area in parallel with an elevated section of
the expressway. A general urban area lies north of the highway with anumber of factories to the south. The highway and the expressway are
assumed to be the sources of the automotive exhaust.
N
Inbound line
Outbound line
Ikegamishinmachi

E
D

Point sourceCLine source
B
A
Fence

Point
2
1
Inbound3
4
Outbound

510m

Figure 1: Locations of tracer gas sources in the studied area
3. OUTLINE OF WIND TUNNEL EXPERIMENTS AND FIELDMEASUREMENTS
3.1 Outline of wind tunnel experiments
The experiments were performed using a thermally stratified windtunnel at the Institute of Industrial Science the University of Tokyo. The

420

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wind tunnel has a cross section of 1.8 m × 2.2 m at the point of
measurement and is 16.5 m in length. A 1/600 scale urban model of acircular area defined by a radius of 510 m from the intersection was used forthe experiment (Figure 2). On the lower left side of the intersection shownin Figure 1, there is a fence under the elevated expressway, between piers
along the centerline of the highway (Figure 3). The fence is intended toremove air pollutants with plants. There are little openings in the fence,
which is covered with thickly grown plants. In the model experiment, a
fence without openings was installed without considering the effect ofconcentration reduction by plants. A total hydrocarbon analyzer was used
for concentration measurements. The mean wind velocity profile isexpressed by U∝Z1/4 at the center of the model installation point. The winddirections used in the experiment include the three dominant directions(south, southwest, and north) and the directions perpendicular to thehighway (southeast and northwest). A total of 139 measurement points at aheight of 1.8 m (in actual size) were established. Ethylene (C2H4) was usedas the tracer gas. Point and line sources of tracer gas were used. The point
sources were set at five locations (A to E in Figure 1), while four sourceswere placed at each location (one source on each of the inbound andoutbound lines of both the highway and elevated expressway). Gas was
exhausted individually for each test. The velocity of exhaust fromautomobiles is negligible because its effect on the flow field is far less thanthe effect of the surrounding buildings. Each exhaust opening, situated atroad surface level, has a diameter of 6 mm. To minimize the effect of theexhaust velocity, a cover was set 5 mm above the exhaust opening. Figure 4
shows the exhaust openings of the point sources. An air stone with adiameter of 10 mm and a length of 1200 mm was used as a line source, andtracer gas was fed into the source from both ends. When the air stone wasused as it was, a large amount of tracer gas flowed out from both ends rather
than the central part of the source. Therefore, the air stone was wrappedwith plastic tape to adjust the exit area so that the gas would be emitted
uniformly from the line source. Line sources were placed at three locations(on the elevated expressway and the inbound and outbound lines of the
highway), and gas was exhausted from each source individually. Figure 5
shows the line sources. Atmospheric stability was set to neutral in principle,
but both stable and unstable situations were tested only for the winddirection SE.

Figure 2: Wind tunnel model

Figure 3: Fence installed under the elevated expressway

Prediction of Pollutant Dispersion Caused by Automotive Exhaust- A Comparison Between Field Measurements and Wind Tunnel Data -421

October 2005, Singapore

Figure 4: Point sources

Figure 5: Line source

3.2 Outline of field measurements
Field measurements were taken from February 1 to 3, 2005.
Measurements were taken at 20-min intervals from 8:45 to 15:05 including
every hour on the hour. The measurement points, 17 points in total, areshown in Figure 6. Measurement points 1 and 15 are on a sidewalk of an
ordinary road, points 2, 3, and 4 are in a neighboring district, points 5
through 12 are on the sidewalks of the highway, and points 13, 14, 16, and17 are in a park. The measurement height was 1.5 m above the ground. A
tracer gas, sulfur hexafluoride (SF6), was exhausted from point A or B on asidewalk of the highway (Figure 6) at a height of 1.5 m. The gas was
exhausted at a rate of about 22.4ℓ/min. At each measurement point,
polluted air was collected with a suction pump into a 20-ℓ bag and wasanalyzed with a multi-gas monitor. The CO concentration of the sampled
air was measured with a carbon monoxide analyzer and the NO
concentration with a nitrogen oxide analyzer. To estimate the emission
rates of automotive exhaust, automobiles passing the intersection werevideotaped from a pedestrian bridge on the east side of the intersection. The
observed automobiles were classified into (1) light and ordinary cars, (2)light and ordinary trucks, (3) large trucks and special vehicles, and (4) buses,
and the number of vehicles that passed were determined for each group.
The meteorological data used was based on the data observed at anenvironmental measurement station near the studied area. Atmosphericstability was not measured. Concentrations were measured at ground level
along the highway. As discussed later, it was assumed that the effect ofemission from the elevated expressway on the ground area was small andthat exhaust sources were only on the highway regarding the measurements.
N
1

Elevated expressway
Local highway
8

4
7

3

2

6
5
9

10

11

A 14
B 13

Fence
0m

100m

12

200m

15
17

16

Figure 6: Field measurement and gas emission points
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4. RESULTS
4.1 Results of wind tunnel experiments
4.1.1 Distribution of the normalized concentration of exhaust from point
sources
For the case of neutral atmospheric stability, measurement results areshown as the normalized concentrations (CE/Co). Here, CE is concentration
measured in the wind tunnel experiments, Co=Q / (UH2), Q is tracer gas
generation rate (=1cc/s), H is the height of the elevated expressway (=1.33cm), and U is the wind velocity at height H (=0.42 m/s).
1) Wind direction SE; Exhaust opening on the inbound line of theground-level highway (D1) (Figure 7)
The gas emitted from the exhaust opening was blocked by a medium-risebuilding located on the leeward side of the opening and was deflected
widely along the highway in the lateral directions. A CE/Co value of 0.001
was observed near the intersection, about 100 m away from the opening
along the highway. A value of 0.68 was observed in the very vicinity of theexhaust opening, whereas values of 0.04 and 0.01 were observed 40 and
N

0.0

0.001
0.001
0.01

N

0.001

0.0

0.0

0.001
0.01
0.05
0.1
0.5

0.0

0

100m

Figure 7: Normalized concentration of Figure 8: Normalized concentration ofgas from an exhaust openinggas from an exhaust opening
on the ground-level highway
on the elevated highway(D1; wind direction SE)(D2; wind direction SE)
N

0.0
0.001
0.001

0.01

0.05
0.1
0.3

0.0

0

100m

Figure 9: Normalized concentration of gas from an exhaust opening
on the ground-level highway (B1; wind direction SE)
Prediction of Pollutant Dispersion Caused by Automotive Exhaust- A Comparison Between Field Measurements and Wind Tunnel Data -423

October 2005, Singapore

150 m leeward of the opening. Attenuation of concentration in the direction
was very large.
2) Wind direction SE; Exhaust opening on the inbound line of theelevated expressway (D2) (Figure 8)
Most of the gas exhausted on the expressway diffused upward, and theeffect of the gas on the ground level was very small. A CE/Co value of 0.03
was observed 40 m leeward of the exhaust opening, which was greater thanthe value of 0.02 observed on the sidewalk right beneath the opening. The
area with non-dimensional concentrations of 0.001 or more extended as far
as 250 m, more extensive than in the case of ground emission (D1).
3) Wind direction SE; Exhaust opening on the inbound line of theground-level highway (B1) (Figure 9)
The gas emitted from the exhaust opening was influenced by the wakeflow of the fence under the expressway and was deflected widely in thelateral directions. A CE/Co value of 0.35 was observed on the sidewalk
right next to the opening, and a value of 0.06 at 35 m leeward of the opening.
Attenuation of concentration in the leeward direction was very large.
4.1.2 Distribution of the normalized concentrations exhaust from line
sources
The distributions of normalized concentrations when line sourceswere on the ground-level highway and elevated expressway (southeastwind) are shown in Figures 10. When gas was exhausted from the highway,
CE/Co values were 0.07 to 0.08 on the leeward-side sidewalk with a fence
under the expressway and about 0.07 in an area in front of a wide mediumrise building without a fence under the expressway. The normalized
concentrations were rather small at the intersection because of higher windvelocities. The normalized concentrations were 0.05, 0.01, and 0.005 at
about 30, 50, and 100 m leeward of the source.
4.2 Field measurements results
4.2.1 Wind directions and velocities over the studied area
Wind directions and velocities observed at the Daishi environmental
station during the measurement period are listed in Table 1. The station is
located at 2km difference with the intersection. The wind directions during
the period were mostly between WNW and NNW.
4.2.2 Emission rates
The traffic volume and emission rates on February 1 are shown in
Table 2 as an example. The emission rates were calculated by assuming
vehicle velocities of 20 and 50 km/h on the inbound and outbound lines of
the highway, respectively, and using emission factors for different vehicle
types. Large trucks and special vehicles outnumbered the other types ofvehicles, and the traffic volume and emission rates were about the same forthe three days.

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N

0.005

0.01
0.03
0.05
0.07
0.0
0.05
0.03 0.005
0.01

Figure 10: Normalized concentration of gas from line sources on
the ground-level highway in wind tunnel experiment( wind direction SE)
Table 1: Wind directions and velocities observed at a height of 16m at
Daishi measurement station of the environment bureau of
Kawasaki City Office Left : wind velocity (m/s)、Right : wind direction
Weather

9 :00

10 :00

2/1

Fine

5.7 WSW

4.6 WSW

2/2

Fine

3.6 WNW

2/3

Fine

1.7 WNW

11 :00

13:00

14 :00

15 :00

7.6 WNW 5.9 WNW

5.5 NW

3.3 NNW

3.7 WSW

3.7 W

2.7 NW

1.9 WNW

0.9 SSE

1.7 NW

3.8 NW

4.1 NNW

4.5 NW

4.5 N

Table 2: Volume of Traffic and of emission rates of automotive
exhaust on the local highway
1) Traffic volume
traffic volume
1st.Feb. 2005
9:45～10：05

Light andLight andLarge trucks

Ordinary
cars

Ordinary Trucks

Special vehicles

Bus

142（125）55（62）

214（222）8（4）10:45～11：05

135（130）65（85）

206（245）

4（3）13:45～14：05

178（145）

63（60）

192（195）5（2）14:45～15：05

180（172）

55（52）

200（176）3（3）a figure in ( ) : outbound lines

2) Emission rates (g/m･h)emission rates
1st .Feb. 2005
9:45～10：05
10:45～11：05
13:45～14：05
14:45～15：05

CO
Inbound
3.08
3.13
3.22
3.13

Outbound
2.11
2.49
2.04
1.97

Inbound
2.99
2.89
2.76
2.76

NOx:*
Outbound
2.08
2.34
1.85
1.70

4.2.3 Distribution of the normalized concentrations of SF6 tracer gas frompoint sources
The measurement results are given as the normalized concentrations(CF/Co). Here, CF is the concentration measured in the field, and Co=Q/(UH2), where Q is the tracer gas generation rate, H is the height of the elevatedPrediction of Pollutant Dispersion Caused by Automotive Exhaust- A Comparison Between Field Measurements and Wind Tunnel Data -425

October 2005, Singapore

expressway (=8 m), and U is wind velocity at height H. Here, H is theheight of the elevated expressway as well as the model experiment. The
distributions measured at 14:00 on February 1 (wind direction NW, source
point A) and 11:00 on February 2 (wind direction W, source point A) are
shown in Figures 11 and 12, respectively. In the case of northwest wind
(Figure 11), CF/Co values were 0.74 at measurement point 11, which wasclose to the gas source, 0.14 at point 10, and 0.07 at point 12. The results
indicate that the tracer gas dispersed laterally along the fence below theexpressway. The gas flowed back windward through gaps in the fence, anda concentration of 0.01 was observed at point 6. CF/Co values were 0.17
(about 1/4 of the concentration near the source) at point 14 (about 15 m
leeward from the source), 0.06 (about 1/12 of the concentration near thesource) at point 15 (100 m leeward from the source), and 0.02 (1/40 of theconcentration near the source) at point 16 (300 m leeward from the source).
In the case of west wind (Figure 12), CF/Co values were 1.6 at point 11,
which was close to the gas source, 0.23 at point 10, and 0.42 at point 14.
Similar to the case of northwest wind, the tracer gas dispersed laterally
along the fence below the expressway. A value of 0.02 was observed atpoint 7, near the intersection. This reflected a flow that bulged toward thenorth side of the intersection at the leeward end of the fence.
N

N

4

8
7

0.07

6

0.01
5

11

0.0

0.74
9

0m

100m

0.17

13

10

0.14

0.29

0.0

0.16

1.60
14

15

0.06
17

0.08
200m

12

11

6

14

10

0.23

16

0.04

0.02

0.0

12

8

7

3

0.01

0.09

0.0

0.0

13

0.42

0.1

0.02

17

0.02
0m

100m

15

0.07
16

0.02

200m

Figure 11: Normalized concentration Fig.12. Normalized concentration ofof tracer gas in case of windtracer gas in case of winddirection = NW,
direction = W,
point source=A
point source=A
4.2.4 Distributions of the normalized concentrations of CO and NO
The normalized concentrations of CO and NO (averages for winddirection NW during the measurement period) are shown in Figure 13. The
relationship between the normalized concentrations of CO and NO for allwind directions is shown in Figure 14. Using the emission rates estimatedin Section 4.2.2, gas generation at distances corresponding to the line
sources in the wind tunnel experiment were assumed for the sake ofcorrelation with the experimental results. The amount of NO generation
was assumed to be 50% of NOX generation. Concentration at each point
was obtained by deducting background concentration, which was given by426

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ICUS Report 11

the concentration measured at a windward point sufficiently distant fromand unaffected by the highway. Figure 13 shows the presence of highconcentration areas near the intersection and under the expressway. The
normalized concentrations of CO and NO are close to each other, although
there are some discrepancies. Figure 14 also shows good coincidence
between non-dimensional CO and NO concentrations. This is probably
because emission from the elevated expressway does not affect to theground level concentration.
4.3 Comparison between the wind tunnel experiment results and fieldmeasurements
4.3.1 Point sources
The normalized concentrations shown in Figure 9 (wind tunnel
results) and Figure 11 (field measurements) are compared. Because thelocations of gas sources and measurement points are different between thewind tunnel experiment and field measurements, there are differences innormalized concentrations near the sources and the westward extent of thewake flow area of the fence. However, similar trends are found in the two
figures regarding lateral dispersion of gas toward the intersection side andattenuation of concentration from the source to 100 m leeward.
4.3.2 Line sources
The normalized concentrations shown in Figure 10 (wind tunnel
results) and Figure 13 (field measurements) are compared; although thewind directions are different, they are both perpendicular to the main street
canyon. The line sources in the wind tunnel experiment had finite lengths,
however it is evaluated to be insignificant because the sources were
sufficiently long in terms of concentrations observed at the measurement
points. A high concentration zone was found only along the highway in thewind tunnel experiments. In the field measurements, CF/Co values were
0.08, 0.04, and around 0.05 at measurement points 6, 11, and 12,
respectively. In the wind tunnel experiment, CE/Co values of 0.07 to 0.08
were found on the leeward-side sidewalk with a fence under the expressway.
Values around 0.05 were found near the intersection, corresponding to point
12. Thus, the experimental results and the field measurements are in good
agreement.
5. CONCLUSIONS
The results of the wind tunnel experiment using point sources of tracer gas
showed that the gas dispersed widely in the lateral directions right after
emission when there was a building or a fence on the windward or leeward
side of the source. The effect of emission from the elevated expressway
was much smaller than that from the ground-level highway. CO and NO
concentrations were measured and traffic volume was surveyed around theintersection; there was a good agreement between the distributions of nondimensional concentrations of CO and NO exhausted from the highway.

Prediction of Pollutant Dispersion Caused by Automotive Exhaust- A Comparison Between Field Measurements and Wind Tunnel Data -427

October 2005, Singapore

The results of the wind tunnel experiment using point and line sources werealso in good agreement with the field measurements. The results indicatethat the experimental data obtained in this study is highly reliable inverifying predictions based on computational fluid dynamics.

1

Measuring point No.

0.01
0.01

Normalized NO
Normalized CO

0.03
0.04 12
0.05
0.05

6

0.01
0.08

14

5

0.02
0.03

10
9

0.03
0.02
0m

100m

0.02
0.03

13

0.01
0.05

0.01
0.01

200m

Normalized NO

0.00
0.00

0.00
0.00

7

3

0.00
0.05

0.08

8

4

0.00
0.02
2

N

11

0.05
0.04
15

0.01
0.02
17

0.00
0.01

W
WNW

SSE
NW

WSW
NNW

0.06

0.04

0.02
16

0.01
0.02

0
0

0.02

0.04

0.06

0.08

Normalized CO

Figure 13: Normalized concentrations Fig.14. Comparison of the normalizedof CO, NO in the case ofconcentrations of CO and NO
wind direction=NW
REFARENCES
I. M. Kennedy and J. H. Kent (1977),“Wind tunnel modeling of carbon
monoxide dispersal in city streets” Atmospheric Environment,11,541-547.
W. Bächlin, W. Theurer and E. J. Plate (1991),“Wind field and dispersion ina built-up area－A comparison between field measurements and windtunnel data” Atmospheric Environment,25A,1135-1142.

428

New Technologies for Urban Safety of Mega Cities in Asia

LEVELS OF POLYNUCLEAR AROMATIC
HYDROCARBONS AND HEAVY METALSIN WATER AND SEDIMENT OF UBEJICREEK, WARRI RIVER IN NIGER DELTA
AREA OF NIGERIA.
OKORO, D., *a; IKOLO, O. A.b
Department of Chemistry, University of Benin, Benin City, Edo State,
Nigeria.
Tel: +234 8033834446; +2348023320809
E-mail: dukeokoro@yahoo.combNational Agency for food and Drug Administration and Control, Central
Laboratory, Oshodi, Lagos, Nigeria. Tel: +234 8023089732
E-mail: ikolo111@yahoo.comaABSTRACTPolynuclear aromatic hydrocarbons (PNAs) and heavy metals levels insurface water and sediment of Ubeji creek in Warri River were determined
and compared with levels observed from Abraka location of Ethiope River(control). All US EPA 16 listed priority PNAs determined by Gas
chromatography using GC – Perkin Elmer Clarius 500, while the heavy
metals were determined by Atomic Absorbtion spectrometry using AAS –Perkin Elmer 31,000. Determined levels of Fe, Zn, V, Ni, Pb exceeded
standard criteria recommended for surface water by FEPA (1991);
ANZECC (1992); US EPA (1996); WHO (1998); DPR (1991) and were in
the following decreasing order of magnitude: Fe > Zn > V > Mn > Ni > Pb
> Cu > Cr > Cd > Co > Hg. Mecury in surface water (0.001 mg/L) was
however higher than interim fresh water guidelines recommended by DPR(1991) and ANZECC (1992). Levels of metals were comparatively higher inthe dry season, while levels of PNAs were generally higher in wet season
compared to dry season. The high molecular weight PNAs (HPNA) which
includes indeno(1, 2, 3, - cd )pyrene, benzo(a) pyrene, benzo(k)fluoranthene,
benzo(b)fluoranthene, chysene and pyrene had elevated levels in the waterand sediment. The range of value for HPNA for water was 0.0055 – 0.023
mg/L and sediment was 0.437 – 0.938 mg/kg. Chemometric analysis
revealed that the heavy metals enter the Warri River via contamination fromfossil fuel combustion; storm water runoff / leachate from land fills, refuse
dumps, boats / ships, vehicle exhaust and corrosion of galvanized steel
structure. The diagnostic concentration ratios of PNAs isomer pair show inwater and sediment of the Warri River, that phenanthrene/anthracene < 10;fluoranthene/pyrene >1; chysene/benzo(a)anthracene <1, which confirms
and permit the conclusion that the PNAs were of pyrogenic origin.

429

October 2005, Singapore

1. INTRODUCTION
Every person alive today carriers approximately 250 chemicals within his or
her body, some chemicals that did not exist prior to 1945 (UNEP, 1997).
This concentration of chemicals within every human being on the face ofthe earth is called the “body burden”, and it is our common legacy from theprocesses of development and industrialization. World War II was acatalyst for the transformation from a carbonhydrate-based economy to apetrochemical-based economy, as chemical substitutes began to be invented
for goods restricted or made available during the war. The economic boom
that followed World War II supported the parallel boom in the invention anduse of chemicals, many of which are associated with the convenience andflexibility of modern living. These synthetic chemicals find their way into
everything – soil, air, water and food. They are in the tissues of plants,
animals and people. Although some are naturally occurring, but chemicals
like polynuclear aromatic hydrocarbons are mostly manufactured orsometimes by-products of chemical reactions and natural phenomenon(ATSDR, 2004).
In the past decade, several measures have been taken to reduce theinput of toxic contaminants into rivers and estuaries, both by treatment ofindustrial wastewater and by the installation of municipal wastewater
treatment plants. There was a reduction in pollutant concentrations in a
number of European estuaries in the 1990s (OSPAR., 2000). It is therefore
interesting to investigate if this trend is also visible in large fresh water
ecosystem like the Ubeji Creek of the Warri River and possibly determine
the specific sources of these contaminants. Polynuclear aromatichydrocarbons (PNAs) are a group of chemicals that are formed during theincomplete combustion of coal, oil, gas, wood, garbage (pyrogenic origin),from emissions of non-combustion derived matter (petrogenic origin) andfrom the post-depositional transformation of biogenic precursors (diagenetic
origin), which generally occur as complex mixtures (Neff, 1979 andCerniglia et al, 1991). In this study, the 16 US EPA priority PNAs listed intable 2 were determined in surface water and sediment of Ubeji creek of theWarri River and Abraka location of the Ethiope River (Control). The
investigation also covers the determination of twelve heavy metals including,
Fe, Zn, Pb, Mn, Cr, Cu, Ni, Cd, Co, Hg, V and As in the described matrices.
The Warri River and Abraka location of the Ethiope River (control),is located in Delta State of Nigeria, Delta State is one of the thirty-six statesthat belongs to the Niger Delta geo-political region of the Federal Republicof Nigeria. Warri is a major industrial city with historical background of
crude oil exploration, processing and refinery activities at its peak. The
Warri River, a tidal fresh water ecosystem, is the recipient of Effluent fromall the petroleum and allied industries located in the urban areas of the town.
The sampling points in Ubeji creek of the Warri River are essentiallylocated on latitude N 50 34.14′ and on longitude E 50 42.25′. The distance
between this point and the control (Abraka location of the Ethiope River
which is on Latitude N 50 49.46′ and on Longitude E 60 06.50′) is about 58.3
kilometer. Both rivers are flat - floored and they drain into the Atlantic
Ocean. They are also prone to flooding, especially during the wet season,

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mainly because of the heavy rainfall, high ground water table and the flat floored valleys (Aweto, 2002). Large stretches, especially the lower reaches
of both rivers are permanently water logged.

2. MATERIALS AND METHODS
2.1 MODE OF SAMPLING, HANDLING AND TREATMENT
Samplings for PNAs analysis were carried out in December, 2003;
February, 2004; May, 2004 and July, 2004. Composite samples of bothwater and sediment in Ubeji Creek of Warri River and Abraka location of
Ethiope River were collected in the described four months. The water
samples for PNAs analysis were collected in a litre amber glass bottle with
Teflon - lined screw - cap, 5mL of 1:1 HCL acid was added and cooled toabout 40C before it was taken to the laboratory prior to analysis (APHA,
1998), while sediment samples, having being collected in a litre chemicallycleaned glass jars with Teflon-lined screw-cap, were cooled to about 40C,
extracted within seven (7) days and extracts analyzed within 40 days.
Composite water and sediment samples for heavy metal analysis werecollected every month between August, 2003 and July, 2004 from the Ubeji
creek of the Warri River. Water samples were collected in a litre polythenebottle that had previously been soaked in concentrated nitric acid for 24hours and rinsed with de-ionised water, were brought to a PH of less than orequal to 2 with concentrated H2SO4 or HNO3 (Barley and Gardner, 1997)
and then stored on ice prior to laboratory analysis, while sediment samples
were collected in a clean glass jar, then acidified with 5ml of concentrated
HCL acid.

3. ANALYSIS
The water samples for PNAs analysis were extracted with methylene
chloride, dried with anhydrous Na2SO4 and solvent – exchanged into hexane.
Clean-up and fractionation was done using silica gel permeation
chromatography. Final extracts after re-concentration using a rotary
evaporator was packed in a 2mL GC vials and analysed with a Gas
Chromatograph (GC), Perkin-Elmer/Clarius 500. Sediment samples, having
being dried with anhydrous Na2SO4 were extracted with a mixture ofdichloromethane (DCM) and acetone, thereafter solvent-exchanged withhexane. Clean-up and fractionation was similarly done using silica gelpermeation chromatography. Final extracts were analysed using the samedescribed GC. Water samples for heavy metal analysis were digested withconcentrated HNO3, (Martin et al, 1992) while sediment samples weredigested with a mixture of HCLO3, H2SO4 and HNO3 in the ratio of 1:2:2
according to the method described by Soster, et al., (1992). Blank were also
prepared in each determinations in the same manner and method using deionized water so as to check the accuracy of the method. The filtrate in bothmatrices were analysed for heavy metals using Flame Atomic Absorption
Spectrophotometer, AAS (Perkins Elmer 31,000), and concentrations

Levels of polynuclear aromatic hydrocarbons and heavy metals in water and sediment of Ubeji creek, Warririver in Niger Delta Area of Nigeria.

431

October 2005, Singapore

calculated from the calibration curve obtained from five dilutions preparedfrom the standards.

4. CHEMOMETRICS
Multivariate mathematical technique, essentially agglomerative hierarchicalclustering technique was employed to reduce the number of variables anddetecting relationships between them. Chemometrics is a multivariate
mathematical and statistical approach to the analysis and interpretation ofanalytical data. Hooper and Peters (1989) used multivariate analysis fordetermining sources of solutes found in wet atmospheric deposition in the
United States. Cluster analysis which was used in this study, is amultivariate exploratory method, whose output is a tree-like diagram called
dendrogram which shows the various associations of the heavy metals.
The % proportion of 2-3 rings PNAs relative to 4, 5-6 rings and Diagnostic
concentration ratios of PNAs isomer pairs were used to apportion sources of
PNAs input into the Ubeji creek of the Warri River. Statistical treatment of
the data obtained were performed using SPSS version 10.00.

5. RESULTS AND DISCUSSION
The results of the mean concentration of polynuclear aromatic hydrocarbons(PNAs) determined in surface water and sediment are presented in Table 1,
while the mean concentrations of heavy metals in surface water andsediment of the Ubeji creek are presented in Tables 2 and 3 respectively.
The levels of PNAs determined in water and sediment were generally higher
in Ubeji creek compared to the levels observed in Abraka location of theEthiope River (control). 0.3121mg/L observed for Total PNAs in water ofthe creek was relatively higher than 0.003mg/L recommended for fresh
water by ANZECC 1992. Similarly, the total PNAs determined in sedimentof the Ubeji creek were in elevated amounts with reference to NOAA
(2000) and ANZECC (2000) guidelines for sediment. These elevated levels
call for serious pollution concern. The composition of the low molecularweight PNAs (LPNA) in the surface water is less than 20% which suggests
a possible pollution from combustion – derived PNAs. Biodegradation anddesorption of LPNAs during transport and deposition was a possible
mechanism for the PNAs compositional difference in the matrices.
The levels of heavy metals observed in water and sediment of the Ubeji
creek were slightly higher than the levels reported in Aladja area of theWarri River in a similar study (Egborge et al, 1986). Concentration of leadin surface water of Ubeji creek was observed to be higher than most of thereferenced guidelines. Although mercury level was observed to be higher
than ANZECC, (1992), it was within the range of the other referenced
guidelines. These values were too close for one to accept that all is well.
Increased urbanization and industrialization in no distant time may increase
the mercury level up to a very deleterious amount. The differences between
the amount determined and that of the referenced criteria are shown in

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Tables 2 and 3 for further understanding. The selected isomer pairs wereused as indices to distinguish between petrogenic and pyrogenic origins for
the PNAs. The ratios calculated in water and sediment as shown in Table 4
indicated that the ratio between phenanthrene/anthracene <10;fluoranthene/pyrene > 1; chrysene/benzo (a) anthracene <1, which confirms
and permit the conclusion that the PNAs were of Pyrogenic origin(Colombo et al., 1989). Agglomerative hierarchical clustering technique
was used as exploratory multivariate method for the
Table 1: Concentrations of polynuclear aromatic hydrocarbons in water &sediment of Ubeji Creek of the Warri River.

COMPONENTS

Surface Water (mg/L)
Mean ±
Mean ±
STDEV
STDEV
Ubeji
AbrakaSediment (mg/kg)
Mean ±
Mean ±
STDEV
STDEV
Ubeji
AbrakaNaphthalene

0.0105 ± 0.013

0.0003 ± 0.00

0.2995 ± 0.446

0.0004 ± 0.00

Acenaphthylene

0.0101 ± 0.012

0.0006 ± 0.00

0.6874 ± 0.542

0.0004 ± 0.00

Acenaphthene

0.0184 ± 0.017

0.0001 ± 0.00

0.9806 ± 0.321

0.0001 ± 0.00

Fluorene

0.0125 ± 0.015

0.0001 ± 0.00

0.5991 ± 0.486

ND

Phenanthrene

0.0024 ± 0.001

ND

0.5119 ± 0.461

ND

Anthracene

0.0036 ± 0.0038

ND

0.5245 ± 0.407

ND

LPNAs

0.0575 ± 0.062

0.0009 ± 0.00

Fluoranthene

0.017 ± 0.0267

0.0011 ± 0.00
ND

3.603 ± 2.662
0.5692 ± 0.276

0.0003 ± 0.00

Pyrene0.0273 ± 0.026

ND

0.9427 ± 0.468

0.0003 ± 0.00

Benzo(a)anthracene

0.0438 ± 0.001

ND

0.7566 ± 0.590

0.0003 ± 0.00

Chrysene

0.0456 ± 0.003

ND

0.4266 ± 0.463

0.0004 ± 0.00

Benzo(b)fluoranthene

0.0098 ± 0.00

ND

0.5124 ± 0.516

0.0007 ± 0.00

Benzo(k)fluoranthene

0.0473 ± 0.007

0.0008 ± 0.00

0.5122 ± 0.507

ND

Benzo(a)pyrene

0.0138 ± 0.0165

ND

1.0320 ± 0.240

ND

Dibenzo(a,h)anthracene

0.0128 ± 0.0173

0.0001 ± 0.00

0.6008 ± 0.594

0.0003 ± 0.00

Benzo(g,h,I)perylene

0.0215 ± 0.0126

ND

0.7688 ± 0.470

ND

Indeno(1,2,3-cd)pyrene
HPNAs
Total PNA

0.0156 ± 0.010
0.2545 ± 0.121
0.3121 ± 0.207

0.000205

0.5826 ± 0.594

0.0011 ± 0.00
0.0022 ± 0.00

6.7031 ± 4.719
9.3595 ± 2.766

ND
0.0023 ± 0.00
0.0032 ± 0.00

LPNA---Low Molecular Weight Polynuclear Aromatic Hygrocarbon; HPNA---High Molecular Weight Polynuclear Aromatic
Hydrocarbon.

heavy metal data to observe their various associations. The average linkage
between groups method used was to see if the heavy metals are grouped insuch a way that reflects their association relating to possible source of entry
into the aquatic medium. The resultant dendrogram obtained for water andsediment are shown in Figures 1 and 2. In Figure 1, the first cluster madeup of nickel and vanadium shows a possible entry via fossil fuel combustion,
while the fourth cluster which includes iron and zinc shows a possible entry
via construction/metal works and corrosion of galvanized steel structures.
Similarly, in figure 2, the second cluster, made up of pb, Cr, As, Cd, and Cushows possible entry via vehicle exhaust, leachate/runoff.

Levels of polynuclear aromatic hydrocarbons and heavy metals in water and sediment of Ubeji creek, Warririver in Niger Delta Area of Nigeria.

433

October 2005, Singapore

Table 2: Concentrations of heavy metals in surface water of Ubeji Creek of
the Warri River including Referenced Guidelines.
Heavy metals

MEAN ± STDEVFEPA,1990

Iron

0,323 + 0,472

0.3 - 1.0

Zinc

0,753 + 0,102

<1

Lead

0,071 + 0,008

<1

0.05

Manganese

0,062 + 0,005

NA

NA

0.05

0.0-0.5

0.05

Chromium

0,066 + 0,011

<1

0.03

0.1

NA

0.05

Copper

0,047 + 0,019

1.0 - 1.5

1.5

1.3

NA

2

Nickel

0,371 + 0,104

<1

<1

NA

0.02

0.02

Cadmium

0,053 + 0,012

<1

<1

0.005

0.0002-0.002

0.05

Cobalt0,017 + 0,004

0.5

NA

NA

NA

NA

Mercury0,0014 + 0,0009

0.001

0.0001

0.002

0.00005

0.001

Vanadium

0,733 + 0,216

0.01

0.01

0.019

NA

NA

Arsenic

0,024 + 0,015

0.05

NA

0.05

0.05

NA

DPR,1991

USEPA,1996

ANZECC,1992

WHO,1998<1

0.3< 0.011

1

50.005-0.05

15

0.02

0.001-0.005

NA

STDEV---Standard Deviation; FEPA---Federal Environmental Protection Agency; DPR---Departmentof Petroleum Resources; USEPA---United States Environmental Protection Agency; ANZECC--Australian-New Zealand Environment & Conservative Council; WHO---World Health Organization;
NA---Not Available;ND---Not Detected.

Table 3: Concentrations of heavy metals in sediment of Ubeji Creek of theWarri River including Referenced Guidelines.
Heavy
metals
Iron
Zinc
Lead
Manganese
Chromium
CopperNickelCadmium
CobaltMercury
Vanadium
Arsenic

MEAN ± STDEVICSQG,2000

NOAA,2000

SQON,1999

ANZECC,2000

255.710 ± 57.81
46.515 ± 12.715
4.771 ± 1.762
6.708 ± 1.434
1.079 ± 0.449
1.821 ± 0.568
4.884 ± 1.887
0.967 ± 0.214
0.705 ± 0.287
0.006 ± 0.004
9.963 ± 3.895
0.467 ± 0.114

NA
123
35
NA
37.3
35.7
NA
0.6
NA
0.17
NA
5.9

NA
150
46.7
460
81
34
20.9
1.2
NA
0.15
NA
8.2

NA
620
530
NA
NA
73
NA
12
NA
10
NA
55

NA
200
50
NA
< 80
65
21
1.5
NA
0.15
NA
20

ICSQG---Interim Canadian Sediment Quality Guidelines; NOAA---National Oceanographic & Atmospheric
Administration in the United States; SQON---Sediment Quality Objectives in the Netherlands

434

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11
C A S E
0
5
10
15
20
25
Label Num +---------+---------+---------+---------+---------+
Ni
7òûòòòòòòòòòòòø
V
11
ò÷
ó
Co
9
òø
ùòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòø
As
12
òú
ó
ó
Pb
3
òôòòòòòòòòòòò÷
ó
Cr
5
òú
ó
Cu
6
òú
ó
Cd
8
òú
ó
Hg
10
òú
ó
Mn
4
ò÷
ó
Fe
1
òòòòòòòòòòòòòòòòòòòòòòòòòûòòòòòòòòòòòòòòòòòòòòòòò÷
Zn
2òòòòòòòòòòòòòòòòòòòòòòòòò÷

Figure 1: Dendrogram of heavy metals in Water ofUbeji Creek.

C A S E
0
5
10
15
20
25
Label Num +---------+---------+---------+---------+---------+
Ni
V
Pb
Cr
As
Cd
Cu
Co
Mn
Hg
Fe
Zn

7
11
3
5
12
8
6
9
4
10
1
2

òûòòòøò÷óòøóòúùòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòø
òú
ó
ó
òú
ó
ó
òú
ó
ó
òôòòò÷óòúóò÷óòòòòòòòûòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòòò÷
òòòòòòò÷

Figure 2: Dendrogram of heavy metals in Sediment of
Ogunu Creek.

Table 4: Selected Isomer Pair ratios
Samples
Phen/Anth Fluo/Pyr Chry/B[a]AWater in Ubeji
Sediment in Ubeji

2.503
1.62

1.606
1.656

0.961
0.564

Levels of polynuclear aromatic hydrocarbons and heavy metals in water and sediment of Ubeji creek, Warririver in Niger Delta Area of Nigeria.

435

October 2005, Singapore

6. CONCLUSION
The relative dominance of the high molecular weight PNAs in all matricesof the Ubeji of creek of the Warri River indicated that the PNAs werepredominantly combustion-derived (pyrogenic) as confirmed by thecompositional differences and the calculations from the selected isomer
pairs. Chemometrics or multivariate analysis revealed that the heavy metals
enter the Ubeji creek via contamination from urban and anthropogenic
activities being carried into it along with storm water runoff.

REFERENCES
APHA, (1998). Standard Methods for the Examination of Water andWastewater, 20th edition Publishers: American Public Health
Association; American Water Works Association; Water Environment
Federation.
ATSDR, 1995. Toxicological Profile for polycyclic aromatic hydrocarbons(PAHs): US Department of Health and Human Services. Public
Health Service, Agency for Toxic Substances and Disease Registry,
Division of Toxicology, Atlanta, GA. pp 23.
Aweto, A., (2002). Outline geography of Urhoboland, Oxford University
Press, Ibadan, Nigeria. pp. 2-4.
Barley, G. E., and Gardner, D., 1977. Sampling and Storage of natural
waters for trace metal analysis. Intro. Journ. Environ. 11: 745 – 746
pp.
Cerniglia, C. E., and Heitkamp, M. A., 1991. Microbial Degradation ofpolycyclic aromatic hydrocarbons (PAH) in the aquatic environment,
Baltelle Press, Columbus, Ohio . 32pp.
Colombo, J. C., Pelletier, E., Brochu, C., and Khalil, M., 1989.
Determination of Hydrocarbon sources using n-alkane andpolyaromatic hydrocarbon distribution indexes. Case study: Rio de
La Plata Estuary, Argentina. Environ. Sci. Technol. 23: 888-894.
Egborge, A. B. M., and Benka-Coket, J., (1986) Water Quality Index:
Application in the Warri River, Nigeria.Environ. Poll. Science.
B.12: 27-40.
Hooper, R. P., and Peters, N. E., 1989. “Use of Multivariate analysis fordetermining sources of solutes found in wet atmospheric depositionin the United States. “Environ. Sci. Technol. 23: 1263-1265.
Martin, T. D., Brockhoff, C. A., Creed, J. T. and Long, S. E., 1992.
Determination of metals and trace elements in water and wastewaterby inductively coupled plasma – atomic emission spectrometry.
I.C.P. Nws tt r, 18(3): 147-169.
Neff, J. M., 1979. Polycyclic aromatic hydrocarbons in the aquatic
environment. Applied science Publ. Ltd., London. 262pp.

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ICUS Report 11

OSPAS, 2000. Water Quality status Report 2000 for the North-East Atlantic
Report. Oslo and Paris Commission for protection of the marine
environment of the North-East Atlantic London, England.
Soster, D. A., Harvey, D. T., Troska, M. R. and Gromms, T. 1992. The
effect of Turbificid oligocheates on the uptake of Zinc by Lake Erie
sediments. Hydrobiologica. 248: 249-258.
UNEP, 1997. Reference method for Marine Pollution Studies, No 31-39.

Levels of polynuclear aromatic hydrocarbons and heavy metals in water and sediment of Ubeji creek, Warririver in Niger Delta Area of Nigeria.

437

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New Technologies for Urban Safety of Mega Cities in Asia

DEVELOPMENT OF NEWENVIRONMENTAL INDICES FOR URBANSUSTAINABILITYRYOZO OOKA, YOSHIHUMI YASUOKA, JUNICHI SUSAKI,
TAKAHIRO ENDO, YOICHI KAWAMOTO
Institute of Industrial Science, The University of Tokyo, Tokyo, JapanHIDENOBU NAKAI, MADOKA NAKASHIMA, REI TAKADATokyo Electric Power Company
MASAHIRO SETOJIMA, MANABU FUNAHASHI
Kokusai Kogyo Co. LTD.
KEIICHI OKADA
Shimizu Corporation
ooka@iis.u-tokyo.ac.jp
ABSTRACTIn this research, the comprehensive assessment indices that becomesthe indicator of the plan for a sustainable city is developed (Environmental
Indices for Urban Sustainability: EIUS). Various indices that evaluatedurban environment have been developed in order to solve the urban
problem including a so-called environmental pollution issue since 1970's inmany countries of the world, especially by OECD. These are the indices that
evaluate mainly the environmental qualities such urban air quality or
various services supported by the administration inside the city. However,
the environmental load such as CO2 emissions that the city activity exerts on
the larger area or the global environment cannot be neglected with the riseof the consideration of global environmental problems in recent years. In
this paper, at first stage, the several items which represent theenvironmental quality inside the city (Health, Services, Safety, etc.) and theenvironmental load outside the city (Energy consumption, Resources
consumption, Environmental pollution, etc.) are selected. Then, these items
are combined in order to construct the comprehensive assessment indices(EIUS) which consider both the environmental quality and theenvironmental load in and outside the city. Furthermore, these indices areapplied for 11 government ordinance specification cities in Japan. The
applicability of these indices is estimated and the sustainability of these 11
cities is examined.
1. Introduction
In Asia, there is a strong tendency for population and functionality toconverge in cities. The economic development in many countries is creatinga problem of runaway urbanization (the megacity problem). These
megacities lag in the creation of urban infrastructure and safety measures, aswell as environmental, educational, and other measures. This is causing
services for city residents to decline, making environmental pollution and439

October 2003, Tokyo

other issues an everyday occurrence, and causing the appearance of slums
and other problems in some areas. Meanwhile, however, the overconcentration of functions in the cities is causing its own problems; theareas around cities are becoming depopulated wastelands.
In addition, the rapid expansion of urban functions is increasing the flowof pollutants (such as sulfur oxides and carbon dioxide) into the air and seas,
which is polluting the global atmosphere and coastal seas. It is highly likelythat this situation will create critical environmental issues on a global scalein the future.
The present research is developing an index to comprehensively assess
urban environments, to serve as a guideline for planning sustainable cities.
Many indices have been created in many countries to assess urban
environments, starting with the OECD in the 1970s. These indices wereused to assess the environment inside the city, in order to resolve such urban
issues as urban pollution. But as awareness of global environmental issues
has increased over the past few years, it has become impossible to ignore
the impact that urban activities themselves have on the global environment.
The present paper identifies measures that specify the quality of life inside
the city and environmental impact (load) outside the city at the municipalgovernment level, and reconstructs an urban-environment index taking bothaspects into account. It also applies this index to Tokyo and 11 government
ordinance specification cities, considers the appropriateness of the measuresused within the index, and compares the sustainability of Tokyo and the 11
government ordinance specification cities.
2. Basic Concept of Creating an Index to Assist Urban Environments
The present research is developing an index to comprehensively assess
urban environments, to serve as a guideline for planning sustainable cities.
This is thus an assessment of cities; but in order to assess an urban
environment, it is first necessary to define just what we mean by "city."
While the definition of "city" is argued by a great many scholars and people
in the field, here the authors define a city as a region under the jurisdictionof a municipal government. The reason the authors define it thusly is
because most environmental measures for cities are carried out at themunicipal level, and so assessing at the municipal level simplifies our work.
The areas inside and outside the city for the urban environmental index
mentioned above are defined as follows: the region within the municipality
is inside the city, and other areas are outside it.
The following points were also taken into account in the creation of thisassessment index.
(1) Consistency
When assessing urban environments, it is vital tocollect detailed data for each city. But the more data one has, the more
complex it becomes to handle, and the more difficult to assess.
Consequently, it is important to summarize data to a certain extend, andcreate a comprehensive index.
(2) Generality
There is great disparity among the set of urban areas
called "cities." For example, in Japan we have cities ranging in
population from more than 8 million in Tokyo (in its 23 wards), to cities

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with fewer than 50,000 people. There are also major differences in their
population makeup, industrial structure, climatic conditions, andeconomic conditions, among others. It is thus necessary to create anindex that is general and fair for all cities; this requires some sort ofstandardization, such as showing figures in per-capita units.
(3) ComprehensivenessAs can be seen in check systems used forenvironmental impact assessment, checks of the impacts and effects ofpolicies must encompass an extremely broad range of phenomena. Put
simply, it is necessary to prepare a set of individual elements that are
well balanced, and put together with the consistency mentioned in item
(1).
(4) Representativeness
Environmental monitoring and the like must
be representative. In other words, measurements of environmental
elements are not representative if they change depending on when or
where in an area they are taken. For example, the location that air
pollution or noise is measured has a great impact on the results. In suchcases, it is necessary to create clear rules for measurement, andinvestigate geographical and temporal representativeness.
(5) IntuitivenessAn index of urban environments should not usedsolely by researchers, government officials, and other experts; it should
also facilitate dialog with city residents. Consequently, the index must
be intuitiveness understandable by residents; it should jibe with theirlive experiences and sensibilities.
(6) Ease of Measurement
No matter how elaborate of an index of urban
environments one creates, it is unusable if one cannot obtain the data
making it up. The data used to calculate the index must be easy to obtain,
and the method to calculate it must be simple.
3. Overview of a Comprehensive Assessment Index for Urban
Environments
In order to assess the environment of a city, it is necessary to assess bothits good and bad aspects. The reason people live concentrated in a city in thefirst place is to reap some sort of benefit. If urban environments are assessedin ignorance of this aspect, one is led to the extreme argument that nothaving cities is best for the environment. We have thus built an index thatassesses both the pros and cons of cities. To put this another way, theauthors evaluate both the benefits gained by residents living inside the city,and the impact on the environment surrounding it. The authors call these
aspects as Quality of Life inside City and Environmental Load Outside City,and define them as follows.
(1) Quality of Life inside City
Table 1 shows examples of each of the elements making up the Quality ofLife inside City aspect. The environment inside the city can be divided into
three major categories: (1) environment and public health; (2) functions andservices; and (3) safety and security.

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441

October 2003, Tokyo(1) Environment and public health: This is an index of level of publichealth, hygiene, and natural richness available to city residents. The
percentage of greenery is used as a measure of the richness of the naturalenvironment. The authors believe this is both relatively easy to measure, andrepresentative. Concentration of air pollutants is an intuitive index of the air
environment. It is difficult to create indices for soil and water quality,
because the conditions of soil and water pollution are highly localized, andthe measurements taken will depend greatly on where they are made.
Consequently, the authors represent these by numbers of patients ofcommunicable diseases. The authors use sewerage connection rate torepresent public health.
Table 1. Index of Quality of Life Inside City
Major
Category
Q1
Environment/
public health

Q2
PublicFunctions/ Services

Q3

Safety/Security

Minor
Category
Naturalenvironment
Air

Assessment Index
Greenery [%]SO2 concentration [ppm]NOX concentration [ppm]
Public health Number ofcommunicable disease
infextions/1,000 people
Sewerage connection [%]Administration Population growth [%]Fiscal index
Habitation
Total housing floor
space per capita
Electrification
Internet access
Education
Library books per capita
Elementary-school
teachers/1,000 people
Preschools/kindergardens/1,000 people
Commerce
Retail stores/1,000 people
Traffic
Total road length per capita
Public transport burden
WelfareWelfare facilities/1,000 people
City park area per capita
Earthquakes
Existing buildings without
adequate earthquakeproofing
Fire
Fires/1,000 people/year
Fire fighters/1,000 people
Storm /Flood Victims/total rainfall
upon damage per year
Crime/
Crimes/1,000 people
accidents
Traffic accidents/1,000 people
Police boxes/stations/
100,000 people
Hospital beds/10,000 people

Weight [%]Minor AI
30
100
30
40

20
20

10

10
20
20
20

20
20
40

1
-10

2
-20

Score
3
-30

4
-45

5
45-

50
50
50

0.007- -0.007 -0.005 -0.003 -0.001
0.07- -0.07 -0.05 -0.03 -0.01
1.0-1.0
-0.7
-0.5
-0.3

50
50
50
40

-60
- -0.3
-0.6
- 27

-70
- -0.1
-0.7
- 32

-80
- 0.1
-0.8
- 36

-90
- 0.3
-0.9
- 40

900.3 0.940 -

30
30
40
30

-80
-60
-1.2
-2.4

-85
-70
-1.6
-2.5

-90
-80
-2.0
-2.6

-95
-90
-2.4
-2.7

95902.42.7-

30

-0.08

-0.09

-0.1

-0.11

0.11-

100
50
50
50
50
100

-6
-2
-10
-0.25
-4
-

-8
-2.5
-20
-0.3
-7
-

-10
-3
-30
-0.35
-10
-

-12
-3.5
-40
-0.4
-14
-

123.5400.414-

50
50
100

0.56-0.7
-

-0.56
-0.9
-

-0.48
-1.1
-

-0.40
-1.3
-

-0.32
1.3-

30
20
20

409-4

-40
-9
-5

-35
-8
-6

-30
-7
-7

-25
-6
7-

30

-10

-13

-16

-19

19-

(2) Functions and services: This is an index of the cultural and social
benefits reaped by city residents. It indicates that the higher the population
growth rate, the greater the attraction of this aspect. Additionally, the higher
a city's fiscal index, the sounder the state of its economy. Sub-category"housing functions" indicates the richness of the living environment. An
element of culture and education is number of elementary-school teachers.

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Although there are no great differences in this area between municipalities
in Japan, it should serve as an index of social maturity when expanded tocities throughout Asia. Another minor category is transportation. In thisminor category, public-transportation utilization responds directly to supply,and is a measure of the degree to which public transportation has beencreated. Meanwhile, road area and traffic volumes should be used to express
convenience of road utilization, but detailed calculations of traffic volumes
are not conducted on a nationwide scale. It has thus been substituted foranother index here.
(3) Safety and security: As the name suggests, this is an index of the safety
and security with which residents can live in the city. The number of out-ofcode buildings is used as a measure of earthquake and fire safety, but
figures on this are not currently kept in Japan. A simple measurement andestimation method and database are needed for buildings at risk ofcollapsing in an earthquake, or in the event of a fire, spreading a fire. It isalso difficult to evaluate flood danger. The level of flooding in urban areas
greatly depends on the sewerage treatment capacity, and other factors arealso large. Hazard maps are needed for this aspect.
Environmental Load Outside City
Table 1 shows examples of each of the elements making up theEnvironmental Load Outside City aspect. The major categories are: (1)energy consumption; (2) resources and materials; and (3) the greater-area
environment.
(1) Energy consumption: This is an investigation of total energy
consumption through the evaluation of primary energy (heat) in relation tototal energy. The lower the total energy consumption, the more sustainable
the city is deemed to be. Thus, the authors do not example individual efforts
to conserve energy here.
(2) Resources and materials: This index is represented by water usage andthe amount of waste. The lower the level of waste, the more sustainable thecity is deemed to be. Thus, the authors do not example individual efforts toconserve resources here.
(3) Greater-area environment: Unlike the environmental and public healthused in the previous section (Quality of Life inside City), this is a measureof the degree to which the city contributes to environmental pollution
outside the city, and to the global environment. Since there will probably bea large difference between the amount of pollution imported by the city andthe amount exported out of the city, this can be represented by the amountof pollution produced inside the city. The calculation of pollution generation
includes all pollution produced by urban activities, rather than just pollution
produced inside the city. For example, with regard to electric power
consumption, air pollution produced by a thermal power plant located far
from the city is included. Additionally, waste that is sent outside the city fortreatment is included in the greater-area environment, as it contributes to theenvironmental impact (load) outside the city.
Each item was also weighted in order to create a comprehensive index.
Weighting should be changed according to the circumstances of each city.
Tables 1 and 2 show sample weighting and scores used for the present

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October 2003, Tokyo

report. The scores were assigned as follows: for each evaluation index,
quality of life and environmental load were each given three points, and thetotal was normalized to a maximum of 5 points. If the levels of both qualityof life and environmental load were improving, the score would be high; ifthey were worsening, the score would be low. It should be noted here that ahigh score for environmental load indicates a low level of environmental
impact. Furthermore, the items for the major categories (Q 1–3 and L 1–3)
have a maximum score of 5 points, in accordance with the weighting shownin Tables 1 and 2. In the table a dash (–) indicates all municipalities do notkeep such data, and the data could not be obtained. Consequently, these
items were eliminated from the present scoring. The collection of this data
will be a future task.
Table 2. Index of Environmental Load Outside City
Major
Category
L1

Minor
Category
Electricity

EnergyGas

Others
L2
Resources/

L3

Water
Resources
Waste

Air

Environment
over wide area
OthersAssessment IndicesElectricity usage[MJ/person/year]
City gas usage[MJ/person/year]
Propane gas usage[MJ/person/year]
Kerosene usage[MJ/person/year]
Tap-water usage[tons/person/year]
Household waste[tons/person/year]
Industrial waste[tons/person/year]
CO2 emissions[tons/person/year]
NOX emissions per capita
SOX emissions per capita
Waste within system
not treated per capita

Weight [%]
Minor
AI
50
100

1
800030-

Score
2
3
8000
7000
-30
-20

4
6000
-15

5
5000
-10

50

100
-

-

-

-

-

-

-

-

-

-

-

-

-

40

100

135-

-135

-125

-115

-105

60

50

600-

-600

-500

-400

-300

50

5-

-5

-4

-3.5

-3

100

100

15-

-15

-10

-7

-3

-

-

-

-

-

-

-

4. Results of Calculation
Fig. 1 shows the index of urban environments scoring results for Tokyoand the 11 government ordinance specification cities in radar charts. Two
designated major cities – Saitama and Shizuoka – recently merged, and thearea of the city changed; for this reason, they do not yet have prepared data,
and thus were excluded from the scoring. The large the area occupied by thecity inside the hexagonal radar chart, the higher its level of environmental
performance.
Sapporo's score was high for Q1 (environment and public health). This isdue to the high proportion of the city area covered by greenery. The scorefor L1 (energy) is also high. The present estimate excludes kerosene usage;
Sapporo is located in a frigid area, and kerosene usage (for heating) is high.
Thus, it is believed that if kerosene usage were added to the estimate,
Sapporo's score in this area would fall.
As with Sapporo, Sendai scored highly in Q1 (environment and publichealth). In terms of load, it also scored highly for L1 (energy). As with
Sapporo, this is likely due to the fact that kerosene usage is not counted in444

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ICUS Report 11

the estimate. The score for L2 (resources) is also high. This is due to thelower generation of household and industrial waste than other cities.
Chiba's score for Q3 (safety) is low. This is due to the relatively highcrime rate there, and the low number of hospital beds per capita. In terms oflow, the scores for L1 and L2 were low. This is probably due to the fact that
Chiba consumes a large amount of energy and produces large quantities ofCO2, because it is an industrial city.
Tokyo (the 23 wards) had low scores for Q3 (safety) and L1 (energy). In
terms of energy usage, the electricity consumption per capita is high. This isprobably due to the concentration of economic activity in Tokyo.
Kawasaki had low scores for Q3 (safety), L1 (energy), and L3 (greaterarea environment). This is because, like Chiba, Kawasaki has thecharacteristics of an industrial city.
Yokohama's score for Q1 (environment and public health) is low. The
reason for the low score for Q1 (environment and public health) inparticular is due to the poor state of air pollution. Overall, environmentalload scores were high.
Nagoya had low scores for Q3 (safety) and L1 (energy). This is also due
to its characteristics as an industrial city.
Kyoto had low scores for Q3 (safety) and L2 (resources and materials).
As with other industrial cities, Osaka had overall low scores forenvironmental load. Its score for L1 (energy), however, was high incomparison with other industrial cities. This indicates that Osaka's industrial
structure is moving from heavy industries to information-intensive
industries.
Kobe's scores for Q1 (environment and public health) and Q2 (functions)were high.
Hiroshima's characteristics are similar to those of Kobe, but its scores
were low for L2 (resources and materials) and L3 (greater-area
environment), resembling an industrial city.
Fukuoka also has characteristics of an industrial city.
Kitakyushu also has characteristics of an industrial city. In this case,however, it had relatively high scores for Q1 (environment and publichealth) and Q2 (functions) for an industrial city.
5. Conclusions
The authors have developed a comprehensive environmental assessment
index for sustainable cities. This has required assessments from theperspectives of both quality of life in the city and the environmental load of
the city. This index was also applied to Tokyo and the 11 government
ordinance specification cities. This has shown the environmental
performance and features of each city. In the future, the authors will work to
obtain a fuller set of data, and expand the assessments to smaller cities inJapan and to cities in Asia.

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October 2003, Tokyo

5

5

4

4

4

3

L3

Q2

L3

3

Q2

3

L3

2

2

2

1

1

1

0

0

0

L2

Q3

L2

Q3

(1) Sapporo

Q3

L1(2) Sendai

Q1(3) Chiba
Q1

Q1

5

5

5

4

4

4

3

Q2

2

L3

3

Q2

3

L3

2

2

1

1

1

0

0

0

L2

Q3

L2

Q3

Q3

L1

(4) Tokyo (23 wards) (5) Kawasaki(6) Yokohama

Q1

5

3

L3

Q2

2

L3

1
0

L2

Q3

5

5

4

4

3

Q2

L1

3

L3

2

2

1

1

0

0

L2

Q3

Q3

5

4

4

2

Q2 L3

Q1
5
4

3

Q2

2

1

1

0

0

L2

(9) Osaka

Q1

5

3

L1

(8) Kyoto

Q1(10) Kobe

L3

3

Q2

2
1
0

Q3 L2

L1

Q2

L2

L1

(7) Nagoya

L3

Q1

Q1

4

Q2

L2

L1

L1

Q2

L2

L1

L1

L3

Q1

Q1

Q1

5

Q3

L1

L2

Q3

L1

(11) Hiroshima(12) Fukuoka

Figure 1. Comprehensive Assessment Indices for Environments of Tokyoand 11 government ordinance specification cities

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EXTRACTION OF PARAMETERS FROMREMOTE SENSING DATA FORENVIRONMENTAL INDICES FOR URBANSUSTAINABILITY
Junichi Susaki, Ryozo Ooka, Yoshihumi Yasuoka, Takahiro Endo, Yo-ichi
Kawamoto; Insitute Industrial Science, University of Tokyo, Tokyo, Japan
Hidenobu Nakai, Madoka Nakashima, Rei Takada
Tokyo Electric Power Company
Masahiro Setojima, Manabu Funahashi; Kokusai Kogyo Co. LTD.
Keiichi Okada; Shimizu Corporation
susaki@iis.u-tokyo.ac.jp

ABSTRACT
Asian mega cities have continued to expand, and accordingly, various
problems, e.g. social, economical and environmental problems, have been
widely recognized in Asia. Especially, environmental issues caused by Asianmega cities will affect not only the areas within mega cities but also thewhole area of Asian countries because the effects will be widely propagatedby atmospheric or marine transportation. Authors have conducted
researches related to comprehensive assessment indices for urban
sustainability, named as Environmental Indices for Urban Sustainability(EIUS). In the framework of EIUS, both the environmental quality and theenvironmental load are focused on. An urban sustainability will be
evaluated based on the scores for all categories of EIUS (Ooka, et. al, 2005).
Most of the environmental data used in EIUS are collected fromstatistical data and those are restricted to point-based data. If area-based
data such as vegetation distribution or urban area distribution are required,remotely sensed technique is quite useful. Remote sensing data also has anadvantage to compare the parameters of different cities by the same criteria.
In the present research, the applicability of remote sensing data to extractarea-based environmental data for EIUS was examined. Landsat Thematic
Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) images,
observed in 1990s and 2000s, were used to extract vegetation index, albedo
and land surface temperature. Urban areas of Bangkok in 1990s and 2000s
were extracted from such parameters. Based on the acquired results, themethodology will be improved and applied to extract urban areas in other
Asian mega cities.

1. INTRODUCTION
Environmental issues caused by Asian mega cities have beenrecognized to be monitored and assessed in an effective manner. Whilesome statistics of mega cities have been reported to date, a systematic
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October 2005, Singapore

assessment is still lacking. Authors have developed comprehensive
assessment indices for urban sustainability, named as Environmental Indicesfor Urban Sustainability (EIUS). The EIUS is based on the framework ofcomprehensive assessment system for building environmental efficiency(CASBEE). The CASBEE was developed for assessment of the efficiency
surrounding a building. In Section 2, EIUS as well as CASBEE are
described. Considering implementation of EIUS, data accessibility is quite adifficult issue. Therefore, we examined the feasibility of application ofsatellite remote sensing data.

2. FRAMEWORK OF EUIS
2.1

CONCEPT OF EUIS

In the field of architecture where mass resources and energy are
consumed, “sustainability” has been one of the most important keywords.
Development of techniques and polices for sustainability is quite
indispensable. CASBEE aims to promote proactive decisions in terms ofenvironmental effects caused by construction and management of buildings.
Therefore, CASBEE focuses on environmental functions of buildings(CASBEE Manual 1, 2003). In CASBEE, “Virtual boundary” is assumed todiscriminate a space inside boundary from a space outside boundary, shownin Figure 1. The space inside boundary refers to the quality of the space
mainly provided by the building. This is called as “Environmental quality”.
On the other hand, the flow from the inside to the outside of boundary canbe regarded as a negative load to the environment. This is called as“Environmental load”. BEE (Building Environment Efficiency) can be
defined as the ratio of “Environmental quality” to “Environmental load”.
Such a simple index can represent both quality and environmental load of abuilding, and enables the comparison between different buildings.
This framework of CASBEE can be applied for environmental indicesfor urban sustainability, or EIUS. Table 1 shows EUIS framework. In the
EUIS, there are two types of categories such as “Quality life of inside city”
and “Environmental load”. Each category has hierarchical structure
consisted of the first classification and the second classification items.
Assessments based on BEE and a radar chart are available in the frameworkof EIUS. Such an evaluation enables a comparison between many cities forthe analysis of urbanization.
Table 1 also represents the results of data availability in Bangkok.
Authors have contacted ministries and departments of Thailand, andexamined data availability. The “Source” in Table 1 means ministries anddepartments of Thailand which can provide the data. Gray column shows
the data were not available. In the case of Bangkok, it was found that mostof data required in the current framework are available.
2.2

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Even though data collection was successfully conducted in Bangkok,
it is not expected to obtain as much data as in other mega cities. Therefore,
the data items should be flexibly changed in accordance with the real data
accessibility. Simultaneously, we have to consider the data source
independent of statistical data collected by organization in different
countries. Another reason for the necessity of another data source is to apply
the same criteria for data collection. While the statistics are useful for thenational analysis, non-unified criteria for the statistics will make aninternational comparison difficult.
Remote sensing has a strong advantage for such problems. Satellite
remote sensing can observe land, ocean and atmosphere from the space. In
most of applications, remote sensing data are converted into physicalparameters or indices. The quantitative and qualitative analysis based on thesame criteria can be implemented by using remote sensing data. Moreover,most of remote sensing data are processed as images, and such area-based
data are quite effective to grasp urbanization. Another advantage of remotesensing data is periodical observation. We have different types of earth
observation satellite and sensors. High resolution data such as Landsat
Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) has
16-day periods. Optical sensor data are easily contaminated by atmosphericeffects, e.g. clouds or aerosols. While we cannot expect many images withgood quality through a year, such periodical observation enables theanalysis of temporal environmental change.

3. FEASIBILITY OF DATA COLLECTION BY REMOTE SENSING
While EIUS mainly deals with various statistics, remote sensing has apotential to be one of the most effective data sources for EIUS. In theframework of EIUS, authors examined the feasibility of data collection byremote sensing.
In terms of spatial resolution of remote sensing data, very highresolution data, e.g. 1 m-spatial resolution data, are available, and those data
can provide the detailed spatial data. However, because of the expensive
data cost, we focus on the usage of high resolution data such as TM andETM+. Those costs are relatively reasonable. Moreover, many Landsat
TM/ETM+ images are available free of charge through the Internet (Global
Land Cover Facility). Such services are quite useful for the analysis
conducted in the present research, i.e. quantitative analysis of temporalchange of urban area. As a result, Landsat TM/ETM+ images were used forthe analysis in the present research. Especially, those images were used forthe extraction of urban areas. As parameters describing urbanization, threeparameters were selected, i.e. Normalized Difference Vegetation Index(NDVI), albedo and land surface temperature (LST). In the following
subsection, methods to derive parameters are described. Most of theconstant values in the following equations are shown in literatures such as(Chander and Markham, 2003) (Landsat 7 Science Data Users Handbook).

Extraction of Parameters from Remote Sensing Data for Environmental Indices for Urban Sustainability 449

October 2005, Singapore

3.1

PARAMETERS OBTAINED FROM REMOTE SENSING

3.1.1 NDVINDVI has been widely recognized as useful for the studies of theland biosphere characteristics and dynamics at regional to global scales.
NDVI has more sensitivity to chlorophyll and less contamination byatmospheric water vapor. NDVI is obtained through calculation ofreflectances of the red and near infrared (NIR), expressed as Equation (1).

NDVI =

ρ NIR − ρ RED
ρ NIR + ρ RED(1)

where ρ RED and ρ NIR denote reflectances at red band and NIR band,
respectively. For Landsat TM/ETM+, band 3 and 4 are used.
3.1.2 ALBEDO
Land surface albedo is a physical parameter that describes the
optical reflectance of the land surface. Albedo is commonly defined as thereflectance of a surface integrated with respect to both wavelength and angle.
Land surface broadband albedo is the fraction of incident (shortwave) solar
radiation reflected in all directions by the land surface. Examples of thealbedo applications include global and regional climatic models forcomputing the surface energy balance, and ecological models. In the present
research, Liang conversion model was used to estimate albedo. The
procedure to estimate albedo from DN value is described in the below(Chander and Markham, 2003). Firstly, DN value was converted into
radiance L by Equation (2). Then, radiance was converted into reflectanceby Equation (3).

Lλ = (Lmax,λ – Lmin,λ)/255 * DN + Lmin,λπ ⋅ Lλ ⋅ d 2
ρλ =Eλ ⋅ cos θ

(2)
(3)

where Lmin,λ and Lmax,λ are the spectral radiances for band λ at digital
numbers 0 and 255, ρ λ unitless planetary reflectance, Lλ spectral radianceat the sensor’s aperture, d earth-sun distance in astronomical units, Eλmean solar exoatmospheric irradiances, θ solar zenith angle in degrees.
Finally, broadband albedo was estimated by applying Liang model for
Landsat ETM+, expressed as Equation (4) (Liang, 2000).

αVIS = 0.443ρ1 + 0.317 ρ 2 + 0.240 ρ3
α NIR = 0.693ρ 4 + 0.212 ρ5 + 0.116 ρ 7 − 0.003
α SW = 0.356 ρ1 + 0.130 ρ3 + 0.373ρ 4 + 0.085ρ5 + 0.072 ρ 7 − 0.0018

450

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11(4)
where α VIS , α NIR and α SW denote VIS albedo (0.4 – 0.7 µm), NIR albedo(0.7 – 2.5 µm) and SW albedo (0.25 – 2.5 µm) for ETM+, respectively.
Hereafter they are mentioned as “VIS albedo”, “NIR albedo” and “SWalbedo”, respectively. ρ n denotes reflectance of band n. In Liang, 2000,
there is no model for Landsat TM. Therefore, Equation (4) was also applied
for the estimation of albedo of Landsat TM.
3.1.3 Temperature
Thermal band data (band 6) from Landsat TM/ETM+ can also be
converted from spectral radiance to effective at-satellite temperature(Chander and Markham, 2003). The conversion formula is described as
Equation (5).
T=

K2
K

ln 1 + 1
 Lλ


(5)

where T denote effective at-satellite temperature in Kelvin, K1 , calibration
constant 1 in W/(m2*sr*µm), K 2 calibration constant 2 in Kelvin, Lλspectral radiance at the sensor’s aperture. The effective at-satellite
temperature values T are referenced to a black body. Therefore, corrections
for spectral emissivity ε are necessary. Equation (6) represents theemissivity correction to derive land surface temperature (LST) St.

St =T
1 + (λ × T ρ ) ln ε(6)where λ is wavelength of emitted radiance (λ = 11.5 µm), ρ = h×c/σ(1.438 ×10-2 m K), σ = Boltzman constant (1.38 ×10-23 J/K), h = Planck’s
constant (6.626×10-34 J s), and c = velocity of light (2.998 ×108 m/s)
(Weng et al., 2004). Emissivity ε can be estimated in many ways. In thepresent research, a methodology reported in (Li et al., 2004) is selected.
Emissivity ε is expressed as Equation (7).

ε = f vε v + (1 − f v )ε s

(7)where ε v and ε s denote emissivity of vegetation and soil, respectively. f v
denotes fractional cover of vegetation (0 – 1). ε v and ε s were assumed as
0.985 and 0.978. Fractional cover f v can be expressed as Equation (8)(Choudhury et al., 1994)

Extraction of Parameters from Remote Sensing Data for Environmental Indices for Urban Sustainability 451

October 2005, Singapore

 NDVI max − NDVI 
f v = 1 − 
 NDVI max − NDVI min a(8)where NDVI max is the NDVI for complete vegetation cover, and NDVI minis the NDVI for bare soil. In the present paper, NDVI max and NDVI min wereassigned as 0.94 and 0.0, respectively. The coefficient a is a function of leaforientation distribution with the canopy. In the present research, a wasassumed as 0.6 for the application.
3.2

EXTRACTION OF URBAN AREAS

In most of applications of remote sensing data, parameters extracted
from remote sensing data or original DN data are used for the classification
to produce thematic map. Our purpose is to extract urban areas from remotesensing images. In usual classification, statistical classifiers have been
applied. Such classifiers have severe shortcoming that they classify on
pixel-basis, which tend to produce patch-like classification results.
Therefore, classifiers based on image processing techniques have been
examined. Recently, a software eCognition has been popular as an effectiveclassification tool (eCognition). It classifies based on segmentation
technique, and eCognition was used to extract urban areas in this research.
3.3

CASE STUDY: BANGKOKIn the present research, Bangkok was selected as a case study
because we completed data collection of Bangkok regarding EIUS. The
purpose is to examine the possibility to extract effective parameters related
to environmental assessment in EIUS. As an effective parameter, urban area
was selected. Both Landsat TM images in 1990s and ETM+ images in2000s were obtained from Web site (Global Land Cover Facility). Twoimages of path 129, row 50 and path 129, row 51 were merged as a mosaic
image. The observed dates are listed in Table 2.
Figure 2 shows a flow of extraction of urban areas from Landsat
TM/ETM images. From original DN values of band 1 to 5 and band 7,
NDVI and albedos were estimated. And, LST was estimated from a thermalband data, i.e. band 6 data. These sets of parameters were calculated for TM
images in 1990s and ETM+ images in 2000s. Firstly, urban areas in 1990s
were extracted. eCognition was used for the segmentation and classificationof urban areas. After urban areas in 1990s were estimated, the areas wereused as a mask layer for ETM+ images. And then, urban areas since 2000s
were extracted. Figure 3 represents the results of urban areas extracted fromLandsat TM/ETM+.

4452

DISCUSSIONSNew Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Figure 3 represents remote sensing can produce area-based
information about urbanization. However, the methodology described in
Figure 2 and the results shown in Figure 3 are preliminary. The results
obtained in the present research should be examined from various
viewpoints, and some improvements are required. Authors examined
combinations of several parameters, i.e. NDVI, albedo (VIS, NIR and SW)
and LST. Among those combinations, the combination of VIS albedo and
LST was found to be effective for the extraction of urban areas. However,these combinations should be examined more.
The methodology to mask urban areas in 1990s needs discussions. In
the beginning, authors extracted urban areas in 1990s from parameters in
1990s and urban areas in 2000s from parameters in 2000s, separately.
However, the urban areas in 2000s were smaller than the urban areas in
1990s. The shrink of the extracted urban areas may be caused by different
atmospheric conditions and different observation seasons. It is quite difficultthat a perfect atmospheric correction is implemented because of lack ofsufficient data related to atmospheric. On the other hand, authors assumed
that the urban areas in 1990s will be urban areas even in 2000s. The
methodology to use the masking is based on such an assumption. However,such assumption should be examined by referring to the existing thematic
map. Validation of extracted urban areas and application of themethodology for other Asian mega cities will be examined in future.

5

CONCLUSIONSIn the present paper, authors report the framework of EIUS andfeasibility of application of remote sensing data for EIUS. EIUS has apotential to enable the comparison of sustainability of Asian mega cities.
However, implementation of EIUS may have difficulty to collect data,
mainly statistics. Even though statistics are collected from mega cities, nonunified criteria make the comparison between mega cities difficult.
Therefore, a feasibility to apply remote sensing data was examined. Remotesensing enables the acquisition of area-based data, which is effective forunderstanding urbanization, and the comparison between many mega cities
under the same criteria. In the present research, NDVI, albedo and LST
were derived from Landsat TM/ ETM+ images obtained in 1990s and 2000s.
Finally, urban areas in 1990s and 2000s were extracted, and it was foundthat remote sensing has a potential to be used for EIUS. The methodology
utilized in the framework of EIUS should be examined.

REFERENCESCASBEE Manual 1, 2003. Institute for Building Environment and Energy
Convservation (IBEC) (in Japanese)
Chander, G. and Markham, B., 2003. Revised Landsat-5 TM Radiometric
Calibration Procedures and Postcalibration Dynamic Ranges, IEEE
Transactions on Geoscience and Remote Sensing, Vol. 41, No. 11, pp.

Extraction of Parameters from Remote Sensing Data for Environmental Indices for Urban Sustainability 453

October 2005, Singapore

2674-2677
Choudhury, B. J., Ahmed, N. U., Idso, S. B., Reginato, R. J., and Daughtry,
C. S. T., 1994. Relations between evaporation coefficients andvegetation indices studied by model simulation, Remote Sensing ofEnvironment, vol. 50 pp. 1-17
eCognition, available at http://www.definiens-imaging.com/
Global Land Cover Facility. Earth Science Data Interface, available at
http://glcfapp.umiacs.umd.edu:8080/esdi/index.jsp
Landsat 7 Science Data Users Handbook, available at http://ltpwww.gsfc.
nasa.gov/IAS/handbook/handbook_htmls/chapter11/chapter11.html
Li, F. Jackson, T. J., Kustas, W. P., Schmugge, J., French, A. N., Cosh, M.
H. and Bindlish, R., 2004 Deriving land surface temperature fromLandsat 5 and 7 during SMEX02/SMACEX, Remote Sensing ofEnvironment, vol. 92, pp. 521-534
Liang, S., 2000. Narrowband to broadband conversions of land surface
albedo I - Algorithms, Remote Sensing of Environment, vol. 76, pp.
213-238
Liang, S., 2003. A direct algorithm for estimating land surface broadband
albedos from MODIS imagery, IEEE Transaction on Geoscience andRemote Sensing, vol. 41, pp. 136-145
Ooka, R., Yasuoka, Y., Susaki, J., Endo, T., Kawamoto, Y., Nakai, H.,
Nakashima, M., Takada, R., Setojima, M., Funahashi, M. and Okada,K, 2005. Development of new environmental indices for urban
sustainability, Proceeding of the Fourth International Symposium on
New Technologies for Urban Safety of Mega Cities in Asia
Weng, Qihao., Lu, D. and Schubring, J., 2004. Estimation of land surface
temperature-vegetation abundance relationship for urban heat island
studies, Remote Sensing of Environment, vol. 89, pp. 467-483

Virtual boundary

Environmental quality (Q)Environmental load (L)BEE (Building Environment Efficiency) =Environmental quality (Q)Environmental load (L)Figure 1: Basic concept of CASBEE. BEE (Building Environment
Efficiency) can be defined as the ratio of “Environmental quality” to“Environmental load” (CASBEE Manual 1, 2003).
454

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Table 1: Framework of EUIS and results of data collection in Bangkok.
Gray column represents data were not available in Bangkok.
Quality of Life Inside City
First Classification
Environment/
Public Health

Second Classification

SourceThird Classification

Degree of nature
Sanitary conditions

Ratio of vegetation coverage
Cases of grievances against pollution
Distribution ratio of sewerage (%)
Air pollution concentration along main roads
Cases of oxidase smog
Ratio of patients of breathing diseases
Ratio of patients of infectious diseases
SO2 Density (ppm)
NOX Density (ppm)
SPM Density (mg/m3)
Administration
Growth rate of population (%)
Financial capability index
Habitation
Floor space of houses (㎡/one person)
Ratio of electrified areas
Ratio of persons equipped with information devices
Education
Ratio of graduates studying in elementary schools
the number of teacher at primary school (the number/1,000persons)the number of the library volumes (the number/one persons)the number of Infant school (the number/1,000persons)Commerce
Retail stores(the number/1,000persons)Traffic
Length of roads/Passing transport
Modal share of public transport(%)
WelfareAreas of urban parks(㎡/person)
Medical welfare facilities (the number/one person)
Earthquake
Ratio of non-earthquake-proof houses (%)
FireFire occurrences (the number/1,000perons/one year)
Ratio of non-fire-proof houses (%)
Rescue operation persons of fire station (the number/1000persons)
Storm and flood damage the number of disasters /the volume of rainfalls (the ratio/one year)
Crime/Accident
Criminal offenses (the number/1000persons/one year)
Traffic accidents (the number/one person/one year)
Field policemen (the number/1,000persons)Beds of sickness (the number/1,000persons)Public Function/
Public Seivices

Safty/
Security

PCD
BMA
PCD
--MPH/BMA(DMS)
MPH/BMA(DMS)
PCD
PCD
PCD
NSO
NSO
---

BMA/NSO
BMA/NSO
BMA/NSO
BMA/NSO
PWD
OTP
BMA
DLP/SSO--BMA (DPS)--DDPM
Royal Thai Police
Royal Thai Police
Royal Thai Police
MPH/BMA(DMS)

Environmental Load
First Classification
EnergyElectricity
Gas
Oil
Water Resources
Waste

Resources

Environment
wide area

Second Classification

overAtmosphere

Remarks;
BMA: Bangkok Metropolitan Administration
DAEDE: Department of Alternative Energy Development and Efficiency

SourceThird Classification
Consumption of electricity (kWh/one person/one year)
Consumption of city gas (MJ/one person/one year)
Consumption of propane gas (kg/one person/one year)
Consumption of kerosene (ℓ/one person/one year)
Water use (m3/one person/one year)
Household refuse (kg/one person/one year)
Industrial wastes (ton/one person/one year)
CO2 Emission Volume (ton/one person/one year)
SO2 Emission Volume (ton/one person/one year)
NOX Emission Volume (ton/one person/one year)
SPM Emission Volume (ton/one person/one year)

MEA--PTT/PTIT
EPPO
MWA
BMA
DIW
DAEDE
DAEDE
DAEDE
DAEDE

EPPO:Energy Policy and Planning Office
MEA: Metropolitan Electricity Authority

DDPM:Department of Disaster Prevention and Mitigation MPH: Ministry of Public Health

DDS: Department of Drainage and Sewerage
MWA: Metropolitan Waterworks Authority
DEQP:Department of Environmental Quality PromotionNSO: National Statistical Office
DIW:Department of Industrail Works
OTP: Office of Transport and Traffic Policy and Planning
DLP: Department of Labour Protection and Welfare
PCD: Pollution Control Department
DMS:Department of Medical Services
PTIT:Petroleum Institute of Thailand
DPS: Disaster Prevention Subdivision
PTT:PTT Public Company Limited
DPT: Department of Public Works, Town and Country PWD: Public Works Department
SSO:Social Security Office

Table 2: TM/ETM+ images used for the analysis. These images wereobtained from Web site (Global Land Cover Facility) (Landsat 7 Science
Data Users Handbook).
Path/Row
TM
ETM+

129/501994/Oct/25
2000/Nov/02

129/51
1994/Oct/25
2002/Jan/08

Extraction of Parameters from Remote Sensing Data for Environmental Indices for Urban Sustainability 455

October 2005, Singapore

1990s Landsat-5 TM
Band 1-5, 7Band 6(Thermal)

Albedo NDVI

LST

Segmentation &Classification

2000s Landsat-7 ETM+
Masking

Urban areas
in 1990s

Albedo NDVI

LST

Segmentation & Classification
Urban areas in 2000s

Figure 2: Flow of extraction of urban areas from Landsat TM andETM+ images

Figure 3: Urban areas of Bangkok, Thailand in 1990s and 2000s
extracted from Landsat TM/ETM+ images. A base map is a composite of
VIS albedo (red), NDVI (green) and LST (blue) of Landsat ETM+ in
2000s. Gray and white areas represent urban areas since 1990s andurban areas since 2000s, respectively.
456

New Technologies for Urban Safety of Mega Cities in Asia

ENVIRONMENTAL IMPACT ASSESSMENT
OF HEAVY METALS ON FISHES AND
CRUSTACEANS IN OGUNU CREEK,WARRI RIVER IN NIGER DELTA AREA OFNIGERIA.
OKORO, D.,*a; OSAKWE, J.b
Department of Chemistry, University of Benin, Benin City, Edo State,
Nigeria.
Tel: +234 8033834446; +2348023320809
E-mail: dukeokoro@yahoo.combMail – In Oilfield & Labouratory Services Limited, Plot 5, 38th Street,
DDPA, Effurun, Delta State, Nigeria. Tel: +234 8032718214
E-mail: osakwejo@yahoo.comaABSTRACT
Water, sediment and some selected faunae were sampled monthly in Ogunu
creek of Warri River between August, 2003 and July, 2004. The samples
were analyzed for twelve heavy metals including iron, zinc, lead, manganese,
chromium, copper, nickel, cadmium, cobalt, mercury, vanadium, andarsenic. Analytical results were compared to data available in the literatureand standard criteria recommended by FEPA, WHO, and ANZECC.
Concentration Factor (CF) and Biotic – sediment Accumulator Factor(BSAF) were used to establish connections between the heavy metals
concentrations in the organisms and the surrounding environment. Verystrong correlations were found to exist between the pairs of iron:zinc andvanadium:nickel, which along with other factors revealed possible
contamination due to increased anthropogenic activities and urbanization.
The results observed in this study indicated that heavy metals were present
in elevated levels as reflected in their bioaccumulation in Chrysichthys
nigrodigitatus, Drepane africana, Palaemon hastatus and Uca pugilator.

457

October 2005, Singapore

1. INTRODUCTION
Fishes and macro invertebrates obtained from the Ogunu creek of the WarriRiver enter the local markets indiscriminately via local anglers andFishermen, which are being consumed daily by humans. The creek is host to
industrial activities from petroleum and allied companies including theresidential and industrial area of a mother oil company. This research work
was aimed at carrying out an investigative study on the pollution level of the
Ogunu Creek of the Warri River with the objective directed towards
obtaining current information about the surface water quality, sedimentquality and levels of twelve heavy metals in selected fishes and crustaceansin the Ogunu creek of the Warri River.
When heavy metals are taken up by an organism, a fraction of it ismetabolized and utilized for its physiological needs (e.g. energy supply,
growth, reproduction) or accumulated in some tissues, and a part, whichcannot be utilized, is released into the environment. The concentration of a
substance in an organism is the result of the difference between the amountof the substance taken in and that released into the environment.
The comparison between the contaminations of an aquatic organism
in relation to that of the water in which it lives is commonly quantified by
the ratio between the concentration of the pollutant in the organism (related
to the wet weight) and that in the water. It is the value of this ratio that wehave referred to in this paper as concentration factor (CF). This same ratio
was referred to as Biological accumulator factor (BAF) by William et al.
(1999), where it was used to calculate the accumulation ofpolychlorobiphenyls (PCBs) in phytoplankton, zooplankton and zebra
mussel (Dreissena polymorpha) in relation to PCB concentration in thewater.
Because sediment seems to be the most important source ofpollutants for benthic species, the pollutant concentration in the organism iscompared with that in the sediment, instead of with the concentration in thewater. This relationship is quantified by the “Biotic-sediment accumulator
factor” (BSAF); which is the ratio between the pollutant concentration in theorganism and that in the surrounding sediments. This factor was also
successfully adopted by Song and Breslin (1998) for heavy metals
concentrations in an amphipod (Diporeia spp.; formally classified as
Pantoporeira hoyi) from Lake Ontario. All water and sediment sampling
was carried out between August, 2003 and July, 2004. The selected faunae
essentially, fishes and crustacean species were all obtained fresh and alivefrom local anglers and fishermen from the mouth of the Ogunu Creek. The
points were water and sediment samples took place are on Latitude N 50
31.80′ and Longitude E 50 42.46′.

2. SAMPLE HANDLING AND TREATMENT
Composite water samples were collected every month from described points
in Ubeji creek of the Warri River in a 1-litre polythene bottles that had
previously been soaked in concentrated nitric acid for 24 hours and rinsed

458

New Technologies for Urban Safety of Mega Cities in Asia

with de-ionised water (APHA, 1998). Composite sediment samples werecollected monthly with the aid of a Van Veen Grab Sampler, stored on ice ina one-litre chemically-cleaned glass jars with Teflon-lined screw-cap, until
the sample could be frozen. All samples were frozen upon returning to thelab for analysis. The selected faunae, after obtaining them, were rapped up
with aluminium foil and kept in ice before proceeding to the laboratory.
Drepane africana (spade fish) were classified as pelagic (living andswimming in the open river) with average weight of 54.04g, Chrysichthys
nigrodigitatus (cat fish) were classified as benthopelagic (live near or at thebottom sediment and feeds mainly on benthic organism) according toMarshall and Merrett (1997) with average weight of 96.85g. Paelemon
hastatus (white shrimp) and Uca pugilator (fiddler crab) were classified as
Benthos with average weight of 30.24g and 17.56g respectively (Ajayi et al.,1986).

3. ANALYSIS
Water samples were digested with concentrated HNO3 in a Pyrex conicalflask (Martin et al., 1992). The resulting solution after digestion was cooled
and filtered through a Whatman filter paper No. 42 into a volumetric flask
and made up to 100 mL mark with de-ionized water. A blank was also
prepared in the same manner and method using de-ionized water. 100 mg/L
stock standards for the various metals were prepared using standards and theconcentrated 30% HNO3. Sediment samples having been air-driedovernight were sieved with a 22 mm sieve aperture. 1.00g of the samples
were weighed into a 100mL Pyrex conical flask and was digested with
15mL of a mixture of the following concentrated acid until dense whitefumes occur in a fume hood. Mixture of acids, Sulphuric acid: Nitric acid:
Perchloric acid were in the ratio 2:2:1. All digested filtrate in water andsediment were analyzed with Flame Atomic Absorption Spectrophotometer(Perkin-Elmer AAS 31,000) according to a modification of the method
described by Soster, et al. (1992). For all the selected faunae, once wholebody of organism was macerated, 5.00g of homogenous blend was weighed
into a pyrex conical flask and 15 mL of a mixture of three concentrated
acids, perchloric, nitric and sulphuric acid in the ratio of 1:2:2, was used todigest sample for 2-3 hours until brown fumes ceased to evolve (Bursell,1975). The content of the flask after digestion was filtered through awhatman GFK glass filter and solution made up to 100 mL mark with deionized water and kept in a heavy metal polythene bottle ready for AAS
analysis.

4. RESULTS AND DISCUSSIONS
The descriptive statistics of all data obtained including Mean, Maximum,
Minimum, Standard deviation along with correlation matrix were calculatedusing the software Kyplot version 2.0 for windows at 95% confidence level.
The results of the mean concentrations of the determined heavy metals in all
the described matrices of the Ogunu Creek of the Warri River are presented

Environmental Impact Assessment of heavy metals on fishes and crustaceans in Ogunu creek, Warri river in
Niger Delta Area of Nigeria459

October 2005, Singapore

in Table 1. Correlation matrix of the metals in water and sediment of thecreek are shown on Tables 2 and 3, while the calculated Concentration
Factor (CF) and the Biotic-Sediment Accumulator Factor for the describedfaunae are respectively presented in Tables 4 and 5.
Table 1: Concentrations of heavy metals in surface water, sediment andselected faunae of Ogunu Creek of the Warri River.
Heavy

Mean ± STDEV

MetalsWater

Sed.(mg/kg)

Iron(mg/L)
0,596 + 0,514(mg/kg)236.50 ± 94.61

Zinc

0,891 + 0,235

Lead

D. africana(mg/kg)C. nigrodigitatus(mg/kg)P. hastatus(mg/kg)U. pugilator(mg/kg)8.621 ± 1.818

12.170± 3.057

15.004±5.652

16.133±5.323

50.164 ± 11.389

5.734 ± 1.345

15.629±7.082

22.906±7.142

28.088±7.487

0,055 + 0,005

3.929 ± 1.406

0.757 ± 0.257

1.67 ± 0.836

1.247 ± 0.094

3.374 ± 1.368

Manganese

0,064 + 0,014

8.222 ± 2.712

1.603 ± 0.155

2.226 ± 0.576

5.254±2.526

12.673±4.558

Chromium

0,060 + 0,009

0.965 ± 0.485

0.083 ± 0.005

0.113 ± 0.031

0.466 ± 0.398

0.874 ± 0.543

Copper

0,030 + 0,021

1.758 ± 0.443

0.302 ± 0.156

0.549 ± 0.090

0.766 ± 0.185

3.978 ± 1.587

Nickel0,301 + 0,110

4.613 ± 2.014

1.569 ± 0.454

4.194 ± 1.626

6.210 ± 1.966

7.827 ± 1.753

Cadmium

0,049 + 0,014

0.697 ± 0.183

0.412 ± 0.158

0.598 ± 0.137

0.805 ± 0.150

0.949 ± 0.137

Cobalt

0,027 + 0,013

0.870 ± 0.437

0.063 ± 0.008

0.084 0.012

0.108 ± 0.022

0.134 ± 0.030

Mercury0,001 + 0,001

0.007 ± 0.001

0.003 ± 0.00

0.005 ± 0.004

0.011 ± 0.005

0.021 ± 0.013

Vanadium

0,589 + 0,226

9.342 ± 4.046

3.153 ± 0.921

8.398 ± 2.267

12.137±3.673

15.592±3.545

Arsenic

0,044 + 0,005

0.623 ± 0.215

0.035 ± 0.009

0.198 ± 0.129

0.381 ± 0.208

0.898 ± 0.201

Sed.—Sediment; STDEV ---Standard Deviation

Table 2: Correlation matrix of heavy metals in surface water of Ogunu
Creek of the Warri River.
Fe
Fe

Zn

Pb

Mn

Cr

Cu

Ni

Cd

Co

Hg

V

As

1

Zn

0.943

1

Pb

0.890

0.955

1

Mn

0.759

0.790

0.861

Cr

0.246

0.238

0.125

0.212

1

Cu

0.648

0.804

0.890

0.732

0.056

1

Ni

0.519

0.479

0.589

0.474

0.274

0.598

1

Cd

0.501

0.373

0.451

0.204

0.232

0.315

0.653

1

Co

0.753

0.811

0.864

0.643

0.327

0.788

0.606

0.716

1

Hg

0.915

0.898

0.878

0.640

0.253

0.768

0.714

0.614

0.803

1

V

0.506

0.459

0.565

0.424

0.257

0.558

0.991

0.690

0.588

0.710

1

As

0.751

0.846

0.856

0.772

0.082

0.676

0.285

0.193

0.709

0.633

0.248

1

1

The determined levels of Fe, Pb, Mn, Cr, Ni, Cd, Co, and V exceeded
standard criteria recommended for surface water by FEPA (1991); WHO(1998); and ANZECC (1992). Lead has a mean value of 0.056 ± 0.005mg/L
in surface water of the creek. This amount in drinking water could substitutefor calcium and be included in bones, which may affect the skeletal systemsof children. The presence of elevated heavy metal levels in the waters of the460

New Technologies for Urban Safety of Mega Cities in Asia

creek indicated that the water may be unsuitable for drinking. The levels ofheavy metals in the matrices were observed to be in the following order ofmagnitude: sediment > crustacean > fish > water. Nickel has its mean value
for surface water in the described creek of Warri River as 0.301 ± 0.110
mg/L which was within the range of values reported for streams in
Colombia, PA (Turchi – Dooley et al., 2001). The observed values were
however higher than most reported local and international standard water
quality guidelines. Nickel has a very strong correlation with vanadium asobserved from the correlation coefficient in water and sediment of the creek(Correlation coefficient > 0.9). Further investigation in both matrices
revealed that their ratio was in V: Ni (2:1). This was an indication that they
were probably from petroleum related sources.
Table 3: Correlation matrix of heavy metals in sediment of Ogunu Creek of
the Warri River.
Fe
Fe

Zn

Pb

Mn

Cr

Cu

Ni

Cd

Co

Hg

V

As

1

Zn

0.821

1

Pb

0.872

0.856

1

Mn

0.798

0.944

0.937

Cr

0.761

0.966

0.836

0.894

1

Cu

0.979

0.810

0.853

0.787

0.769

1

Ni

0.747

0.959

0.814

0.919

0.946

0.777

1

Cd

0.874

0.948

0.862

0.928

0.893

0.866

0.905

1

Co

0.446

0.811

0.695

0.805

0.878

0.491

0.868

0.677

1

Hg

0.937

0.780

0.757

0.713

0.759

0.953

0.738

0.848

0.438

1

V

0.704

0.949

0.791

0.917

0.935

0.737

0.997

0.895

0.882

0.706

1

As

0.688

0.875

0.723

0.831

0.889

0.747

0.931

0.894

0.779

0.742

0.932

1

1

Aquatic sediments are principally derived from weathering processes, withmajor transportation from terrestrial sources under high runoff from storms
and floods. In addition, discharges from urban, and industrial activities arepotential sources of particulates. Anthropogenic contaminants, including
heavy metals and nutrient elements are associated with particulate anddissolved inputs to natural waters like the Ogunu Creek of the Warri River.
Iron had one of the highest concentrations and the observed values for fishsamples were well above the ones reported for fish samples in Rima River,
Sokoto, Nigeria (Abdulrahman et al., 2004). The observed values for zinc infish samples of the Ogunu Creek were within the values reported for fishes
in the Lagos Lagoon (Tomori, 2004) and Cooks River, Australia (Gupta,
1997). The observed mean value of zinc in Uca pugilator of the Ogunu
Creek was in agreement with mean value reported for same specie of crab in
Degema District of Rivers Sate, Nigeria (Ogbonda, 1992). These values
were however, below allowable limits of Australian New Zealand Food
Authority (ANZFA, 1992). Cadmium had elevated levels in all fish samplesof the Creek when compared to allowable limits of ANZFA (1992). The
observed values were in agreement with those recorded in previous studies
conducted for fish samples in Warri River (Nwajei, et al, 2004). The levelsof cadmium observed for crustaceans in the Creek were relatively highEnvironmental Impact Assessment of heavy metals on fishes and crustaceans in Ogunu creek, Warri river in
Niger Delta Area of Nigeria.

461

October 2005, Singapore

when compared with reported levels in crustaceans of Forcados River(Ndiokwere and Eloke, 2001). Mercury had a range of 0.003 – 0.021 mg/kg
in all selected faunae tested. These values were low compared to ANZFA(1992) allowable limits and the levels reported in fish samples of Cooks
River, Australia (Gupta, 1997), but were higher than the value
recommended for fish by Tennesse Water Quality (1998). The CF and
BSAF in all metals for the selected faunae were in the following order ofmagnitude: Uca pugilator > Palaemon hastatus > Chrysichthys
nigrodigitatus > Drepane africana. The crustaceans including fiddler crab
and the white shrimp exhibited higher bioaccumulation potentials comparedto the fishes. However, bioaccumulation was stronger in benthopelagic
catfish compared to the pelagic spade fish as observed in Tables 4 and 5.

Table 4: Concentration Factors (CF) of described Faunae of Ogunu Creekof the Warri River.
Metals
Iron
Zinc
Lead
Manganese
Chromium
CopperNickelCadmium
CobaltMercury
Vanadium
Arsenic

D.africana
0.04
0.11
0.19
0.19
0.09
0.17
0.34
0.59
0.07
0.43
0.34
0.06

C.nigrodigitatus
0.05
0.31
0.43
0.27
0.12
0.31
0.91
0.86
0.10
0.71
0.90
0.32

P.hastatus
0.06
0.46
0.32
0.64
0.48
0.44
1.35
1.15
0.12
1.57
1.30
0.61

U.pugilator
0.07
0.56
0.86
1.54
0.91
2.26
1.70
1.36
0.15
3.00
1.67
1.44

Table 5: Biotic-Sediment Accumulator Factor (BSAF) of described Faunaeof Ogunu Creek of the Warri River.
Metals
Iron
Zinc
Lead
Manganese
Chromium
CopperNickelCadmium
CobaltMercury
Vanadium
Arsenic

462

D.africana
14.44
6.44
13.83
25.05
1.38
10.03
5.21
8.48
2.37
2.73
5.35
0.8

C.nigrodigitatus
20.43
17.55
30.42
34.78
1.88
18.24
13.92
12.31
3.16
4.55
14.25
4.52

P.hastatus
25.19
25.72
22.71
82.09
7.77
25.45
20.6
16.56
4.06
10
20.6
8.7

U.pugilator
27.09
31.54
61.46
198.02
14.57
132.16
25.97
19.53
5.04
19.09
26.46
20.5

New Technologies for Urban Safety of Mega Cities in Asia

5. CONCLUSION
Heavy metals investigation produced significant results that revealed muchunusual characteristics in the quality of water, sediment and faunae of the
Ogunu creek of the Warri River. Uca pugilator, Palaemon hastatus andchrysichthys nigrodigotatus bioaccumulated heavy metals in the creek,
indicating that they are good indicators for biomonitoring of pollution of
aquatic environment.

REFERENCE
Abdulrahman, F. W., and Tsafe, A. I., 2004. Trace metals Composition in
Fishes from Sokoto Ruma River. Published in: 27th Int’l Conf. of the
Chemical Society of Nigeria. pp 219-223.
Ajayi, T. O., Ukpe, E. T., Ssentongo, G. W., 1986. Marine FisheryResources of Nigeria: A review of exploited Fish stocks. Chapter 6
page 3.
APHA, 1998. Standard Methods for the Examination of Water andWastewater, 20th edition Publishers: American Public Health
Association; American Water Works Association; Water
Environment Federation.
Burrel, D. C., (1975). Atomic spectrometric analysis of heavy metal
pollutant in water. Ann Arbor Science publishers, Inc., Ann Arbor,
Michigan.
Gupta, L., 1997. Environmantal Health Assessment of Fish and Oyster fromthe Cooks River – heavy metals and organochlorine pesticides
CSAH public health unit. Technical Report . 4pp.
Marshall, N. B., and Merrett, N. R., 1977. The existence of a benthopelagic
fauna in the deep-sea, in A voyage of Discovery, George Deacon
70th Anniversary Volume, edited by M. V. Angel, pp. 483-497,
Pergamon Press, Oxford.
Martin, T. D., Brockhoff, C. A., Creed, J. T., and Long, S. E., 1992.
Determination of metals and trace elements in water and wastewaterby inductively coupled plasma – atomic emission spectrometry.
I.C.P. Nws tt r, 18(3): 147-169.
Ndiokwere, C. L., and Eloke, F. O., 2001. Environmental Impact Assesmentof Petroleum exploitation on fish and mollusks in the Niger Delta
Forcados River as a case study. Msc thesis.
Nwajei, G. E., and Okrija, B. O., 2004. Cadmium, Chromium, Lead andZinc Concentrahoria in fishes, Earthworm and soil from Warri River,
Nigeria. Published in: 7th International conference of the Chemical
Society of Nigeria pp. 155-158.
Ogbonda, C., 1992. Bioaccumulation of Heavy metals in mollusks andcrustaceans in Mangrove Area of River State. M. Phil thesis.
University of Benin, Nigeria.
Song, K. H., and Breselin, V. T., 1998. Accumulation of contaminant
metals in the amphipod Diporeia Spp. In Western Lake Ontario. J.
Great Lakes Res., 24: 949-961.

Environmental Impact Assessment of heavy metals on fishes and crustaceans in Ogunu creek, Warri river in
Niger Delta Area of Nigeria.

463

October 2005, Singapore

Soster, D. A., Harvey, D. T., Troska, M. R., and Gromms, T., 1992. The
effect of Turbificid oligocheates on the uptake of Zinc by Lake Erie
sediments. Hydrobiologica. 248: 249-258.
Tomori, W. B, Aiyesanmi, A. F., and Obijola, O. A., 2004. Heavymetal
quality Assessment of Marine Fishes of Lagos Lagoon. Published in27th Int’l Conf. of Chemical Society of Nigeria pp 252-256.
Turchi-Dooley, S., and Wallace, J., 2001. A preliminary study on Trophic
level Analysis for Heavy Metals in Aquatic Macroinvertebrates in
two streams in Columbia, PA.
William, E. J., Manchester-Neesvig, J. B., Agrell, C., and Armstrong, D. E.,
1991. Influence of ortho-substitution homologous group on
polychlorobiphenyl bioaccumulation factors and fugacity ratios inplankton and Zebra mussels (Dreissena polymorpha). Environ.
Toxicol. Chem., 18: 1380-1389.

464

New Technologies for Urban Safety of Mega Cities in Asia

FLOOD FORECAST AND FLOODCONTROL STRUCTURES OPERATIONFOR FLOOD CONTROL OF HA NOI CITY
Tran Thuc, Nguyen Xuan Hien, Dang Quang Thinh, Huynh Thi Lan Huong
Institute of Meteorology and Hydrology, Vietnam
thuc@netnam.vn
ABSTRACTThe Red River system, with a catchment area of about 143,000 km2,
is the biggest river system in North Vietnam. There are three main river
tributaries, namely, Da River, Thao River and Lo River. The river basin is
affected mainly by flood, inundation and storm surge. Flood protection
system in the area includes river and sea dyke, flood regulation byreservoirs, flood diversion and detention.
Numerical models were applied for flood forecast for the Red Riversystem, especially for Ha Noi, the capital of the country. The objective is toimprove the forecast accuracy and forecasting lead time, and to provide atool for the operation of flood control structures. Rainfall-runoff model isused for headwater computation and forecast, and hydrodynamic model isapplied for flood routing in the river network downstream. Two models
were applied for the Red River System; namely: (i) Hydrological Modeling
System (HMS) and HECRAS; and (ii) MIKE-11 system. HMS and HECRAS
models give very good results in rainfall-runoff computations, flood routing,and flood control structure operation. However, the models do not has
module for error updating, a crucial module fore flood forecasting. It isthen cannot be applied in real time flood forecast. The MIKE-11 model,
with separate modules for rainfall-runoff, flood routing, reservoir and otherstructures operation, especially module for automatic error update. The
model is the applied for the Red River flood forecast.
The models were used for real-time flood forecast for the flood
seasons of 2003 and 2004. Results of are found very satisfactory. The model
system is, therefore, recommended for operational real-time flood forecast.
Introduction
Two model systems are applied for rainfall-runoff andhydrodynamic computation and forecast for the Re River system, North Viet
Nam. They are: (1) HMS and HECRAS models; and (2) MIKE-11 system.
The HMS and HECRAS give good results in rainfall - runoff,hydrodynamic, reservoir operation and flood control structures operations.
However, the models do not have error updating module - a very important
module for forecasting, therefore, the model cannot be used for operational
flood forecast.

465

October 2005, Singapore

The MIKE-11 model system has the advantage that it has separate modules
for rainfall-runoff, flood routing, reservoir and other structures operation,
especially module for automatic error update. The model is then applied for
the Red River flood forecast.
NAM model is a lumped parameters rainfall-runoff model. It isbased on a system of vertical tanks and linear storage. Each sub catchment
is treated as one unit.
Governing equations for unsteady 1-D open channel flow in the river
system, used in the Mike-11 model, are as follows:
Continuity equation:

∂Q 
∂Q

dt − ρ  Q +dx dt = ρ dA dx = ρ
dx dt
∂x 
∂t

in which:

∂Q ∂A
∂Q
∂h
and
=
−B
=0
∂t
∂t
∂t
∂t

Momentum equation:∆M ∆(M .U ) ∆P F f Fg
=
+
−
+
∆t
∆x
∆x ∆x ∆x(2)

where: momentum: M = ρ h b U , momentum flux: M f = ρ h b U U ,ρ gU 2
1,
ρ g b h 2 , friction term: F = ∆x b
2
C2
gravity term: P = ρ g A S .

pressure term: P =The governing equations are solved by implicit 6-point numerical
scheme (Bbott - Inoescu).
FLOOD FORECAST FOR THE RED RIVER SYSTEM
Model Calibration and Verification

NAM model is applied for headwater hydrological forecast. The Da,
Thao, Lo, Cau, Thuong and Luc Nam Rivers are subdivided into 6, 8, 8, 1, 1,
and 1 sub-catchments, respectively. The headwater computational scheme isshown in Fig.1.
Six-hour rainfall data at stations in the river basin in 2001 and 2003
are used for model calibration and verification, respectively. Results ofmodel calibration and verification are shown in Table 1.

466

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Table 1: Results of rainfall-runoff model calibration and verification

Sub Catchment

Nash Sutcliffe Coefficient

StationCalibration

Verification

Da River

Ta Bu

78%

75%

Thao River

Phu Tho81%

79%

Lo River

Vu Quang

78%

78%

Cau RiverThai Nguyen

77%

76%

Thuong River

Cau Son80%

81%

Luc Nam River

Chu

71%

75%

S«ng §µTrung¸ i KiÒu

S«ng
Thao

NguyªnGiang

S«ng L«

Hµ
Giang

KG

S«ng G©m

KG

KG

M¹n H¶oB¾c MªLý TiÕn
§é

VÜnh
Tuy

KG

KG

S«ng NËm Na

Lai
Ch©u

S«ng Ch¶y
KG

Ngßi
Thia

KG

S«ng NËm Mu

KG

Chiªm
Ho¸

KG
KG

Yªn B¸i
Thanh S¬n

KG

KG

B¶n
Cñng

Na
Hang

KG

B¶o YªnB¶o HµS«ng Bøa

KG

T¹ Bó

KG

Lµo CaiS«ng Ngßi Thia

NËm
Giµng

KG

Hå Th¸c
Bµ

Tuyªn
Quang

KG

Phó Thä

KG

KG
KG

Vô
Quang

KG

Hå Hoµ B×nh
KG

BÕn Ngäc
ViÖt Tr×

Fig. 1: Headwater Computational Scheme

MIKE-11 model is applied for flood forecast and flood control
structures operation for the Red River system. Rivers in the scheme
includes: Da, Thao, Lo, Hong, Cau, Thuong, Luc Nam, Duong, Thai Binh,
Kinh Thay, Kinh Mon, Lai Vu, Gua, Da Bach, Moi, Mia, Luoc, Lach Tray,
Hoa, Tra Ly, Dao, and Day river.
The river system consists of 25 main rivers, divided into 52 river
reaches with 792 river cross-sections. In which, Da River has one reach with
51 cross-sections, Thao River has one reach with 27 cross-sections, LoRiver has two reaches with 19 cross-sections, Red River has 8 reaches with156 cross-sections, Thai Binh River has 5 reaches with 44 cross-sections,
Luoc River has one reach with 34 cross-sections, Duong River has one
reach with 31 cross-sections. Flood control structures in the Red Riversystem such as: Hoa Binh dam, Day River flood diversion structure, Tam
Thanh, Lap Thach, Luong Phu - Quang Oai flood detention areas are

Flood Forecast and Flood Control Structures Operation for Flood Control of Ha Noi City

467

October 2005, Singapore

presented in the scheme of computation. Operational procedure of flood
control structures is presented in model and scheme of computation isshown in Fig. 2.

23
24
26
28
27

31

32

33

34

35

36

37

223

433
434
435

435

390

436
436

391
392

437

437

393

Qu¶ng C-

224

226

438
443
443

630
228

231
635

633

634

587

639

638

636

637

449

40

449

41

450
42

tr¹m thuû v¨n

450

Chò

451

43

451

43
44

464

452

44

452

S¬n T©y(H, Q)

455

51

458
462
480

562
563

R17

R18

805

806

807

138

860

267 268

269 270271

272 273274 275276

277

278 279

290

291

292

293

294

295

296

581

346
358

658

Nh- T©n (H)359

Phó LÔ (H)

615

297

159

S«ng V¨n óc

539

611

619
620
623

549

624
625

552
554
556

584

517
518

583

584

519

585
520

520

S«ng Th¸i B×nh

370

519

370

306

598

KiÕn An (H)

582

585

361

TiÒn TiÕn

518

365

631

582 581

630

575

296

Qói Cao

362
304

586

Quang Phôc(H)
521

521

371
372

150
309
308

522
374

310

523
5
37

159

312

524
6
37

524

311

158

37

157

6
37

156

5

310

155

522
373

309
309

153

523

151
152

154

37

7

313
160

Th¸i B×nh

525§«ng Xuyªn (H)

314

161

§«ng Xuyªn (H)
314

315

162
163
164
165

295

363

149

163
164
165

166
167

358

657

243

305
148

166
353

172 171 170 169168 167

354

659
660
661

656

662

351
352

354
655

333 332

174 173351 350
352
353

654

S«ng Ninh C¬

657
658

653

147

162
349

302

QuyÕt ChiÕn

146

161
348

349

656

360

350
652

S«ng §¸y348 347

655

347

362
359

335 334 333

336 335 334

Trùc Ph-¬ng
(H)

160

345

654

346
651

360

337 336

338 337

301

311

652

339 338

340 339

300

307
377

653

340

650

299

378
378

Nam §Þnh

294

364

303

312

379

379

298

300

313

380

381

297
145

299

315

380

381

382
382

293

328

168
169
170
171
172

328

383
383

292

363

298

329
329

384
384

291

362

141

143

330
330

385

649

290

142

173
174

331
331

647 385

648

289

371

646

278

372

645

TriÒu D-¬ng

140

276 277

373

644

302

274 275

4
37

643

301

273

S«ng Trµ Lý

642

271 272

S«ng Ho¸ 364

641

269 270303

149 148 147 146 145 144

144

266 267 268

304

143 142

640

595

578
265 266

264 265

305

141

T¶o Xu©n638
639

S«ng Hång

651

650 649 648 647 646

Ninh B×nh

597

579
263 264

262 263306

140 139636 Gi¸n KhÈu637

157 156 155 154153 152 151 150

676

S«ng Hång

672

640

668 669

645 644 643 642 641

660

Chanh Ch÷

138

139
673

666

579

137

158

858

136

596

580

755
85
9

665

135

H-ng Yªn754KiÕn An (H)

580

R16

804

137

R15

857

577

132

663

135 134

741

662

136

661

595
578

134

S«ng L¹ch Tray

576

131
664
665
666
667
668

133

739

594
577

132

133

738

663

737

660

590
593

131

659

557
592

517
516

515

130

731

H-ng Thi

591

574

513
514

129

516

515

130

575

840

129

556

575

S«ng MÝa

514

729

730

555

591
574

513

728

842

627

554

589

572
573

511
512

727

839

626

Do Nghi (H)
553

590

573

512

841

589

572

511

726
838

593

725
837

664

588

571

Trung Trang
510

836

675

587

592

509

724

588
586

594

723

510

509

835

587

571

553

629

B¸ Nha508

722

S«ng CÊm

628

555

627
508

626

506
507

Ngäc §iÓm

625

596

1
83

721

625

552

570

720

624

551

576
570

507

83
0

481

551

S«ng Gïa

506
719

569

505

718
828
829

Cao Kªnh
(H)

550

568

504

833

569

505

676

623

550

568

504

717
827

R12 674

612

566
567

503

2
83

716

R13

622

503

826

R11

549
567

502

715

620

613

565

499
714

619
618

621

614

500

825

618
617

547

501

677

617
616

546

548

502

R10

616
615

613

566

501

713

82
3

BÕn TriÒu (H)

545

609

612

564

Qu¶ng §¹t

500

712
822

608

611

565

499

711

821

797

544

610

561

494
495
496

0
82

R8

819

R9

562

498

710

796

R7

543

607

614

8
81

498
795

824

542

605

610

563

597

R6

497

709

564

794

Phó L-¬ng

7
81

497

81

793

R5

1

81
0

81

2

708
5
81

604

S«ng

493

129
130
131

496

132

783

560

491
492

801

805

777

782

781

541

An Phô
603

621

98

133
134

0
80

806

779

540

601

561

495

707
778

560

493

706

776

539

538

606

492

494

538
537

600

559

491

537
536

An Bµi

599

622

490

705

804

775

536
535

534

602

558

488
489

96

704

133

535

534
533

S«ng §¸ B¹ch

94
96
97

132

489

95

703

132

481

487

93

487

95

7

803

131

533
532

558

488

702

130

532
531

486

97
701

129

531
530

BÕn B×nh

490

809

79

802

700

S«ng Kinh ThÇy
530

529

485

91

92

80
8

6
79

699

529
528

625

89

94

798

792

528
527

484

93

R4

791

527
526

483

87
88

486

91

5
79
834

R2

867
790

526

525
483

92

698

S«ng Kinh ThÇy
262

261
482

540

261
260

C¸t Khª

541

260
259

90

696

697

R1

258

542

259

257

603

90

Hµ Néi (H,Q)

695

256

484

794

472

459
461
256

250
249

BÕn Hå

543

248 249247 248

544

247

246

485

694

R3
789

245

545

245 246546

244

243 244

547

243

242

S«ng §uèng

548

241 242240 241598

240

238 239609

238 239

236 237557

236 237

235

482

85
86
87
89

88

693

86

599

234 235
233 234

Th-îng C¸t
(H,Q)

85

479

479

Ph¶ L¹i

232 233
231 232

Lôc Nam(H)463
424 425 426 427 428 429 430 431 432

423 424 425 426 427 428 429 430 431 432

84

692

473

S«ng
Lai Vu

833

691

474
474

462

S«ng CÇu

422

83

R20

690

792
793

788

475
475

461
421

423

82

476

476

480

82
83

855

80
81

84

788

79
1

§¸p CÇu (H)79

478 477

S«ng Th¸i B×nh

81

802
856

422 421

80

678

477

473

460

419
79

85
4

685

420

78

784
0
79

787

9
78

78

R19
686

472
459
478

460
420

463

418

85
3

786

418

419

687

471

2
85

57

688

466
471

458

784

688

470

457

V©n Cèc

56

786

689

470

457

55
785

469

53
54

787

469

456

851

801

764

785

468

52
456

R23
763

600

50

467

601

49
50
85
0

51

Bèi
VÜnh T-êng

466

468

49
843

798

BÕn M¾m

455

48

467

56
48

129

47

47

465

S«ng Lôc Nam

45

75
6

75
7

845

759

h-íng dßng ch¶y
465

46

605

42

41

S«ng Hång

84

8

R22

tªn mÆt c¾t

448

39

9
84

800

597
448

606

37

607

36

608

35

602

34

604

33

45

844

tªn ®o¹n s«ng

446

632

n

32

846

762

nót « ruéng

445

631

230

38

807

444

229

M«
Kinh

31

Qu¶ng Oai

761

biªn trªn

442

629

227

40

760

biªn d-íi

Chò

559

30

635

758

KiÕn An (H)
440
441

39

R21
BÊt B¹t

Chó thÝch

438

441

628

442

225

439
439

394
395

440

222

389

S«ng Th-¬ng

221

434

388

464

28 29

S«ng §µ

756

219
220

433

387

447

799

757

218

CÇu S¬n

386

447

27

29 30

217

444

225 224 223
207 208 209 210 211 212

203

22
230 229 228

208 209 210 211 212 213

2138

176 177 178 179 180

26 25 23204 205 206

199 200 201

22 21

862

86
1

3
86

Hoµ 177 178 179 180 181
B×nh

864

227 226

R24
Tam Thanh

216

445

222 221 220

10

9

9
10
11

215

446

219 218788395 394 393 392 391 390 389 388 387 386

6

6
7

214

632

5

5

633

4

217 216 215

4

634

3

3

635

214

2

2

808

Th¸c Huèng

Vô Quang

1

213

1

Phó Thä332

175

Ba L¹t (H)H×nh S¬ ®å tÝnh thuû lùc theo m« h×nh VRSAPhÖ thèng S«ng Hång - Th¸i B×nh
(tµi liÖu ®Þa h×nh n¨m 2000)

Ba L¹t (H)Fig. 2: Downstream Flood Routing Computational Scheme

Upstream boundaries are hourly discharges at 6 hydro-stations: Hoa
Binh, Yen Bai, Phu Ninh, Thac Buoi, Cau Son and Chu. Downstream
boundaries are tidal water level at hydro-stations: Nhu Tan, Truc Phuong,
Ba Lat, Dinh Cu, Dong Xuyen, Quang Phuc, Kien An, Cua Cam, and Don
Son.

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Water level/discharge data at hydrological stations in 1996 and 2000
are used for model calibration and verification, respectively. Results ofmodel calibration and verification are shown in Table 2. It is found that thecomputed results are in good agreement with observed data.
Table 2: Results of hydrodynamic model calibration and verification

No

Station

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

Trung Ha
Viet TriSon Tay
Ha NoiThuong Cat
Luc Nam
Phu Lang Thuong
Pha Lai
Cat KhePhu Luog
Ben Binh
Cao Kenh
Don SonAn PhuQuang Dat
Ba NhaTrung Trang
Ben HoModel Calibration
Efficiency Absolute(%)
Error (m)
98
0.00
98
0.10
98
0.12
98
0.22
97
0.17
97
0.04
90
0.04
96
0.10
89
0.10
92
0.29
91
0.01
95
0.05
95
0.15
89
0.04
91
0.02
78
0.16
87
0.02
82
0.10

Model Verification
Efficiency Absolute(%)
Error (m)
96
0.30
97
0.36
95
0.48
95
0.34
97
0.34
96
0.16
98
0.03
97
0.06
94
0.15
93
0.39
95
0.35
97
0.03
91
0.04
83
0.43
91
0.01
79
0.06
76
0.13
92
0.32

Results of Operational Flood Forecasts

Operational flood forecasts are conducted for flood season of 2003
and 2004. Flood forecast are done for all computational nodes of the model,
in which more attention are focused for importation locations in the river
system, i.e. Ha Noi, Thuong Cat, Pha Lai, Son Tay and Hung Yen.
Results of Headwater Flood Forecast

Forecasts are carried out for water level at Yen Bai, Tuyen Quang
and flow to Hoa Binh reservoir. Forecast time is 24 hours. Totally, there are
92 bulletins are issued. Accuracy of flood forecast is 83%.
Results of Flood Forecast for Downstream

Forecasts are done for 24 hours, 36 hours and 48 hours. Results offlood forecast for downstream location are shown in Table 3. It is found thatthe accuracy of flood forecast using the model system is acceptable for

Flood Forecast and Flood Control Structures Operation for Flood Control of Ha Noi City

469

October 2005, Singapore

operational flood forecast for the Red River system. It is comparable withconventional method currently used in the river basin.
Table 3: Results flood forecast for Ha Noi and Pha Lai stations

StationNo of 24-hour forecast
No of accurate forecast
Confidential level
Min error
Max error
No of 36-hour forecast
No of accurate forecast
Confidential level
Min error
Max error
No of 48-hour forecast
No of accurate forecast
Confidential level
Min error
Max error

Flood season in 2003

Flood season in 2004

Ha Noi
29
25
86 %
0 cm
56 cm
29
20
69 %
0 cm
77 cm
28
20
71 %
0 cm
137 cmHa Noi
46
37
81 %
0 cm
64 cm
46
33
71,7 %
0 cm
117 cm45
32
71,1 %
0 cm
175 cm

Pha Lai
29
19
66 %
1 cm
148 cm
28
17
61 %
1 cm
163 cm

Pha Lai
46
35
76 %
1 cm
35 cm
46
31
67,4 %1 cm
43 cm

CONCLUSIONSMIKE-11 model system has special modules in which flood
forecasting module has updating function that evaluate and eliminate
deviations between observed and simulated discharges/water levels in thehindcast period to improve the accuracy of the model results in the forecast
period. Moreover, the model also has reservoir operation and flood control
structure operation functions. Thus, MIKE-11 system can be applied for
purpose of operational hydrological forecast for the Red River system.
Results of operational forecast are found satisfactory.
Experience has been gained in applying the model for operational
forecast. In the coming time, development and enhancement of model will
be conducted to improve forecast accuracy.
REFERENCES

1. Hydro-meteorological Service of Viet Nam, Hydrological data in 2003,
2004.
2. Tran Thuc, Report of Operational Flood Forecast in Flood Season 2003
and 2004.
3. MIKE-11 User's Manual, 2003.
4. HEC-RAS User's Manual, 2003.
5. HEC-HMS User's Manual, 2003.

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FLOOD CONTROL INVESTIGATION OF
HAD YAI CITY, SOUTHERN THAILAND
TAWATCHAI TINGSANCHALI
Professor, School of Civil Engineering,
Asian Institute of Technology, Thailand
Email Address: tawatch@ait.ac.th
AKAPOB TEERAORANIT
Former graduate student, School of Civil Engineering,
Asian Institute of Technology, Thailand
Email Address: akapob@hotmail.com

ABSTRACT
Had Yai City in Songkhla province situates in the Utaphao river basinin Southern Thailand. Rapid development of the city obstructs the natural
waterways and decreases the flood drainage capacity from the city to
Songkhla Lake. Four major floodings occurred in Had Yai in 1942, 1969,
1988 and 2000 resulting in enormous damages to the city. Utaphao river
basin has a total drainage area 2305 km2. Khlong Utaphao is the main riverin the basin and drains water from Had Yai city to Songkhla lake. The
length of Khlong Utaphao is about 112 km. The estimated drainage capacity
is 420 m3/s. Floods in the Utaphao river basin are influenced by northeast
monsoon. The average annual rainfall in the basin is approximately 1800
mm. In November 2000, the largest flood ever occurred and caused severe
damages to 11 Provinces including Had Yai. 2,200,000 people were affectedby the flood and 8,300 people were evacuated. 59 people and 1,600,000 live
stocks were killed and 269,230 ha of farmlands were damaged. The total
damage is estimated about one billion US dollars. It is required to find flood
control measures for Had Yai.
The flood in October to December 2000 is selected for calibration of
MIKE-11 model. The verification of the hydrodynamic model is done for1988 flood. Compared to the observed data, the results of model
calibration and verification are satisfactory. The effects of three proposed
flood control schemes are investigated by considering the flood in 2000
namely; scheme 1) shortcut channel, scheme 2) flood diversion channels
and scheme 3) shortcut plus flood diversion channels. The shortcut channel
is found to reduce water level just enough to eliminate flooding at Had Yai.
For the two flood diversion channels, they have large effect on flood leveland duration at Had Yai. The combination of diversion channels andshortcut channel yields only a little better result compared to the case ofdiversion channels only. Recommendations on flood control measures are
given.

471

October 2005, Singapore

1. INTRODUCTION
Had Yai city in Songkhla province situates in the lower part of
Utaphao river basin and is the meeting point of many canals. Rapid
development causes Had Yai to be one of the important city and center forbusiness and tourism in southern region of Thailand. This development
obstructs the natural waterway and cannot conveniently drain water to Thale
Sap Songkhla lake. Because of its geographical location Had Yai is very
prone to flood because all the runoffs in the river basin combine together inthe city. Utaphao river basin has a total drainage area 2,305 km2. Khlong
Utaphao is the main river in the basin and drains water from Amphoe Sadao
to Amphoe Had Yai city before it drains into Thale Sap Songkhla (Songkhlalake). The length of Khlong Utaphao is about 112 km. General topographyof Utaphao river basin is low lying plain which has high mountains at the
upstream and slope to downstream area. The eastern and western areas aremountainous and plateau. The estimated drainage capacity is 420 m3/s or
36.3 million m3/day. The depth of Khlong Utaphao is 2 to 12 meters and has
the average width is about 40 meters. Tidal effects in Songkhla lake cause
flood in Utaphao river basin. The average maximum water level in
Songkhla lake is 0.60 m. msl or more in November to December. The
average minimum water level is 0.25 m. msl or less in June to August. The
lake water level normally varies from –0.25 to +0.25 m. msl and does notaffect to drainage system of Khlong Utaphao. The heaviest rainfall is in
November and the minimum rainfall is February. The average annual
rainfall in the basin is approximately 1800 mm ( NESDB, 2001).
Floodings in the Utaphao river basin, as well as in southern region ofThailand, are generally caused by heavy rainfalls which resulted from
cyclones or low pressures centers developed in the Gulf of Thailand.
Changing economic, demographic and physical conditions have greatly
increased flood occurrence. Economic growth and growing populations
have caused increasing frequency and severity of flood disaster in the basin
because of changing in land use. Unregulated town and country
development, invasion of natural waterway and the green area cause land
use changes. Rapid development, such as construction of building,trespasses the green area and decrease catchment area which result flood in
Utaphao river basin. Human interventions such as roads can also cause
floods because they obstruct the natural water way. (Kasetsart University,2002).
The lake major floods in Utaphao river basin such as in November
1988, November 1991 to January 1992 and November 2000, caused
enormous losses. In November 2000, the largest flood ever occurred andcaused severe damages to 11 Provinces including Had Yai. 2,200,000
people were affected by the flood and 8,300 people were evacuated. 59
people and 1,600,000 live stocks were killed and 269,230 ha of farmlands
were damaged. The total damage was estimated to be about one billion US
dollars. The estimated flood depth in Had Yai city is 2-3 meters as shown in
Figure 1.It is required to find flood control measures for Had Yai ( Prince
Songkhla University, 2002 ).

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ICUS Report 11

Figure 1: Areal photo of flooding in Had Yai City in November 2000

2. FLOOD MODELING IN UTAPHAO RIVER BASIN
2.1 Model setup
Flood modeling in Utaphao river basin is performed using MIKE11
model (DHI and AIT, 1996). The model setup consists of rainfall runoff
model and hydrodynamic model. The rainfall-runoff model NAM embedded
in MIKE-11generates lateral inflows from various sub-basins to the mainriver. Utaphao river basin can be divided into 13 sub-basins. The rainfall ineach sub-basin was calculated by using Thiessen Polygon method. For
hydrodynamic model there are 27 river cross-sections located along
Utaphao, the main river. All the surveyed cross sections were input into
MIKE 11 cross section data base. The upstream model boundary is thecomputed discharge by NAM model from rainfall at station X-172. The
downstream boundary is the observed water levels at X-194 in Songkhla
lake.
2.2 Model calibration
The model is calibrated and verified by recent data set in this study.
The Manning roughness number along Utaphao river is varied from 20 to 30
m1/3/s. The calibrated relative resistance range from 1 to 50. The storage
width ranges from 20 m to 4,000 m. The value of the calibrated resistancefactor is from 0.5 to 1. The calibration results of water levels X-44 areshown Figure 2. The simulated water levels from the model are comparedwith the observed water levels for station X-44. The simulated water levelfor station X-44 shows a good agreement with the observed water level

Flood Control Investigation of Had Yai City, Southern Thailand

473

October 2005, Singapore

especially at peak values. The time to peak and rising limb simulatedhydrograph at station X-44 agree with the observed value. However, thefalling limb recesses quite slow for station X-44. The calibration results ofdischarge at X-44 are shown Figure 2. The shape of simulated hydrographis quite the same as the shape of observed hydrograph. The rising limb andthe falling limb of the simulated hydrograph have good agreement with theobserved one. The peak value of simulated discharge at X-44 is quite
different but the time to peak is the same as the observed data. The
efficiency index of model is quite high (0.87 for water level and 0.93 fordischarge). The correlation coefficients of water level and discharge atstation X-44, are 0.94 and 0.97 respectively.

10

S imulated W L
O bserved W L
Water Level (m msl)

8

6

4

2

0
21/9/00 0:00

D ate
11/10/0 0
0:00

31/10/00
0:00

20/11/00
0:00

10/12/00
0:00

30/12/00
0:00

19/1/01 0:00

1000
Simulated Discharge

Observed Discharge

Discharge (m^3/s)

800

600

400

200
Date
0
20/9/43 0:00

10/10/43 0:00

30/10/43 0:00

19/11/43 0:00

9/12/43 0:00

29/12/43 0:00

18/1/44 0:00

Figure 2: Calibration results of water level and discharge at station X-44

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2.3 Model verification
The verification of the calibrated hydrodynamic model is done in theflood year of 1988 at station X-44. The period of verification is from
October to December. The results of simulated daily water levels anddischarges obtained from the model in this verification are shown in Figure
3. The simulated water levels obtained from the model verify that the model
gives a good result for flood peak values and timing to peaks, but thesimulated hydrograph does not well fitted to the observed hydrograph. The
simulated discharge hydrograph at X-44 has good agreement with theobserved hydrograph for the flood peak value, timing to peak as well as therising limb and the falling limb. The efficiency index of model is quite high(0.77 for water level and 0.83 for discharge). The correlation coefficients inwater level and discharge are between 0.95 and 0.92 respectively for X-44.
8

Simulated WL
Observed WL

Water level (m msl)

6

4

2

Date
0
14/9/88 0:00

4/10/88 0:00

24/10/88 0:00

13/11/88 0:00

3/12/88 0:00

23/12/88 0 :00

12/1/89 0:00

600

Simulated Discharge
Observed Discharge

Discharge (m^3/s)

500

400

300

200

100

0
14/9/1988 0:00

Date
4/10/1988 0:00 24/10/1988 0:00 13/11/1988 0:00 3/12/1988 0:00

23/12/1988 0:00 12/1/1989 0:00

Figure 3: Verification results of water level and discharge at station X-44

Flood Control Investigation of Had Yai City, Southern Thailand

475

October 2005, Singapore

3. PROPOSED FLOOD CONTROL MEASURESThe effects of proposed flood control measures are investigated byusing flood situation in November 2000. There are three schemes of
proposed flood control measures as shown in Table 1. The proposed flood
control measures are shown in Figure 4. The general channel crosses
sections of short cut and diversion channel is shown in Figure 5 and thedetails of them are shown in Table 2. The model setup and result of eachscheme can be described as following:
Table 1: Components of Structural Measures in Each Scheme.
Structural Measures
SchemeDiversion Channel
Shortcut Channel (C1)
(D1 and D3)
I
x
II
x
III
x
x

Songkhla Lake

Chainage
107,350
Diversion
ChannelShortcut
ChannelDiversion
ChannelHad Yai City
(X-44)

X-90

Flow
Direction

Chainage 0 000

Figure 4: Model configuration of Utaphao river for the
proposed flood control measures

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

D

1

1
Z

Z
B

Figure 5: General cross section of short cut and diversion channels
Table 2: The dimensions of cross sections of short cut and diversion channel
ChannelStation to Station

C1
*D1
*D1
*D3
*D3
*D3

0+000
0+000
14+460
0+000
3+600
6+700

A
(mP2P)
7+765
372
14+460372
21+343.718 216
3+600
220.5
6+700
184.5
8+200
130.5

n
0.025
0.025
0.018
0.025
0.025
0.025

Bed
Slope S
1:15,800
1:80001:4000
1:10,000
1:10,000
1:10,000

B
(m)
50
50
24
40
32
20

D
(m)
6
6
6
4.5
4.5
4.5

Side Slope
(Z)
2
2
2
2
2
2

(* Royal Irrigation Department, Thailand)
3.1 Flood control scheme I
This scheme consists of shortcut channel (C1) between station 90+890
and station 103+850 along Utaphao river. The length of shortcut channel is
7.765 km. The longitudinal slope of shortcut channel is about 1:15,800. The
Manning number of the channel has been assumed to be 40 m1/3/s and theside slope is 1:2. The results of this scheme are shown in Figure 6 for waterlevels at station X-44.
10

Simulated WL (Scheme I)
8

Simulated WL (No Scheme)

Water Level (m msl)

Observed WL (year 2000)
6

4

2

Date
0
21/9/2000
0:00

1/10/2000 11/10/2000 21/10/2000 31/10/2000 10/11/2000 20/11/2000 30/11/2000 10/12/2000 20/12/2000 30/12/2000
0:00
0:00
0:00
0:00
0:00
0:00
0:00
0:00
0:00
0:00

9/1/2001
0:00

Figure 6: Comparison of simulated and water level at station X-44 ,flood control scheme I
Flood Control Investigation of Had Yai City, Southern Thailand

477

October 2005, Singapore

The shortcut channel does not have much effect to station X-90
(upstream from station X-44) in term of flood volume and duration of flood
because it is far from the shortcut channel. The simulated water level at X44 is 7.38 m msl and the water level change of station X-44 is about
decreasing –0.79 m compared to without any flood control measures. The
shortcut channel has effect on water level at X-44. The simulated maximum
water level is just at the bank level, so there is no flooding at this station.
3.2 Flood control scheme II
The purpose of this scheme is to study the effect of diversion channels,
proposed by Royal Irrigation Department. The model consists of two
diversion channel namely: D1 and D3 as shown in Figure 4. Alignment ofdiversion channel, D1, is on the west of Had Yai city and reach from
Utaphao river upstream the gauging station X-44 to Songkhla lake. The
length of the channel is 21.343 km. Another diversion channel, D3, is on theeast and extends from Utaphao river downstream Had Yai city to Songkhla
lake. The length of D3 is 8.2 km. The result of this scheme is shown in
Figure 7 for water level at station X-44.

10
Simulated WL (Scheme II)
8

Simulated WL (No Scheme)

Water Level (m msl)

Observed WL (year 2000)
6

4

2

0

Date

21/9/2000 1/10/2000 11/10/200 21/10/200 31/10/200 10/11/200 20/11/200 30/11/200 10/12/200 20/12/200 30/12/200 9/1/2001
0:00
0:00
0 0:000 0:000 0:000 0:000 0:000 0:000 0:000 0:000 0:00
0:00

Figure 7: Comparison of simulated and water levels at station X-44,
flood control scheme II
The simulated water level X-44 is 5.6 m msl. Water level change of
X-44 is decreased by -2.57 m, which is lower than the bank level, comparedto the case without flood control measures. The purpose of diversion
channel is for flood protection to Had Yai city so there is large effect on thewater level at station X-44.

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3.3 Flood control scheme III
Scheme I and scheme II are combined that consists of shortcut
channel (C1) and diversion channels (D1 and D3) as shown in Figure 4. The
detail of each channel is the same as described earlier. The result of thisscheme is shown in Figure 8 for the water levels at station X-44. The
simulated maximum water level at X-44 is 5.04 m msl. The water level atstation X-44 is decreased by 3.13 m, which is lower than the bank level,compared to without flood control measures.

10
Simulated WL (Scheme III)
Simulated WL (No Scheme)

Water Level (m msl)

8

Observed WL (year 2000)

6

4

2

0

Date

21/09/200 1/10/2000 11/10/200 21/10/200 31/10/200 10/11/200 20/11/200 30/11/200 10/12/200 20/12/200 30/12/200 9/01/2001
0 0:000:00
0 0:000 0:000 0:000 0:000 0:000 0:000 0:000 0:000 0:00
0:00

Figure 8: Comparison of simulated and water levels at station X-44,
flood control scheme III
4. RESULTS AND DISCUSSIONS
It can be seen that each scheme can reduce flood damages. For
scheme I, the shortcut channel, has larger effect on water level at X-44 (HadYai city). The shortcut channel can reduce the maximum water level at X-44
by –0.79 m compared to without flood control measures. The shortcut
channel results in better drainage water from Utaphao river to Songkhla lake.
Utaphao river can drain water to Songkhla lake faster than without flood
control measures. In this scheme, the shortcut channel, C1, alone can get ridof flooding at Had Yai city (X-44). For Scheme II, the maximum water levelat X-44 is reduced by –2.57 m compared to without flood control measures.
The reason of the reduction of water depth at X-44 is D1 works as aninterceptor of local inflow or side flow from sub-basins and drain thesideflow or local inflow to Songkhla lake directly. Another reason is thatsome of the runoff from upstream is diverted from Utaphao river so the
maximum water level at Had Yai city (X-44) is reduced and causes no floodin the city. For the diversion channel, D3, it is located downstream of Had
Yai city. The effect of D3 is less than D1 and it can help in decreasing flood

Flood Control Investigation of Had Yai City, Southern Thailand479

October 2005, Singapore

discharge and reduction of flood period in Had Yai city (X-44). Scheme III,is a combination of the diversion channels (D1 and D3) and the shortcut
channel, C1.For scheme III, the maximum water level at X-44 is reduced by
3.13 m compared to without flood control measures. The reason of the
reduction of water level at X-44 is the same as in scheme II but there is anadditional support from the shortcut channel to quickly drain water toSongkhla lake.
5. CONCLUSIONS AND RECOMMENDATION
Three schemes of flood control measures for Utaphao river basin areproposed for Had Yai city. Scheme I consists of a shortcut channel (C1).
Scheme II consists of two diversion channels namely D1 and D3. Scheme
III is the combination of Scheme I and Scheme II. It consists of the shortcut
channel (C1) and two diversion channels, D1 and D3. The flood control
measures can reduce flood water level at Had Yai city at station X-44 by –0.786 m, -2.566 m and –3.126 m respectively. There is very little effect bythese structural measures on water levels for station X-90 located upstreamof Had Yai city.
The shortcut channel will not pass through the residential areas, its
cross section is nearly the same as the diversion channels but its distance isshorter. The construction cost of the shortcut will be likely less than thediversion channels. The shortcut alone would be sufficient to protect floodat Had Yai at a lower cost. Therefore the shortcut should be recommended
for the flood control scheme of Had Yai.The study on effects of the flood
control schemes in terms of environmental and socio-economic in Utaphaoriver basin should be done to evaluate the feasibility of the project.
REFERENCES
DHI and AIT, 1996. Flood Modeling Programme in Thailand: Floodmodeling in Utaphao River Basin: Summary report. Asian Institute ofTechnology, Bangkok, Thailand.
Kasetsart University, 2002. Study and Analysis for Development of Master
Plan for Flood Management and Environmental Impact, Utaphao
River Basin, Songkhla Province. Kasetsart University, Bangkok,
Thailand. (in Thai)NESDB (Office of National Economic and Social Development Board),
2001. Flood Protection Plan for Utaphao River Basin, Hat Yai
District, Songkhla Province. Office of National Economic and Social
Development Board, Songkhla, Thailand. (in Thai)
Prince of Songkhla University, 2002. Seminar Report for Prevention andSolving Flooding Problems in Hat Yai city. Researech andDevelopment Office, Prince of Songkhla University, Songkhla,
Thailand. (in Thai)

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New Technologies for Urban Safety of Mega Cities in Asia

DEVELOPMENT OF POSSIBLE TSUNAMIEXPOSURE ESTIMATION MODULEFOR TSUNAMI DISASTER RESPONSE
Masasuke TAKASHIMA, JSPS research fellow
Institute of Industrial Science, The University of Tokyo, JAPANtakashim@iis.u-tokyo.ac.jp
Shunichi KOSHIMURA, Associate Professor
Disaster Control Research Center, School of Engineering, Tohoku Univ.
koshimura@tsunami2.civil.tohoku.ac.jp

Kimiro MEGURO, Professor
Institute of Industrial Science, The University of Tokyo, JAPANmeguro@iis.u-tokyo.ac.jp

ABSTRACTIn Indian Ocean Tsunami Disaster, Dec. 26, 2004, it was more than one
month after the event occurred that the overview of the damage situation in
the affected countries was revealed. It is indispensable, especially in thelarge scale disaster, to know the big picture of damage situation such as
possible affected area, affected population in early stage for effective deployment of limited resources under the international coordination among
various donor countries and NPOs.
To address above-mentioned needs, our research group is developing an
information system to support tsunami warning, disaster response and relief. When a tsunami occurred anywhere in the world, this WebGIS-based
system estimates and publishes various kinds of possible damage situation
information such as, tsunami arrival time, maximum tsunami height, severely affected area, affected population (Possible Tsunami Exposure; PTE)
due to the tsunami in the early stage.
In this paper, we report the development of PTE estimation module in thesystem. In this module, PTE is estimated in 30’’ by 30’’ grid from maximum tsunami height based on numerical simulation, population data andelevation data along the coast line. Landscan provided from Oak Ridge National Laboratory and STRM30 provided from NASA are basically used as
global population and topological data. Using the module, we estimatedPTE of Indian Ocean Tsunami Disaster, Dec. 26, 2004 and that of anothertsunami which hit northern Sumatora in Mar. 28, 2005. The relationshipbetween PTE and actual damage in each affected countries was examined.
As a result, it was confirmed that the estimated PTE is consistent with reported damage and that the module could assess the PTE due to the eventwith enough accuracy to get the big picture of the event.

481

October 2005, Singapore

1. INTRODUCTION
In case of large scale disaster, it tends to require lots of time and resources to grasp total damage situation. In Indian Ocean Tsunami Disaster,Dec. 26, 2004, huge tsunami swept Indian Ocean rim countries such as Indonesia, Sri Lanka, India and Thailand as shown in Figure 1. 169,752 deadand 127,294 missing were reported as of Feb. 22, 2004. It took more than
one month after the event occurred that the overview of the damage situation in the affected countries was revealed.
Delay of grasping damage situation leads delay and inefficiency of response and relief activities by affected countries, donor countries andNPOs. So, it is required to identify severely damaged areas in very earlystage and then concentrate limited resources on those areas for getting detailed damage situation efficiently. In such first stage screening, grasping
big picture of total damage is important rather than pursuing precise number. Especially, it tends to require more time for most of developing countries to grasp damage situation because of lack of disaster information andcommunication system and because of high vulnerability against natural
disasters which cause larger damage with same extreme natural force compared with developed countries.
PTE estimation module we introduce in this paper is developed forscreening severely damaged area. This module is applicable to tsunami disaster which occurred anywhere in the world with recent development of tsunami simulation technology and global demographic and topographic database. All of these global database used in the module are available in publicdomain. This global applicability is an advantage of the module in applying
it to the tsunami disaster which occurred in developing countries. In case oftsunami, the module receives maximum tsunami height simulated by tsunami researchers and calculates PTE in reasonable time. As a result, possible total affected population, affected population by countries and by regions and possible severely affected area can be published via Web-GIS.
Such information will help stakeholder countries and organizations torecognize the significance of the event and to know which country or area
should be prioritized in relief activity. Sharing common view against thesituation among the stakeholders will lead efficient coordination.
In this paper, the PTE estimation process and data required in the process
are described in chapter 2. Then, application of the module to Indian Ocean
Tsunami Disaster, Dec. 26, 2004 and another tsunami which hit northern
Sumatora in Mar. 28, 2005 is introduced and it is shown that the estimated
PTE is consistent with reported damage and that the module could assess
the PTE due to the event with enough accuracy to get the big picture of theevent in chapter 3. Chapter 4 is concluding remarks.

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New Technologies for Urban Safety of Mega Cities in Asia

Development of Possible Tsunami Exposure Estimation Module for Tsunami Disaster Response

Figure 1：Possible maximum tsunami height of Indian Ocean tsunami ,Dec. 23, 2004 simulated by S. Koshimura, Tohoku Univ. (2’grid)and Population distribution of Indian Ocean rim countries based on Landscan2003, Oak Ridge National Laboratory (30’’grid)(LandScan Global Population Database. Oak Ridge, TN: Oak Ridge National Laboratory. Available at http://www.ornl.gov/gist/.)0160,345

Population0

Possible maximum
tsunami height[m]18.40

ICUS Report 11483

October 2005, Singapore

2. PTE ESTIMATION MODULE
In this module, PTE is estimated in the process shown in Figure 2.
The module was developed on ArcGIS. Input data are maximum tsunami
height (MTH), population distribution and DEM. Output is PTE by MTH
and by region or country.
2.1 Data required in the module
2.1.1 Maximum tsunami height (MTH)
Any data provided in ArcGIS grid or ASCII format can be used. Basically, MTH must be provided by numerical simulation from tsunami researchers. In our research group, MTH can be calculated on the basis ofglobal bathymetry data provided in 2’ grid by National Geophysical Data
Center wherever tsunami occurs in the world.
2.1.2 Population
Any data provided in ArcGIS grid or ASCII format can be used.
Landscan provided from Oak Ridge National Laboratory is used as global
population data with default setting (Figure 1). It is provided in 30” grid.
Landscan data is not census based data. Reported total population within apolitical boundary is allocated in each grid considering land use, proximity
to the major road, slope, and night-time city light. So, Landscan should be
used to know gross configuration of population. If census based statistics insimilar spatial resolution is available in the target region, it will lead more
precise result.
2.1.3 DEM
Any data provided in ArcGIS grid or ASCII format can be used.
STRM30 provided from NASA is used as global topological data with default setting. It is provided in 30” grid.
2.2 PTE estimation process
At first stage, coastal population grid and coastal MTH grid is extracted. Then, coastal population grid at elevation less than 30m is extracted
by using DEM grid to avoid overestimate of coastal population which a tsunami can affect. Then, coastal population grid at elevation less than 30m is
assigned to nearest coastal MTH grid. Finally, coastal population exposed toa certain MTH in a certain region is calculated.
In this process, whole population in 30” grid along shoreline is included in PTE without considering local topography. 30” is approximately
900m in low latitude area. So, this module may overestimate PTE in casethat coastal area is mountainous or may underestimate PTE in case that
there is large flat plane next to shoreline. How far a tsunami come to inland
depends on local coastal topography. The process to evaluate coastal population which a tsunami can affect should be reviewed for further study.

484

New Technologies for Urban Safety of Mega Cities in Asia

Coastal
Population(Population on
the grid along
shoreline)

Distribution ofPopulation(Landscan2003,
30’’ grid)

Development of Possible Tsunami Exposure Estimation Module for Tsunami Disaster Response

Population in Lowland(Coastal Population at televation
less than 30m)

Figure 2: Potential tsunami exposure (PTE) estimation process flow

DEM
(SRTM, 30’’ grid)

Coastal MTH(MTH on the gridalong shoreline)

Distribution of
Maximum
Tsunami Height(Simulated, 2’ grid)

Potential
TsunamiExposure (PTE)

ICUS Report 11485

October 2005, Singapore

3. ESTIMATION OF PTE IN ACTUAL TSUNAMI DISASTERS
3.1 PTE of Indian Ocean tsunami disaster, Dec. 26, 2004
PTE of Indian Ocean Tsunami Disaster (M9.0), Dec. 26, 2004 was estimated with PTE estimation module introduced in previous chapter. The
result is shown in Table 1. Indonesia had largest coastal population in lowlands. It can be seen that Indonesia had larger PTE for MTH larger than 5m
compared with other countries. On the other hand, India and Sri Lanka hadlarger PTE for MTH which ranges from 2m to 5m. As a whole, Indonesia
had largest PTE among the affected 11 countries and India, Sri Lanka andThailand followed. Compared with other countries, PTE of these four countries were apparently dominant.
Reported number of dead and missing as of Feb. 22, 2005 (CNN) is
shown at the bottom of Table 1. Indonesia had largest number of dead andmissing (236,169) and Sri Lanka (35,672) , India (16,416) and Thailand(8,388) followed at that time. These numbers corresponded to 13.3%, 3%,
0.4% and 6.4% of PTE for MTH larger than 1m in each country, respectively. This result shows the vulnerability of Indonesia against tsunami ishigher than other three countries.
It can be said that countries which had larger PTE tend to have larger
number of dead and missing. And also, it can be seen that dead and missing
in a country got larger sharply when the country had PTE for MTH larger
than 7m. Dead and missing was very limited when there is no PTE for MTH
larger than 7m.
3.2 PTE of tsunami disaster in Mar. 28, 2004
In Mar. 28, 2004, another large earthquake (M8.7) and tsunami occurred along the Sunda trench and hit northern Sumatora. Although themagnitude was considerably large and the source area was adjacent to thatof the previous event, the damage was very limited. Indonesia had several
hundred dead and missing. No damage was reported in other countries
which were affected in the previous event.
We also applied the module to estimate the PTE of the event. As a result, it was clarified that only Indonesia had moderate PTE compared withthe previous event. No country had PTE for MTH larger than 7m. It was
confirmed the module could assess the PTE due to the event with enoughaccuracy to get the big picture of the event and within reasonable calculation time.
As a result of above-mentioned application, it can be said that PTE
estimated by the module is reflecting actual damage situation as a whole.
This result supports that PTE estimation module we developed can be used
to get a big picture of tsunami disaster.

486

New Technologies for Urban Safety of Mega Cities in Asia

MaximumTsunaim
Height[m] Indonesia India
ThailandSri Lanka Myanmar Malaysia
Bangladesh Maldives
Somalia
Kenya
Tanzania Seychelles Australia Total
0 8,178,490 6,923,301
898,902 1,188,898 1,305,493 1,347,390 2,370,781
328,164
420,947
552,882 1,092,660
19,17375,347 24,702,428
1 1,775,482 4,403,036
130,425 1,188,898
950,480
369,769 1,451,794
328,164
387,148
520,322 1,025,921
17,299245 12,548,983
2
446,557 1,947,329
130,421 1,070,477
252,752
307,918
403,176
268,382245,536
224,134
330,9408,947
05,636,569
3
156,750
953,828
108,485
586,008
65,30319,080133,810
139,998
1,412
360
2,893
0
0
2,167,927
4
93,604
149,938
41,285
159,962
5,343
0
2,743
0
6
0
0
0
0
452,8815
67,13945,711
18,954
79,274
1,780
0
1,790
0
0
0
0
0
0
214,648
6
56,793
19,786
9,780
35,612
23
0
98
0
0
0
0
0
0
122,092
7
49,2798,266
8,366
17,854
0
0
0
0
0
0
0
0
0
83,765
8
39,563
6,626
4,168
2,022
0
0
0
0
0
0
0
0
0
52,379932,203
4,048
4,039
1,345
0
0
0
0
0
0
0
0
0
41,635
10
18,596
2,826
2,430
493
0
0
0
0
0
0
0
0
0
24,345
11
10,821
1,878
15
346
0
0
0
0
0
0
0
0
0
13,06012
10,200
444
13
0
0
0
0
0
0
0
0
0
0
10,657
13
7,024
100
0
0
0
0
0
0
0
0
0
0
0
7,124
14
6,878
100
0
0
0
0
0
0
0
0
0
0
0
6,978
15
319
100
0
0
0
0
0
0
0
0
0
0
0
419
16
173
100
0
0
0
0
0
0
0
0
0
0
0
273
17
0
100
0
0
0
0
0
0
0
0
0
0
0
100
18
0
92
0
0
0
0
0
0
0
0
0
0
0
92
19
0
92
0
0
0
0
0
0
0
0
0
0
0
92
death
122,232
10,776
5,395
30,974
59
68
2
82
150
1
10
3
0
169,752
missing
113,937
5,640
2,993
4,698
0
0
0
26
0
0
0
0
0
127,294death+missing
236,169
16,416
8,388
35,672
59
68
2
108
150
1
10
3
0
297,046

Table 1：Cumulative possible tsunami exposure due to Indian ocean tsunami disaster Dec. 26, 2004, by maximum tsunami heightfor Indian Ocean rim countries

ICUS Report 11

Development of Possible Tsunami Exposure Estimation Module for Tsunami Disaster Response487

October 2005, Singapore

4. CONCLUSION
In this study, we developed PTE estimation module which is applicable globally. Then, we applied the module to Indian Ocean Tsunami Disaster, Dec. 26, 2004 and another tsunami which hit northern Sumatora in Mar.
28, 2005 to calculate the PTE of both events. As a result of examination ofrelationship between estimated PTE and actual damage, it is shown that theestimated PTE is consistent with reported damage and that the module
could assess the PTE due to the event with enough accuracy to get the big
picture of the event.
The module we introduced in this paper can be used not only inemergency response but also in risk analysis for possible tsunami disasters
in future by preparing simulated MTH of future tsunami scenario as input
data. To prepare for future tsunami disaster, risk evaluation against possible
scenario is indispensable. But, the target area get larger, it is almost impossible to conduct detailed risk assessment for all target area. Since our module can provide gross configuration of risk due to future scenario, we canconcentrate our resources on the high risk area for detailed assessment.
As mentioned in chapter 2, in the PTE estimation process, whole
population in 30” grid along shoreline is included in PTE without considering local topography. How far a tsunami come to inland depends on local
coastal topography. The process to evaluate coastal population which a tsunami can affect should be reviewed for further study.

REFERENCES
Dobson, J. E., E. A. Bright, P. R. Coleman, R.C. Durfee, B. A. Worley.
2000. "LandScan: A Global Population Database for Estimating
Populations at Risk," Photogrammetric Engineering & Remote Sensing Vol. 66, No. 7, July 2000, pp. 849-857.
NASA(2000) : SRTM (Shuttle Radar Topography Mission) ,http://www2.
jpl.nasa.gov/srtm/
National Geophysical Data Center (2005) : 2-Minute Gridded Global Relief
Data,http://www.ngdc.noaa.gov/mgg/fliers/01mgg04.html

488

New Technologies for Urban Safety of Mega Cities in Asia

CREATING AN INTEGRATED WATERGEODATABASE FOR ENVIRONMENTALRISK MANAGEMENTAKIYUKI KAWASAKI, YUICHI SATO and SATORU SADOHARA
Graduate School of Environment and Information Sciences,
Yokohama National University, JAPANakiyuki@arc.ynu.ac.jp

ABSTRACT
Considering urban environmental problems requires investigatingwater resource availability and supply, especially in relation to humanactivity. An integrated water geodatabase for environmental risk
management was created in this study to visually and interactively
understand water supply and circulation. The geodatabase covers fromupstream ecosystems in mountain and forest regions, to middle anddownstream areas primarily marked by human activity such as agriculturalareas, and urban areas with artificial water supply systems (pipes, drainage
canals, etc.). Underground water was not considered at this moment.
Integrated water database have not been well understood in Japandue to vertically divided water authorities and lack of suitable tools for
integration. ESRI ArcGIS and ArcHydro technologies were utilized to build
the geodatabase by digitizing paper maps of waterworks, sewage systems(storm and sanitary), and irrigation canals (industrial and agricultural) ofindividual municipal administrations. Attribute data was then included likeflow direction, water quantity and some quality data, junction types, as wellas natural surface water flow in each watershed calculated with a Digital
Elevation Model.
The geodatabase was built for both the main water network in
Kanagawa Prefecture (macro level) and for the local water network in
Isehara City (micro level), and the connectivity between the macro andmicro levels was databased.
By using this geodatabase, the impact of human activity on water
quality and quantity can be clarified by investigating the change of water
quality and quantity flowing through areas with a specific land use(residential, agricultural, industrial, etc.) in urban areas. As a conclusion,
environmental risk management in urban area using the geodatabase andfuture works are described.

1. INTRODUCTION
Since the last half of the 20th century, species extinction anddestruction of ecosystems have increased rapidly due to a swift increase in489

October 2005, Singapore

population, and use of toxic chemicals, etc. Especially, preservation ofbio/eco-systems in Asia is critically important.
Yokohama National University has started “Environmental Risk
Management for Bio/Eco-systems” as a 21st Center of Excellence programby MEXT (the Japanese Ministry of Education, Culture, Sports, Science,
and Technology) since 2002. Our program has the following goals:- Collect and analyze the environmental risk of terrestrial and aquatic
bio/eco-systems in East Asia by investigating relationships between
ecosystems and human activity (like using toxic chemicals).
- Establish bio/eco environmental risk assessment methods and develop
concepts and ideas for risk management.
- Build networks among related domestic/international organizations, andprepare easy data-retrieve system not only for researchers, but also forgovernment and the general public.
In order to consider “Management”, not an individual (traditional)
research approach but a multidisciplinary integrated approach is necessary
to understand the mechanism of complicated bio/eco-systems. In this study,
an integrated water geodatabase was built for both the main water network
in Kanagawa Prefecture as a proto-type of macro level, and for the local
water network in Isehara City as a micro level, since Kanagawa Prefecture,including Isehara City is a common research field in our COE program.
Integrated exhaustive water geodatabase is an important infrastructure
for environmental managements, but it does not exist in Japan due tovertically divided water authorities and lack of suitable tools for integration.
Water is the key of integration of multidisciplinary research, because
it moves chemicals from upstream where ecosystems in mountain and forest
regions, through middle and downstream areas primarily marked by humanactivity such as agricultural areas, and urban areas with artificial watersupply systems (pipes, drainage canals, etc.), to the ocean. Through the

Figure 1: Framework of our COE program: “Environmental Risk
Management for Bio/Eco-Systems”

490

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

water flow, many researchers could join it. Their research interest and data
could be combined with water flow.
Additionally, by building water database, not only the effect fromhuman activity to natural ecosystems, but also the effect from ecosystem tohuman activity could be under stood through the water, because water flow
circulate inside the basin.

2. Integrated Water Geodatabase.
2.1

Water map resources

Integrated water geodatabase for environmental risk management.
have not been well understood in Japan due to vertically divided waterauthorities and lack of suitable tools for integration. ESRI ArcGIS and
ArcHydro technologies were utilized to build the model by digitizing paper
maps of waterworks, sewage systems (storm and sanitary), and irrigation
canals (industrial and agricultural) of individual municipal administrations.
Attribute data was then included like flow direction, water quantity andsome quality data, junction types, as well as natural surface water flow ineach watershed calculated with a Digital Elevation Model. Undergroundwater is not considered at this moment. The list of water map and data
resources for our geodatabase is shown table 1 and table 2.
2.2 Kanagawa Prefecture macro-level
In order to understand the whole water system in Kanagawa
Prefecture, the water comes from out side Kanagawa Prefecture has to beconsidered. As shown at Figure 2, more than 1/4 surface of Mt. Fuji is
included in Sagami-river basin and Sakawa-river basin, where are the main
Table 1: Data resources (Kanagawa Prefecture macro map)
N am eA rea

S cale P ublish D ate

D ata R esource

K anagaw a P refecture 1:100000

2001/04

D ept.of plannning,K anagaw a P ref.

W ater m anagem ent block m ap K anagaw a P refecture 1:100000

2002/04

D ept.of environm ent and agriculture,K anagaw a P ref.

W ater quality gaging m ap

K anagaw a P refecture 1:100000

2002/04

D ept.of environm ent and agriculture,K anagaw a P ref.

R iver,harbor,coastalm ap

K anagaw a P refecture 1:100000

2003/03

K anagaw a P refecture.

S agam i-river preserve m ap

Sagam i-river basin

1:50000

2005/04

O ffice of preservation,K anagaw a P ref.

S agam i-river facilities m ap

Sagam i-river basin 1:100000

W ater utility m ap

2001/04

O ffice of preservation,K anagaw a P ref.

S akaw a-river basin sew er m ap Sakaw a-river basin

1:25000

2003/02

O ffice of sew er preservation,K anagaw a P ref.

S akaw a-river M iho dam m ap

1:50000

1996/03

B usiness m anagem ent agency,K anagaw a P ref.

Sakaw a-river basin

Table 2: Data resources (Isehara City and Yokohama City micro map)
N am eU rban planning m ap

A rea
Isehara C ity

S cale P ublish D ate
1:15000

2004/03

D ata R esource
D ept.of urban planning,Isehara C ity

R iver basin m ap

Isehara C ity

1:15000

2002/11Isehara C ity

P ublic sew er planning m ap (S anitary)

Isehara C ity

1:15000

2003/03D ept.of sew er,Isehara C ity

1:15000

2003/03

P ublic sew er planning m ap (S torm )Isehara C ity

A griculturalirrigation and spring m ap

Isehara C ity (1:10000) 2005/06

D ept.of agriculture,Isehara C ity

D ept.of sew er,Isehara C ity

W ater w orks m ap

Yokoham a C ity 1:30000

2004/04

D ept.of sew er,Yokoham a C ity

R iver m ap

Yokoham a C ity 1:30000

2004/12

D ivision of river,D ept.of sew er,Yokoham a C ity

R iver planning m ap

Yokoham a C ity 1:30000

2004/10

D ivision of river,D ept.of sew er,Yokoham a C ity

P ublic sew er planning m ap

Yokoham a C ity 1:30000

2005/03

B ureau of environm ent creation,Yokoham a C ity

Creating an Integrated Water Geodatabase for Environmental Risk Management491

October 2005, Singapore

drinking water resources for Kanagawa-Prefecture (2,415km2, 8.5 million
populations).
Figure 3 shows waterworks map from Kanagawa prefecture, sewage
systems map (storm and sanitary) from Kanagawa sewage foundation,
Kanagawa Prefecture, are digitized to create integrated water utility network
database in Kanagawa Prefecture. Artificial water supply systems (pipes,
drainage canals, etc.) are maintained in whole Kanagawa Prefecture in order
to distribute drinking water from Mt. Fuji and Sakawa-river basin and
Sagami-river basin to almost the entire citizen in Kanagawa Prefecture.
Mainly center and east part of Kanagawa Prefecture has highly urbanizedlanduse. Especially, City of Yokohama, Japan’s 2nd largest city (3.5 million
populations) is 100% rely on the water carried thought artificial pipes from
Sakawa-river and Sagami-river.

Figure 2: More than 1/4 surface of Mt. Fuji is included in
Sagami-river basin and Sakawa-river basin

Figure 3: Main artificial water supply systems (pipes, drainage canals, etc.)
in Kanagawa Prefecture492

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Setting a flag

Upstream tracing

Downstream tracing

Figure 4: An example of network tracing from a point to upstream or
downstream though Kanagawa waterworks database.
In this geodatabase, attribute data was then included like flow
direction, water quantity and some quality data, junction types, as well as
natural surface water flow in each watershed calculated with a Digital
Elevation Model. Thus, the attribute on the network could be traced
interactively. Figure 4 shows an example of networking tracing from a point
to upstream or downstream though Kanagawa waterworks database.
Therefore, this database could be utilized for the specifying the point
sources of pollution and the effected area of a point on the network.
Additionally, each connection point on the network, called “node” such as
pumping, water purification plant, can be behave as a bulb, so many kind of
simulation (e.g. Find common ancestors, Find connected, Find loops, Find
disconnected, Find path upstream, Find path, Trace downstream, Find
upstream accumulation, Trace upstream) could be used.
2.2 Isehara City micro-level
Isehara City is most suitable to understand local water circulation andwatershed environment in Kanagawa Prefecture, since almost all of city area
is included in one large watershed from Mt. Oyama (1,251m), and has thediversity of landuse in small city area (55km2) as Figure 5 shows. Sewage
systems map (storm and sanitary) from Isehara Sewer Foundation,
agricultural irrigation canals, spring waters and weirs map from Dept. ofAgriculture, Isehara City, and the results our field work, are digitized tocreate integrated water utility network database in whole city area(Figure 6).
Detailed (mainly 1:2500 based) waterworks, sewer (sewage andstorm), irrigation water (agriculture and industrial), spring water, drainage
area, are in a geodatabase. This geodatabase can be considered as anintegrated whole rather than as a set of separate data layers using ArcHydro

Creating an Integrated Water Geodatabase for Environmental Risk Management493

October 2005, Singapore

technologies. It allows us to support behavioral modeling because the
ArcHydro concept all features in the database are uniquely labeled hydrofeatures. It is a powerful idea to think about water flow.
The creation of an integrated database, instead of a collection of data
layers, is a key accomplishment of this geodatabase design, providing astronger foundation for building water resources application in GIS has
previously exited.
How water resources agencies subdivide a given landscape intodrainage units (watershed) may vary significantly from one agency to

Figure 5: Artificial water supply systems and natural surface

Figure 6: Extraction of agricultural Irrigationfrom 1:2500 terrain maps

494

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Figure 7: A consideration of the area of drainage units (watershed) using
25m DEM and drainage area map by Dept. of Sewer, Isehara City.
another or even within the same agency when different kinds of analyses areundertaken. All of these watershed delineations serve legitimate but
different purposes. There are an infinite number of ways to subdivide thelandscape into watersheds, and no unique way serves all purposes.
Therefore, we are considering the area of drainage units (watershed)using 25m DEM and drainage area map by Dept. of Sewer, Isehara City.
We have to establish the size and methodologies the drainage units(watershed) using GIS for the “Environmental risk management for bio/ecosystems”.

3. Future Works
3.1 Integration with COE geodatabase collected by many scientists
As a future work, we will integrate this water database into COE
integrated geodatabase. 18 faculties and 14 post doctoral fellows from many
research fields such as natural sciences, social sciences, agriculture andengineering, are joined our COE program. Many of them convert their fieldsurvey data and research results into integrated geodatabase (Kawasaki et al.,2005). PRTR [Pollutant Release and Transfer Register] factories andcompanies, dioxin risk assessment for water creatures, fagaceae [buna-rin]
forest, soil from various depths, and so forth are databased in a common
GIS format by our COE researchers for data sharing and further overlay
analysis.
By this integration, water network database is used to connect the
research results by COE researchers from upstream ecosystems in mountainand forest regions, to middle and downstream areas primarily marked byhuman activity such as agricultural areas, and urban areas. It will exceed
the difference of not only spatial field but also their specialized research
field. This will become a starting point of multidisciplinary environmental

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Figure 9: These points show PRTR- registered factories and companies,
dioxin risk assessment for water creatures, fagaceae [buna-rin] forest, soil
from various depths, and so forth are databased by our COE researchers.
research for the “Environmental Risk Management for Bio/Eco-systems”
using GIS and water as a common tool.
3.2 Stakeholder map
As table 1 and table2 show, many organizations and authorities have arelationship for water resource management. Due to vertically divided waterauthorities, not only data and information related to water resource
management, but also human connectivity are distributed. We often went
many authorities to collect data and information related to water, thought

Figure 10: An image of schematic database“Stake holder map forwater resource management in Kanagawa Prefecture”

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the introduction, we have to go from personnel at an authority to anotherpersonnel at another authority all around large Kanagawa Prefecture.
Through our experience, we would like to create a “Stake holder map forwater resource management in Kanagawa Prefecture” as not spatial-drawn(traditional) map but schematic map (Figure 10). GIS and relational
database management technologies are utilized to create this schematic map.
Almost all of the data and information, and human connectivity related
water resources management between authorities including personnel at
authorities, researchers, NPO, etc., could be relationally databased using
spatial information as a “key”. Building the stakeholder map in Kanagawa
Prefecture is still underway.

4. Conclusions
An integrated water geodatabase for environmental risk management
was created in this study to visually and interactively understand watersupply and circulation. The geodatabase covers from upstream ecosystems
in mountain and forest regions, to middle and downstream areas primarily
marked by human activity such as agricultural areas, and urban areas withartificial water supply systems, though underground water was notconsidered at this moment. The geodatabase was built for both the main
water network in Kanagawa Prefecture (macro level) and for the local water
network in Isehara City (micro level).
This database using ArcHydro technologies provides an elegant
tracing capability – the ability to trace upstream or downstream acrossdrainage areas, so we can determine the region of hydrologic influence ofany location on the landscape. Also, we can determine watershed properties,
such as average precipitation or runoff, and accumulate them going down
stream so that we can estimate the flow in streams and rivers. At the use ofthis database using ArcHydro technologies continues to grow, furtherhydrologic analysis and modeling capabilities will become available.

ACKNOWLEDGEMENT
Special thanks to SADOHARA & YOSHIDA laboratory’s Waterteam members for their dedicated work to this study: Ms. ASANO Mayuko,
Mr. FANG Ji, Mr. INOUE Yusuke, Mr. IZUMI Masahiko, Mr. SUZUKI
Wataru, Mr. TERAHATA Yuki, Mr. YOSHIDA Kohei, Mr. YOSHIDA
Sho, Ms. WANG Dongzhi, and Mr. YAERMAIMATI Tawaikuli.
This work is contribution to the 21st Century Center of Excellence
Program: “Environmental Risk Management for Bio/Eco-systems” (Leader:Prof. URANO Kohei, YNU) by MEXT (the Ministry of Education, Culture,
Sports, Science, and Technology).

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REFERENCES
Arctur, D., and Zeiler, M., 2004. Designing Geodatabases –Case Studies in
GIS Data Modeling. ESRI Press, California, USA.
Kawasaki, A., Suzuki, W., Park Y. J., Sadohara, S., and Urano, K., 2005,
Development of a Spatial Data Sharing System supporting
Multidisciplinary Environmental Research at a University - Forminga World-class Center of Excellence for “Environmental Risk
Management for Bio/Eco-systems” No. 1 -, Theory and Applicationsof GIS, Vol.13, No.1, pp.83-89 (Japanese).
Maidment, R. D., 2002. ArcHydro: GIS for Water Resources. ESRI Press,
California, USA.
Yokohama National University, 2005. 21st century COE program“Environmental Risk Management for Bio/Eco-systems” web site.
http://www.bio-eco.eis.ynu.ac.jp/
Zeiler, M., 2002. Modeling Our World –The ESRI Guide to Geodatabase
design . ESRI Press, California, USA.

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ENVIRONMENTAL ASSESSMENT OF
URBAN UNDERGROUNDINFRASTRUCTURENIKOLAI BOBYLEV
United Nations University, Tokyo, Japan
bobylev@hq.unu.edu

ABSTRACTThe paper will discuss application of two forms of environmental
assessment for urban underground infrastructure appraisal: environmental
impact assessment and strategic environmental assessment. Environmental
decision-making and multi-criteria analysis methods will be studied. Some
data and analysis on city of Tokyo urban underground infrastructure stateof-the-art, sustainability, and vulnerability will be given.

1. INTRODUCTION
According to the United Nations Population Division, in July 2005, theworld gained 6.5 billion inhabitants; almost half of them are living in urban
areas. As 95 percent of population growth occurs in developing world, 10
new megacities will appear in developing counties by 2010. Asian
megacities have the highest population density: up to almost 400 people perhectare in Mumbai, India. These facts indicate places where urban problems
are concentrated, and where major challenges for researches and developers
exist. Development of sustainable urban underground infrastructure is oneof those challenges. Integrated development of urban underground facilities
can contribute towards improvement of transport accessibility, air quality,
noise level reduction, and, overall, increase safety, reliability, andenvironmental quality in densely populated and built urban areas.

2. URBAN UNDERGROUND INFRASTRUCTURE
Conduits, storages, and transport systems has the longest history of
being a part of urban underground infrastructure (UUI). Urbanization andadvancements in construction technologies in the 20th century facilitateddevelopment of a widespread UUI, which provides many services, indowntown areas in particular. Well developed infrastructure includes public
and private transport facilities, storages, energy supply utilities, retail,commercial, community services, civil defense and emergency rescue
facilities.

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2.1 State-of-the-art
UUI has a huge potential for assisting cities to develop in a sustainable
way. However, components of UUI are quite complicated structures, which
require to be built using careful long-term planning and modern
sophisticated construction technologies. Decisions on development or
redevelopment of UUI are never straightforward, they always involve many
conflicting criteria which must be taken into consideration, many
stakeholders are involved and many tradeoffs have to be made.
One of the significant obstacles in new UUI development iscongestion of underground space beneath urban areas, and megacities inparticular. UUI as cities themselves, was evolving historically, thus valuable
underground space at the depth of 5-10 meters has been already occupied byoutdated, old infrastructure, which has difficulty to comply withrequirements of growing metropolises. This old infrastructure has been inpermanent, continuous operation, and its maintenance, modernisation,
renovation, and redevelopment associates with many difficulties such assuspension of vital urban services (e.g. utility supply, transport).
Megacity of Tokyo, with a population of 35 million people (United
Nations Population Division, 2004) has a significant volume of UUI. Taking
these facts into account, it is appropriate to refer to experience of the Tokyo
central area in historical development of underground space.
UUI at the Iidabashi station in Tokyo is a good example of congested
underground space and disintegrated networks of different functional
purposes (Figure 1). Here underground space is filled with 4 subway lines,
electric power lines, gas pipes, communication lines, water supply pipes,
sewer conduits. Figure 2 illustrates and table 1 indicates density of utility
networks under major roads of central Tokyo. Table 2 shows typical
distribution of public utilities in a street cross-section.

Figure 1: Dense UUI under Iidabashi station, Tokyo (source: Ministry of
construction of Japan; ITA).

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Table 1: Length of utility networks under major roads in central Tokyo(from Deep underground utilization law and its benefits, Matsumoto, 2005).
Utility
Total length, km Length per 1 km of road, km
Telecommunication 2737
17.0Electricity
1498
9.3
Gas
326
2.0
Water network
367
2.3
Drainage311
1.9
Table 2: Distribution of public utilities in a street cross-section in Tokyo(data obtained from Tokyo Metropolitan Government).
Depth, m Part of a street, under which utilities are locatedPavementRoad
0-3
Electricity, gas, water,
Electricity, gas, water, sewer,
sewer, cables.
cables.
Air conditioning
Shopping malls, motor ways,
facilities of the adjacentparking facilities.
buildings.
3-5
Shopping malls, motor ways, parking facilities, metro stations.
Electricity, gas, water, sewer, cables.
6-10
Motor ways, metro stations and train tracks.
Sewerage collector, cables.
10-30
Motor ways, metro stations and train tracks.
Sewerage collector, specialized tunnels, cables.
Some Tokyo areas have quite up-to date UUI, those areas tightly
connected with good modern redeveloped above-ground environment.
Effective city planning that utilises multi-level approach with separation ofdifferent transport streams was implemented in Shinjuku area.
Although some complexes of UUI are being created on an advanced
technological and design level, Tokyo UUI can not be considered as asustainable one, because of disintegration and many weak points in a chainof inter-connected facilities.

Figure 2: Dense city utility lines appear to be a hindrance for new UUIdevelopment (source: ITA).

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2.2 Sustainability and vulnerability issues
Sustainable development is a development that meets the needs of thepresent generation without compromising the ability of future generations tomeet their needs (Brundtland Commission, 1987). Breheny (1990) definedurban sustainability as the achievement of urban development aspirations,subject to the condition that the natural and man-made stock of resources
are not so depleted that the long term future is jeopardized. Following above
definitions the role of UUI in urban sustainability can be viewed from atleast two points: UUI helps to archive urban development aspirations, andurban underground space is a valuable natural nonrenewable resource.
Taking this two considerations into account it is natural to conclude that
careful assessment is needed before making decisions on utilizing urban
underground space.
Sustainability of UUI can’t be considered apart from city’ssustainability as a whole. Regarding UUI it is appropriate to consider its
contribution, positive as well as negative to sustainability of urban territory.
Main positive contribution of UUI is provided by opportunities fordevelopment at high environmental standards, negative contribution isrelated to bad planning and design of UUI. Environmental assessment is an
instrument for linking UUI development plan with the sustainability concept.
The present paper limits sustainability considerations to one of its threepillars: environmental one. Methods which fall under broad definition ofsustainability appraisal are used for integrating two remaining pillars:
economy and society.
Vulnerability analysis in regard to UUI can be considered as two
problems (1) city vulnerability and contribution of UUI to this characteristicof a city, and (2) vulnerability of UUI.
Considering the first problem, city’s vulnerability, UUI could increase
it, as well as decrease. UUI can contribute towards decreasing city’svulnerability by creating an extra layer of facilities, doubling functions ofsome systems and creating emergency response facilities. UUI is a vital partof urban system, so failure to provide its services will increase city’svulnerability.
The second problem, vulnerability of UUI can be studied byconsidering natural and artificial disasters, to which UUI could be exposed.
Those disasters include natural (earthquakes, floods, unfavorable
atmospheric conditions), and artificial ones (terror attacks, fires, equipment
failures, construction failures). Vulnerability considerations are limited in
the present paper to external for UUI factors (It is assumed that UUI is
reliable, i.e. provides the services for which it was designed).

3. ENVIRONMENTAL ASSESSMENT
Environmental assessment (EA) is a process of determining,
forecasting, valuating, and elaborating solutions for mitigation of impacts on
the environment. Environmental impact assessment (EIA) and strategic
environmental assessment (SEA) are specific tools of EA and environmental

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decision-making (EDM), which has a developed methodology and legal
base in most developed countries and international organizations concerned.
3.1 Environmental decision-making
Much of what falls under the collective heading of EDM can beclassified as efforts to identify and quantify environmental risks, and to set
priorities and implement policies for managing those risks (Andrews andValverde, 2004). The application of assessment methods generally entails
the use of science and professional judgment. Collectively, these methods
and judgments are used to group development options into defined
categories. In this way, decision making provides a framework thatfacilitates the formulation and framing of strategic management options.
There is much that risks analysts can learn about speaking scientific “truth”
to political “power,” starting with an appreciation that neither truth nor
power are absolutes in the real world of EDM (Price, 1965). Typical models
of decision processes acknowledge three distinct stages of analysis:
identification of the need to make a decision, developing alternative choices,and selecting a preferred choice (Janssen, 1992).
3.2 Scale of consideration
EIA and SEA considering environmental impacts at a different level:
EIA is dealing with projects (e.g. a particular underground facility), andobjects of SEA are policies, plans, and programs (PPP) (e.g. strategy forunderground space development in a megacity). Figure 3 shows applicationof EA procedures and methods depending on the scale of proposed UUIdevelopment.

S
EA

policyEnhancing city’s sustainability,
safety, economic prosperity

plan

Creating, upgrading urban
underground infrastructure

program

EIA

project

Development, redevelopmentof a set of undergroundstructures

Creating, renovating of anunderground structure

Figure 3: Different scales of EA methods application

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3.3 Environmental impact assessment
EIA is a process of examining the environmental consequences ofdevelopment projects in advance of decision-making. EIA normally starts
when feasibility studies for a particular development are in place. EIA is aprocess, thus it should be extend throughout and be integrated with the
project planning and decision-making, so that necessary amendments to bedone in planning and design to mitigate negative environmental impacts.
Project approval stage is a climax of the EIA process, when the decision to
be or not to be has to be made. However, permission to go ahead with adevelopment project does not mean end of EIA process; project follow-up,
monitoring of impacts, and implementation of mitigation measures are very
important.
EIA process generally consists of the following steps:• Screening – identification if considered project requires EIA;
• Scoping – identification which impacts needed to beaddressed;• Establishment of environmental baseline;• Development of alternatives;• Impacts evaluation;• Proposing impacts mitigation and monitoring measures;• Presenting findings and discussion of the results withstakeholders involved, including public.
EIA is required for most of the underground structures – components
of UUI. Main adverse environmental impacts take place during undergroundstructure construction period.
3.4 Strategic environmental assessment
SEA is a relatively new tool of EDM which was largely developed in
1990s. Partidario and Clark (2000) define SEA as a systematic on-goingprocess for evaluating, at the earliest stage of decision-making, theenvironmental quality and consequences of alternative visions anddevelopment intentions incorporated in PPPs, ensuring full integration of
relevant biophysical, economic, social and political considerations.
Generally, as it is seen from the above definition, SEA incorporates a broadarray of issues. The following definition appears to be more suitable forachievement of SEA which is focused on environmental issues: SEA is aprocess of evaluating the environmental impacts of PPPs at a strategic level
to ensure environmentally sound decision-making.
SEA considerations should be embedded in a process of PPP
elaboration as early as possible. This means that environmental experts aretaking part in a PPP elaboration and facilitate the process on a par with otherexperts, rather than evaluate already taken decisions. SEA is dealing withmuch broader scope of multidisciplinary information than EIA. Outcome of
SEA is a broad brush indication about magnitude of environmental impacts
most lucky to be, rather than predictions of quantifiable environmental
values.

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SEA process generally embraces the following considerations:• Identification of the strategic action objective;• Incorporation of sustainability issues;• Identification of targets and indicators;• Establishment of environmental baseline;• Development of alternatives;• Impacts evaluation;• Impacts mitigation and monitoring.
SEA, analyzing conflicts between different objectives of PPPs, aimed
to show explicitly trade-offs that should be made while selecting alternativefor UUI development.

4. CONDUCTING ENVIRONMENTAL ASSESSMENT OF UUIThe range of methods that can be used for EA of UUI embraces awide variety, from experts’ workshops and public involvement to usage ofcomputer models and scenarios building. Let’s mention some important
methods: aggregation, checklists, cost-benefit analysis (CBA), Delphi
surveys, geographic information systems (GIS), life cycle assessment(LCA), matrices, multi-criteria analysis (MCA), overlapping maps, scenario
development. MCA (this term is equal to multi-criteria decision analysis)
techniques are applicable to a very broad range of issues where decisions
are needed to handle complex situations involving alternative options
evaluated along several conflicting criteria.
Some recent works on EA (European Commission 5th Framework
projects PROSPECTS (2004) and SUSTOOLS (2003)) explore integrative
approach, combining CBA and MCA. Those combinatory techniques
provide opportunities for obtaining assessment based on substantial volumeof quantitative information, however for strategic UUI development PPPs
this kind of detailed data is unavailable in many cases. Stand alone MCA iscurrently seen as the most appropriate method for UUI EA, since it’s basic
ability to be implemented doesn’t depend on information availability.
4.1 Multi-criteria analysis
MCA is a method of decision analysis, that involves the use of scoring
and weighting systems based on criteria, in order to test and compare theimpacts of alternatives. MCA is not a method that provides the ‘right’solution of a complex problem, simply because no such solution exists.
Alternatively, MCA helps stakeholders to effectively handle complex
decisions in which the level of conflict between criteria is beyond intuitive
solutions. In addition, MCA has reliable tools for detecting and mitigation
conflicts and disagreements between stakeholders upon criteria prioritizing(Belton and Stewart, 2002). MCA methods can be divided according to an
aggregation rule into two broad categories: multi-attribute value theory
methods and outranking methods (Holland, et al., 2004).

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Multi-attribute value theory methods are aiming at associating aunique number (value) representing the overall strength of each alternative
if all criteria are taken into account. Weights in this method play the role ofscaling factors in the sense that they relate scores in one criterion, to thescores of all other criteria. This means that by assigning weights of relative
importance, stakeholders implicitly determine how much units in one
criterion they are willing to give up, in order to improve the performance ofanother criterion by one unit.
Outranking methods proceed to a pairwise comparison of alternatives
in each single criterion in order to first determine partial binary relations
denoting the evidence that ‘an alternative a is at least as good as alternativeb’.
Both methods, multi-attribute value methods and outranking methods
are suitable for the assessment of UUI; however the author finds outranking
methods more accurate because of technique of pairwise comparison.
Table 3 shows a step-wise procedure of MCA methods and its relation
to EA of UUI.
Table 3: A summery of MCA process with respect to EA of UUI.
MCA steps
Comment for EA of UUIEstablishment of the Identification of assessment object (what exact
decision context
components of UUI needed to be assessed):• piecemeal/integral assessment?
• how many assessments should be
conducted?
• what are the constrains?
Identificationofthe Identification/developmentofalternative
options to be assessed
options (e.g. variations of design solutions, oreven alternative types of infrastructure)
Identification of criteria
Development of a set of multi-disciplinary
criteria, and composing them in a hierarchy
structure
Weighting – assigning Identification of priorities at all the levels of theweights for each of the hierarchy structure (e.g. which impacts are
criteria
more important: on atmosphere or litosphere?)
Scoring – assessment of Comparison of impacts form different PPPs, or
expected performance of project options
each
optionagainstcriteria
Combining the weights Technique depends on particular MCA method
and scores
Results examination
Examinationofdifferent
alternatives
performance in terms of environmental impacts
Sensitivity analysis
Results reliability check
MCA process, shown in table 3 is likely to involve substantial
iteration, with feedbacks to earlier steps. Good quality MCA should be donewith many iterations, which allow identifying crucial points for decision-

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making and explicitly addressing them in subsequent considerations(Dodgson et al., 2000).
MCA can be built up from any level of quantification, though better
quality of data is available, more reliable results of assessment will beobtained. Requirements for information quantification differ from EA scale.
Sadler (2002) suggested that in most cases of SEA qualitative informationon the basis of expert judgment is sufficient. EIA normally has higher levelof quantification than SEA, Therivel (2002) suggested that quantification
should be considered where effects are already close to a threshold. Share ofqualitative information is usually more than a half in input data for UUI EA.
Thus, there is a substantial uncertainty in MCA, namely it arises from input
data accuracy, composition of a hierarchy structure, scores, and weights
assignation. Sensitivity analysis addresses those uncertainties and appears to
be a vital element for MCA.
Sensitivity analysis seeks to assess the extent to which the overall
attractiveness and hence ranking of strategies changes as plausible changes
are made to key input assumptions, reflecting the degree of uncertainty thatmight surround them. The output from such investigations of sensitivity
would be a deeper understanding of how vulnerable any particular packageof measures might be to changes in key input assumptions. A response tohigh levels of sensitivity might involve search for more detailed information
or diminishing the uncertainty surrounding a particular input, or redesigning of the alternatives set to seek to make it less susceptible.
Going beyond sensitivity tests, there are a number of other approaches
to uncertainty (expected utility theory, real options approach) (Dixit andPindyck 1994). For most UUI EAs sensitivity analysis is sufficient tool toassure accuracy and truthfulness of MCA results.

5. CONCLUSION
Population growth, urbanization, and aspiration for improving life
standards and the environmental quality in urban areas motivate thedevelopment of UUI. Development and redevelopment of UUI in
megacities central areas is a pressing problem. The UUI development has
both beneficial and adverse environmental impacts. The contribution of wellplanned and designed UUI to megacity sustainability is significant, although
UUI is vulnerable to natural and technogenic disasters. EA is an effective
tool for achieving better quality of UUI performance. The EDM for UUIapplications utilizes different EA methods and depends on a scale ofproposed development: EIA at a project level and SEA for PPPs. MCA is aneffective tool of decision analysis, applicable for EIA and SEA.
EA is a relatively new area of science; experience in EA of UUI isvery exiguous yet. Given the need for UUI development in megacities,
future research is needed in the area of environmental impacts of UUI and
its potential contribution towards megacity sustainability.

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ACNOWLEGEMENTS
Author would like to acknowledge the contribution of the following
organizations, which provided opportunities for conducting research: Japan
Society for Promotion of Science; United Nations University; University ofTokyo.

REFERENCES
Andrews, C.J., Valverde, A.L.J., JR, 2004. Analysis in support of theenvironmental decision-making. Comparative Risk Assessment andEnvironmental Decision Making, Kluwer.
Belton, V., Stewart, T. J., 2002. Multiple Criteria Decision Analysis: An
integrated approach. Kluwer Academic Publishers, Dordrecht.
Breheny, M. 1990. Strategic Planning and Urban Sustainability.
Proceedings of the 1990 Town and Country Planning Association
Annual Conference. TCPA, London.
Dixit, A.K., Pindyck, R.S., 1994. Investment under Uncertainty. Princeton
University Press, Princeton.
Dodgson, J., Spackman, M., Pearman, A.D., Phillips, L.D., 2000. MultiCriteria Analysis: a Manual. Department of the Environment,
Transport and the Regions, London.
Holland, M. et al., 2004. Tools for sustainability Development andapplication of an integrated framework.
Janssen, R. 1992. Multiobjective Decision Support for Environmental
Management. Kluwer Academic Publishers, Dordrecht.
Levett-Therivel Sustainability Consultants, 2002. Draft Guidance on theStrategic Environmental Assessment Directives: Proposals forpractical guidance on applying Directive 2001/42/EC “on theassessment of the effects of certain plans and programmes on theenvironment” to land use and spatial plans in England.
Matsumoto, R., 2005. Deep underground utilization law and its benefits.
Proceedings of the World Tunnel Congress 2005 "Underground space
use – Analysis of the Past and Lessons for the Future", Istanbul.
Minken, H. et al. 2003. Deliverables of PROSPECTS Project. Institute ofTransport Economics. Oslo.
Partidario, M.R., Clark, R., eds., 2000. Perspectives on Strategic
Environmental Assessment. Lewis Publishers.
Price, D.K. 1965. The spectrum from truth to power. The Scientific Estate.
Belknap Press, Cambridge.
Sadler, B., McCabe M., eds., 2002. UNEP Environmental Impact
Assessment Training Resources Manual, Second Edition. UNEP,
Geneva.

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INTERACTIVE STRUCTURAL DYNAMICSLEARNING KITAshutosh Kumar & B. Rajesh Babu
M.Tech in Computer Aided Structural Engineering
IIIT Hyderabad
India
and
Ramancharla Pradeep Kumar
Earthquake Engineering Research Centre
IIIT HyderabadIndiae-mail: ramancharla@iiit.ac.in

ABSTRACT
Natural disasters like earthquake, landslide, flood, drought, cyclone, forest
fire, volcanic eruption are quite common in different parts of the globe.
These natural disasters lead to the loss of life, property damage and socioeconomic disruption. Earthquakes are one of the worst among the natural
disasters. Seismic zonation map given in IS 1893:2002 shows that India ishighly vulnerable for earthquake and over 60% of India is prone tomoderate to major earthquakes. During past century, India has witnessedmore than 650 earthquakes of magnitude greater than 5 and during past 15
years, 6 earthquakes of magnitude over 6.
From recent earthquakes, it is very well understood that lack of awarenessis one of the contributing factors for huge casualty losses. In order toincrease the awareness about the effects of earthquakes amongprofessionals involved in construction, it is necessary to make themunderstand the concepts of structural dynamics and earthquake engineering.
For this, we have developed a software tool called Interactive Structural
Dynamics Learning Kit (ISDLK) for explaining structural dynamics in a
simple manner. For convenience in explaining the concepts, we divided thetool into six modules. Each module contains few experiments with good
G.U.I. In these modules, user can input the value and he/she can find thedesired results with explanation using graphical diagram. At the end ofsixth module, user can understand the complete dynamic behavior of astructure. ISDLK aims to help students, architects and design professionalin understanding structural dynamics.
1. INTRODUCTION
According to latest seismic zonation map given in IS: 1893: 2002,
more than 60% of India is prone to earthquakes. Metropolitan cities like
Delhi, Calcutta, Mumbai, Chennai, Ahmedabad etc., lie in zone III or above.

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If we look at past 15 years, India has witnessed 6 moderate earthquakes
causing around 40,000 casualties and innumerable property loss. This loss iscaused mainly due to collapse of structures. Hence, it is very important tobuilt capacity in professionals for ensuring earthquake resistantconstructions.
Earthquake engineering education in India though started early, it has not
picked up to the extent what is required at present (NPEEE 2003). This isclearly evident from the damages during previous earthquakes. The maindrawback for this is that average civil engineer in the country is not getting
enough formal training in the concepts of structural dynamics andearthquake engineering during his undergraduate training period. The reason
is that in most of the universities, these topics are not incorporated into thecurriculum. Even during post-graduate training, very few institutes areemphasizing on earthquake engineering. Because of the fast growth inmulti-storied constructions in urban areas of the country, there is a strong
need for incorporating structural dynamics/earthquake engineering studies
into the curriculum.
Contrarily, even if we incorporate these topics into curriculum, we do nothave sufficient trained faculty to teach these topics. Hence there is a very
urgent need for us to develop manpower in this field. To address this issue,
we developed Interactive Structural Dynamics Learning Kit (ISDLK),
where a faculty with some knowledge on structural engineering can be able
to learn by himself the fundamentals of structural dynamics. This virtuallaboratory will introduce the user, the concepts of structural dynamics invery lucid way. User can interact with the experiments using GUI developedon Visual Basic platform.

2. ISDLK MODULES
It is necessary to design and construct earthquake resistant dwellings in theseismic prone zones. Normally houses are built to withstand vertical load
only and as a result they collapse when subjected to horizontal forces
produced by earthquake waves. For understanding of behavior of lateralload, we should have better understanding of structural dynamics. For easy
understanding of structural dynamics, we have divided the tool in six
different modules. Name of different module as listed below
1) Simple oscillator
2) Single degree of freedom system
3) Response due to arbitrary force
4) Response spectrum5) Multi degree of freedom system
6) Vibration control

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2.1 Module 1: Simple oscillator
In this module, basic concepts of simple oscillator are explained. Initially,an example of simple pendulum is taken and the basic terminology i.e., what
is initial displacement, initial velocity, natural frequency and time period are
explained. Each of these terms is illustrated by giving an example, whereuser can enter his value and observe the behavior of structure for his input.
At the end, two experiments are illustrated i.e., i) simple oscillator and ii)
mass and spring.
2.1.1

Experiment 1: Simple oscillator

In this experiment, user will input the desired displacement and upon
inputting that he/she can see the pendulum vibrating at a given initialdisplacement and adjacent to it a dynamic plot will appear showing the time
history of oscillator. User can pause the oscillation and check thedisplacement at any given time instant. Figure 1 shows illustration ofexperiment 1.
2.1.2

Experiment 2: Mass and springThis experiment gives the option for entering initial displacement and initial
velocity to initiate free vibration in a mass and spring system. After setting
the input parameters, user can see the influence of initial conditions in theadjacent plot showing the time history of the system. User can experiment by
setting one parameter zero and varying other to check the system response.
2.2 Module 2: Single degree of freedom system

Figure 1: Iinitial displacement and initial velocity
In this module, basic concepts of a single degree of freedom system are
introduced. It explains initially the procedure to obtain the dynamic
equilibrium equation and later it’s various forms with respect to presence
and absence of forcing function and natural damping. This module is alsopresenting two experiments i.e., i) mass, spring and damping system and ii)
response generator for linear systems.

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Figure 2: Experiment showing effect of damping
2.2.1

Experiment 3: Mass, spring and damping

In this experiment, user has option to input the desired displacement,
velocity and damping. Upon inputting that he/she can see the vibration ofmass and adjacent to it a dynamic plot showing the time history of the

Figure 3: Response generator for linear oscillator
system. In this plot, user can see the influence of damping on the vibration
amplitude. Response of the system will decay exponentially and the samecan be seen in experiment.
2.2.2 Experiment 4: Response generator for linear systems
This experiment introduces user the concept of damped forced vibration.
This is a convenient experiment to find out the response of linear single
degree of freedom system for a given mass, stiffness and damping for agiven force. Force can be any arbitrary force or an earthquake force. Figure

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4 shows the snapshot of experiment 4. From this figure, it is clear that we
can see the input force and output response of the system simultaneously.
User can experiment by changing the parameters and observing the
response. Under special cases, user can verify free and undamped vibrations
also. In this experiment the following cases are possible viz., a) freeundamped vibrations, b) free damped vibrations, c) forced undamped
vibrations and d) forced damped vibrations.
2.3 Module 3: Response due to arbitrary force
In many practical situations the dynamic excitation is neither harmonic nor
periodic. Thus we are interested in studying the dynamic response of SDF to
excitations varying arbitrarily with time. A general procedure is developed
to analyze the response of an SDF system subjected to force varying withtime. This module has subdivided into three sub module. i) response due tounit impulse ii) response due to rectangular impulse iii) response due to halfcycle.
2.3.1 Experiment 5: drawing response for arbitrary force
User has four options to choose from different condition. Clicking on theoption button he/she will get the desire result related to impact of unit
impulse and step force

Figure 4: Response due to unit impulse for damped system
2.3.2 Experiment 6: drawing response due to Rectangular ForceThe normalized deformation depends only on td/Tn. the ratio of pulse
duration to natural vibration period of the system, not separately on td or Tn.
The nature of the response is seen to vary greatly by changing just the
duration td of the pulse. However no matter how long the duration, thedynamic response is not close to the static solution, because the force isInteractive Structural Dynamics Learning Kit

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suddenly applied. User can view the different condition for td/Tn and find the
response history.

Figure 5: Response due to Rectangular pulse force
2.2.3 Experiment 7: drawing response due to Half Cycle Sine Pulse ForceThe normalized deformation depends only on td/Tn. the ratio of pulse
duration to natural vibration period of the system, not separately on td or Tn.
The nature of the response is seen to vary greatly by changing just the
duration td of the pulse. However no matter how long the duration, thedynamic response is not close to the static solution, because the force issuddenly applied. User can view the different condition for td/Tn and find the
response history.
2.4 Module 4: Response spectrum
Engineers to quantify the effect of an earthquake often use response spectra.
Response spectrum is a plot between time period and maximum response ofa linear single degree of freedom system oscillator. In this module, response
spectrum concept is explained by showing some oscillators with different
mass and stiffness properties but same natural period. It is explained herethat the maximum response of a single degree of freedom system oscillator
to a given earthquake ground motion depends on natural period anddamping only.
2.4.1 Experiment 8: Spectrum generator for a given earthquake record
This experiment generates response spectrum for a given component ofearthquake record. Here user can input the earthquake record, desired
response (i.e., displacement, velocity or acceleration), frequency range of
response and damping. Then, oscillator corresponding to each frequency
will be subjected to the earthquake motion and maximum response is stored.
All such stored maximum responses are plotted with respect to their natural
frequency to form response spectrum. At the end, few examples problems

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m3
k3
k2

m2

m1

P3

P2
P1

k1

u 1 (t)P 1 (t)Kcmu 3 (t)u 2 (t)Kcm

P 2 (t)Kcm

P 3 (t)Figure 6: Lumped mass idealization of three-story building

Figure 7: Modal analysis tool
are also given to explain the procedure how to use response spectrum plot(and tripartite plot also).
2.5 Module 5: Multi-degree of freedom system
If the systems have more than one degree of freedom (as shown in fig. 6) the
motion is more complex and the vibratory motion is considered to possess as
many separate harmonic motions as there are degrees of freedom. Procedure
to develop characteristic equation and solution for eigen values and eigen
vectors is explained by keeping mathematics minimal. In this module, two
experiments are there to explain i) modal analysis and ii) interpretation ofmode shape.
2.5.1 Experiment 8: Modal analysis tool
In this experiment, modal analysis can be performed for n degree of freedom
system. Initially user has to select number of degrees of freedom and thenenter the mass and stiffness parameters corresponding the each floor. Then
program calculates natural frequencies and mode shapes of the system. For
each natural frequency, program calculates the maximum response fromalready generated response spectrum. After finding out maximum, it
multiplies the quantity with mode shape to give maximum response at eachfloor level. And then these values are multiplied with participation factor toInteractive Structural Dynamics Learning Kit

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Figure 8: Demonstration of mode shapes
give participation that mode in total response. Similarly, the maximum
response is calculated for other frequencies also. Finally, these values are
combined using appropriate modal combination rule. In this experiment, twomodal combination methods are explained i.e., a) Square root of sum ofsquares (SRSS) and b) Complete quadratic combination (CQC).
2.5.2 Experiment 7: Interpretation of mode shape
This experiment is especially developed to explain the user the concept ofmode shape and contribution of each mode in the total response. Threemode shapes are considered in this example. Three participation factors
corresponding to each mode shape are used. User is tempted to vary theseparticipation factors and check the effect of each mode on the total response.
A snap shot of the same is shown in the figure 8.
2.6 Module 6: Vibration control
Structural control of building is very much needed for earthquake resistantdesign. Structural control techniques can be broadly classified into two types
namely passive control and active control. With reference to buildings inpassive control methods special members are added to the structure. The
strength and stiffness characteristics of these members depend on the levelof structural response experienced by them.
In active control methods, ground motion and structural response aremeasured through sensors, called seismometers. These inputs are fed to acomputer which calculates forces required to be applied through special
members to modify the building response to the desired level. These special
members are called active control devices.

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This module contains the description about vibration control and different
methods of vibration control. It contains one experiment for finding the
response of structure due to tuned mass damper.
2.6.1 Experiment 11: Time History Analysis of by Tuned Mass Damper

Figure 9: Experiment for Tuned Mass Damper
In this experiment, Tuned mass Damper analysis can be performed for n
degree of freedom system. Initially user has to select number of degrees of
freedom and then enter the mass, stiffness and damping parameters
corresponding the each floor. Then program calculates the time history
analysis for given earthquake record. Graphs has plotted for the structure
before the tuning and after the tuning effect.

3. CONCLUSIONSIn order to increase the awareness about the effects of earthquakes
among professionals involved in construction, it is necessary to make themunderstand the concepts of structural dynamics and earthquake engineering.
To address this issue, we have developed a software tool named Interactive
Structural Dynamics Learning Kit. This is an easy tool for users tounderstand structural dynamics. Mathematics is kept very minimal in
explaining the concepts. Total 9 experiments are used to explain thefundamentals of structural dynamics. User is tempted to experiment with theparameters and understands the influence of various parameters on the total
response.

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REFERENCES
National Programme on Earthquake Engineering Education, A ministryof HRD (GoI) initiative, March 2003.
Evangelos Petroutrsos, 2002. Mastering Visual Basic 6.0, B.P.B.
Publishers, New Delhi.
Anil K.Chopra, Dynamics of Structures theory & Application to
Earthquake Engineering, Prentice Hall of India, New Delhi 1996.

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THE GREAT SUMATRA-ANDAMANISLANDS EARTHQUAKE (MW = 9.0) OF 26
DECEMBER 2004: POTENTIAL
VULNERABILITY OF BUILDINGS AND
INFRASTRUCTURES IN REMOTE
METROPOLITAN AREAS
KAZI REZAUL KARIM AND TSO-CHIEN PAN
Protective Technology Research Centre, School of Civil and Environmental
Engineering, Nanyang Technological University, Singapore
crkkazi@ntu.edu.sg

ABSTRACT
Resulting from the rapid economic growth and development, manyhigh-rise buildings and complex infrastructure systems have been
constructed in South-East Asia. The main active seismic sources thatgenerate numerous earthquakes in the region are the Sumatra fault and theSumatra subduction zone. During the past 30 years, the high-rise buildingsin the major metropolitan areas of the South-East Asian region havereportedly felt the tremors from many medium to large earthquakes in
Sumatra. Although there has not been any seismic damage observed so far
in this region, the seismic performance of buildings to larger and closer
Sumatra earthquakes has yet to be investigated. In this paper, the SumatraAndaman Islands earthquake, damages, public responses, and theearthquake ground motions recorded in Singapore are reported.
Discussions on the local seismic hazard in this region are also presented.
The recent Sumatra-Andaman Islands earthquake of 26 December 2004 has
given another fresh reminder of the potential seismic hazards andvulnerability of buildings and infrastructures in the region. It caused severe
damage and a massive loss of life in the region, where earthquake-resistantdesign is not specifically required. The observations on the damages, public
responses and the ground motions recorded in Singapore due to the recent
Sumatra-Andaman Islands earthquake support the continued monitoring
and research in the low seismicity zones.

1. INTRODUCTION
The massive undersea earthquake (Mw = 9.0) of 26 December 2004 occurred
off the north-west coast of Sumatra, Indonesia as depicted in Figure 1. It
caused tsunamis around the Indian Ocean with a global death toll
approaching 290,000 (as of 22 March 2005), making it the deadliest tsunami
ever recorded. The epicenter of the earthquake was 908 km north-northwest

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from Singapore. The main tremors and a series of aftershocks from therecent earthquake were also reportedly felt in several areas of Singapore. A
local newspaper reported that the areas where the tremors were felt are
Tanjong Rhu, Marine Parade, Toa Payoh, Siglap and Meyer Road (Today,
27 December 2004). At these locations, the tremors caused no damage.
Singapore is located in a low seismicity region of Sunda plate, where
the Sumatra fault and the Sumatra subduction zone, are located more than
350 km away. While earthquakes have never posed any real problems for
Singapore, previous large earthquakes have induced tremors felt in
Singapore (Pan, 1995; Pan and Sun, 1996; Pan, 1997; Pan et. al., 2001). It istherefore reasonable to postulate that larger and closer earthquakes in
Sumatra might result in higher, or even damaging, ground motions on the
Malay Peninsula. This is further accentuated when coupled with the fact thatearthquake-resistant design has yet to be specifically required in the current
regional building codes. In this paper, the Sumatra-Andaman Islands
earthquake, damages, public responses, and the earthquake ground motions
recorded in Singapore are reported. Discussions on the local seismic hazard
in this region are also presented.

2. THE GREAT SUMATRA-ANDAMAN ISLANDS EARTHQUAKEOF 26 DECEMBER 2004
2.1

Main ShockThe Sumatra-Andaman Islands earthquake occurred in Banda Aceh
(off the West Coast of Northern Sumatra), Indonesia, on 26 December 2004,
at 00:58:53 UTC (26 December 2004, 08:58:53 Singapore Time).
According to the USGS National Earthquake Information Center (NEIC),the epicenter of the earthquake was located at 3.298° N and 95.778° E,
under the Indian Ocean, off the west coast of Banda Aceh in Northern
Sumatra Island. The epicenter was about 250 km south-southeast of Banda
Aceh, Sumatra, and 908 km of south-southwest of Singapore, as shown in
Figure 1. The focal depth (30 km) was reported to be shallow. The tremors
from the earthquake were reportedly felt with intensity VIII at Banda Aceh
and V at Medan, Sumatra and II to IV in parts of Bangladesh, India,
Malaysia, Maldives, Myanmar, Singapore, Sri Lanka and Thailand.
2.2

Aftershocks

Preliminary locations of larger aftershocks following the megathrustearthquake show that approximately 1200 km of the plate boundary slipped
as a result of the earthquake. Aftershocks are distributed along much of theshallow plate boundary between northern Sumatra (approximately 3° N) tonear Andaman Island (at about 14° N) as shown in Figure 1. The main
shock of the earthquake on 26 December 2004 was followed by many
aftershocks. Following the main shock, aftershocks were collected from theIncorporated Research Institutions for Seismology (IRIS). Occurring

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Figure 1: Epicentral locations of main shock and major aftershocks(M≥5.0) of the Sumatra-Andaman Islands earthquake of 26
December 2004
between 26 December 2004 and 1 January 2005, there were about 145
aftershocks with minimum magnitudes of about 5.0. Figure 1 shows theepicentral locations of the large aftershocks. By comparison with other large
megathrust earthquakes, the width of the causative fault-rupture was likely
over one-hundred km. From the size of the earthquake, it is likely that the
average displacement on the fault plane was about fifteen meters (IRIS).
The sea floor overlying the thrust fault would have been uplifted by several
meters as a result of the earthquake.
2.3

Tectonic Summary

There was a great tsunami reported following the tsunamigenic
subduction earthquake with sudden deformation of seabed. The devastating
megathrust earthquake of 26 December 2004 occurred on the interface of
the India and Burma plates and was caused by the release of stresses that
had developed as the India plate subducts beneath the overriding Burma
plate. The India plate begins its descent into the mantle at the Sunda trench,
which lies to the west of the earthquake's epicenter. The trench is the surface
expression of the plate interface between the Australia and India plates,
situated to the southwest of the trench, and the Burma and Sunda plates,
situated to the northeast. In the region of the earthquake, the India plate

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moves toward the northeast at a rate of about 60 mm/year relative to the
Burma plate. This results in an oblique convergence at the Sunda trench.
The oblique motion is partitioned into thrust-faulting which occurs on theplate-interface that involves slip directed perpendicular to the trench, andstrike-slip faulting which occurs several hundred kilometers to the east of
the trench and involves slip directed parallel to the trench. The 26 December
2004 earthquake occurred as the result of thrust-faulting.
2.4

Damages in Banda Aceh and Other Areas

While an official assessment report has to be made, there has beenreportedly widespread damage to residential buildings, commercial
buildings, military buildings, religious buildings and infrastructural facilities.
Most of the buildings damaged were non-engineered, traditional wooden
and masonry structures. Engineered infrastructural facilities thatexperienced severe damage include railway tracks and bridges. Sumatra’s
northern Aceh province is situated about 150 km north of the epicenter ofthe magnitude 9.0 earthquake. In the Aceh province, distinction between the
structures damaged by the earthquake ground shaking directly or the
resultant tsunami cannot yet be clearly made.
Infrastructural facilities that experienced damage due to theearthquake and tsunami include railway tracks, roads and bridges. They
include overturning of railway tracks in Colombo and Telwatte, Sri Lanka,
complete collapse of several spans of a bridge in India, failure due tosubsidence of a bridge in Indonesia, and damage induced on a road in Banda
Aceh. In Indonesia, The Jakarta Post (4 January 2005) reported that adiesel-fired power plant was destroyed by the earthquake. In Kalpakkam,
India, a nuclear power plant was shut down before waves spread into that
region. According to the Asian Age (27 December 2004), “the second unitof the atomic power station was shut down after sea water entered its plantbut the key installation was declared safe”.
In Thailand, the local Phuket International Airport was suspended for
operations due to failures of the control tower and communication systems
and also flooding of the runway. In Indonesia, the local Iskandar Muda
Airport in Aceh was also closed (The Jakarta Post, 27 December 2004),
where the airport operator PT Angkasa Pura II secretary Kasmin Kamil wasquoted, “Our control tower and communication system are damaged, andthe runway is submerged”. Most of the residential buildings that weredestroyed are non-engineered structures. The types of damage included
collapse and cracking of masonry walls and collapse of wooden frames that
support the roof. A common phenomenon was ‘sliding’ failure of roof tiles
due to insufficient attachment to the roof frame. However, in Kuala Lumpur,
Malaysia, The Star (27 December 2004) reported damage caused by theearthquake on an engineered residential structure, which was a reinforced
concrete building.

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2.5

Socio-Economic Responses to Asian Crisis

As a result of the tsunami, many countries around the Indian Ocean in
Asia experienced casualties and damage. On 31 December 2004,
Singapore’s Prime Minister called for an urgent meeting of the Associationof South-East Asian Nations (ASEAN) leaders. The meeting was held on 5
January 2005 in Jakarta, Indonesia. Attending this meeting were leadersfrom China, Japan, India, Australia, the United States and European Union.
Also attending are representatives from the United Nations, World Bank,
Asian Development Bank and World Health Organization. The meeting of
the ASEAN leaders is to coordinate the relief efforts for the victims of thetsunami and also to outline the management of the donations pledged bycountries and worldwide. To date (5 January 2005) aid pledges from aroundthe world is nearing US$4 billion.
The Prime Minister of Malaysia, Datuk Seri Abdullah Badawi,
announced that Malaysia will appeal to the Organization of Islamic
Conference (OIC) countries to aid the children in Aceh made orphans by thetragedy. Also, the government has set aside RM50 million to aid the fishingcommunity that was devastated by the tsunami (The Star, 5 January 2005).
Associate Professor Hoe I. Ling of University of Columbia has urged
Malaysia to carry out a seismic hazard study to promote earthquake
awareness and preparedness (The Star, 4 January 2004). The framework forthe proposed study includes estimating the worst-case scenario earthquake,evaluating the integrity of existing building, soil response assessment, risk
assessment and instrumentation of selected buildings.
The Republic of Singapore Air force mobilized pilots for ferrying
food, water, clothes and relief crew to inaccessible places. Singapore Armed
Forces landing ships stocked with engineering equipment, transport vehicles
and 196 personnel set off for Sumatra on 4 January 2005. The City Harvest
Community Services sent a team to Banda Aceh to support the existing
Indonesian and Swedish doctors in the hospital. The team also brought withit 15 tones of food, drinks and medicine.
2.6

Seismic Instrumentation and Recorded Ground Motions in
Singapore

In 1996, the Meteorological Services of Singapore (MSS) installed a
network of seismic stations, which consists of two down-hole arrays (BES
and KAP) of strong-motion stations and five teleseismic stations (BTDF,
FTC, NTU, PTK and SJA). The two down-hole arrays are located on the
Kallang formation of Quaternary deposits. The main station, located in the
Bukit Timah nature reserve and denoted as BTDF, is a Global Seismic
Network (GSN) station, which is equipped with a comprehensive set of
sensors to record ground tremors continuously. BTDF is located on a rockoutcrop site. The recorded ground motion time histories are transmitted to
the MSS headquarters to be processed and analyzed.

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Figure 2: Seismic stations in Singapore (SAFER Array)
The Nanyang Technological University (NTU) has also installed two
additional seismic stations, one inside the campus (denoted as NYC) and theother in the basement of a high-rise office building in the central business
district (denoted as RP). The NYC station is located on a firm residual soil
site, and the building in which the RP station is located sits on rigid caissons.
The seven MSS and two NTU stations form an array called the Singapore
Array for Earthquake Response (SAFER). The locations of the SAFER
array stations are depicted in Figure 2.
The two NTU stations (NYC and RP) and four of the MSS stations(BES, BTDF, NTU, and PTK) were triggered during the Sumatra-Andaman
Islands earthquake. Ground motions from the main shock (Mw = 9.0) on 26
December 2004 (00:58:53 UTC) and one major aftershock (Mw = 7.5) later
the same day (04:21:26 UTC) were successfully recorded. The epicenters ofthe main shock and large aftershocks are shown in Figure 1. Baselinecorrected accelerations of the recorded ground motions at different MSS
seismic stations due to the main shock are shown in Figure 3. Table 1
summarizes the peak ground acceleration (PGA), peak ground velocity(PGV), and peak ground displacement (PGD) of each component of groundmotion recorded at each seismic station due to the main shock.

3. DISCUSSIONS
Although the magnitude of the Sumatra-Andaman Islands earthquake
is larger (Mw=9.0) compared to the ones of the previously felt events,
however, it induced less ground shaking and structural response than
expected both in Kuala Lumpur and Singapore. This could be explained
from the distribution of aftershocks as depicted in Figure 1. It suggests thatthe rupture plane extended from the Simeuleue Island. The epicenter was

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Figure 3(a): Baseline-corrected acceleration (EW component) in
mm/s2 of the main shock (2004/12/26 00:58:53 UTC) of
the Sumatra-Andaman Islands earthquake, recorded in
Singapore

Figure 3(b): Baseline-corrected acceleration (NS component) in
mm/s2 of the main shock (2004/12/26 00:58:53 UTC) of
the Sumatra-Andaman Islands earthquake, recorded in
Singapore

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Figure 3(c): Baseline-corrected acceleration (UD component) in
mm/s2 of the main shock (2004/12/26 00:58:53 UTC) of
the Sumatra-Andaman Islands earthquake, recorded in
Singapore
located beneath the Simeuleue Island and the rupture may have initiatedbeneath the island, and propagated in a northeast direction. That probably
explains why the ground shaking in Banda Aceh (R=250 km, MMI VI-VIII,
estimated PGA=70-100 cm/s2, estimated PGV=8 cm/s) was stronger thanthat in the cities located southeast of the epicenter, such as Medan (R=300
km, MMI IV-V). Compared to these cities closer to the epicenter, distancefrom the epicenter is the most probable reason why the tremor was felt lessin Kuala Lumpur (R=650 km) and Singapore (R=908 km). Therefore, theintensity of the ground shaking in the region was smaller than that would be
expected from such a giant earthquake.
As more tall buildings are present in Singapore today and the numberof felt events is increasing recently, the possibility is not remote that suchfar-field ground motions can induce larger response of buildings. Firstly, as
compared to the Sumatra-Andaman Islands earthquake, the smaller but
closer Bengkulu earthquake (Pan et. al., 2001) has led to: (a) morewidespread tremors felt, and (b) larger far-field PGAs induced. Secondly, it
has been noted that the Bengkulu earthquake was not really the maximum
credible earthquake that may occur in Sumatra (Sun and Pan, 1995). Sun
and Pan (1995) found that the moment magnitude of an earthquake with a
10% probability of being exceeded in 50 years in Sumatra region was 8.5.
Therefore, the possible effects of very large earthquakes in the
subduction zone or on the Sumatra fault with an epicenter closer toSingapore than the Sumatra-Andaman Islands or Bengkulu earthquake canoccur. Hence, the effects of these large earthquakes on the high-risebuildings in Singapore and Malay Peninsula need to be investigated further.

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Table 1: Summary of the ground motion parameters
recorded in Singapore due to the SumatraAndaman Islands earthquake
Event date
and time[UTC]

Parameter
Stn

BES

BTDF

26 December

NTU

2004
00:58:53
NYC

PTK

RP

Comp

PGA
[mm/s2]PGV[mm/s]

PGD
[mm]

EW

2.80

1.97

4.69

NS

3.36

2.73

6.44

UD

2.24

2.66

6.53

EW

2.42

4.26

14.36

NS

3.13

5.10

17.50

UD

4.02

6.97

19.41

EW

1.10

1.26

3.35

NS

0.74

1.29

3.26

UD

0.55

0.72

1.53

EW

3.24

6.09

13.92

NS

4.02

6.96

19.25

UD

4.72

7.67

21.25

EW

1.50

2.09

4.44

NS

1.55

2.90

6.43

UD

1.70

2.59

6.99

B1A

5.34

5.49

16.92

B1B

4.10

6.78

20.21

4. CONCLUDING REMARKSIn this paper, the Sumatra-Andaman Islands earthquake, damages, public
responses, and the earthquake ground motions recorded in Singapore arereported. Discussions on the local seismic hazard in this region are alsopresented. The recent Sumatra-Andaman Islands earthquake of 26
December 2004 has given another fresh reminder of the potential seismic
hazards and vulnerability of buildings and infrastructures in the region. It
caused severe damage and a massive loss of life in the region, where
earthquake-resistant design is not specifically required. The observations on
the damages, public responses and the ground motions recorded in
Singapore due to the recent Sumatra-Andaman Islands earthquake support
the continued monitoring and research in the low seismicity zones.

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5. ACKNOWLEDGMENTS
The authors would like to thank Mr. K. K. Mah of the Meteorological
Services of Singapore, National Environment Agency, Prof. J. M. W.
Brownjohn of the Department of Civil Engineering, University of Plymouth,
UK, Mr. C. L. Lim, Mr. X. T. You, and Mr. C. L. Leong of the Nanyang
Technological University. Without their help, this work would not havebeen possible. The public responses in Indonesia, Singapore and Malaysia
were taken from major newspapers in each country. They are The Jakarta
Post (Indonesia), The Straits Times (Singapore), The New Strait Times, andThe Star (Malaysia).

REFERENCES
Pan, T.-C., 1995. When the doorbell rings – a case of building response to along distance earthquake. Earthquake Engineering and Structural
Dynamics 24, 1343-1353.
Pan, T.-C., and Sun, J., 1996. Historical earthquakes felt in Singapore.
Bulleting of the Seismological Society of America 86, 1173-1178.
Pan, T.-C., 1997. Site-dependent building response in Singapore.
Earthquake Spectra 13(3), 475-488.
Pan, T.-C., Megawati, K., Brownjohn, J. M. W., and Lee, C. L., 2001. The
Bengkulu, Southern Sumatra, earthquake of 4 June 2000 (Mw = 7.7):
Another warning to remote metropolitan areas. SeismologicalResearch Letter 72(2), 171-185.
Sun, J., and Pan, T.-C., 1995. The probability of very large earthquakes in
Sumatra. Bulleting of the Seismological Society of America 85, 12261231.

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EMERGENCY ROUTING ALGORITHM
BASED ON THE 3D-GIS
ZHU Qing1, LI Yuan1, TOR Yam Khoon2
LIESMARS, Wuhan University, P.R.China
zhuq66@263.net; liyuan@lmars.whu.edu.cn
2School of Civil & Environmental Engineering, NTU, Singapore
cyktor@ntu.edu.sg
1

ABSTRACTAn increasing number of disasters (such as fire, collapse, poison gas
leakage, bombing, etc.) are reported frequently with huge losses of life andasset both on the surface and underground in mega cities. The highpopulation density and complicated urban environment often make rescue
work difficult due to the absence of powerful and emergency response tools,
which consider multi-dimensional uncertainties and dynamic factors, to aid
in the disaster risk management and decision making. The advent of 3D-GIS
technology provides new perspective for such emergency rescue andattracts a lot of attention in the last several years. This paper introduces an
emergency routing algorithm which deals with the multi-dimensional
information (DEM, texture, graph, symbol, simulation results).
Based on the 3D-GIS, it is possible to calculate the shortest vehicle
evacuation route, in full 3D environment, during emergency situation. The
focus of this paper is on 3D “route mining”, i.e. to extract the crucial andmeaningful “clues” for emergency vehicle routing in a 3D city landscape,and to improve the conventional 2D shortest path algorithm by considering
the information provided by the 3D emergency “clues” into 3D dynamic
network and “weights” of road segment. The model was constructed andtested in 3DGISTM software using a case study of Wuhan, China.

1. INTRODUCTION
Modern city now gradually extends in the third dimension, both
upwards and downwards (Zlatanova, 1999). With all kinds of natural andman-made factors, an increasing number of disasters, such as fire, collapse,
poison gas leakage, bombing, etc., are reported frequently with huge lossesof life and asset both on the surface (road flyover, multi-storey building) andunderground (tunnel, subway station) in mega cities. Such disasters
occurring in areas of high population density and complicated urban
environment often make rescue work more difficult due to the absence ofpowerful and emergency response tools, which consider multi-dimensional
uncertainties and related dynamic factors, to aid in the disaster risk
management and decision making.

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The advent of 3D-GIS technology provides new perspective for such
emergency rescue and attracts a lot of attention in the last several years. 3DGIS has promised to manage as well as to intuitively visualize multidimensional data (DEM, texture, graph, symbol, simulation results). For
example, it is possible to depict in three dimensional spaces, the verticallydisjointed structure (overpass or underpass), realistic terrain environment,
building and its surrounding circumstance. It is also possible to simulation
traffic flow and human behavior in a complex urban system. These are
beyond the ability of the traditional 2D GIS. 3D objects presented as 2D
projections in GIS may loose some of their properties (Texture, graphic,height, etc) and spatial relationships to other objects (Miller and Shaw,
2001).
Researches on emergency routing problem, in 3D environment,
attracts diverse interests, such as needs and requirements analysis,
methodology development, data collection and management, data
integration and mining, data visualization, positioning and navigation.
Pollitt et al (1995; 1996) developed a network-based vehicle routing
algorithm in 3D environment, which considers static impedances (roadsegment length in 3D dimension, gradient, and different routing speed) anddynamic impedances (turn, lane changes) with the use of Dijkstra algorithm.
Laakso (2002) discusses the use of 3D navigation map inrouting/wayfinding. Through analyzing the spatial knowledge, i.e. landmark
knowledge, routing knowledge, survey knowledge, vis-a-vis 2D and 3D
map, he indicates the importance of landmark in 3D environment for
navigation in a city environment. Slavick et al (2005) demonstrate the utilityof 3D visualization to meet military and homeland security needs for eventrelated data in an intuitive display. Through the description of Tactical
Operations Center (TOC) 3D program, it shows the importance of the use of
3D models, military symbology, and homeland security symbology in a 3D
navigable environment. Kwan and Lee (2005) proposed a navigablenetwork which integrates 2D transportation network and multi-levelstructure to support 3D emergency response system. Their work emphasizes
the integration of intelligent transportation system (ITS) and intelligent
building system (IBS) into an emergency routing system. Nanda (2004)
utilizes 3D positional information to provide more efficient and reliablerouting. He proposes a new hierarchical, zone-based 3D routing algorithm
that uses multi-path routing in 3D. Another important extension of 3D
application in emergency routing is 3D web-base GIS with the use of 3D
visualization function, such as flythrough (Held et al., 2004).
However, real 3D emergency routing algorithm, which has ability tointegrate both multi-dimensional and dynamic emergency “clues” into 3D
environment, is still limited. One reason is that, much attention were spent
on 3D modeling and visualization in 3D-GIS and yet to embark on theanalysis of the multi-dimensional information in 3D-GIS, for instance routemining. Another reason is that, emergency simulation of human behavior,traffic dynamic change, hazard proliferation, and many others are studied in

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2D or 2½D space to get emergency “clue”. Shortest routes are also
calculated in 2D space, basing on fully intersected, planar network (Miller
and Shaw, 2001). For real 3D emergency routing algorithm, the crucial
multi-dimensional and dynamic emergency information, the knowledge of
emergency situation, and shortest path algorithm, should be integrated in a
3D-GIS platform.
In this paper, the idea of a multi-dimensional and dynamic emergency“clue” is illustrated as well as its special function in efficient vehicle routing.
The shortcomings of traditional planar network in emergency situation will
be discussed next. Finally, a 3D dynamic network, which improves theconventional 2D shortest path algorithm by considering the multidimensional information (DEM, texture, graph, symbol, and simulation
results) and emergency “clue” is outlined. The model was constructed andtested in 3DGISTM software using a case study of Wuhan, China.

2. EMERGENCY “CLUE” AND 2D NETWORKEmergency vehicle routing problem is very complicated and dynamic
in real disaster situation. Take earthquake for example, it may break trafficsystem (flyover etc.) directly; destroy buildings around the road networkand thus cause traffic congestion. It may also bring flood - which block
traffic in some lowlands – as well as fire which further threaten human lifeand make people panic and flee away from building to road surface. All of
the above knowledge is known as emergency “clues”. They are both multidimension and dynamics, and bring great challenges to the development ofemergency vehicle routing algorithms. Emergency clues have great
potentials to avoid unnecessary incident and direct vehicle to get to thedestination safer and faster. With the use of emergency “clues”, ourtraditional routing problem can be extended to suit real emergency cases
better. In 3D-GIS environment, multi-dimensional data (including 3D
network) are available; however, the problem lies n how to “mine” theimportant emergency clues and integrate them to improve the efficiency of
current route mining algorithm in real emergency situation.
Our traditional vehicle routing approach has been adapted from staticand deterministic algorithm to dynamic and stochastic algorithm (Eklund etal., 1996; Gendreau et al., 1996; Lu, 2001; Guo et al., 2002; Bent andHentenryck, 2004) with the appearance of complicated transportation
phenomena (such as turn restriction, multi-lane, lane changing) in many
applications. Although many improved strategies such as lane-based (Covaand Johnson, 2003), non-planar network model (Fohl et al., 1996), dynamic
segmentation approach, case-based, knowledge-based method (Liu et al.,
1994; Ginty and Smyth, 2001) and hierarchical representation (Hock and
Srikanthan, 2000) can improve the efficiency of routing in dynamic andstochastic environment, they are all implemented in 2D environment withthe support of 2D planar or 2D non-planar network based on graph theory.
Furthermore, when the road network of the city is very complicated andEmergency Routing Algorithm Based on the 3D-GIS

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dense which is typical in mega city, it will take too long for the algorithm tofind the shortest path (Liu et al., 1994).
3D
2D
2D/3D Distance2D network

3D network

Figure 1: 2D/3D road network
Incorporating 3D information allows more accurate understanding ofpotential vehicle conflicts in real-time. 3D network overcomes the problem
made by 2D planar at least from two aspects: first, it can measure the true
distance across sloping or hilly terrain; second, it can represent 3D
structures such as overpasses or underpasses (Figure 1). For complex spatial
analysis, like emergency routing, 3D network has the potential to detect
incident made by multi-dimensional damage. In this paper, in response toreal 3D environment and quick response for emergency, 3D dynamic
network is constructed for better represent the real situation (under/overpass,gradient, the location of potential incident, etc) of road network. Next, basedon 3D dynamic network, Dijkstra algorithm is developed to find “shortest”
routes in the 3D emergency environment with the use of emergency “clue”
from 3D-GIS.

3. 3D DYNAMIC NETWORKIn traditional planar node-arc graph, the underlying assumption is thatspatial data is stored and referenced in a 2D coordinate system. In contrast, a
3D system allows the z-coordinate to be represented as a geometric property
and as such, features are represented in their true geometric form (Pollitt,1995). Furthermore, 3D dynamic network needs some special function todeal with the specific requests for emergency vehicle routing in disastersituation. Firstly, emergency vehicle is in moving condition and tracked byon-board GPS in real time. If the network structure is changed by any
sudden incidents，it needs to recalculate the routes from current vehicle
point (new start point) to the original destination (original end point).
Second, sudden incident may break the transportation network, and thissituation should be reflected timely in an updated network structure. These
two needs call for dynamic transportation network with abilities to depict
the dynamic events (location of vehicle location, incident location anddisaster location). Lastly, for quick and flexible response, the events can bereflected directly on the transportation network. The user must be able toselect point in the road structure or structure near road network to effect thechange or instruction, and the algorithm will determine and display theappropriate path.
There are several methods to construct basic 3D network in 3D-GIS.
In 3D environment, it possible to construct 3D transportation network

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intuitively on DEM-based road surface, which reflects the real situation of
traffic network, including under/overpass, slope, incident point, vehicle
location and destination point, etc. With the support of map “snap” function,
it is possible to add events (vehicle point, incident point, disaster point) tothe basic 3D network to form a dynamic emergency network.
OriginIncident

Destination(x,y,z)(x,y)

Figure 2: 3D emergency dynamic transportation network
3D dynamic network is presented by the standard notation N= {V, E,
W} (G= {V, E}, W= {w(vi, vj)}), where the nodes V correspond tointersection, turning point, origin, incident point, and destination; arc E
connecting nodes represent road segmentation; weight W shows the abilityof arc connectivity. In 3D dynamic network, the potential D(v) is a changing
value, which represents the time to travel to a node at the time the node isbeing scanned. Corresponding to some special operation in 3D dynamic
network, the following symbols are given:
N – the number of nodes (|V|)
M – the number of arcs (|E|)D(v)- the current potential (travel time) of nodes
S(v)- the current status tag of nodes
PutVex(G, v, value)- put the vertex v in graph G and give its value
InsertVex(G, v)- insert vertex v in graph G
DeleteVex (G,v)- delete the vertex v in graph G
DeleteArc (G, v, w)- delete the arc from vertex v to w in graph G
From planar network to 3D network, the ambiguity situation ofunder/overpass in 2D graph can be eliminated. Similarly, from static
network to dynamic network, real-time information about vehicle, disasterpoint, and incident location can be directly considered into routing process.
However, for quick response, a better way to improve routing efficiency
through optimizing the 3D dynamic network and reduce the research spaceis still necessary. In different cases, the optimization result is diverse andposes special strategies to “intelligently” optimize the 3D network. Morespecifically, knowledge (“clue”) indicate to the shortest path algorithm
where it should search and where it should not (Liu, Choo et al., 1994). Start
point (S) and destination point (D) make basic 3D network add only one
vertex each, however, every incident point adds two vertexes on the network
segment and break the segment between the two vertexes. The next step isto eliminate the hanging points (vertexes) of the network “tree” till
optimization result (the degree of each vertex d(v)≥ 2) is achieved. Take
Figure 3 as example, after optimization, the unnecessary vertexes are
eliminated and the total numbers of vertexes are reduced greatly.

Emergency Routing Algorithm Based on the 3D-GIS

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Case 1

Planar Network Case 2

S

S

D

Optimization

D

Figure 3: Optimization of 3D dynamic transportation network
In short, the process of 3D dynamic routing is composed by two parts:
the building and optimization of 3D network; and using algorithm to findthe shortest path, as follows:
Putvex(G,v, value) in 3D environmentÎbuilding basic 3D network
InsertVex(G, vi), InsertVex(G, vs), InsertVex(G, vd)∈VÎbuilding dynamic 3D network(vi: incident point, vs: start point, vd: destination point)
DeleteVex(G, v(i)) and DeleteArc (G, v(i), v(i))Îeliminate hanging points → optimization
Node labeling and Dijkstra algorithm → find the shortest path

4. EMERGENCY ROUTING ALOGRITHM
For well-connected network, Dijkstra's algorithm implementation
have a lower computational complex (Liu et al., 1994; Pollitt, 1995; Eklund
et al., 1996; Zhan and Noon, 1998), and therefore commonly used in many
dynamic and stochastic vehicle routing cases. In 3D network, an importantcharacteristics of the implementation of Dijkstra algorithm lies in thedetermination of “weights” for each arc. Sophisticated routing algorithms
can base route selection on multiple metrics, combining them in a single(hybrid) metric. In 3D-GIS, the following metrics are to be considered tosuit emergency cases well: segment length (the distance between the points
in 3D), gradient impedance, travel speed, volume (vehicles per minute,vehicles per hour), and vehicle type, level of service (LOS), etc. For quick
emergency response and management, “time” as unique metrics has beencommonly used in many routing cases. Basically, traveling time isdetermined by travel distance and travel speed. In real 3D environment,
travel distance is usually unchanged and shaped by urban landscape;however, travel speed is not constant and difficult to be denoted in a single
value due to complex transportation phenomenon and traffic rule. Usually,
vehicle will travel slower on steeper slope, lesser lanes, and larger numberof traffic light controls, etc. As a result, it specially requests a measure to
combine those multiple criteria into one “weight” to determine vehicle
speed.

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Distance = ∆x 2 + ∆y 2 + ∆z 2
Speed=Standard speed ∗ Weights
Distance
Time=
Speed
∆z
Gradient=100 ∗2∆x + ∆y 2

(1)
(2)

(3)
(4)

n

Weights= ∑ scorei ∗ weight i

(5)

i =1

Distance: the 3D distance of two nodes in real world
Speed: the vehicle speed in different transportation condition
Time: the time taken to travel between two nodes
Gradient: slope between two nodes
Weights: the summation of the product of score and weight of thecontributing criteria or factors
The methodology which seemed to be well suited to support thedecision making process in selecting the “best” alternative from a number offeasible alternatives under the presence of multiple choice criteria anddiverse criterion priorities was MCE (Pettit and Pullar, 1999). For each arc,
the MCE matrix is used to determine its weights for vehicle travel speed inreal emergency situation. In this paper, we just give an example of using
MCE matrix to score and weight for the three major factors (Table 1). For
different cases, the choice of factors, score, and weight can be different.

Table 1: Example MCE matrix to determine speed weights
Factors
Weights
Grade
ScoreiWeighti
1-5%～5%
Gradient
0.2>5% or <-5%
0.6
1
1～2
Lane number
0.3
>2
1.5
1
1
Light control number
0.5
>1
0.5
In Short, an important issue of using Dijkstra algorithm in 3D
emergency environment is to determine the “connectivity” or “weight” ofeach road segment in a multi-dimensional environment. MCE method
provides a framework to decide the speed weights through synthesizing
potential factors in road network system. Corresponding to the above MCE
matrix, the process of “weights” determination for each arc is illustrated asfollows:
Optimize 3D dynamic network
Initial Standard Speed
Calculate 3D distance of each road segment: 3D_Distance(V,W)
Calculate 3D_Gradient(v,w), Num_Lane(v,w), Num_Control(v,w)
Score 3D_Gradient(v,w), Num_Lane(v,w), Num_Control(v,w)

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Calculate speed weights
Calculate Arc_Length(v,w)
Next, we use a case study done in Wuhan, China, to show the resultsof emergency routing algorithm in 3D-GIS. The software adopted is
3DGISTM; the system provides two kinds of view: global view andnavigation view (Figure 4). The incidents points (from Incident 1 to
Incident 4) are inputted on-screen using cursor and 3D dynamic network
optimization process will be followed. Different from traditional routing
algorithm, the proposed emergency routing algorithm will be able to avoid
unnecessary road segment as well as consider multi-dimensional
information, such as slope, traffic control and lane numbers. In 3D-GIS
environment, building with texture, landscape, traffic signal, etc., can be
added into routing system to improve the quality of routing visualization.

Figure 4: Results of emergency routing in 3D-GIS

5. CONCLUSION

Disasters in urban region often present multi-dimensional anddynamic characteristics. Though many researchers have developed all kindsof techniques to visualize 3D landscape, to locate incident with the use of
GPS or mobile GIS and to simulate disaster phenomena with the support ofdynamic model in 3D-GIS environment, most of shortest path algorithms
are still conducted with a 2D GIS with the adoption of 2D road network andwithout consideration of multi-dimensional and dynamic emergency “clues”
and knowledge. In this paper, we propose an emergency routing algorithm
based on the 3D-GIS, and emphasize on the construction and optimizationof 3D dynamic network, and the way to determine multi-dimensional
weights for road segment. It has been found that 3D dynamic network has
the potential to depict real traffic system (over/underpass) and its dynamic
relationship with emergency “clues”. The number of nodes and arcs in a 3D
dynamic network can be greatly reduced, thus improves the efficiency andeffectiveness for emergency routing. MCE method is used to evaluate theoverall weights for travel speed in each road segment. It considers multidimensional and dynamic factors in real vehicle routing process. In
3DGISTM, through inputting of 3D dynamic incident and considering ofmulti-dimensional road “connectivity”, Dijkstra algorithm can be improved
to implement in our 3D emergency routing practice. 3D visualization of theemergency routing results (Global and Navigation Model), improves the536

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understanding for emergency situation and efficiency of disastermanagement.
The performance of emergency routing largely depends on how wellemergency-related characteristics are arranged into algorithm. The work inthis paper only gives a general description on the development ofemergency routing algorithm based on the 3D-GIS. In the next stage, theproposed emergency routing algorithm is to improve the scalability of 3D
dynamic network, to include a number of other emergency “clues” (such as
traffic congestion, flood, etc.), to measure the true distance and theimpedance over 3D curved surface for travel, to automatically extract
incident point on 3D dynamic network. More heuristic strategies are also to
be explored to improve the computation speed of Dijkstra algorithm in 3D
environment.

REFERENCES

Bent, R. W. and Hentenryck, P. V., 2004. Scenario-based planning forpartially dynamic vehicle routing with stochastic customers.
Operations Research, Volume 52 (6), 977-987.
Cova, T. J. and Johnson, J. P., 2003. A network flow model for lane-based
evacuation routing. Transportation Research 37: 579-604.
Eklund, P. W., Kirkby, S., and Pollitt, S., 1996. A dynamic multi-source
Dijkstra's Algorithms for vehicle routing. Australian and New ZealandConference on Intelligent Information Systems: IEEE Press, 329-333.
Fohl, P., Curtin, K. M., Goodchild, M. F., and Church, R. L., 1996. A NonPlanar, Lane-Based Navigable Data Model for ITS. In: Proceedings,
Seventh International Symposium on Spatial Data Handling, Delft,
August 12-16 (M. J. Kraak and M. Molenaar, eds.).
Gendreau, M., Laporte, G., and Seguin, R., 1996. Stochastic Vehicle
Routing. European Journal of Operational Research 88(3-12).
Ginty, L. M. and Smyth, B., 2001. Collaborative Case-based Reasoning
application in personalised route planning. the Fourth International
Conference on Case-Based Reasoning (ICCBR). 362-376.
Guo, Y., Xie, B., and Guo, Q., 2002. Overview of Stochatic Vehicle
Routing Problem. Journal of Southwest Jiaotong University 10(2).
Held, G., Abdul-Rahman, A., and Zlatanova, S., 2004. Web 3D GIS for
Urban Environments. Proceedings of the International Symposiumand Exhibition on Geoinformation 2004 (ISG2004), 21-23 September,
Kuala Lumpur, Malaysia, CDROM, 12 p.
Hock, Q. K. and Srikanthan, T., 2000. A hierarchical representation of
roadway networks. 7th World Congress on Intelligent Transportation
Systems.
Kwan, M.-P. and Lee, J., 2005. Emergency response after 9/11: thepotential of real-time 3D GIS for quick emergency response in microspatial environments. Computers, Environment and Urban Systems
29: 93-113.
Laakso, K., 2002. Evaluating the use of navigable three-dimensional maps

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in mobile devices. Master's thesis, Helsinki University of Technology,
Helsinki, November 2002.
Liu, B., Choo, S.-H., Long, S.-M., Lee, S-C., Poon, F-P., and Tan, H-H.,
1994. Integrating Case-Based Reasoning, Knowledge-BasedApproach and Dijkstra Algorithm for Route Finding. Proceedings of
the Conference on Artificial Intelligence Applications, pp.149-155.
Lu, X., 2001. Dynamic and stochastic routing optimization: algorithm
development and analysis. Ph.D., Civil Engineering, 2001. 139 pp.
Adviser: Amelia C. Regan.
Miller, H. J. and Shaw, S.-L., 2001. GIS-T Data Models. Geographic
Information Systems for Transportation: Principles and Applications,
Oxford University Press: 480PP.
Nanda, S. and Gray, R. S., 2004. Spatial multipath location aided ad hocrouting. Proceedings.13th International Conference on Computer
Communications and Networks (IEEE Cat.no.04EX969) 2004,
pg.544-544.
Pettit, C. and Pullar, D., 1999. An integrated planning tool based upon
multiple criteria evaluation of spatial information. Computers.
Environment and Urban Systems 23: 339-357.
Pollitt, S., 1995. A 3-D spatial information system for emergency routing inOkayama city. Honours Thesis, 1995 Department of Computer
Science, University of Adelaide, November 1995.
Slavick, D., Christopher, Moore, 2005. 3D Visualization Bolsters Homeland
Security.http://www.geointelmag.com/geointelligence/article/artic
leDetail.jsp?id=162588.
Zhan, F. B. and Noon, C. E., 1998. Shortest Path Algorithms: An Evaluation
using Real Road Networks. Transportation Science 32(1): 65-73.
Zlatanova, S., 1999. An alternative for a 3D GIS. Proceedings of theInternational symposium and exhibition on Modern information and
GPS technology-aspects and implications of their application, 11-12
November, Sofia, Bulgaria, pp.221-231.

538

New Technologies for Urban Safety of Mega Cities in AsiaAPPLICATION OF A COUPLEDSIMULATION METHOD FOR
PREDICTING FIRE SPREAD
IN A MODELED URBAN AREATAIFENG JIANG
Graduate School, the University of Tokyo, Japan
HONG HUANG, RYOZO OOKA
Institute of Industrial Science, the University of Tokyo, Japantfjiang@iis.u-tokyo.ac.jp

ABSTRACT
Research into fire spread dynamics in built-up districts under certain
meteorological conditions is of critical importance to fire safety issues. The
objective of this paper is to apply an approached coupled simulation method
for the prediction of urban fire growth and spread by combining a onedimensional wood pyrolysis model, gaseous combustion model, withcomputational fluid dynamics (CFD) method. In this research, theapplication of the coupled method is conducted on basis of al CFD code anddivided into four sequential steps, which is also elaborated in this paper. As
well, the calculation over a modeled urban area under certain assumed
meteorological condition has been carried out to analyze the feasibility ofthe method. The simulation results illustrate detailed temperature andconcentration distribution as well as the heat transfer characteristics on thewall surface via both convection and radiation. The phenomena of fire
spread within the objective domain are also reproduced.

1. INTRODUCTION
Fire is arguably one of the most complex phenomena, embracing as it
does in many cases subsonic chemical reaction flows, fluid dynamics,
combustion, kinetics, radiation, and multi-phase flow (Novozhilov, 2001).
Companying with the revolutionary progress in CFD modeling and radical
improvements in computation capacity over the last several decades,
simulations of the fire dynamic have advanced significantly in terms of thealgorithms for combustion physics and mathematical modeling acrossalmost all respects related to fire phenomena. In order to minimize the lifeand property loss caused by fire accidents, especially large scale fires occur
in urban districts with dense populations and building, the simulation of fire
behavior is of great interest and critical importance to fire safety issues. As
early as the 1950s, researches into fire had been already developed as ascience. However, because of its complexity, fire simulations were still along way off and required great effort. Di Blasi (1993) developed a539

October 2005, Singapore

theoretical model to study the effect of gas flow on the spreading flames,
while Quintiere (1981) proposed a semi-empirical method. In terms of theessential importance of burning wood and other cellulosic materials, Kung
(1972) has made significant contribution in developing a wood pyrolysis
model. Recently, the CFD method was also undertaken for a temporal studyof flame propagation and fire growth in indoor fires in order to closer
approximate reality. Yan (1996) has analyzed flame propagation oversurface lining material in an indoor corner fire by means of CFD. Threedimensional transient turbulent gas flow, combustion, heat transfer, andpyrolysis of a charring material were all taken into consideration. However,that study is still in its preliminary stage, and restricted to compartmental
fires.
This paper aims to extend the simulation of fire growth and spreadfrom indoor scale to urban districts, which are apparently larger in scale andcomplexity of geometrical configuration. In this research, a one-dimensional
wood pyrolysis model is proposed to be utilized and coupled with a CFD
code. The method is introduced and as well a trial case in a modeled urban
area is carried out.

2. URBAN FIRE SPREAD MECHANISM

Wind
風Firebrands
火の粉飛散
Radiation
放射Contact
接炎 fireConvection
熱気流(対流）Figure 1: Illustration of urban fire spread
The mechanism for urban fire spread phenomena can be roughly
divided into four sequential stages as follows (Novozhilov, 2001):
1). Heating up: The building blocks’ surface temperature increases as
it receives the incident net radiative heat flux and convective, conductive
heat flux transferred by fluid flow from an upwind high temperature region.
2). Ignition: As it continues to be heated, once the surface temperature
exceeds the material’s critical temperature for pyrolysis, ignition occurs. In
this stage, the surface material is converted to gaseous volatiles and residual
char.
3). Fire growth and spread: After ignition, the combustion of material
and gaseous volatiles produces a thermal plume and exports thermal energy
feedback to the surfaces of contiguous and nearby blocks. Moreover, thefirebrands bringing high energy will potentially contribute to great increaseof surface temperature at their landing areas. If the surface temperaturereaches up to the critical temperature of pyrolysis, combustion begins.
Therefore, the fire zone expands. The schematic is shown in figure 1 (Otake,2004).

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New Technologies for Urban Safety of Mega Cities in Asia

4). Decay: At this stage, since all volatile fuel is consumed, the firegradually goes extinct.

3. DESCRIPTION OF THE MATHEMATICAL MODEL
3.1 CFD model
Both the density and temperature in the fire flame experience extreme
fluctuations. Therefore, the assumption of the incompressible fluid(Boussinesq approximation) doesn’t stand up, thus the plume must be
considered as the compressible fluid. For this solution, the Favre-averaged(Favre, 1969) process is introduced for the mass, momentum, enthalpy, andgas species transport. Moreover, a modified k-ε model, proposed by El
Tahry (1983) for compressible reciprocating engine flows, is employed.
3.2 Gaseous combustion model
Burning reaction in the gaseous phase is modeled by employing theeddy break-up model (Magunussen, 1976) here, which has already been inwidespread used in fire modeling. The reaction rate is determined by theslower of the turbulence dissipation rates for either the fuel or oxygen:% , AY% /i)w f = - r(e/k) min(AYfO2(1)
Where, A – constant, 4.0; i – stoichiometric ratio of O2 to fuel; Y –mass fraction.
In this paper, propane is chosen as the representative gaseous volatile
as generally treated in the other researches. The following chemical reaction
is assumed (Novozhilov, 1996):
Cn H m + (n- s+mmm)(O 2 + 3.76 N 2 ) → sC+ (n- s) CO 2 + H 2O+ 3.76(n- s+ ) N 2
4
2
4
(2)

S is a parameter to define the amount of soot produced. A non-zerovalue results in some of the carbon remaining as soot, with a consequent
reaction to CO2. The value of s can be determined from the soot conversion
factor which is chosen from experimental data; for example, 2% for propane(Yan, 1996). The soot concentration is determined from the species equationand treated as a gas-phase species.
Radiation is solved in parallel with the governing equations. The
absorption and emission of gas and soot are considered. Scattering isomitted due to the small diameter of the soot. The effect on radiation
intensity is represented by the following radiation transport equation:dI
σ=-(k g +k s )I+ (k g +k s )T 4
ds
π
(3)

where I – radiation intensity in the direction of the solid angle Ω,
W/sr; s – transfer distance of the radiation flux, m; kg, ks – absorption
coefficients for gas and soot.

Application of a coupled simulation method for predicting fire spread in a modeled urban area541

October 2005, Singapore

The calculations for kg and ks are based on equation (4), which is proposedby Novozhilov (2001):Tk g =0.28exp() k s =1264f v T
1135(4)
3.3 Wood pyrolysis modelingIn this research, the walls of building blocks are assumed to be
wooden slabs with a constant depth of 0.20m. It is because wooden
apartment still remain in widespread use by residents in modern-day Japan.
Wood pyrolysis contains varieties of phenomena related to transient
conduction, incident radiation, variable properties, Arrhenius decomposition,and heat of reaction. A pyrolysis model by Kung (1972), based on partial
differential equation, is employed as a simplified description of these
phenomena. As described above, heat received on surfaces penetrates into
the interior virgin wood along a direction normal to the surface. When thetemperature in any element reaches pyrolysis temperature, ignition occurs.
The decomposition rate is controlled by the Arrhenius reaction (7).
.
∂ ( ρ h) ∂  ∂T  .
∂ρ
= λ
+
q
q
Q pyro + Sx
(5)
(6)
 0x
0x = −∂t∂x  ∂x 
dt
 E 
∂ρ
= − ρ w aA 0 exp  −dt RT 

(7)

a = ( ρ − ρ c ) /( ρ w − ρ c )(8)

λ = aλw + (1 − a)λc(9)

Cp = aCp w + (1 − a)Cpc(10)Here, Qpyro – heat of pyrolysis, J/kg; S – hear source in local
element except pyrolysis heat release, W/m3; subscripts w and c denotevirgin wood and char respectively. Detail properties can be referred totable 1 (Kudou, 1999).
In this modeling, three assumptions are adopted additionally:
1) Ignition temperature in considered as constant value.
2) All volatiles escape to the surface as propane and soon after are
consumed in pyrolysis.
3) Pyrolysis converts the material from virgin wood to char, while
residual char will not pyrolyze further.

Parameter

Wood Density:

542

Table 1: Material properties used.
Unit

ρw

3

Value

[kg/m ]

525.0

Wood Heat Conductivity: λw[W/m/k]0.11

Specific Heat of Wood : Cpw
Wall Thickness : σw
Char Density: ρcChar Heat conductivity : λc

[J/kg/k]m[kg/m3][W/m/k]1300.0
0.15
191.0
0.07

New Technologies for Urban Safety of Mega Cities in Asia

Specific Heat of Char : Cpc
Pyrolysis Temperature : Tpyro
Reaction heat of Pyrolysis : Qpyro
Activation Energy : E
Pre-exponential factor A0[J/kg/k]K[J/kg][J/mol]1/s

1000.0623.0
1.8×106
1.04×105
4.33×106

4. DESCRIPTION OF COUPLED SIMULATION METHOD

Input DataWind Velocity,
Direction,
Temperature, etc.

Wall Boundary
Data
Wall Temperature,
Mass Release Rate,
Roughness, etc.

Flow Field

CFD Code

Meteorological
Data

CFD ResultWind velocity,
Direction,
Temperature, etc.

Boundary Data
Incident Radiation
Heat Flux, Convective
Heat Flux

Wood Pyrolysis Program

Calculation of time step i

Renewing wall boundary data of time step i+1

Figure 2: Algorithm of the proposed coupled simulation method

In this research, an alternative calculation is utilized for the coupledsimulation. The approach is so called semi-unsteady method since CFD
simulation is carried out in steady status, while wood pyrolysis in unsteady.
The calculation for each time step consists of four distinct processes.
1). First, meteorological conditions, wall temperatures, mass flux atwall et al, are read into the CFD code as initial data.
2). Steady CFD simulation is employed via a CFD code to obtain flow
specifications including gas velocity, temperature, species concentration,
radiant and convective heat flux to building surfaces, and surface
temperatures.
3). Radiant and convective heat flux data at building surfaces are readfrom the CFD results and then input into the wood pyrolysis program.
Calculation covers all meshes on the building surfaces as well as the interior
elements arranged along the normal line according to each surface mesh.
Updated surface temperatures, heat flux, propane release rates for the nexttime step are prepared.
4). CFD simulation for the next time step is carried out by using theboundary conditions updated by the newest data obtained from the pyrolysis
routine.
In terms of such proposed semi-unsteady prediction, the time stream isdivided into time steps with constant interval. Here, for example, if the timeinterval is set in 10 seconds, time step i+1 means 10 seconds later from time
step i.

Application of a coupled simulation method for predicting fire spread in a modeled urban area543

October 2005, Singapore

5. OUTLINE OF COMPUTATION

To specify the validation of the coupled simulation method, predictionof the fire spread with a modeled urban area was carried out. The details of
the calculation are described as follows.
5.1 Calculation domain configuration

Figure3: Geometrical configuration of the modeled urban area

The whole calculation domain covers a dimension of 95m(X) ×70m(Y)×70m(Z), in which one block in upwind location with a scale of4m(X) × 4m(Y) × 4m(Z) is defined as fix burning surface (fire source),
exhibiting a constant heat release. The block in bigger size (10m(X) ×10m(Y)×16m(Z)) is positioned 1.0 m downstream from fire source and istreated as the prediction objective. The mesh system is in unstructured form,
with a total number of 140,669. For better prediction accuracy, extruded
mesh is created with a size of about 0.2m adjacent to block’s surface.
For convenience of the following examination to simulation results,
one Y=36m section in X-Z plane and three check points on the upwind wallof building block are defined, which can be referred to figure 3.
From previous investigations, in the case of wooden apartment fires,the average surface heat release rate is generally 1.5MW/m2. From equation(23)(Hayashi, 2002), the surface heat release rate can be converted into themass release rate of propane.
(23)
V=AQ/(ρC3H8×QC3H8)
Where, A – area, m2; Q – average surface heat release rate, 1.5
MW/m2; ρC3H8 – density of propane, 1.9kg/m3; QC3H8 – heat of combustionof propane, 4.646×107J/kg; V– presumed propane mass release rate, m3/s.
Hereby, the boundary condition of the fix burning surface is defined
as inlet, with a constant concentration 1.0 of propane, and fix velocity alongnormal direction Unormal=0.017m/s.
5.2 Boundary settings

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New Technologies for Urban Safety of Mega Cities in Asia

Table 2: Boundary conditions.

Inlet

Sky, Side-boundary
Wall
Burning surface

U=2.0m/s, V=W=0.0, T=293.0K
k=1.5×(I×U)2.0, I=0.1
ε=Cµk3/2/L, L=1.0m, Cµ=0.09
Free slip wall
Generalized log law
Unormal=0.017m/s, T=623.0K

The settings for each boundary are referred to table 2.
The principle of discretization is obtained by utilizing first-order
upwind scheme for convection term, while second-order central scheme forrest terms. The pressure and velocity coupling in CFD prediction isachieved by utilizing the SIMPLE algorithm. The program of wood
pyrolysis is solved in full implicit method
CFD simulation is performed on the commercial code STAR-CD(Version 3.24). For the coupled method solution, the time interval between
each time step is fixed at 10 seconds and totally 110 time steps calculation
has been carried out. The time intervals set for implicit solution of wood
pyrolysis is 0.1s.
For reasonable solution accuracy, a strict convergence criterion forresidual is specified as 10-4.

6. RESULT DISCUSSION
Simulation results created by supposed couple method are discussed
in this part. From the investigation, feasibility of the approach to fire spread
simulation for a modeled urban area is examined.
6.1 Temperature distribution

0s
20s
40s
60s
Figure4: Temperature distribution at each time stepin the Y=36m section (K)Application of a coupled simulation method for predicting fire spread in a modeled urban area545

October 2005, Singapore

0s

20s

40s

60s

Figure5: Temperature distribution in the upwind wall (K)The Y=36m vertical section locates in the X-Z plane along the centerline of the fire source. The temperature distributions of this section at
specified time step are demonstrated in figure 4. While figure 5 shows thetemperature change of the upwind wall of the building block at the sametime step.
At initial stage (time = 0s), gaseous propane runs out from the firesource (fix burning source) and starts to combust immediately, thus to heatup the local air where reaction occurs. The air with extremely hightemperature, appearing as fire flame, climbs up by buoyancy driven force
and is suppressed and inclines to leeward region from effect of urban windand hence embraces the upwind wall of the building block locating at thedownstream area. Observing the contour figure, the temperature of the core
part of flame is as high as over 1693K. Moreover, large part of thewindward side and rooftop of the building are found to be covered with hot
air with the temperature of over 800K. Hence, significant heat flux given
from fire flame to this region can be estimated.
Examining the surface temperature change from figure 5, the fire
growth in the upwind wall of the building block can be observed apparently.
From 20s, the area adjacent to flame exhausted from fix burn surface has
appeared began to be burning. Moreover, an expected expansion of theburning area has been reproduced from the result at 40s and 60s in Figure 5.
At 40s, about 30% of the upwind wall reaches pyrolysis stage, while at 60s
nearly half of the wall can be found burning.
Since material of the upwind wall began to pyrolyze and thus releasepropane, combustion reaction occurs at the region near to the wall. In figure
4, the temperature distribution from 20s changes as fire flame has been
exhausted from the block surface in downstream area. The high temperatureareas specified by red color increase gradually as time go on. At time step
equals to 60s, in lower part of the gap between the two buildings, flame withhigh temperature air can be observed
From this discussion, the fire spread behaviors are considered to be
reproduced.
6.2 Profiles at the check points

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New Technologies for Urban Safety of Mega Cities in Asia

1.7E+05

700

1.6E+05650

1.5E+05550

1.2E+05500

1.1E+05450

1.0E+05

400

Heat Transfer (W/m2)

1.3E+05

9.0E+04350

8.0E+04
7.0E+04300

6.0E+04250

5.0E+04200

4.0E+04150

3.0E+04

Temperature(K)600

1.4E+05100

2.0E+0450

1.0E+04
0.0E+00

0

10

20

30

40

Convective
Heat Transfer
Radiative
Heat Transfer

50

60

70

80

90

0
100 Time(s)Point1 Point2 Point3

Temperature

Figure6: Heat flux and surface temperature profiles at each checkpoint.

Figure 6 illustrates the comparison of incident radiation, convective
heat flux obtained in the three check points at each time step, as well as thesurface temperature profile. The definition of each check point can bereferred to figure 3.
Point 2 is located straightly behind the exhausting flame from fix
burning surface, which results into reasonable highest heat flux get among
the three points. At 20s, the heat flux obtained at point 2 is shown an
intensive increase; it is because the flame begins to be exhausted from its
adjacent area at this time step. Therefore, the surface temperature of point 2
climbs up quickly and reaches the pyrolysis temperature, thus ignition
occurs in local area at 30s. The location of point 1 and point 3 are not right
into the area embraced by flame from the fire source, the temperaturechange much slower than point 1.
In addition, for each check point, the incident radiation flux can befound far greater than the convective heat transfer. In case of point 1,
radiation flux get various in range of 4.5×104~1.6×105W/m2, while theconvective heat flux is averagely one order smaller than it. Therefore,
radiation flux given from fire source can be considered as the critical factor
to cause fire spread between the buildings.
7. CONCLUSION

In this research, a coupled method is supposed for the fire spread
simulation within urban district. In this approach, a combination of CFD
model, combustion model, radiation model, and wood pyrolysis model, isconsidered. The feasibility of the method is examined by conducting
validation simulation over a modeled urban area. From the prediction results,
a detailed temperature distribution, either at the surface or in fluid flow, andApplication of a coupled simulation method for predicting fire spread in a modeled urban area547

October 2005, Singapore

any other parameter data can be obtained, which proves urban fire and its
spread behaviors to be reproduced.
To discuss the prediction accuracy of the coupled method in this urban
fire spread simulation, a comparison between the simulation results and firetunnel experimental data or other investigation result of the real accidents
are taken into consideration in future research work.

REFERENCES

B. F. Magunussen, 1976, On mathematical modeling of turbulent
combustion with special emphasis on soot formation and combustion,
Proceedings 16th Symposium (International) on Combustion, 719-729.
Di Blasi, 1993, Modeling and simulation of combustion process of charringand non-charring solid fuels, Prog. Energy Combust Sci, 71-104.
EI Tahry, 1983, k-ε Equation for Compressible Reciprocating Engine Flows,
AIAA, J. Energy, 345-353.
Favre, A., 1969, Problem of hydrodynamics and continuum mechanics, Soc.
Indust. Appl. Mech., 231-266.
H. C. Kung, 1972, A Mathematical Model of Wood Pyrolysis, Combust.
Flame, 185-195.
H. Otake, 2004, Simulation of flames and thermal plume in urban fire underwindy condition, J. of Industrial Science Research, University ofTokyo, 11-16.
Quintiere, J. G., 1981, A simplified theory for generalizing results from aradiant panel rate of flame spread apparatus, Fire Mater., 5.
V. Novozhilov, B. Moghtaderi, D. F. Fletcher and J. H. Kent, 1996,
Computational fluid dynamics modeling of wood combustion, Fire
Safety Journal, 69-84.
V. Novozhilov, 2001, Computational fluid dynamics modeling ofcompartment fires, Prog. Energy Combust Sci, 611-666.
Y.Kudou, H.Hayasaka, 1999, Internal temperature distribution andcombustion characteristics of wood, The 36th national heat transfer
symposium (in Japanese)
Y.Hayashi, Y. Ohmiya, 2002, Study on flames and thermal plumes inducedby fires under windy condition. The 17th national symposium on windengineering (in Japanese), 173-184
Yan, Z. H., 1996, CFD experimental studies of room fire growth on wall
lining materials, Fire safety journal, 201-238.

548

New Technologies for Urban Safety of Mega Cities in Asia

PREDICTION OF URBAN HEAT ISLAND IN
TOKYO METROPOLITAN AREA IN 2020
YOICHI KAWAMOTO1 and RYOZO OOKA2
1
Graduate School of Engineering, the University of Tokyo, Japan
2
Institute of Industrial Science, the University of Tokyo, Japan
kwmt@iis.u-tokyo.ac.jp

ABSTRACTIn large cities in Japan, as exemplified by Tokyo, temperature
increases in summer due to urbanization, i.e. the urban heat island effect,
are becoming very serious. If no countermeasures are taken, it is likely thaturban heat islands will become ever more serious and prediction of theeffect of future urbanization on urban heat islands is necessary. On theother hand, three-dimensional meteorological meso-scale models are often
used to determine the mechanisms of urban heat islands. However it isnecessary to represent the properties of building canopies precisely in orderto analyze the spatial and temporal distribution of temperature in urban
environments. Therefore, in this paper, the urban thermal environment in
the Tokyo metropolitan area is analyzed and predicted by means of ameteorological meso-scale model based on the Mellor-Yamada model level2.5 with incorporation of an urban canopy model. In order to predict thestate of the Tokyo metropolitan area in 2020, firstly the authors estimate thetotal floor space based on the projected population. For analysis with ameteorological meso-scale model incorporating an urban canopy model,
details of the building conditions such as building density or building size
will have to be estimated. In the analysis targeted on the present (in 1997)
Tokyo metropolitan area, detailed data is provided with GIS (Geographic
Information System) data prepared by the Tokyo Metropolitan Government.
On the other hand, for the analyses targeted on the future (in 2020), there isno detailed data. Therefore, in this paper, five types of future urban
compositions are assumed. These five cases targeted on the future and one
targeted on the present are analyzed and evaluated. The case studies showthat different building conditions, despite having the same total floor space,
will affect the thermal environment differently.

1. INTRODUCTION
In large cities in Japan, as exemplified by Tokyo, urban heat islands
have become very serious problems. If no countermeasures are taken, it islikely that urban heat islands will become ever more serious and predictionof the effect of future urbanization on urban heat islands is necessary.
Therefore, in this paper, the urban thermal environment in the Tokyo
metropolitan area is analyzed and predicted by means of a meteorologicalmeso-scale model based on the Mellor-Yamada model level 2.5 (Mellor and549

October 2005, Singapore

Yamada, 1982) with incorporation of an urban canopy model (Ooka, 2004).
In order to predict the state of the Tokyo metropolitan area in 2020, firstly
the authors estimate the total floor space based on the projected population.
For analysis with a meteorological meso-scale model incorporating an urban
canopy model, details of the building conditions such as building density orbuilding size will have to be estimated. However, such future conditions are
not very apparent. Thus, the authors estimate the building conditions in2020 from the present building conditions and the prediction of the total
floor space increase in 2020.

2. OUTLINE OF FUTURE PREDICTION
It is predicted that the population in Tokyo’s 23 wards will increase
until 2010 as a reflection of the population concentration in the center of thecity in recent years, and gradually decrease afterwards (Figure 1, solid line).
The total floor space in these 23 wards is predicted based on this populationtransition. Ikaga (2000) has predicted that the floor space per person will
increase by 4 square meters for residential use and also by 4 square meters
for non-residential use from 1997 to 2020 in Japan (Figure 2). The authors
applied these prediction results to Tokyo’s 23 wards (Figure 1, dotted line).

Figure 1: Projected population and floor space in Tokyo’s 23 wards

Figure 2: Prediction of floor space per person in Japan (Ikaga, 2000)

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

In this paper, the thermal environment in the Tokyo metropolitan area
is analyzed with a meteorological meso-scale model incorporating an urban
canopy model. Therefore, the buildings’ compositions have to be estimated.
In the analysis targeted on the present (in 1997) Tokyo metropolitan area,
detailed data, e.g. building area, floor space, building height, building use
and land use, is provided with GIS (Geographic Information System) dataprepared by the Tokyo Metropolitan Government. On the other hand, for the
analyses targeted on the future (in 2020), there is no detailed data. Therefore,
the urban composition in the Tokyo metropolitan area in 2020 has to besupposed. In this paper, the following five types of future urban
compositions are assumed. Figure 3 shows the concepts for each case.
Case 0: Present
The building compositions expressed using GIS data prepared in 1997.
Case 1: Becoming multistory
The height of all buildings in Tokyo’s 23 wards increases according
to the increase in the total floor space.
Case 2: Overcrowded
The building area of all buildings in Tokyo’s 23 wards increases andother land use decreases according to the increase in the total floor space.
Case 3: Inner city concentration
Buildings in the center of Tokyo only become overcrowded, whilebuildings in other areas of Tokyo remain unchanged from present conditions.
Case 4: Towards uniformity
The size and density of buildings are assumed to be uniform
throughout Tokyo’s 23 wards.
Case 5: More high-rise and ground greening
The building area taken up by all buildings in Tokyo’s 23 wards ishalved and the height they become very high to reflect the increase in the
total floor space. Released land is greened.

Figure 3: Concept of case study

Prediction of Urban Heat Island in Tokyo Metropolitan Area in 2020551

October 2005, Singapore

3. SIMULATION MODEL
In the meso-scale analysis, which was originally developed to predictthe climate above the surface boundary layer, a one-dimensional heatbalance model is usually used for the ground boundary conditions. In thisconventional model, a roughness parameter is employed in order to present
the effect of the building complex. As the vertical grid size adjacent to theground surface must be made several times larger than the roughness length
in the conventional model, physical phenomena within the surface layer
cannot be estimated. Furthermore, the definition of surface temperature israther vague in the conventional model because its relationship with ground,roof and wall surface temperatures is unclear. Therefore, it is necessary toinclude the effect of the urban canopy precisely in order to analyze thethermal environment at pedestrian level in an urban area. On the other hand,the one-dimensional urban canopy model is also typically used to analyzeurban thermal environments (Kondo, 1998) (Ashie, 1999). Although thismodel can easily predict the thermal environment at pedestrian level, it is
not empowered to consider the effect of local climate due to the assumptionof a horizontally homogeneous flow and temperature field. Thus, theauthors have developed a new meteorological meso-scale model based on
the Mellor-Yamada model level 2.5 incorporating an urban canopy model(Ooka, 2004).
The following five factors relating to the building complex areincorporated into the meteorological meso-scale model; (1) wind reduction
by the building complex, (2) production of turbulence by the building
complex, (3) solar radiation heat transfer inside and outside of the building
complex, (4) long-wave radiation heat transfer inside and outside of thebuilding complex, and (5) sensible and latent heat transfer from the building
surface. Four factors related to the plant canopy are also incorporated into
the meteorological meso-scale model; (1) wind reduction by the plant
canopy, (2) production of turbulence by the plant canopy, (3) solar radiation
absorption by the plant canopy, and (4) transpiration from the plant canopy.
Figure 4 shows the concept figure of meteorological meso-scale model
incorporating the urban canopy model.

Figure 4: Concept figure of meteorological meso-scale model incorporating
the urban canopy model

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

4. OUTLINE OF ANALYSIS
4.1. Analysis domain
Figure 5 illustrates the analysis domain, which covers 480 km (eastwest) × 400 km (south-north) × 9.6 km (vertical direction). The wholeanalysis domain (Grid 1) is nested into three sub-domains; Grid 2, Grid 3
and Grid 4 as illustrated in Figure 5. Table 1 also summarizes the size andgrid discrimination of each domain.
Japan sea
(25℃)

Grid 1(8km)(25℃)

Grid 2(4km)(26℃)
Grid 3(2km)
Tokyo bay
(28℃)
Pacific ocean(27℃)

Grid 3(2km)

Grid 4(1km)Tokyo bay
(28℃)

Figure 5: Analysis domain

Grid 1
Grid 2
Grid 3
Grid 4

Table 1: Analysis domains and grid arrangements
Computational Domain
Horizontal Grid
Grid Number
Size [km][km]（x × y × z）
480 × 400 × 9.6
60 × 50 × 49
8
232 × 200 × 9.6
58 × 50 × 49
4
96 × 96 × 9.6
48 × 48 × 49
2
40 × 40 × 9.6
40 × 40 × 49
1

4.2. Meteorological Meso-scale Model
The Mellor-Yamada model level 2.5 is employed for meteorologicalmeso-scale analysis in this paper. The urban canopy model described above
is incorporated into this analysis.
4.3. Analysis Condition
In this paper, analysis is conducted for the thermal environment on
July 24th, which represents a typical summer meteorological situation. The
simulations are started from 6:00 a.m. on July 23rd, and time integration is
performed for 42 hours. The initial wind direction and velocity are set southerly
2.0 m/s at a height of 9.6 km from the ground surface in the whole
computational domain. Here, the ground surface is classified into 10 types ofland-use, and surface parameters, such as albedo, roughness length Z0, heat
capacity, and moisture availability β are set individually following the landuse conditions.

Prediction of Urban Heat Island in Tokyo Metropolitan Area in 2020553

October 2005, Singapore

Table 2: Surface parameter
Moisture
Roughness
Land Use
Albedoavailability
length [m]Rice paddy

0.5

0.20

0.05

Farming

0.3

0.10

0.01

Orchard

0.3

0.20

0.05

Forest

0.3

0.15

0.05

Park

0.3

0.10

0.01

Vacant land

0.3

0.20

0.01

Buildings

0.0

0.10

0.05

Paved Road

0.0

0.10

0.01

Other land

0.0

0.10

0.01

Water site

1.0

0.03

0.001

5. RESULTS AND DISCUSSION
Figure 6 shows the horizontal distribution of air temperature and windvelocity of the analytical results of case 0 (present) at a height of 2 meters
above the ground surface. The time is set as 13:00 hours. The domain for
the evaluation is Grid 4; which has a horizontal mesh size of 1 km. In
addition, an aerial photograph of the Tokyo metropolitan area, covering thesame domain as the analytical domain Grid 4, is also shown. In theanalytical results, the sea breeze blowing in from Tokyo bay can be
represented. In terms of the air temperature distribution, the temperature risein the northwest of Tokyo is represented, whereas conversely, the airtemperature decrease near big rivers and large open green spaces isrepresented too. Such a tendency shows good agreement with observation
data on a typical summer’s day by AMeDAS (Automated Meteorological
Data Acquisition System), as recorded by the Japan Meteorological Agency.
Figure 7 shows a comparison of air temperature of analysis and observation.
35

Nerima34

Large open
green space

33
32
31
30

Otemachi

Big rivers
Average in Tokyo 23 wards: 32.82°Ca) Wind velocity and temperature(July 24th 13:00, 2m height)b) Aerial photograph

Figure 6: Analytical result and aerial photograph (Grid4)

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ICUS Report 11

analysis result
AMeDAS (mean value of fine days)
35

Air Temperature [°C]

Air Temperature [°C]

35
33
31
29
27
25
0

4

8

12

16

20

24

33
31
29
27
25
0

4

8

12

Time [h]Time [h]a) Otemachib) Nerima

16

20

24

Figure 7: Comparison of air temperature of analysis resultand AMeDAS observation data
Figure 8 shows the air temperature differences between the analyticalresults of Cases 1-5 in 2020 and Case 0, as the present situation. In Case 1,
which assumes more multistory buildings, as the buildings are higher, thesky view factor from ground level is reduced and short- and long-wave
radiation directed at the ground is further interrupted by the buildings. As aresult, the air temperature in Case 1 decreases throughout the whole area
compared with that in Case 0. In Case 2, the overcrowded scenario, the airtemperature rises in the whole area due to decreased wind velocity near the
ground surface because of the increase in resistance from buildings. In Case
3 where buildings are concentrated in the center, there are two large
domains where the air temperature increases and decreases. In the center ofTokyo, the concentration area, the air temperature decreases by 2.5°C at
most at 13:00 hours compared with the present situation. However, thetemperature rises on the leeward side, and this high temperature range
extends as far as Saitama Prefecture. In Case 4, with buildings arranged
uniformly throughout Tokyo’s 23 wards, the air temperature rises in thecenter of Tokyo, but on the other side, it decreases in other districts. As aresult, the overall difference in temperature is small. In Case 5, whichfeatures a transition to high-rises and ground greening, the air temperature at
ground level falls significantly because of the greater radiation interruption
by the plant canopies.

6. CONCLUSIONS
1) The total floor space in Tokyo’s 23 wards in 2020 has been predictedbased on population projections.
2) Case studies into the progress of the heat island phenomenon in 2020
were conducted.
3) The case studies show that different building conditions, despite having
the same total floor space, will affect the thermal environment
differently.

Prediction of Urban Heat Island in Tokyo Metropolitan Area in 2020555

October 2005, Singapore

≦+2

≦+1

≦+0.5

≧-0.5

≦+2
≦+1
≧-0.5

≦+0.5
Average in Tokyo 23 wards: -0.10°C

Average in Tokyo 23 wards: +0.20°Ca) Case1 (Multistory)b) Case2 (Overcrowded)

≦+0.5
≦+1.5
≧-3
≦+1

≧-2
≧-0.5
≦+0.5
≧-0.5

Average in Tokyo 23 wards: +0.01°C

Average in Tokyo 23 wards: -0.05°Cc) Case3 (Concentrated)d) Case4 (uniform)

≧-2

≧-3
≧-2
≧-1
≦+0.5
Average in Tokyo 23 wards: -1.44°Ce) Case5 (High-rise + Greening)f) Map aroundthe Tokyo Metropolitan Area

Figure 8: Distribution of temperature change (July 24th 13:00, 2m height)

REFERENCES
Ashie, Y., V. T. Ca and T. Asaeda, 1999, Building canopy model for the
analysis of urban climate, Journal of Wind Engineering and Industrial
Aerodynamics, Vol. 81, 237-248
George L. Mellor and Tetsuji Yamada, 1982, Development of a Turbulence
Closure Model for Geophysical Fluid Problems, Reviews ofGeophysics and Space Physics, Vol.20, No.4, 851-875

556

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Ikaga, T., Murakami, S., Kato, S. and Shiraishi, Y., 2000, Estimation of CO2
emission associated with building construction and operation till 2050
in Japan, Journal of Architecture, Planning and Environmental
Engineering, NO.535, 53-58
Kondo, H. and F. Liu, 1998, A study on the urban thermal environment
obtained through one-dimensional urban canopy model, Journal ofJapan Society of Atmospheric Environment, 33 (3), 179-192
Ooka, R., Harayama, K., Murakami, S. and Kondo, H., 2004, Study on
Urban Heat Islands in Tokyo Metropolitan Area Using a
Meteorological Mesoscale Model Incorporating an Urban Canopy
Model, The 5th Symposium on the Urban Environment, 9.15

Prediction of Urban Heat Island in Tokyo Metropolitan Area in 2020557

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558

New Technologies for Urban Safety of Mega Cities in Asia

OPTIMAL DESIGN OF SMOKE CONTROLSYSTEM IN ROOM FIRE USING CFD AND
GENETIC ALGORITHMS
HONG HUANG, RYOZO OOKA, SHINSUKE KATO, HONG CHEN
Institute of Industrial Science, The University of Tokyo, Japanhhong@iis.u-tokyo.ac.jp
ABSTRACTIn fire-prevention designs for buildings, the major concerns are
ensuring safe evacuation in the event of a fire and preventing the fire fromspreading. On the other hand, improving the degree of design freedom andreducing costs are also expected. In recent years, research into the optimal
design in the fields of building construction and building environments hasapparently increased. It is thought that a similar optimization approach
could also be applied to building designs for fire prevention. In thisresearch, the vestibule pressurization smoke control system in an officeroom is optimized using a coupled approach of Computational Fluid
Dynamics (CFD) and Genetic Algorithms (GA). The design parameters
include the locations and sizes of the smoke extraction, and the air supply
vents are selected using GA to maximize the airflow rate through thedoorway of the vestibule, which would ensure that the smoke does not
escape to the vestibule during evacuation. The fire-driven flow
characteristics are simulated by the Fire Dynamics Simulator (FDS)(developed by the National Institute for Standards and Technology (NIST))
which is based on the fundamental conservation of heat, momentum andmass using a Large Eddy Simulation (LES) method.
1. INTRODUCTION
Preventing smoke from entering a stair shaft is very import in smoke control
design. One approach is by pressurizing the stair shaft or the vestibule
adjacent to the stair shaft with outdoor air. Thus, there are basically two
types of pressurized smoke-control systems. One is a stair pressurization
system, the other a vestibule pressurization system. While the stairpressurization system is common in the United States and Canada, thevestibule pressurization system is now popular in Japan. In this study, thevestibule pressurization system will be discussed. For the system, the air
supply rate necessary to maintain a sufficent pressure differential is usually
determined using a zone model (Matsushita et al., 1998) or some simplified
calculation method (Kujime et al., 2000). However, it is difficult to specify
a detailed design of the system, for example, the sizes and locations of the
air supply vents, using these methods. Therefore, the possibility exists thatsmoke may flow into the vestibule or stairwell in local areas even if thenecessary air supply rate is satisfied. With the rapid developments made incomputational fluid dynamics (CFD), it is now possible to analysis thethree-dimensional distribution of velocity, temperature, pressure and so on.

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CFD affords us a fine tool to analyze the aforementioned problem.
Meanwhile, there is no doubt that an optimized design for a smoke control
system is expected.
In recent years, research into optimal designs in the fields ofbuilding construction and building environments has apparently increased.
A coupled approach using Computational Fluid Dynamics (CFD) and
Genetic Algorithms (GA) has been attempted in HVAC design (Kato et al.,2004) and outdoor thermal environment design (Chen et al., 2004). It isthought that a similar optimization approach could also be applied tobuilding designs for fire prevention. In this research, the smoke control
system for an office room is optimized with a coupled approach using
Computational Fluid Dynamics (CFD) and Genetic Algorithms (GA).
2. OPTIMIZATION SYSTEM COUPLING GA AND CFD FOR
SMOKE CONTROL SYSTEM DESIGN
2.1 Optimization system
The optimization system coupling GA and CFD for smoke control
design, which is based on a feedback system (Kim et al., 2002, Chen et al.,2004), is shown in Fig. 1. This system is comprised of three parts: A.
Setting optimal problem; B. CFD analysis of fire dynamics, C: Evaluationof smoke control system and optimal process control. In part A, the design
objective and design parameters are determined. Meanwhile, theoptimization method and the evaluation method for optimal design aredetermined. In part B, CFD analysis is conducted to provide spatial andtemporary distribution of the variables of interest of fire evolution. In part C,
if the optimum solution satisfies the design objective, the results are
obtained. If it doesn’t satisfy the design objective, the design parameters
will be selected by GA and fed back to the CFD analysis for the next
evaluation. The feedback loop will continue until the optimum solution
satisfies the design objective.
A. Setting Optimal Problem

B. CFD Analysis

Design Objective
Maximum airflow rate
through door, maximum
pressure difference, et al.

Input data
Design parameters,boundary conditions, firesize, and so on.

C. Evaluation and Control

Design Parameters
Size of supply vent,location of supply vent, air
supply velocity, et al.

CFD simulation
RANS, LES, and so on

Optimization method
GA, SA, et al.

Simulation results
Velocity, temperature,and so on

Change of Design Parameters
Feedback

Selecting Design Parameters
using GA
Not satisfy the design objective

Evaluation Method of Smoke
Control System for Optimal
DesignEvaluation of the System
Satisfy the design objective

Optimal Design Results

Figure 1. Optimal design system coupling GA and CFD for smoke control design

2.2 Two-step optimal design process

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In generally, theFirst Step Design
feedback loop in Fig. 1
Setting Optimal Problem
Simplified CFD Analysis
will be one thousand or
Design Objective
Coarse mesh, steady state
condition, et al.
more. If a detailed
Design Parameters
CFD
analysisis
Optimization method
Selecting Design
conducted in every
Parametersloop, it will impose a
Evaluation Method of Smoke
using GA
Control System for Optimal
highcomputational
Designload, as well as take
First Step Optimal
Design Results
much time. In this
Detailed CFD Analysis
study,atwo-step
Case 1Case 2Fine mesh, transient
optimization process iscondition, et al.
Case 3…
used (Kim et al., 2002;
Optimum 1
Optimum 2
Chen et al., 2004) toSecond Step Optimal
reduce the calculation
Optimum 3…
Design Resultsload and time taken to
Second Step DesignfindtheoptimalFigure 2. Two step optimal design method
solution. Fig. 2 shows
the process. In the first-step design, a simplified CFD analysis using acoarse mesh is conducted out of consideration for the calculation load. The
high ranking solutions from the first step optimal design results will beselected as candidates for the second step design. In the second step design,a detailed CFD analysis using a fine mesh is conducted only for the highrank solutions. Finally, the optimum solution is obtained.
2.3 CFD simulation
CFD modeling has been successfully applied to various fire safety
problems, and its role in fire research is steadily increasing as the models
progressively become more robust and sophisticated, and validation studies
render them more reliable (Novozhilov, 2001). CFD models are naturallyclassified based on the methods by which they treat turbulence phenomena.
The two major groups may be identified as Reynolds Averaged NavierStokes (RANS) models and Large Eddy Simulation (LES) models. In thisstudy, the fire-driven flow characteristics are simulated by the Fire
Dynamics Simulator (FDS) (developed by the National Institute forStandards and Technology (NIST)) which is based on the fundamental
conservation of heat, momentum and mass using a LES method (McGrattan
et al., 2004). FDS is now a well-used tool for solving practical fire problems
in fire protection engineering and in the study of fundamental fire dynamics
and combustion.
3. APPLICATION OF THE OPTIMAL DESIGN SYSTEM ON
VESTIBULE PRESSURIZATION SYSTEM DESIGN
3.1 Design object
The design object is shown in Fig. 3. This is a simplified officebuilding with 10 stories. The office is of length 10 m, width 10 m and height
2.5 m, and an adjacent corridor is of length 8.0 m, width 3.0 m and height

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4.0m

StairsFire

Window

2.0m

1.5m

6.0m

Corridor

Elevator

B
A

0.25m

Office room

Y

4.0m

2.0m

Vestibule

2.0m

1.0m

Elevator

X
3.0m

3.0m

10.0m

Figure 3. The design object

2.5 m. The office has a doorway of width 1.5 m and height 2.0 m opening
into the corridor. A vestibule, which has two doorways opening to thecorridor and the stairs, is provided. The heights of the doorways are 2.0 m.
The smoke control system consists of smoke extraction from the office anda pressurization process through the vestibule. The vestibule is pressurizedwith outdoor air using a supply air fan to prevent smoke from entering thevestibule and the stairwell.
3.2 Design objective
As has already been mentioned, the air supply rate necessary tomaintain a sufficent pressure differential is usually determined using thezone model (Matsushita et al., 1998) or some simplified calculation method(Kujime et al., 2000). However, it is difficult to specify a detailed design ofthe system, for example, the sizes and locations of the air supply vents,using these methods. Therefore, the possibility exists that the smoke may
flow into the vestibule or stairwell in local areas even if the necessary air
supply rate is satisfied. In this study, the average airflow rate through thedoorway between the vestibule and the corridor during the evacuation timeis selected as the design objective. The design parameters are selected using
GA to maximize the airflow rate during evacuation, which would ensurethat the smoke does not escape to the vestibule. That is, at the same time, nobackward wind occurs through the doorway.
3.3 Design parameters
The air supply rate is set at a constant 4.17 m3 /s based on thecalculations of Kujime et al. (2000) and Matsushita et al. (1998). Usually,
air is also supplied from the elevator shaft, but the airflow from the elevatoris assumed to be zero for simplicity because such air is minimal comparedto that from the vestibule. Patterns of smoke extraction vents and air supply
vents are shown in Figs. 4-6. The locations and sizes are changed. In the562

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Pattern 1

Pattern 2

Pattern 3

Pattern 4

Pattern 5

Figure 4. Patterns of smoke extraction vents

Pattern 1

Pattern 2

Pattern 3

Pattern 4

Pattern 5

Pattern 6

Pattern 7

Pattern 8

Figure 5. Patterns of air supply vents (facing the doorway and side wall)

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Pattern 1

Pattern 2

Pattern 3

Pattern 4

Pattern 5

Pattern 6

Pattern 7

Pattern 8

Figure 6. Patterns of air supply vents (ceiling)vestibule, the vents are assumed to be a combination of vents in the ceiling,
the straight wall facing the doorway or the side wall adjacent to the stairs.
3.4 Fire scenario
The fire scenario is important in smoke control system design. The
following fire scenario is assumed here. The fire size is set to be 1.0 m ×1.0
m in the middle of the office. The fire was quantified by assuming a fast t2
fire. That is, Q = at2. This assumption is reasonable for an office. A and the
maximum heat release rate are set to be 0.015 and 500 kW respectively(Ikehata et al., 2004). The smoke control system starts 20 minutes after thefire starts. The window is also assumed to be open 20 minutes later. Smoke
extraction will stop if the temperature of the smoke entering the duct ishigher than 280°C. The doorway adjacent to the stairs in the vestibule isopen.
3.5 Evacuation time
Evacuation generally consists of three stages: burning room
evacuation, burning story evacuation and whole building evacuation. The
evacuation time for this office building is calculated based on thefundamental theory of evacuation (Tanaka, 1993). The result is shown in
Fig. 7. The evacuation time for the fire story is 48.5 s, and for the wholebuilding is 208.5 s.
20 s

Evacuation start of officeEvacuation of office
Arrival in vestibule
Arrival at stairs
Evacuation start for other stories
Arrival at stairs for other stories

20 s = 2×sqrt (10×10)
40 s
46 s
48.5 s
40 s

20 s = max (20m/1.0m/s, 25 people(p)/(1.5p/ms×1.5m)
6 s = 6m/1.0m/s
2.5 s = 2.5m/1.0m/s
40 s = 20s × 2
68.5 s68.5 s = 40s + 28.5s
208.5s

Evacuation time stair in stair
208.5 s = 68.5s + 10 × 3.5m/0.25m/s

Figure 7. Calculation of evacuation time564

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Table 1. Setting the multi-island GA
Size of Sub-Population
10
Number of Islands
5
Number of Generations
20
Total Individual Size
1000 (10×5×20)
Rate of Crossover
0.5
Rate of Mutation
0.02
Rate of Migration
0.5
Rate of Tournament
0.4Interval of Migration
4

3.6 GA method
Genetic algorithms (GA) are used to select the optimum solution
candidates, and control of the optimum inquiry process. GA is a method
which solves the optimization problem by imitating the organic evolutionary
process. Here, the optimum solution candidate, which is called an“Individual”, is considered to be a living entity. As with organic evolution,
the individual’s information is described by the sign row called“Chromosome”, and matches the individual and the chromosome one to one.
GA performs the genetic operations – such as the selection, crossover, andmutations – on the chromosome of each individual, and the fitness(objective function) of each individual is calculated to evaluate them. The
individual with the highest fitness value among all the inquired individuals
becomes the optimum individual (Chen et al., 2004).
Moreover, a more efficient Genetic Algorithm, which is called the“Multi-island Genetic Algorithm”, is used in this research. The method is a
distributed genetic algorithm. The feature of this method is that the
population in one generation is divided into several sub-populations, and thegenetic operations are performed independently in each sub-population. An
exchange of individual information called “migration” is performed
periodically between sub-populations. Therefore, the procedure for GA
operations in this research is actually performed as follows. First, the initial
population (the first generation) is determined randomly as an initial value.
Next, fitness is calculated respectively using FDS simulation. Individuals
with the highest ranking fitness are selected from the entire population
based on the selection rate set by the designer. The GA operations such as
simple crossover or mutation are performed at random for selectedindividuals according to the crossover rate or mutation rate that has been set.
The offspring (individuals) of the next generation are produced by the above
operations, and these operations are repeated. During multi-island GA, theexchange between individuals – called migration – is performed between
each island based on a migration interval. Each island of migration isdecided at random, and individuals are exchanged between predeterminedislands according to the migration rate. The above process is repeated, andthe optimum inquiry is performed for the number of generations set by thedesigner. The parameters in this study are shown in Table 1.
4. RESULTS

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4.1 First step selection
The curve of GA
selection in the first stepby multi-island GA and
CFD are shown in Figure
8. It can be seen that the
maximum airflow throughthe doorway converges atabout 2.5 m3/s. Some
values higher than 2.5
m3/s are shown, but these

First
step

Secondstep

Case
Extraction
Vestibuleceiling
Vestibulestraight
Vestibulelatteral
Total airflow (m3/s)
Total airflow (m3/s)

Figure 8. Curve of GA selection

Table 2. Results of the two-step selection
1
2
3
4
4
4
2
3

5
3

6
1

5

-

-

-

5

5

-

4

4

4

-

-

-

-

-

-

-

-

2.525

2.516

2.512

2.510

2.508

2.504

2.482

Penalty

Penalty

Penalty

2.442

2.449

also exhibit a backward flow through the doorway. The results of the top six
cases are shown in Table 2. The best one is the combination of pattern 4(see Fig. 4) for the smoke extraction vent and pattern 5 (see Fig. 6) at thevestibule ceiling for the pressurization vent. The top six cases in the firststep are selected for a detailed CFD analysis using a fine mesh in the second
step.
4.2 Second step selection
The results of the detailed CFD analysis in the second step are also
shown in Table 2. It is found that a backward flow exists through the
2.5

2.5

B

A
2.0

2.0

case 1case 6case 1case 6

1.5

Z (m)

Z (m)

1.5
1.0

1.0

0.5

0.5
0.0

0.0
0.0

1.0

2.0
U (m/s)

3.0

0.0

1.0

2.0
3.0
U (m/s)4.0

Figure 9. X-axis velocity at site A and B in the vertical direction
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doorway near the bottom in Cases 2, 3 and 4, and consequently these cases
are exempted. The final top three cases are Cases 1, 6 and 5. The maximum
airflow through the doorway of the vestibule is 2.482 m3/s. Because the total
air supply rate is 4.17 m3/s, it is clear that some air flows to the stairwell
through the open doorway adjacent to the stairs. Figures 8 and 9 show theX-axis velocity at site A and B (see Fig. 3) for Cases 1 and 6. The velocity
at the lower part is higher than the higher part because the air is supplied
from the ceiling. Some tendencies can be found that for extraction vents, thesquare pattern is better than rectangular; for pressurization vents, ceilingvents are better. The results are a little different from the first step due to the
influence of the grid resolution. But the 2-step selection method used here is
still an effective approach for determining the optimal design bearing in
mind the computational costs.
5. CONCLUSIONSIn this research, the vestibule pressurized smoke-control system in an
office is optimized with a coupled approach using Computational Fluid
Dynamics (CFD) and Genetic Algorithms (GA). The 2-step selection
approach is used here. The result of the second step is a little different fromthe first step due to the influence of the grid resolution. However, the 2-step
selection method used here is still an effective approach for determining the
optimal design bearing in mind the computational costs.
Fire inevitably involves many uncertainties, such as, the site of the fire,
whether the window is open or not, and so on. The optimal design shouldhave considerable reliability in cases where such uncertainties exist.
Therefore, a reliable optimal design based on a reliability analysis will be
performed in future work.

REFERENCES
Chen, H., Ooka, R. and Kato, S., 2003. Study on design methods forpleasant outdoor thermal environment using Genetic Algorithms (GA)and coupled simulation of convection, radiation and conduction,
Optimum arrangement of trees for design of pleasant outdoor thermal
environment, J. Archi. Plann. Environ. Eng. AIJ, 576, 65-71.
Kato, S. and Lee, J. H., 2004. Optimization of hybrid air-conditioning
system with natural ventilation by GA and CFD, 25th AIVC
Conference, Ventilation and Retrofitting.
Kim, T., Kato, S. and Murakami, S., 2001. Two step optimal design methodof indoor thermal environment based on CFD simulation and Genetic
Algorithm, Summaries of Technical Papers of Annual Meeting
Architectural Institute of Japan, D2, 771-772.
Kim, T., Kato, S. and Murakami, S., 2002. Optimal design method of indoor
thermal environment based on CFD simulation and Genetic Algorithm,
Part 1, Development of prototype of optimal design method,
Transactions of the Society of Heating, Air-Conditioning and SanitaryEngineers of Japan, 84, 53-60.
Kujime, M., Matsushita, T. and Tanaka, T., 2000. Hand Calculation method

Optimal Design Of Smoke Control System In Room Fire Using CFD And Genetic Algorithms

567

October 2005, Singapore

for air supply rates in vestibule pressurization smoke control system, J.
Archi. Plann. Environ. Eng. AIJ, 511, 1-8.
Ikehata, Y., 2004. Design fires for means of egress in office buildings,
Summaries of Technical Papers of Annual Meeting Architectural
Institute of Japan, A-2, 113-114.
Matsushita, T., Kujime, M., Takano, K., Kanatani, Y. and Tanaka, T., 1998.
Calculation method of air supply rate in vestibule pressurization
smoke control system for office building, Part 3: Calculation bycomputer model of smoke movement prediction. Summaries ofTechnical Papers of Annual Meeting Architectural Institute of Japan,
167-168.
McGrattan, K. and Forney, G., 2004. Fire Dynamics Simulation (version 4)
User’s Guide, National Institute of Standards and Technology.
Novolzhilov, V., 2001. Computational fluid dynamics modelling ofcompartment fires, Progress in energy and combustion science, 27,
611-666.
Tanaka, T., 1993. Fundamental of building fire safety engineering, Building
Center of Japan.

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STUDY ON THERMAL EVALUATIONOF HOT OUTDOOR ENVIRONMENTUSING 2-NODE MODEL AND PHS MODELSHINSUKE SAWASAKI 1, RYOZO OOKA 2,
TOMONORI SAKOI 3 and KAZUYO TSUZUKI 3
1
Graduate School of Engineering, The University of Tokyo, Japan
2
Institute of Industrial Science, The University of Tokyo, Japan
3
National Institute of Advanced Industrial Science and Technology, Japan
sawasaki@iis.u-tokyo.ac.jp

ABSTRACT
There is extended potential for serious mishaps like “HeatDisorder” arising in the harsh hot outdoor environment during summer. An
appropriate thermal index is required in order to evaluate the risk of such
accidents. There are two major human thermal regulation models, i.e. the2-Node Model (2NM) in SET* and Predicted Heat Strain Model (PHSModel) for evaluation of the thermal environment. However, these models
were developed for the indoor or labor environment, and it is not clear
whether these are applicable to Japanese people in a hot outdoor
environment. Furthermore, there are no popular indices with which toevaluate tolerance or safety. The purpose of this study is the development of
an index for hot outdoor environment. For the initial investigation, subject
experiments are performed in a laboratory to better comprehend thephysiological response of the human body to heat. The results are comparedwith the computed values from the 2NM and PHS Model. The computed coretemperatures of both models accommodate the experimental values in allcases. As for skin temperature and water evaporation, the computed values
from 2NM accommodate the experimental values in resting cases, while the
PHS Model value accommodates the experimental values from exercise on atreadmill. Furthermore, the applicability of these models to hot outdoor
thermal environment is considered.

1. INTRODUCTION
There is extended potential for serious mishaps like “HeatDisorder” arising in the harsh hot outdoor environment during summer. An

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appropriate thermal index is required in order to evaluate the risk of such
accidents. There are two major human thermal regulation models, i.e. the2-Node Model (2NM) in SET* and Predicted Heat Strain Model (PHSModel) for evaluation of the thermal environment. However, these models
are developed for the indoor environment, and it is not clear whether these
are applicable to Japanese people in a hot outdoor environment.
Furthermore, there are no popular indices with which to evaluate toleranceor safety.
The purpose of this study is the development of an index for hot
outdoor environment. For the initial investigation, subject experiments are
performed in a laboratory to better comprehend the physiological responseof the human body to heat. The results are compared with the computed
values from the 2NM and PHS Model.

2. Subject Experiment2.1. Outline
Fig. 1 shows the setup for the experiment, while Table 1 presents anoutline of the subject experiment. This experiment is performed in a test
chamber whose air temperature and relative humidity can be arbitrarily
controlled. The subject persons rested for over 60 minutes in an anteriorroom, then remained for 60 minutes (or 30 minutes) in the test chamber.
During the test-chamber period, all physiological factors were measured anddeclarations of psychological factors were accepted.

Figure 1: Setup for the Subject Experiment
Table 1: Outline of Subject ExperimentTime

From 29 November to 20 December 2004

Place

Ultimate Environment Test Chamber, I.I.S., The University of Tokyo

Subject University students (5 men and 4 women in healthy condition)
Case

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4 cases per subject

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2.2. Measurement Factors
Table 2 presents the measurement factors. Core temperature ismeasured as the tympanic temperature using infrared radiation. Mean skintemperature is calculated from 8 skin temperature sensors on the forehead,right back, left upper chest, right upper arm, left lower arm, left hand, rightanterior thigh and left calf by weight averaging based on ISO 9886. Water
evaporation is calculated from the change of weight determined by anaccurate weight scale.
Table 2: Measurement Factors

Psychologicalfactors

Physiologicalfactors

Environmental
factors

FactorAirtemperatureWalltemperature
Relative
humidity

Equipment

Place

Thermocouple
thermometer

0.7, 1.1 & 1.7 meters
above floor
4 wall surfaces,
16 points

AssmanpsychrometerHot-wire
Air velocity
anemometerCore
Infrared clinicaltemperaturethermometer
Skin
Thermocouple
temperaturethermometer
Accurate
Evaporative rate
weight scale
Personal
thermal state
Declarations
Personalof him/herself
comfort state
Personal
tolerance

Interval

1 min.

1.1 meters above floor
1.1 meters above floor
Tympanic membrane

5 min.

8 points

1 min.
–

5 min.

–

5 min.

2.3. Experimental Conditions
Table 6 shows the conditions of each case. Case 0 is the standard
case, and Cases 1, 2 and 3 are those that evaluate the effect of activity, airtemperature and relative humidity respectively. In Case 2, the subjects walkon a treadmill at a speed of 0.9 [m/s] (equivalent of 2.0 met), but stop forabout 20 seconds when mounting the weight scale. The same preparedclothes are worn, namely a white tee shirt and white short pants. For thesafety of the subjects, the experimental span for Case 1 was shortened to 30
minutes.

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Table 6: Experimental Conditions

Experimental
conditions

Case

0

1

2

3

Air Temperature [°C]

35.7

35.7

39.4

35.7

MRT [°C]

35.7

35.7

39.4

35.7

Relative humidity [%]

46.4

46.4

51.9

72.5

Subject
conditions

Air Velocity [m/s]Metabolic rate [met]

0.16
1.0

1.9

1.0

1.0

(at rest)(treadmill)(at rest)(at rest)

39.2

38.3

Clothing Insulation [clo]SET* [°C]

0.3
34.0

33.4

3. Experimental Results
3.1. Transitions in Core Temperatures
Fig. 2 shows the transitions of core temperature. The value of eachcase is the average for all subjects, and the vertical lines on the locus ofCase 0 indicate the standard deviations. In all cases, the core temperaturerose by about 0.5°C in the first 15 minutes, and then tended to stabilize. The
standard deviation was about 0.2°C.
3.2. Transitions in Mean Skin Temperatures
Fig. 3 shows the transactions of mean skin temperatures. In allcases, the mean skin temperature rose by about 2.0°C in the first 10 minutes.
In Cases 0, 2 and 3 under low metabolism, the mean skin temperature kept
on rising slowly. On the other hand, it began to decrease after a peak at 15
minutes in Case 1 under high metabolism. The standard deviation was about
0.6°C.
3.3. Cumulative Water Evaporation
Fig. 4 shows the amount of weight reduction, i.e. the cumulative
amount of water evaporation. It increases linearly in all cases. And thegradient in Case 1 is more than twice those of the other cases. The standard
deviation was about 0.03 [kg/m2] after 60 minutes.

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Core Temperature [°C]37.4
Case 0Case 2

37.2

Case 1Case 3

37.0
36.8
36.6
36.4
36.2
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Figure 2: Transitions of Core Temperatures

Skin Temperature [°C]

36.5
36.0
35.5
35.0
34.5
34.0

Case 0Case 2

33.5

Case 1Case 3

33.0
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

55

60

Figure 3: Transitions of Skin Temperatures

Evaporation ［kg/m2]

0.14
Case 0Case 1Case 2
Case 3

0.12
0.10
0.08
0.06
0.04
0.02
0.00
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

Figure 4: Cumulative Water Evaporation

4. Comparison between the Experimental and Computed Values
4.1. Outline of 2-node model
The 2-Node Model (2NM) was proposed by A. P. Gagge et al. forthe calculation of SET* and so on. 2NM assumes that the human body iscomposed of two nodes, i.e. a central core and a skin shell, and calculates
the thermal balance respectively. The physiological response of sweating is
also built into this model, which might be more relevant in a hotenvironment. Thus 2NM is thought to be a reliable model for hot
environment. However, 2NM was developed for indoor environments, and it
is not clear whether it can be applied to hot outdoor environment.

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4.2. Outline of Predicted Heat Strain Model
Predicted Heat Strain Model (PHS Model) was proposed by
J. Malchaire et al. for evaluation of hot labor environments, and is being
discussed for incorporation in revisions to ISO 7933. The PHS Model
predicts transitions in core temperatures with consideration of the required
evaporative rate to maintain a steady thermal equilibrium, the response
characteristic of evaporation, and thermal storage of the skin. Even though
the PHS Model is developed based on a large number of subject
experiments, it is aimed at labor conditions. Additionally, it is not clear
whether a model developed in Europe can be applied to Japanese people in
hot outdoor urban environments because of the differences in evaporative
characteristics, physical attributes and climate.

4.3. Computational Conditions
Table 7 presents the preset values for both models. Concerning the
PHS Model, two cases are computed on the basis of correspondence to 2NM,
i.e. PHS Model (33.7) and PHS Model (34.1). Other conditions are inaccordance with the experimental conditions presented in Table 6.
Table 7: Computational Conditions
2NM

PHS (33.7)

Weight70 [kg]

Surface area

1.8 [m2]

Initial coretemperature

36.8 [°C]

Initial skintemperature
Convective heattransfer coefficient33.7 [°C]
Seated:hc = 3.1 (0< Vair <0.2)
Treadmill:
hc = 6.5 Vtreadmill0.39

PHS (34.1)

34.1 [°C]
Maximal value of:hc = 2.38 (Tsk - Ta)0.25
hc = 3.5 + 5.2 Vair
hc = 8.7 Vair0.6

5. Comparison Results
5.1. Comparison of Core Temperatures
Figs. 5 to 8 present a comparison of the core temperatures in eachcase respectively. Along with Section 3, the experimental values of each574

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Core Temperature [°C]case are the average of all subjects, and the standard deviations are indicatedas vertical lines on the experimental locus. Even though the computed value
for 2NM is about 0.2°C higher than for the PHS Model after 60 minutes inCases 2 and 3, both models follow approximately the same excursion andcorrespond well to experimental values in all cases.

37.4
ExperimentPHS(33.7)

37.2

2NM
PHS(34.1)

37.0
36.8
36.6
36.4
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Core Temperature [°C]

Figure 5: Comparison of Core Temperature (Case 0)
37.4
37.2
37.0
36.8
ExperimentPHS(33.7)

36.6

2NM
PHS(34.1)

36.4
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Core Temperature [°C]

Figure 6: Comparison of Core Temperature (Case 1)
37.4
ExperimentPHS(33.7)

37.2

2NM
PHS(34.1)

37.0
36.8
36.6
36.4
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Core Temperature [°C]

Figure 7: Comparison of Core Temperature (Case 2)
37.4
ExperimentPHS(33.7)

37.2

2NM
PHS(34.1)

37.0
36.8
36.6
36.4
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Figure 8: Comparison of Core Temperature (Case 3)

Study on Thermal Evaluation of Hot Outdoor Environment Using 2-Node Model and PHS Model575

October 2005, Singapore

5.2. Comparison of Skin Temperature

Skin Temperature [°C]Figs. 9 to 12 present a comparison of skin temperatures in eachcase respectively. The computed value for 2NM is about 1.2°C higher thanfor the PHS Model after 60 minutes. In Cases 0, 2 and 3 under low
metabolism, 2NM corresponds well with the experimental values. However,
2NM does not concur well with the experimental values in Case 1 underhigh metabolism.
38.0
ExperimentPHS(33.7)

37.0

2NM
PHS(34.1)

36.0
35.0
34.0
33.0
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Skin Temperature [°C]

Figure 9: Comparison of Skin Temperature (Case 0)
38.0
ExperimentPHS(33.7)

37.0

2NM
PHS(34.1)

36.0
35.0
34.0
33.0
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Skin Temperature [°C]

Figure 10: Comparison of Skin Temperature (Case 1)
38.0
37.0
36.0
35.0
ExperimentPHS(33.7)

34.0

2NM
PHS(34.1)

33.0
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Skin Temperature [°C]

Figure 11: Comparison of Skin Temperature (Case 2)
38.0
ExperimentPHS(33.7)

37.0

2NM
PHS(34.1)

36.0
35.0
34.0
33.0
0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Figure 12: Comparison of Skin Temperature (Case 3)576

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

5.3. Comparison of Cumulative Water Evaporation

Evaporation [kg/m2]

Figs. 13 to 16 present a comparison of cumulative water
evaporation in each case respectively. In all cases, the values for the PHS
Model are 0.2 [kg/m2] greater than for 2NM after 60 minutes. In Cases 0, 2
and 3 under low metabolism, 2NM corresponds well with the experimental
values. On the other hand, the PHS Model corresponds well with theexperimental values in Case 1 under high metabolism.
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00

Experiment
2NM
PHS(33.7)
PHS(34.1)

0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Evaporation [kg/m2]

Figure 13: Comparison of Cumulative Water Evaporation (Case 0)
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00

Experiment
2NM
PHS(33.7)
PHS(34.1)

0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Evaporation [kg/m2]

Figure 14: Comparison of Cumulative Water Evaporation (Case 1)
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00

Experiment
2NM
PHS(33.7)
PHS(34.1)

0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Evaporation [kg/m2]

Figure 15: Comparison of Cumulative Water Evaporation (Case 2)
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00

Experiment
2NM
PHS(33.7)
PHS(34.1)

0

5

10

15

20

25

30
35
Time [min.]

40

45

50

55

60

Figure 16: Comparison of Cumulative Water Evaporation (Case 3)

Study on Thermal Evaluation of Hot Outdoor Environment Using 2-Node Model and PHS Model577

October 2005, Singapore

6. Concluding Remarks
Subject experiments were performed in a laboratory to better
comprehend the physiological response of the human body to heat. The
experimental conditions are in the following ranges; 35.7<Ta<39.4[°C],35.7<MRT<39.4[°C], 46.4<RH<72.5[%], VEL<0.16[m/s], 1.0<MET<1.9[met],
and CLO=0.3[clo].
Then experimental values of the core temperature, skin temperatureand cumulative water evaporation were compared with the computed values
for the 2NM and PHS Model. The core temperature for both models follows
approximately the same excursion and corresponds well with theexperimental values in all cases. The skin temperature for 2NM is higher
than for the PHS Model in all cases. In low metabolic cases, 2NM
corresponds well with the experimental values. On the other hand, 2NM
does not concur well with the experimental values in the high metaboliccase. Cumulative water evaporation for the PHS Model is greater than for
2NM in all cases. In low metabolic cases, 2NM corresponds well with theexperimental values. Conversely, the PHS Model corresponds well with theexperimental values in the high metabolic case.
On the whole, 2NM corresponds well with experimental values in
low metabolic cases, while the PHS Model corresponds well withexperimental values in high metabolic case. Hereafter, the following points
should be considered for development of a physiological model for hot
outdoor environments; Modification of the evaporative model for 2NM
under high metabolic conditions or apportionment between the 2NM andPHS Model.

REFERENCES
A. P. Gagge et al., 1971, An Effective Temperature Scale Based on A Simple Modelof Human Physiological Regulatory Response, ASHRAE Transactions Vol.77,
pp.247-262
A. P. Gagge et al., 1986, A Standard Predictive Index of Human Response to The
Thermal Environment, ASHRAE Transactions, Vol. 92-1, pp.709-731
ISO 7933, 2004, Ergonomics of the thermal environment – Analytical
determination and interpretation of heat stress using calculation of thepredicted heat strain, International Organization for Standardization
ISO 9886, 2004, Ergonomics – Evaluation of Thermal Strain by Physiological
Measurements, International Organization for Standardization
A. P. R. Fobelets and A. P. Gagge, 1988, Rationalization of The Effective
Temperature ET*, as A Measure of The Enthalpy of The Human Indoor
Environment, ASHRAE Transactions Vol.94-1, pp.12-31
J. Malchaire et al., 2001, Development and Validation of the Predicted Heat Strain
Model, British Occupational Hygiene Society, The Annals of Occupational
Hygiene, Vol.45, No.2, pp.123-135

578

New Technologies for Urban Safety of Mega Cities in Asia

GEOINFORMATICS AND
PUBLIC DOMAIN SYSTEM MODEL ON
THAILAND MEGA PROTOTYPE SAFTY
Assoc.Prof. Dr. Hansa Vathananukij
Faculty of Engineering, Kasetsart University,
50Paholyothin, BKK10900, Thailand
E-mail: fenghsv@ku.ac.th ,URL: http://gis.eng.ku.ac.th

ABSTRACT
Geoinformatics of MODES/Terra 500 resolution contained five multispectral bands, performed good correlation with mean monthly hydroinformatics, was one of a rather modern high frequency earth observation
imageries. Thus has been assimilated and assessment to mega multipurpose prototype in Thailand. Together with essential hydroinformatics
from GAME-T data mining did play much important role with consequential
interest through renowned soil and water public domain system model.
Pasak river reach is one of the new enormous regimes with complex
purpose and rapidly population enlargement in Thailand, that could digest
in term of geo-informatics database such as topography, land cover andriver system etc., through three series in dry circumstance of MODES/Terra
imageries. Spatial analysis on best correlation of band3, band5 and band6,of MODES/Terra were distinguished to classify, transfer and verify in both
regulated and unregulated methodology upon soil and water public domain
system model.
Data analysis interface has been modified by data analysis
programming and data access approached on access basic standard querylanguage. This appropriate model calibrations and verifications, admissible
ensued on high percentage of correlation efficiency and affirmable best
arbitrated on mega scale-mild slope potentiality together with un-implied ineither continual or sufficient hydroinformatics investigation. Consequenceof assessment could illustrate risk and safety potentiality quantity on the
prototype area.

Keywords: Geoinformatics, Hydroinformatics, Public Domain System, Data
Analysis Program, Standard Query Language, MODIS/Terra, SWAT

579

October 2005, Singapore

1. INTRODUCTION
Whereas the Chaophraya regime has been regional characterized bymonsoon, spatial and intensive heavy rainfall, increased mean rainfall
intensity attitude as rainfall variations with plenitude could cause both flash
and sluggish floods, landslide and debris flow. Pasak river basin is one ofmega tributary drainage area that comes upon the lower Chaophraya areasof Thailand which rapidly increased population in recent year.
While most popular water resource models that have been employed in
Thailand were costly licensed, SWAT(Soil and water assessment tools)
model, could inundated simulation which major caused of water-related
extreme event, was attempted to structure, verify and renown an innovative
public domain revolutionize to geoinformatic system model as SWAT,
SWAT/GIS.

500 resolution of MODES/Terra was a rather modern high frequency
satellite imagery which contained five multi-spectral bands, did perform
good correlation with hydro-informatics system played much important role
to surface and water assessment.
2. PROTOTYPE AREA
A feather shaped of Pasak basin, 16,292 square kilometers surface area with
350 kilometers length and 45 kilometers width was selected as mega
prototype domain. Thus basin has been one of the dense population, covered
area of seven provinces which are Loei, Petchaboon, Lopburi, Saraburi,
Nakornratchasima, Chaiyaphum, and Phranakorn-sriayuthaya as illustrated
in figure 1. Principal topography is hilly feature, mountainous enclosureand a few flatness while Petchaboon terrain compassed on upper part andflood plain at lower part merged to the Chaophraya main river at
Phranakorn-sriayuthaya province. Open channel regime flows from north tosouth with shorten east to west tributaries.

640

750

7 50

00

790

LOEI
PHITSANULOKDAN SAINAM PUNG RIVER

10PASAK RIVERN
0

20 Km.

NAM NAO

LOM KAOLAM SAKPASAK RIVERKHAO KHOSTUDY AREA
PHETCHABUNPHETCHABUNSYMBOLAMPHERPROVINCE REGIONAMPHER REGIONTAMBON REGION
BASIN REGION
RIVER

CHAIYAPHUM
CHON DEAN

Pasak
Prototype

NONG PHAI

BUNG SAM PHAN
NAKHON SAWANWICHIAN BURIR
K RIVEPASA

THEP SATITKHOK CHAROENLAM SONTICHAI BADANSA BOT

SON TIDAN KHUN TOD

RIVER

LOP BURI
THA LAUNG
PHATTHANA NIKHOM

Figure 1: Prototype area

PASAK CHONLASIT DAM

WANG MUANG

PHRA PHUTTHABATNONG DON
BAN MOSARA BURIPASAK RIVERNAKHON RATCHASIMA

MUAK LEKPAK CHONG

KAENG KHOISARA BURINONG KHAE

WIHANDAENGNAKHON NAYOK

PHRA NAKHON SI AYUTTHAYA
640

580

750

7 00

7 50

790

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

3. SPATIAL ASSESSMENT
While innovative geoinformatics technology is widely spread throughacademic area, high frequency of MODIS/Terra earth observation satellite isone of them with selected multi-spectral bands 3, 4, 5, 6 and 7. Dry season
in year 2003, resulted high reflectance relations, were intentional selected
extent, geo-coded studious specify on both geoinformatics and hydroinformatics database system over beneficially regulated mega area of northcentral plain Pasak prototype. Assessment consequence on basin delineationand digital elevation model were illustrated in figure 2.

Figure2: Basin delineation and DEM
This prototype has been aligned further studiousness in both supervised andunsupervised assessments, for monitoring updated circumstance of digital
information system scenario such as topography, soil, land covers, streams
and etc., as shown in figure 3.

Topography

Soil

Land coverStreamFigure3: Geoinformatic system

Geoinformatics and Public Domain System Model on Thailand Mega Prototype Safety581

October 2005, Singapore

4. PUBLIC DOMAIN SYSTEM MODEL AND ASSESSMENTThe Soil and Water Assessment Tool (SWAT) model is continuation longterm effort of non-point source pollution modeling. This continuous timemodel designed either to simulate continuous event, long time periods withof agricultural management effect and could apply to large and small
watersheds. The most current geo-informatics data available were initial
input in the model that could digest in term of digital database such as
topography, soils, land cover and river system which basely employed onwater balance equation as follows:
SWt = SW + ∑ ( Ri − Qi − ETi − Pi − QRi )

Q=

where
and

(1)

( R − 0.2s ) 2, R > 0.2s
R + 0.8s(2)

Q = 0.0, R ≤ 0.2 s

(3)

100
s = 254(
− 1)
CN

(4)

Geoinformatics and hydrologic information has been approached convert
for model utilization. Investigated precipitation from 14 stations, weather
information 5 stations together with actual surface stream flow from 8
stations were selected for model calibration and verification as shown infigure 4.
100

101

102

250
17

17

28032
28042

RainFall mm.

N

28013

200

# 880
#

28053

150

920

28073

100

#

960

1040

28102
28111

50

28142

1080

#

1120

1160

19052

Rainfall (mm)

15

960
1040

36013
36023
36032
36043
36082
36092

100

36122
Apr-02

Apr-01

Apr-00Apr-99Apr-98Apr-97

Apr-96

Apr-95

Apr-94Apr-93Apr-92

Apr-91

Apr-90Apr-8936192
Apr-8840 KilometersApr-870

Apr-8640

0Apr-85#

Apr-84

00
10

25172

400
300
200

0
10 8

88
0

19113
19342

#

20
11

#

19092

500

#
2001
Raingage Stations
Pasak River
Pasak Basin

1/4/00600

Apr-83680 72 0

1/4/96700

Apr-81760

1/4/92

Pasak Monthly Rainfall 1981-2003 of 13 Selected Stations

960

#
#

800

1/4/88

#

#

960
840

1/4/84

Date

#

920

15

16

Apr-82

11
2

0

#

1000

28152
00
12

40

12

16

0
1/4/80

Date

100

101

102

Figure4: Hydroinformatic system
Model was calibrated, verified and monitored on surface stream flow.
Confine prototype which was divided into 86 hydrologic respond units/
eight sub-basins with data analysis program interface as shown in figure 5.
100°30'101°00'101°30'

102°00'


11
10


17°00'

N
16°30'


16°00'

15°30'


15°00'

Calibrtstadc.shp
Riverdc.shp
Subdc.shp
11
12
14
15
17
19
20
21
22
3
5
7
Calibration
8 Area
9
Area1
Area2
Area3
Area4
Area5
Area6
Area7
Area8

#

3

21

#

14°30'



17°00'

2#

1

16°30'

12

#

22

4
#

5


16°00'

13

14
#

6
18

15
7

15°30'

#

8#16
9


15°00'

17
19
20
#



100°30'

101°00'30

101°30'030

14°30'

102°00'60 Kilometers

Figure5: Data analysis program

582

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

5. CONCLUSIONS:SWAT model has been affirmable best arbitrated on Thailand megascale-mild slope potentiality with perfectly runoff analyses results as incorrelation coefficients of figure 6. Consequent intricacy from SWAT model,
MODIS/Terra spatial supervised classification and sufficient hydroinformatic
system have been combined into geoinformatic summation polygon ofpotential area and could illustrate risk and safety potentiality quantity on themega prototype area for urban expansion, dry season agriculture andsluggish flood as illustrated in figure 7 and table 1.

Figure6: Correlation analysis

Figure 7: Risk and safety potentiality

Table 1: Provincial Potential Area
Province
Potential areas sq.km.
Loei
120.5
Petchaboon
2,900.0
Lopburi
1,200.0
Saraburi
565.0

6. ACKNOWLEDGEMENT:This research has been continuously supported by RM-GIS Center, Facultyof Engineering, Kasetsart University, National Research Council ofThailand and Geoinformatics and Space Technology Development Agency
since 2003.

Geoinformatics and Public Domain System Model on Thailand Mega Prototype Safety583

October 2005, Singapore

REFERENCES
Arnold, J.G.Williams, R.Srinivansan, K.W.King and R.H.Griggs., 1995
SWAT – Soil and Water Assessment Tool Draft Users Manual, USDA
– ARS, Temple, TX Arnold, J.G. R.Srinivansan, R.S.
Hansa V.1998., River Engineering. Physics Center CO.LTD., 120 p.
Hansa V, Kittipong T., 2002. Thailand Tributaries Relativity Assessment
through Geoinformatic System and SWAT Modelling. ProceedingsInternational Workshop on GAME-T and Hydro-meteorologicalStudies in Thailand and Southeast Asia, Chiengrai, Thailand. Pp.62-68
Hansa V., 2003. Geographic Information System/Geoinformatic System.
Physics Center CO.LTD., 151 p.
Hansa V., Thitikorn P., 2003. Design Flood Application throughGeoinformatic System and AutoCAD Land Development Desktop
Model. Proceedings International Forth Regional Symposium on
Infrastructure Development in Civil Engineering, Bangkok, Thailand.
pp.1087-1093
Hansa V. 2003., Public Domain Model (SWAT/GIS) Development on Nan
River Basin. Proceedings International Symposium on the Climate
System of Asian Monsoon and its Interaction with Society, Khon
Khaen, Thailand. pp.15-23
Hansa V. 2004., Geographic Information System / Geoinformatics System.
Physics Center CO.LTD., 150 p.
Hansa V. 2004., Portentous Flood Exposition on Geoinformatic System.
Proceedings International Symposium on Water Resource and Its
Variability in Asia in the 21stCentury, Epochal, Tsukuba, Ibaraki,
Japan. pp.25-28.
Hansa V. 2004., Sustention Models for Water Resource Management. 2nd
APHW Conference jointly with 1st AOGS Annual Meeting, Suntec
International Convention and Exhibition Center, Singapore. Volume II
pp.668-676
Hansa V., 2005. Geoinformatic Public Domain Model on Upper Ping River.
Proceedings Interdisciplinary Workshop on Multi-scale Governanceof Forests, Village and Water in the Upper Ping River Basin,
Northern Thailand Lotus Pang Suan Kaew Hotlel, Chiang Mai.
Hansa V., 2005. Near Real Time MODIS/TERRA on Hydro-informatics for
Agriculture in Thailand. Proceedings International Seminar on Near
Real Time Agriculture Activity Monitoring Using Multi-Temporal
MODIS Earth Observation Satellite Data: Faculty of Engineering,
Kasetsart University, Bangkok, Thailand. pp.10-22
Muttiah, P.M. Allen.1999., Continental Scale Simulation of the Hydrologic
Balance. J. American Water Res. Ass., 35(5). pp.1037 – 1050.
Michael F.G., 1998. GIS and environmental modelling. Fort Collins. GISWorld Books, 486 p.
Sloto, R.A., Crouse M.Y., 1996. HYSEP: A Computer program for stream
flow hydrograph Separation and analysis. U.S.Geological Ecological
Survey Water-Resources Investigations Rept 96-404. 46 p.
Steven T. B., 1998. Brush/Water yield feasibility studies, Blackland
Research and Extension Center. 720 E. Blackland Rd., Temple, Texas.

584

New Technologies for Urban Safety of Mega Cities in Asia

PATH FINDING IN 2-LAYER 1-IRS
TOPOLOGIES FOR REAL-TIMEEVACUATION SYSTEMSCHEN PO-HAN (cphchen@ntu.edu.sg), FENG FENG
(feng0009@ntu.edu.sg), HSU WEN JING(hsu@ntu.edu.sg),
DUH BEEN-LIRN(mblduh@ntu.edu.sg).
Nanyang Technological University, Singapore.

ABSTRACT
Some previous research (Chen and Feng, 2005) has introduced 1Interval Routing Scheme (1-IRS) techniques from computer network routing
to inside-building shortest Euclidean path finding. 1-IRS topologies, which
frequently appear in indoor areas like campus and commercial buildings,
have been analyzed in that research and static 1-IRS algorithms have been
improved into dynamic 1-IRS algorithms. In that research, a generalprocedure has been given in order to combine Dijkstra’s shortest pathfinding algorithm with 1-IRS information of individual Element Classes(EC) to compute the shortest path between any two locations in a large
complex network.
From our observation, the complex networks with certain properties
can be given 2-layer 1-IRS information, with which shortest paths can befound without Dijkstra’s shortest path algorithm involved at all. This article
introduces the concept of 2-layer 1-IRS and then identifies the properties,
with which certain complex topologies can use 2-layer 1-IRS technique tofind shortest paths.
With the findings of our research, Dijkstra’s shortest path algorithm
can be totally replaced with the 2-layer 1-IRS technique in the complex
networks with certain properties. With the routing information provided by
the intervals, new functions like real-time digital guide can be added to thereal-time evacuation system in addition to its application on optimal pathfinding.
1. INTRODUCTION
The emergency evacuation system under our research is a mobile andwearable computing system, which supports location-aware computing, andoffers services that are relevant to the mobile user’s current location (Beadle
and Harper, etc. 1997). Mobile user’s outdoor location can be given by GPS.
And by now, some commercial location trackers have been able to giveindoor location information with a wireless network, like IEEE 802.11 WiFi wireless LAN. Nowadays, the average accuracy of this type of location
tracker can be up to 3-5 cm. Under this accuracy level of the location585

October 2005, Singapore

trackers, some location-aware algorithms can be implemented on the realtime systems, like the one under our research. After a building’s indoor area,
especially passageways and staircases, is abstracted to be a minitransportation network in certain way, the shortest path from the mobileuser’s current location to any location in the network can be given by certain
algorithms. Dijkstra’s shortest path algorithm (Dijkstra, 1959) is the classic
one, which can be used for the networks in any topologies. But for somespecial topologies, other algorithms can be applied independently from any
Dijkstra’s thoughts. Interval routing schemes (IRS) in computer network
routing are in this category and is the main topic of this paper. Some
research (Chen and Feng, 2005) has introduced the routing concept popularin computer networks into Euclidean shortest path finding. This article istrying to extend that research from 1-IRS dynamic algorithm to 2-layer 1IRS dynamic algorithm.
2. PREVIOUS WORKWith certain abstraction method, a large indoor area can beconverted into a transportation network. All the networks used in this article
are abstracted with the method, with which all passageways and staircases
are represented by their middle lines or approximate middle lines (Chen andFeng, 2005). These connected lines look like transportation rails and to alarge degree resemble the regular walk ways people may follow whenroaming the building.
Some topologies of the networks abstracted with above method,which appears frequently inside modern buildings, have been identified andthey are called Element Classes (EC) (Chen and Feng, 2005). They are trees,rings, 2D and 3D grids. For the shortest path finding with an EC, a routing
technique, named Interval Routing Scheme (IRS) can be applied instead ofDijkstra’s shortest path findind algorithm.
IRS has been discussed in a number of research articles, which havebeen summarized (Gavoille, 2000). Actually interval routing scheme isbased on representing the routing table of a computer network stored at eachnode in a compact manner. In this method, each node is assigned a distinct
label from the set {1, 2… n}. Arcs are bi-directional and are labeled with
one or several subintervals of the interval [1…n] so that for any node v theintervals associated with outgoing edges from v are pair-wise disjoint andtheir union covers [1…n]. When a message with destination v arrives at
node u, the message is forwarded on the unique outgoing edge labeled withan interval containing the label of v.
In most cases, [1…n] is the cyclic interval, i.e., all subintervals areunderstood to wrap around. Such a scheme is the called a circular intervalrouting scheme (CIRS). Variants of the scheme include linear intervalrouting schemes (LIRS), in which [1…n] is viewed as a linear interval; kinterval routing schemes, in which edges can be labeled with at most k

586

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

intervals (k-IRS). An interval routing scheme for which all messages arerouted along shortest paths is called an optimal scheme.
Some highly regular networks, such as 2D grids and 3D grids (alias
meshes), admit optimal 1-LIRS (Leeuwen, and Tan, 1987). Trees and rings
admit optimal 1-CIRS (Santoro and Khatib, 1985). In a computer network,
the message source and target are two static computers, whose locations are
assumed not changed in the network. So the routing tables like IRS intervals
are filled according to the network hops and they can only be used todetermine the optimal route between any two static computers. A research(Chen and Feng, 2005) found that the topologies like girds, trees and rings
also frequently appear inside modern buildings. In order to provide real-time
shortest path finding and road guide functions for an evacuation system(Chen and Feng, 2005), the usage of 1-IRS technique were extended fromrouting for two static nodes to any two dynamic (mobile) nodes. And the
IRS intervals for all static (dummy) nodes are filled according to the
Euclidean distance of the arcs instead of hop numbers. In addition to 1-IRS
dynamic algorithms developed, a systematic method of calculating optimal
paths in complex networks, which consist of multiple connected EC, wereintroduced as well (Chen and Feng, 2005). This method combines 1-IRS
and Dijkstra’s algorithm, and can be applied to any topologies. In our
research we are discussing another series of topologies, which are composedof multiple EC connected in a certain way. This series of topologies also
appear frequently. Multiple layer 1-IRS, especially 2-layer 1-IRS technique
is introduced and applied on this series of topologies without any Dijkstra’salgorithm involved.
3. 2-LAYER 1-IRS TOPOLOGIESIn 1-layer dynamic 1-IRS algorithms (Chen and Feng, 2005), allstatic nodes in the EC (a tree, a ring or a grid) are labeled from one, andeach arc are given an appropriate interval (Leeuwen, and Tan, 1987, Santoro
and Khatib, 1985). After the labeling of the nodes and arcs, the network can
be input to the algorithms. The source node represents the location of themobile roamer, and the target node the destination the roamer request the
shortest path for. So the source and target nodes are deemed as dynamic,
which are determined in real time. A dynamic node’s location is simplified
to be adjacent to two and only two static nodes, which are called Gating
Nodes (GN). When the distance to each GN is determined, a dynamic
node’s location is determined and can be input to the algorithms. 1-layer
dynamic 1-IRS algorithms were developed for 1-layer 1-IRS topologies(EC), which are trees, rings and grids. Hereafter, we define the 2-layer 1IRS topologies with the following properties:
i)
ii)
iii)

A 2-layer 1-IRS topology consists of multiple connected EC.
One of the EC is deemed as first-layer EC (FLEC). And all other EC
are deemed as second-layer EC (SLEC).
Each SLEC intersects with FLEC with one and only one node,
which is called Crossing Node (CN) of the SLEC to the FLEC. This

Path Finding in 2-Layer 1-IRS Topologies for Real-Time Evacuation Systems

587

October 2005, Singapore

iv)

node can be a dummy node or any dynamic node in FLEC and
SLEC.
All SLEC are connected with FLEC only by CN. There are no otherconnections between SLEC. Each node belongs to a SLEC or the
FLEC. Each arc belongs to a SLEC or the FLEC.

The topologies with above properties are defined as 2-layer 1-IRS
topologies and after the node and arc labeling introduced in the next section,
the network of this series of topologies can be input to the 2-layer 1-IRS
procedure introduced later.
4. 2-LAYER 1-IRS LABLING
Within each EC, the nodes and arcs are labeled with appropriate
methods (Leeuwen, and Tan, 1987, Santoro and Khatib, 1985). Thereafter,
each static node is given an EC identity number (ECID). The static nodes
within the same EC have the same ECID.
According to the properties of 2-layer 1-IRS topologies, each SLEC
are connected with FLEC only by one CN. This CN can be a static ordynamic node of the SLEC and FLEC. As a static node can be deemed as a
special dynamic node, the consideration of only dynamic cases is enoughfor our purpose. So let CN be a dynamic node of the SLEC and a dynamic
node of the FLEC. The distance of the CN to its two GN in SLEC and the
distance to its two GN in FLEC are recorded.
5. 2-LAYER 1-IRS PROCEDURE
After above node and arc labeling, the network can be input to the 2layer 1IRS algorithm, which is based on the dynamic 1-IRS algorithms. A
systematic flowchart is used to demonstrate this algorithm in Figure 1.
If s and t have the same ECID, their GN and distance to GN arerecorded. With this information and 1-IRS labeling already done, the 1-IRS
dynamic algorithms (Chen and Feng, 2005) can find the shortest path.
According to the property of 1-IRS topologies, this path is the shortest path.
If one among s and t are located in FLEC, and the other is located in
SLEC. The shortest path is composed of 2 parts. One is in FLEC and theother part is in the SLEC. These two parts are connected at the CN of the
SLEC to the FLEC. The part in FLEC is the path from the dynamic node (sor t) to the CN and is calculated by the 1-IRS dynamic algorithms with
FLEC’s 1-IRS interval information. The part in SLEC is the path fromanother dynamic node (s or t) to the CN and is calculated by the 1-IRS
dynamic algorithms with SLEC’s 1-IRS interval information.

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If s and t are located in different SLEC, the shortest path is composedof 3 parts. One is in FLEC and the other 2 parts in the source and target
SLEC respectively. The 2 parts in SLEC are calculated by the 1-IRS
dynamic algorithms with each SLEC’s 1-IRS interval information. The partin FLEC is the path between the CN of the two SLEC and is calculated by
the 1-IRS dynamic algorithms with FLEC’s 1-IRS interval information. The
overall shortest path is these 3 paths connected by two CN.
In the next section, an example is given to illustrate this procedure.

Figure 1: 2-layer 1-IRS procedure
6. AN EXAMPLE TO ILLUSTRATOR THE PROCEDURE
To illustrate the procedure in the previous section, we take network of
N1-B3 and N1.1-B3 of Nanyang Technological University for example.
The passageway topology of N1-B3 is a 2x3 2D grid; the N1.1-B3 a
2x2 grid. They are connected by a straight passageway. The network isshown in Figure 2. A and B are the dynamic nodes representing thepassageway’s two ends.
Segment AB can be deemed as a simple tree, which is an EC. N1.1-B3
and N1-B3 are EC as well. If segment AB is treated as the FLEC and two
grids as SLEC, we find that the network has all properties of 2-layer 1-IRS
topologies. So we can apply the 2-layer 1-IRS procedure to find the shortest
path between any two dynamic nodes on the network rails.

Path Finding in 2-Layer 1-IRS Topologies for Real-Time Evacuation Systems589

October 2005, Singapore

We call the SLEC with A as the CN EC1, and the SLEC with B as the
CN EC2. After the node and arc labeling, the IRS interval information is as
in Figure 3.

Figure 2: Example network topology

1,1

[2]

[1]

s

1,2

[3,4]

[3,4]

[1,2]

[1,2]

1,3

[4]

[3]
FL,1

1,4

[2]
[1]

2,1

2,2

FL,2
[2,4]

[3,4]

[1,2]

2,3

[1,3]

[4]

2,4

[5,8]

[1]
[5,8]

[5,8]

[5,8]

[1,4]

[1,4]

[1,4]

[1,4]

2,5

[6,8]

[5]

2.6

[7,8]

[5,6]

2.7

[8]

t

[5,7]

2,8

Figure3: 2-lay 1-IRS labelling
The label of a node contains the EC number followed by a 1-IRS nodelabel. The FLEC is labeled as FL, which contains only two nodes. Theinterval for each arc is only effective within it’s own EC and has nothing to
do outside of it. If s and t are located in the way shown in Figure 3, the GN
information of s and t are tested first. As GN of s (node (1,1) and (1,2)) arelocated in EC1, and GN of t (node (2,7) and (2,8)), s and t in different SLEC.
Then the first part of the path is from s to the CN of EC1, which is node(FL,1). This part can be calculated by dynamic 1-IRS algorithm directlywith the IRS interval information in EC1. The second part of the path isfrom t to the CN of EC2, which is node (FL,2). This part can be calculated
by dynamic 1-IRS algorithm directly with the IRS interval information inEC2. The final part of the path is from EC1’s CN to EC2’s CN. This part

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can be calculated by dynamic 1-IRS algorithm directly with the IRS interval
information in FLEC. The final path is got by adding these 3 parts together.
With the properties of the 2-layer 1-IRS topologies, this path is guaranteed
to be the shortest path from s to t.
When s and t are located in one SLEC and the FLEC respectively, it’s
just a degenerate case of the above situation. And the procedure can beapplied in a similar way.
And also note that, the node label includes two parts, the first one is
the ECID and the second one is the id with the EC. A node has a first layer
id, which is ECID here, and a second layer id, which is the labeling within
the SLEC it’s located in. That’s where the term “2-layer” comes from.
7. CONCLUSION AND FUTURE WORKIn this research, the properties of 2-layer 1-IRS topologies are
discussed. As this series of topologies appear frequently inside modernbuildings, a systematic procedure on the basis of dynamic 1-IRS algorithms
are developed to solve the shortest path finding problem. This procedure is amore effective alternative for Dijkstra’s algorithm for 2-layer 1-IRS
topologies in terms of computation complexity. Additionally, it can provide
some other application potentials than Dijkstra’s algorithm, such as realtime road guide and real-time road mark in virtual reality systems.
Computer networks and buildings’ internal topologies often takesimilar high regular topologies. The reason may be that they are both
artificial products of human minds, which prefer orderliness, standardizationand easiness of reproduction. Due to the characteristics of computer
networks, a variety of routing techniques have been applied very early. IRS
has been applied to Euclidean networks recently. This research is anextension of this application from dynamic 1-IRS to 2-layer IRS technique.
It’s very likely that k-IRS can also be extended to 2 or more than 2 layer
situations to deal with shortest path finding problem for more complex
networks.
REFERENCES
Beadle, H., Harper, B., Maguire, G. Jr., and Judge, J., 1997. Location aware
mobile computing. In Proc. ICT ’97 (IEEE/IEE Int. Conf. on
Telecomm.), Melbourne, Australia.
Chen P. H. & Feng F., 2005. Path finding for real-time evacuation systems
for large indoor areas. 22nd International Symposium on Automation
and Robotics in Construction (ISARC 2005).
Dijkstra E.W., 1959. A note on two problems in connection with graphs.
Numerische Mathematic,1:269-71.

Path Finding in 2-Layer 1-IRS Topologies for Real-Time Evacuation Systems

591

October 2005, Singapore

Gavoille, C., 2000. A survey on interval routing. Theoretical Computer
Science, 245, 217-253.
Leeuwen, Van J., Tan, R. B., 1987. Interval routing. The Computer Journal,
30, 298-307.
Santoro, N., Khatib, R.,1985. Labeling and implicit routing in networks. The
Computer Journal, 28, 5-8.

592

New Technologies for Urban Safety of Mega Cities in Asia

ASSESSMENT OF ADVERSE EFFECTS TOUTILITIES CAUSED BY MASSEXCAVATIONKONG GUANGYA,YANG WENYI,XIAO YI
Tiandi Science and Technology Co. Ltd, China
DR JEFFREY WANG
Tritech Consultants Pte Ltd, Singapore
e-mail: tritech@tritech.com.sg

ABSTRACT
It is always a critical problem for the designers and engineers to haveaccurate assessment of the status of the utilities, especially those settlementsensitive utilities, namely the water mains and sewer lines around the
excavation area. However, all those utilities are buried in 2 to 4m deep
below the ground level and the actual conditions of the pipes and joints can
not be easily inspected and assessed. When the settlement and differential
settlement reach to some critical values, the sewer line and water mains will
burst out due to the failure of pipe and joints and cause an unexpected
failure of excavation. In addition, it is not possible to carry out the mass
excavation to the same depth of the whole station box. The excavation
depths are expected to be uneven and hence the induced ground settlement
around the station box is not uniform even if the soil conditions are thesame. As such, the differential settlement of the diverted water pipes iscritical.
A back-analysis method is proposed focusing on the actual stresscondition of the water pipes induced by the differential settlement along thepipe and advises in time to the engineers the status of the utility. The
assessment is based on the actual settlement readings from the deep
settlement markers along the pipes. The stress inside the pipes can be
estimated solely on the basis of monitoring data without the additional
information of excavation and soil conditions.

1.

GENERAL

It is always a critical problem for the designers and engineers to assess thestatus of the utilities, especially those settlement-sensitive utilities, namely
the water mains and sewer lines around the excavation area. However,normally those utilities are buried in 2 to 4m deep below the ground level
and the actual conditions of the pipes, and joints can not be easily inspected
and assessed. When the settlement and differential settlement reach to some593

October 2005, Singapore

critical values, the sewer line and water mains will burst out due to unevensettlement caused by mass excavation.
Practically it is not possible to carry out various 2-D or 3-D analysis for the
purpose of predicting the utility settlement profiles for unlimited possible
excavation schemes. It is of importancy to assess the actual conditions of thewater pipes at every case. One of the practices is to impose a very stringent
criteria of settlement and differential settlement, which can cover all theworst condition. However, this will inevitably cause the great difficulties
and increase unnecessary cost, hence is considered insensible.
Back-analysis method introduced here focuses on the actual stress conditionof the pipes induced by the differential settlement along the pipe and advises
in time to the engineers the status of the utility. The differential settlementof the pipes can be obtained by installing the deep settlement markers andthe back-analysis can be carried out at the time required. Hence the actual
excavation scheme could be modified by the early planing, re-schedule aswell as control of the progress of the work at any time according to themonitoring results of settlement along the pipes.

2

METHODOLOGYAs shown in Fig.1, the water pipe will deform as the ground settles. Assume
settlements of pipes at points A, B, C be δA, δB, and δC respectively. For any
type of deformed pipes, the general differential equation of the elastic curveis(a) Before Settlement

ACB(b) After Settlement
FIG. 1 UTILITY SETTLEMENT DUE TO GROUND MOVEMENT.

EI

d2y
=M
dx 2
(1)

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where
M ⎯ bending moment of pipes;
E ⎯ elastic modulus of the pipe;
I ⎯ moment of inertia;y ⎯ settlement of pipe in respect to original location.
Assuming that total n numbers of deep settlement markers are installed tomonitor the settlement of pipe, the deformed curve of pipes can be estimatedon the basis of settlement readings at any time.
As shown in Fig.2, the deformed curve of pipes can be described as:yx

DEFORMED
CURVE

FIG. 2 DEFORMED BEAM AND THE COORDINATION SYSTEM.

y = y 0 + A1 x + A2 x 2 + ⋅ ⋅ ⋅ + An x n(2)
where x is the distance to reference point;
y is the settlement of pipes at x in respect to the original level.
At the point ( xi , y i ), the monitored settlement is δ i , namely y i = δ s .
Substituting (xi, δi) into Eq. (2), we havem

ϕ m ( x ) = Π ( x − xi )
i =1

(3)
and
a j = Π ( x j − xi )i≠ j(1≤j≤m)(4)thenl j ( x) =ϕ m ( x)(x − x j ) ⋅ a j(1≤j≤m)(5)andmy = ∑ δ j ⋅ l j ( x)j =1

Assessment of Adverse Effects to Utilities Caused by Mass Excavation595

October 2005, SingaporemΠ ( x − xi )m= ∑ δ j ⋅ i =1
(x − x j ) ⋅ a j
j =1
m

δj

j =1

(x − x j ) ⋅ a j= ϕ m ( x) ⋅ ∑(6)
The induced bending stress inside the pipe can be obtained from thefollowings
M
πR 2 t1
d2yEI=⋅
πR 2 t
dx 2
2
1
3 d y
=
⋅ EπR t 2
πR 2 tdx
2d y= ER 2dx

σ b max =(10)
The pipes may be subjected to internal pressure (Fig.3) and thecorrespondent tensile stress inside the pipes can be expressed as

σ 1 = 0 (along pipe direction)σ2 =σt =

qR
t

(11)
where σ t is the tensile stress induced by internal pressure.

2

1

1

q

2

FIG. 3 INTERNAL PRESSURE OF WATER PIPE.

Under the combination effects of bending stress and tensile stress induce bydeflection and internal pressure of pipe respectively, the failure criteria of
pipe could be written as596

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

σ 2 b max + σ 2 t + σ b maxσ t = σ 2 y(12)where σy ⎯ yield stress of pipe.
3

CASE STUDIES

Two cases studies are presented here to show the application of backanalysis method for assessment of water mains near mass excavation. One
case is the assessment of stress level of water main at the particular date andthe other is under worst settlement readings during the course of excavation.
The project site is the construction of Serangoon Station box, north east line,
Singapore. The station box requires mass excavation upto 22 to 25m below
existing ground level. Water mains and sewer lines have been diverted asutility verges around the station box. The close distance of the utility verge
to the soldier piles retaining wall is less than 1m. The diameters of water
pipes range from 150mm to 800mm. As confirmed by the Authority of PUB,
Singapore, the connections of water pipes are socket-type for those withmax. 300 mm diameter and welded-type for those with more than 300 mm
diameter. All materials of water pipes are composed of steel.
Due to the close proximity of the diverted utility verge, the mass excavation
at Serangoon Station is expected to cause ground settlement with amagnitude up to 80 mm to 100 mm. This settlement of ground will
inevitably cause the settlement of the utilities around. In addition, it is notpossible to carry out the mass excavation to the same depth of the wholestation box. The excavation depths are expected to be uneven and hence theinduced ground settlement around the station box is not uniform even if thesoil conditions are the same. As such, the differential settlement of thediverted water pipes is very critical.
The above described back-analysis method has been used for the assessmentof the water pipes at Serangoon Station since the start of the excavation. The
results of assessment has been submitted to Authorities and provided afundamental and in-time information to the relevant parties. Meanwhile, theconclusions of the assessment have been verified through out the project.
3.1

Case 1- Assessment of stress level of water pipes for a particulardate

A few of deep settlement markers have been installed along the utilities
verges around Serangoon Station. The readings of settlement markers along
the utility verge on the particular date is shown in Fig.4 and listed in Table 1.

Assessment of Adverse Effects to Utilities Caused by Mass Excavation

597

October 2005, Singapore

1.50 (L293G)-7.15 (L261G)-36.20 (L292G)

Settlement ( mm )0-41.10 (L205G)-30.80 (L247G)

50-0.30 (L207G)

100

-50

-100

-150

Note: "
-200
0

50

100

150

200

250

Distance ( m )FIG. 4 SETTLEMENT PROFILE OF UTILITIES AT SERANGOON STATION.

Table 1 Monitoring Reading of Settlement Markers along utility
verge on 27/8/1998 at Serangoon Station
Monitored
Distance
Utility
Settlement
toNo.
Settlement
as per
L247 (G)Markers
27/8/1998
1
L 247 (G)0.0 m
-30.80 mm
2
L 205 (G)22.0 m-41.10 mm
3
L 261 (G)92.4 m-7.15 mm
4
L 207 (G)131.1 m0.30 mm
5
L 292 (G)
154.6 m-36.20 mm
6
L 293 (G)186.9 m1.50 mmxi
δi

As described above, we can get the following on the basis of the above
readings:d2y
σ b max = ER 2dx
= ER(7.2 *10 −10 x 3 − 1.8 *10 −7 x 2 + 1.22 * 10 −5 x − 1.86 * 10 −4 )(16)
The stress states inside the water pipes at Serangoon Station can be checkedaccordingly. The results of stress checking are listed in Table 2.

598

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Table 2 Estimation of Stresses inside Water Pipes due to the excavation at
Serangoon Station (as per 27/8/98)
NominalDiameter of
Pipes

mm
800(Steel)
700(Steel)300(Ductile
Iron)
150(Ductile
Iron)

InducedElastic
Modulus Maximum
Bendingof PipeStressExtern Thick- Yield Strength Maximum
ness of Of Pipes
alInternal
Diamet pipe
Water
er of
Pressure
Pipes
mm
mm
N/mm2
N/mm2
825.9 8.0
275
1.2
667.2 6.3
275
1.2
326.0 7.2420
1.2

kN/mm2 N/mm2
205
5.46
205
4.41
205
2.16

170.0

205

6.3

420

1.2

1.12

(Cont.)
NominalDiameter of
Pipes

Remarks
Mises
InducedMaximum CombinedStressTensionStressStressmm
800(Steel)
700(Steel)300(Ductile
Iron)
150(Ductile
Iron)

N/mm2
61.94
63.54
27.17

N/mm2
64.85
65.86
28.31

O.K
O.K
O.K

16.19

16.78

O.K

The results of assessment indicate that the maximum bending stress inducedby the uneven settlement inside water pipe is only 5.46 N/mm2,
which
are only 2% of allowable stress. The combined stress with consideration of
settlement and internal water pressure is 63.5 N/mm2, which is very muchless than the allowable yield stress of 225 N/mm2 and 420 N/mm2
respectively. Hence, the actual stress conditions of the water pipes atSerangoon Station are judges to be safe with the monitored settlement. As
matter of fact, no special action was taken after this conclusion was drawn
and there was no abnormal phenomenon or burst out of water pipes
observed.

3.2

Case 2- Estimation of stresses inside water pipes under the worst
condition (δmax = 100 mm)

The worst case refers to the condition that due to the uneven excavation, thedifferential settlement reaches to the maximum values, which could occur.
Table 3 is the assumed worst condition along the utility verge at Serangoon
Station.

Assessment of Adverse Effects to Utilities Caused by Mass Excavation599

October 2005, Singapore

Table 3 Predicted Worst Condition of Settlement along Utility
Verge at Serangoon Station
Expected
Distance
Utility
MaximumtoNo.
Settlement
Settlement
L247 (G)Markers

1
2
3
4
5
6

L 247 (G)L 205 (G)L 261 (G)L 207 (G)L 292 (G)L 293 (G)0.0 m22.0 m
92.4 m131.1 m154.6 m186.9 mxi

0.00 mm-100.00 mm
0.00 mm-100.00 mm
0.00 mm-100.00 mm

δi

Similarly, we can get
y = 1.84 *10 −10 x 5 − 8.6 *10 −8 x 4 + 1.39 *10 −5 x 3 − 8.95 *10 −4 x 2 + 1.84 *10 −2 x
(17)
and

σ b max = ER(3.68 *10 −9 x 3 − 1.03 *10 −6 x 2 + 8.34 * 10 −5 x − 1.79 *10 −3 )(18)
The results of stress assessment are shown in Table 4.
From the above analysis, it can be concluded that under the predicted worst
combination of utility settlement, i.e., maximum settlement of utilities
reaches 100 mm, the induced stress due to bending and internal pressure isabout 30% of the yield strength, which is still acceptable.
4

CONCLUSIONSThe back–analysis method makes use of the monitoring data from thesettlement markers along the utility line. The stress inside the pipes can be
estimated solely on the basis of monitoring data without the additional
information of excavation and soil conditions. This method has been applied
to Serangoon and Woodleigh Stations during the period of construction andit has been proven to be very effective and reliable.

Table 4 Estimation of Stresses inside Water Pipes due to the Excavation at
Serangoon Station (Predicted Worst Conditions)NominalDiameter of
Pipes

External Thickness Yield
Strength
Diameter of pipe
Of Pipesof Pipesmm
800(Steel)
700(Steel)

mm
825.9
667.2

600

mm
8.0
6.3

N/mm2
275
275

MaximumInternal
Water
Pressure
N/mm2
1.2
1.2

Elastic
Modulusof PipekN/mm2205
205

InducedMaximum
Bending
Stress
N/mm2
23.11
18.67

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11300(Ductile
Iron)
150(Ductile
Iron)(cont.)
NominalDiameter of
Pipes

mm
800(Steel)
700(Steel)300(Ductile
Iron)
150(Ductile
Iron)

326.0

7.2

420

1.2

205

9.12

170.0

6.3

420

1.2

205

4.76

InducedMaximum
TensionStressRemarks
Mises
Combined
StressStress

N/mm2
61.94
63.54
27.17

N/mm2
76.17
74.65
32.70

O.K
O.K
O.K

16.19

19.02

O.K

REFERENCESREFERENCES

Land Transport Authority Singapore, 1996. North East Line - Contract 704,
Design Criteria. Unpublished report, Singapore
Skempton, A. W., Mac Donald, D. H., 1956. The Allowable Settlement of
Buildings, Proc ICE, Part III, 5, 727-784.
Burland, J. B., Wroth, C. P., 1974. Settlements of Buildings and Associate
Damage SOA Review, Conference on Settlement of Structures, Cambridge,
611-654, Pentech Press, London.

Assessment of Adverse Effects to Utilities Caused by Mass Excavation

601

October 2005, Singapore

602

New Technologies for Urban Safety of Mega Cities in Asia

ASSESSMENT OF BUILDING DISTORTION
AND MOVEMENT AROUND THE
EXCAVATION BOX
YANG WENYI,KONG GUANGYA
Tiandi Science and Technology Co. Ltd, China
DR JEFFREY WANG
Tritech Consultants Pte Ltd, Singapore
e-mail: tritech@tritech.com.sg

ABSTRACTOne of the problems associated with the ground settlement due tomass excavation is the impact to the adjacent building. The commonly usedmethod to estimate the induced strains is the Deep Beam Model asrecommended by Burland, J.B et al. (1974). When buildings on the shallow
foundation affected by a settlement trough are assumed to follow the
deformed ground at the foundation level. However, the buildings on piles
will not deform with the same settlement profile of ground. It is difficult to
use the deep beam method to estimate the distortion and tensile strains.
Even though it is possible to assume that the settlement of the pile heads isequal to the settlement at certain depth of the piles, the accuracy andreliability of the estimated values is greatly influenced by the excavation
depth, pile length as well as the distance of the piles to the excavation
The deep beam method has been extended to the piled foundation toassess the building deformation with consideration of details of excavationand strutting system, soil conditions and the distance. The application of theextended deep beam method indicates that the predicted values are in good
agreement with the measured values. The conclusion drawn by the extended
deep beam method, i.e. the buildings are basically safe during all the stagesof construction, is verified by the facts of observation and monitoring for thebuildings.

1.

GENERAL

The commonly used method to estimate the induced strains is the Deep
Beam Model as recommended by Burland, J.B et al. (1974). The building
can be idealized as a beam with span L and height H deforming undercentral point load to give a maximum deflection δ . The height H is taken as
the height from foundation level to the caves. The roof of the building is
usually ignored. When buildings on the shallow foundation affected by asettlement trough are assumed to follow the deformed ground at thefoundation level.

603

October 2005, Singapore

However, the buildings on piles will not deform with the same settlement
profile of ground. It is difficult to use the deep beam method to estimate thedistortion and tensile strains. Even though it is possible to assume that thesettlement of the pile heads is equal to the settlement at certain depth of thepiles, the accuracy and reliability of the estimated values is greatly
influenced by the excavation depth, pile length as well as the distance of thepiles to the excavation.
The following section will concentrate on the development of the method toestimate the distortion and tensile strains of buildings on piled foundation.
2

DEEP BEAM MODEL METHODAs shown in Fig. 1, the building is supported by shallow foundation and theheight of the building is H, length of building L (Lh in hogging zone and Ls
in sagging zone). Then the bending strain ε b and the diagonal strain ε d canbe expressed as recommended by Burland, J.B et al (1974).

δ
εb =

L
L
3I E
(
+
)
12t 2tLH G

(1)

δ
εd =

L
HL2 G
(1 +
)
18 I E(2)

where

H is the height of the building;E
is the relation between Young’s modulus and shearG
modulus of the building;
L is the length of the considered building span;
I is the second moment of the equivalent beam height of the3
building at the respective zone: in sagging zone I = H
and in hogging
123
zone I = H;
3
T is the furthest distance from the neutral axis to the edge ofthe equivalent beam at the respective zone: t = H in sagging zone and2t = H in hogging zone;
δ is the maximum relative settlement at the considered span

604

New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11δis the ratio between the maximum relative settlement at theLconsidered span and the length of this span.
SAGGINGZONE

HOGGINGZONE

BUILDING

EXCAVATION(a) SHALLOW FOUNDATIONHOGGINGZONESAGGINGZONE

BUILDING

EXCAVATION(b) PILE FOUNDATION

FIG. 1 GENERAL CASE OF A BUILDING AFFECTED BY A SETTLEMENT TROUGH.

The average horizontal strains ε h for the respective sub-span (sagging andhogging) can be calculated by determining the horizontal movements ateither end of a building span and the span length as below:εh =δ h 2 − δ h1
y 2 − y1

(3)
where
span;

δ h1 is the horizontal displacement at the beginning of theδ h 2 is the horizontal displacement at the end of the span;y1 is the distance from centre line to the beginning of a span;y 2 is the distance from centre line to the end of a span.

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The total horizontal strains can be estimated from the summation of theabove two components:

ε bt = ε h + ε b(4)Diagonal (shear) strains can be determined by making use of a Mohr’s circleof astrain. If a tensil horizontal strain ε h is induced in the building, acompressive strain of –0.3 ε h will be resulted in vertical direction (assuming
Poisson’s ratio of 0.3). With two points on the Mohr’s circle ( ε h , ε d ) and (0.3 ε h , - ε d ), the circle can be obtained. The total diagonal strain ε dt due todiagonal distortion can be calculated as:

ε dt = 0.35ε h + [(0.65ε h ) 2 + ε d 2 )]0.5(5)3

EXTENSION OF DEEP BEAM MODEL METHOD

As observed in most cases, the settlement of piled foundation due to
excavation is mainly attributed to two parts, namely the settlement of pile
toe and the settlement due to deflection of the piles.

δ pi = δ toe + δ def(6)
where δ pi is the total settlement of pilehead (i) due to adjacentexcavation;δ toe is the settlement of soil at the level of pile toe;δ def is the settlement of pile head caused by the horizontal

displacement of foundation piles.
In case that the toe level of piled foundation is lower than the excavationlevel, δ toe will be negligible. In case that the toe level of the piled
foundation is higher than the excavation level, the settlement of pile toes canbe estimated by proportion the ground settlement of soil according to theratios of the pile length and the excavation depth.
It is difficult to estimate the pile head settlement due the horizontal
deflection of piles induced by adjacent excavation. However, the elongationof the piles is negligible in comparison of the pile deflection. The pile headsettlement can be reasonably assumed to be equal to the maximum
deflection of piles caused by adjacent excavation.

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11δ toe = δ v

H −L
H
(7)

and

δ def = ρ pile
(8)

Where δ v is the settlement of soil at the ground level of the considered pile
location.
H is the excavation depth,
L is the length of pile,ρ pile is the maximum deflection of pile caused by excavation.
The pile head settlement at every location of piles could be estimated basedon the method proposed by H. G. Poulos et al (1980), which takes into
consideration of details of excavation, bracing and soil condition. Afterobtaining the settlement of pile head (i), the distortion and tensile strain of
the buildings can be assessed by using Deep-Beam Method accordingly.

4
CASE STUDY ASSESSMENT OF POSSIBLE DAMAGES TOHDB BLOCKS AT SERANGOON STATION, NEL,SINGAPORE
In an urban environment such as Singapore, land available for infrastructuredevelopment is continually decreasing. As a result, more infrastructure areconstructed underground. The construction of such underground spaceoften entails excavating below existing grade down to depths of 20m oreven more.
Serangoon MRT Station forms part of North East Line (NEL) in Singapore.
The construction of the station box involved up to 25m deep mass
excavation, braced by soldier piled retaining wall.
There are a few of HDB Blocks located at close proximity of Serangoon
Station Box. Those adjacent buildings may be affected by the excavation
work nearby. Instruments like building and column settlement markers, tapeextensometers and tiltmeters were installed monitored continuously during
the process of excavation.
As shown in Fig.2, HDB Blocks 412 and 413 are resting on the H pilefoundation as indicated in Figs 3 and 4. Since the toe levels of the H piles
are below the excavation level for concourse area, the settlement of pile toe
due to excavation is negligible. The settlements of the Building Blk 412 and413 have been predicted according to the method described above.

Assessment of Building Distortion and Movement Around the Excavation Box607

October 2005, Singapore

L814(G)

L817(G)

L815(G)

L819(G)

L818(G)
L838(G)

L820(G)

L821(G)

L840(G)

L839(G)

L837(G)
I 206

L841(G)
L242(G)
L842(G)

SP420

I 211

SP419

EXL 120.000

SP634

SP367

EL 106.850

SP389

EXL 120.000

SP388

L247(G)SP359

GW(S)211

I 208

SP412

L246(G)

SP411

I 207

GW(P)203

SP310
L206(G)

L205(G)

L297(G)(VALVE)

L805(G)

L249(G)

L290(B)

L250(G)TE 201

TM 207,208

SP306

EXL 120.000

L255A(G)L254(G)

EL 102.850

TM 203,204

L270A(G)TE 204
TM 205,206

L288(B)

L280(C)EXL 120.000

L282(C)TE 202

L289(B)
L281(C)TE 205

TE 207

L291(B)TE 203

L258(G)TE 206

L252(G)

L256(G)TE 208GW(S)212

L257(G)

L251(G)TE 209

L259(G)

L273A(G)L274(G)

L275A(G)

Table 1 is the comparison between the predicted building distortion byextended Deep Beam Method and the measured values. The distance of thebuilding to the excavation, the stiffness of the soldier piles retaining wall,
the spacing of the struts and the soil conditions are considered according to
the method described above.

Table 1 Comparison between the Predicted and Measured Deformation of
HDB Buildings at Serangoon Station
Buildings
Items
Instrument
Maximum Values
Measured
Predicted
TensileTE2010.65mm
1.23mmDeformatio TE202
BLK 412nTE2021.32mm
1.12mmTE203
Inclination TM207
0.03arc
0.01arc
TM208
0.01arc
0.01arc
Settlement L290(B),6.0mm
7.74mm
L291(B),
L282(C)
TensileTE204Deformation TE205
0.9mm
1.27mmBLK 413TE205
TE206
1.44mm
1.09mmInclination TM205
0.02arc
0.01arc
TM206
0.03arc
0.01arc
Settlement L280(C),L281(C),
5.0mm
9.0mm
L288(B),
L289(B)608

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ICUS Report 11

The results of comparison are satisfactory in view that the magnitudes ofpredicted and measured values are about the same. The predicted values arein good agreement with the measured valued and the conclusion drawn by
the prediction, i.e. the buildings are basically safe during all the sages of
construction, is verified by the facts of observation and monitoring for thebuildings.

LEGENDEL

ELEVATION LEVELEGL

EXISTING GROUND LEVELEXLEXCAVATION LEVELSTRUTS

FIG. 3 TYPICAL SECTION OF BLOCK 412 IN RELATION TO EXCAVATION.

LEGENDEL

ELEVATION LEVELEGL

EXISTING GROUND LEVELEXLEXCAVATION LEVELSTRUTS

Assessment of Building Distortion and Movement Around the Excavation Box

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October 2005, Singapore

5

CONCLUSIONS

The deep beam method has been extended to the piled foundation to assess
the building deformation with consideration of details of excavation andstrutting system, soil conditions and the distance. The application of theextended deep beam method indicates that the predicted values are in good
agreement with the measured values. The conclusion drawn by the extended
deep beam method, i.e. the buildings are basically safe during all the stagesof construction, is verified by the facts of observation and monitoring for thebuildings.

REFERENCES
Burland, J. B. and Wroth, C. P., 1974. Settlements of Buildings andAssociate Damage SOA Review, Conference on Settlement of Structures,
Cambridge, 611-654. Pentech Press, London.
Peck Ralph. B, 1969. Deep Excavations and Tunneling in Soft Ground.
State-of–Art Report.7th ICSMFE,Mexico City, Vol. 1, 156-167.
Poulos, H. G., 1980. Pile Foundation Analysis and Design. John Wiley &Sons, New York.

610

New Technologies for Urban Safety of Mega Cities in AsiaUBIQUITOUS REAL TIME MONITORING
AND ALERT APPLIED TO EXCAVATIONWORKSGUAN HONG TAN, YE KONG POH, MAX STRINGER
SysEng (S) Pte Ltd, SINGAPORE
syseng@singnet.com.sg
JAMES MW BROWNJOHNUNIVERSITY OF SHEFFIELD, UNITED KINGDOM,James.brownjohn@sheffield.ac.uk
ABSTRACTAs cities expand to Mega cities, new higher buildings, additional roads,
expanded highway bridges and underground structures will be built toincrease land utilization and transportation capacities. These trends
increase the demand for the Ubiquitous Real Time Monitoring and Alert
Systems of adjacent buildings and infrastructures to minimize theconstruction risks and insurance costs. In modern cities, the infrastructures
for the Internet and Wire-less communications have more extensive
coverage due to the consumer demands for Mobile phones and Internet
access. Today Mobile Internet is already a reality for users to accessinformation anytime and anywhere, a ubiquitous environment, such as news,
share prices, games and emails. By leveraging this Mobile Internet
infrastructure, sensors in any excavation work can be integrated into a
Ubiquitous Real Time Monitoring and Alert system for monitoring structuraland soil movements. With the shortening of construction schedules, work
progresses continuously for 24 hours a day and 7 days a week. Hence themonitoring has to also follow with continuous Real Time Monitoring andAlert. With the Mobile Internet, the users can then have these missioncritical information deliver to their personal mobile devices such as Mobile
Phones and Pocket PCs. Today wire-less networks are already common inbusinesses and homes to provide a ubiquitous experience, making thistechnology more acceptable to the more traditional construction industry.
This ubiquitous information demand will fully automate the monitoring andalert systems to send the right information, to the right location, to right
person to make the right decision for any actions to be taken. The paper will
discuss the integrated multi-discipline system approach and the challenges
in implementing an outdoor full-scale Ubiquitous sensor network used in themonitoring struts in excavation site.
Keywords: Ubiquitous Real Time Monitoring Alert M2M Wireless GPRS

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October 2005, Singapore

1. INTRODUCTION
The transformation of cities to Mega cities will pose new challenges as old
building will be replaced with new higher buildings, roads will be expandedwith more highway bridges, and underground structures will be built toincrease land utilization and transportation capacities. In all modern cities,
the Internet and Wire-less communications infrastructures have more
extensive coverage. This forms the basis to provide Ubiquitous Real Time
Monitoring and Alert systems, as the same public infrastructure will now
carry mission critical data from sensor to the end user mobile devices
instantly. Today Mobile Internet is already a reality for user to accessinformation anytime and anywhere globally, a ubiquitous environment, suchas news, stock prices, games and emails. With the shortening of construction
schedules, work progresses continuously for 24 hours a day and 7 days aweek. Hence the monitoring has to also follow with continuous Real Time
Monitoring and Alert. With the Mobile Internet, the users can then havethese mission-critical information deliver to their personal mobile devices
such as Mobile Phones and Pocket PCs. Wire-less networks are alreadycommon in businesses and homes to provide a Ubiquitous experience. This
will fully automate the monitoring and alert system to send the rightinformation to the right person to make the right decision for any actions to
be taken. To provide the user with Ubiquitous environment, the whole
information chain must be examine such that the entire information flow
challenges can be analyzed from the sensor information until they reach theuser mobile devices, for the sensor data upload and data download via wireless means.
2. REAL TIME MONITORING AND ALERT SYSTEM

Fig 1. A typical Real Time Monitoring and Alert System

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Vibrating Wire Strain Gages (VWSG) are installed at the struts to measure
the strut forces. Data loggers are used for collecting VWSG data fromconstruction sites continuously at every 10 minutes intervals and upload to a
website. The Geotechnical and Structural designers require the data for
analyzing the behavior of the construction sequence and system. The datafrom the same VSWG sensors from sites can now be shared. The site staff
now can make real time judgment during the excavation process, where thereaction time is very short for remedial action. Figure 1 shows the Real Time
Monitoring and Alert system described by Tan (2004) using Machine-toMachine (M2M) technologies. In this system, a wire-less General Packet
Radio Service (GPRS) modem is used to transmit the data from the datalogger to the central server. GPRS is used as an always-connected wire-lesscommunication system. In this system, the monitoring and alert responsetime is in the order of minutes time scale. Real time is only meaningful when
the actual sensor readings are taken and then send to the end-users inminutes. Today, many real time systems narrowly define the time from when
the data of the office computer is sending out to various end-users and it
neglects the time delay, which could be in hours, when the VWSG sensor
data uploads to central server.
The GPRS data speed is 32,000 bps, which is very much faster than the
GSM of 9,600 bps. This makes it suitable for wire-less real time monitoring
and alert systems. The cost for using GPRS network depends on the amountof data transfer. The data logger is always connected to the central server.
Data can be transmitted between the logger and server immediately when thelast channel of sensor is measured. Hence, there is no connection time delay.
The information can then be access by multiple users through the Internet.
Through the use of Infocomm Technologies (IT) and Internet technologies
in instrumentation and monitoring, engineers and decision makers could
access to the data from their desktops or notebooks from anywhere in theworld as mentioned by Alaghehbandian (2003) and Radulescu (2003).
3. THE CHALLENGES OF REAL TIME MONITOING AND ALERTSYSTEM
With Real Time Monitoring, the sensor data streams into the central server
system at a high data rate. Traditional manual monitoring and alert system
will experience user information overload if a manual EXCEL spreadsheet
based system is used. The computer system will slow down and manually
the user cannot cope up with the high data rate. Hence a fully automatedinformation flow system is a solution to overcome such a challenge.
In a Real Time Monitoring site in a excavation site, the Real Time
Monitoring and Alert system monitors 810 Vibrating Wire Strain Gage (VWSG) and 44 Load Cells readings every 10 minutes. Two VW SGs monitor astrut with its individual temperature sensor and the Load Cell has 4 VW SGs
and 1 Temperature sensor. Hence there is a total of 810 VW+ 810T + 44 x 4
VWSG + 44 T = 1,840 sensor readings per 10 minute measurement cycle.
The data rate is then 1840x 6 x 24 = 264,960 data points per day. In an

Ubiquitous Real Time Monitoring and Alert applied to Excavation Works613

October 2005, Singapore

EXCEL spreadsheet system, the system will be overloaded. One solution to
overcome EXCEL limitations is to use a more efficient softwaredevelopment platform such as C.

Fig 2. Sensor Level movements in time sequence
At high-volume data rate in the real time system, any sensor noise orintermittent failure will cause unnecessary alerts. Fig 2 shows sensor level
movements in time sequence. In Real Time Monitoring system, when thesensor level exceeds the Alert Trigger Level, SMS will be sent out.
However, if the sensor data only exceeds this threshold only once, it is most
likely that this sensor reading contains false readings caused by noise. But
on the other hand, if the sensor readings maintain above the Alert Trigger
limit, then the sensor reading must trigger an SMS alert. With a manualsystem, the amount of data is insufficient and slow to provide a reconfirmation within minutes that there is a trigger alert as the manual datacollection and analysis cycle time is usually in the order of hours. There is aneed for a Monitoring System Design Strategy to overcome false alert andprevent user overload. In a manual system where the readings are done twice
per day, there will be 3,680 readings per day. A 0.1% false reading means 4
false alerts. For the same 0.1% false readings in 264,960 real time data, itwill mean 265 false readings, which are unacceptable for Quality data. Usinga Real time monitoring and alert system will improve the Quality standardsof the instrument service provider, as the user will have higher quality
expectation in the whole process of sensor installation, cabling, grounding,system setup, commissioning and monitoring.
A monitoring system deployed by the authors were used in an excavationsite over 18 months and had 143,078,400 VWSG data collected. The total
false alert readings over that period was 1,203 and they were mainly in the614

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initial stage of familiarization by the contractor. This works out to be 8 false
readings per million readings as a Data Quality index. As the sensors andelectronics are used in outdoor environment, noise is a perpetual problem
causing false SMS alerts. Noise can cause the sensor readings to increase or
decrease from their actual values. Hence the alert levels have upper andlower bounds assigned to each sensor.

Fig 3. Strut forces time series readings over days
Field results of Fig 3 from a site show that the VWSG readings for strut at
Level 1 strut 1 have very clean readings while for those strut at Level 1 Strut
4 shows noisy VWSG readings. By compressing the time scale, these strut
force readings have now been interpreted as a waveform for signal analysis
where the rules of digital signal processing come into consideration.
Traditionally when the user takes only a few reading per day, such timeseries information is not available for analysis.
At every 10 minutes, the sensor readings stream to a central server incontinuous. If there is a trigger event as shown in Fig 4. The system will
send SMS alerts, but that point which exceeds the trigger value might be atrue reading or a false trigger caused by noise. After that trigger and if thenext measurement cycle exceeds the trigger limit, then the site engineers
take it with more attention. However if the next cycle, the sensor readings
drop, then it is classified as a false trigger. Various smart alert algorithms
can be used but however the choice is always by the end users.
By integrating the sensors into the Ubiquitous environment, it requires across-disciplinary engineering team, which has to understand each other’s
objectives, constraints, risks and maintenance effort in the system. The
engineering skills from the domain expertise of Structural and Geotechnical,
Electronics, Communications and Software to design and maintain thesystem through out the entire life span of the project.

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October 2005, Singapore

4. UBIQUITOUS ENVIRONMENT FOR DELIVERING DATA INTO
THE HANDS OF THE END USERSIn Fig 1, the users receive SMS text alerts on their mobile phones and theyrequire a PC connected to the Internet to view and analyze the sensor
historical trend. Fig 4 shows the SMS Alert text message while the time
chart data is taken from a PC website screen shot. By linking the server data
to the new generation of Mobile phones and Pocket PCs, which have larger
graphical displays, the sensor charts can now be delivered as shown in Fig 5.
Both mobile devices are growing tremendously and this platform makes it
easier for the sensor data to be delivered in the Ubiquitous environment on
the same unit.

Fig 4 SMS Alert on a mobile phone and screen shot of a PC Internet WebinterfaceFig 5 Crack sensor time chart displayed on an Ericsson Mobile phone and a
HP iPAQ Pocket PC

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5. BENEFITS OF UBIQUITOUS REAL TIME MONITORING AND
ALERT SYSTEM
The main advantage of the Ubiquitous Real Time Monitoring and Alertsystem is obviously the Real Time alert where the site staff gets urgent data
instantly when sensors exceed their limits. The other benefit is to provide theusers and designers the actual on-site forces acting on the struts whenconstruction works progresses. This increases the productivity of the
Geotechnical consultants by having their verification of the design via theInternet instead of visiting the site, which could be hours drive away. The
data is also shared with multiple users and this makes collaborative workeasier across the globe. This brings the important site data into the hands ofthe users via wire-less communication technologies of Mobile Internet,
hence reducing the unproductive time of traveling to site to retrieve data or
requiring a PC for data access. It also helps to raise the Data Quality
standards as it impose new challenges to provide Reliable Data timely to all
stake holders of the project.
6. CONCLUSION
Data Loggers have been used in monitoring systems for many years,
especially for projects, which required continuous monitoring. They aremainly used for design verification, monitoring, investigation works andresearch. Using M2M technologies of wireless communications, Mobile
Internet devices and services, these monitoring systems have evolved into a
Ubiquitous Real Time Monitoring and Alert systems, where the information
are needed in a matter of minutes rather than hours at any time andanywhere. Using available proven technologies, Mission Critical Real Time
Monitoring and Alert systems are used to monitor and deliver informationfrom the sensor until the end users in minutes. When the sensor readings
exceed their predefined limits, the system automatically sends SMS alerts tomultiple users within minutes. The Ubiquitous system delivers the important
information onto the mobile devices of the users. This compression of thetotal delivery time, from the remote site sensor to the user, is useful to
inform site problems immediately for critical projects so that preventive
actions can be mobilize faster. It gives users more reaction time to organize,
to investigate and to prevent collapses or failures rather than having data to
confirm that the site had problems. With the wider acceptance of Mobile
Internet technologies by the consumer sector, the relevant technologies havebecome easily accessible for wider deployment in the civil engineering
sector. This forms a new cluster of Ubiquitous mission critical monitoring
and real time alert systems based upon the M2M technologies.
REFERENCES
Tan G.H. Ng T.G. and Brownjohn, J. ,2004. Real Time Monitoring and Alerts
Systems for Civil Engineering Applications using Machine-to-MachineTechnologies, International Conference on Structural and Foundation Failures, 2– 4 August 2004.

Ubiquitous Real Time Monitoring and Alert applied to Excavation Works617

October 2005, Singapore

Alaghehbandian, A., Abe, M. and Fujino, Y.,2003. An Internet OrientatedPlatform for Structural Health Monitoring, Proceedings of First International
Conference on Structural Health Monitoring and Intelligent Infrastructure, 13-15
November 2003, Tokyo, Japan, pp. 339-344.
Radulescu, D.C., Radulescu, C. and Sereci, A.M. ,2003 Structural healthmonitoring 24/7 broadcasting system, Proceedings of First International
Conference on Structural Health Monitoring and Intelligent Infrastructure 13-15
November 2003, Tokyo, Japan, pp. 971-976

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New Technologies for Urban Safety of Mega Cities in Asia

COMPUTATIONAL FLUID DYNAMICSSIMULATION OF THERMAL BEHAVIORUNDER WORKING WATER SCREENSIN A TUNNEL
DR. REIKO AMANOThe University of Tokyo Visiting Professor
Kajima Corporation, Tokyo, Japan
amanor@iis.u-tokyo.ac.jp
DR. HITOSHI KURIOKA, OSAMU IMAZEKI
Kajima Corporation, Tokyo, Japan

ABSTRACT
Recently, research using Computational Fluid Dynamics (CFD) on
the flow fields and temperature fields of various fire phenomena has been
progressing. CFD is a practical analysis tool for most fire phenomena. In
this research, both actual experiments using a 1/2 scale tunnel andnumerical analysis by CFD were carried out in a tunnel, and both sets ofresults were compared. The fire experiments were performed using the 1/2
scale tunnel equipped with water screens.
CFD analysis of the fire field, when water screens are activated, wascarried out using measured heat release rates. When the water screens areworking, the inside of the tunnel is sectioned by the water screens. The heatflow generated from a fire source is cut off by the water screens, andcirculates around the inside of the section.

1. INTRODUCTION
Since heat and smoke caused by a fire rapidly permeate the whole ofan enclosed underground space, in general, it is necessary to partition a firezone in order to prevent any occupants from being overwhelmed by heatand smoke when taking refuge. We have proposed a water screen
partitioning technology (hereafter referred to as WS) which can cut off theflame and smoke using water screens made by spraying water fromsprinkler heads arranged in a line at certain intervals on the ceiling of thepartitioned boundary. It may well be that this will be applied as one of the
new fire prevention technologies for deep tunnels.
In order to estimate the efficiency of the fire prevention section with
the WS, fire experiments using a 1/2 scale tunnel model have been carriedout for the understanding of thermal behavior in any closed undergroundspace. The experiments are excellent so far as the grasp of physicalphenomena is concerned. However, there are environmental problems incarrying out the experiments as well as high labor and material cost.

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October 2005, Singapore

Furthermore, studies on the effects of such various factors as thevariation in tunnel shape, the direction and shape of a fire source and any
ventilation system are restricted by cost and time. Therefore, in theexperiments using this water sprinkling system there are many factors thatare difficult to measure. Also, it is often difficult to conduct flow
visualization tests for understanding the behavior of thermal flow.
On the other hand, the numerical simulations carried out by thecomputational fluid dynamics (hereafter referred to as CFD) can rapidly andquite universally grasp the behavior in the fire field caused by changes in
the conditions. CFD is a useful tool for solving the problems in experiments
due to the fact that the flow visualization can be made using computer
graphics. Recently, studies 1)~3) on the application of CFD to fire phenomena
have been developed and it is now in the stage of practical use in the
research and development field. Kawabata et al. reported on an investigation
into a tunnel fire simulation using a turbulent model LFS. With regard to the
LFS code with a water drop model built-in in the case of water sprinklingequipment working, the Building and Fire Research Laboratory belonging
to the National Institute of Standards and Technology (NIST) of the
Department of Commerce in U.S.A developed a fire dynamic simulator(hereafter referred to as FDS) 4).
This study aims at confirming the practicality of the CFD whenwater sprinkling equipment such as WS is activated. This paper reports on
the comparison between the results of the fire experiments and the FDS
simulation results.
2. EXPERIMENT METHOD 5)
2.1 Road Tunnel Model
The experiments were carried out in a large space facility with aheight of 25m, a breadth of 25m and a length of 120m. A 1/2 scale box typemodel of a submerged tunnel of the first AA class in the Road Standards
was used in the experiments. This model is 2.7m high, 5.4m broad and18.2m long. The model was placed in close vicinity to the wall of the large
experimental facility. Partitioned boundaries were installed near both
openings of the model. Water sprinkler heads used for the WS were fitted tothe ceiling in two lines at an interval of about 1.6m. 5~6 heads were
installed in each line at intervals of 1.0m in a zigzag pattern.
2.2 Establishment of the Fire Source
The heat release rate (Q model) was established at 1.5MW by taking
into account the reduced scale ratio of the model for the fire source 6) under
the assumption of 7m for a spatial height of the actual tunnel and largesized automobiles such as vans (corresponding to 15MW).
Altogether, 23.3l n-heptane mixed with 5% toluene for visualization
was burnt over a 10 minutes period on a circular plate (diameter of 1000mm
×height of 200mm) placed on the floor at the center of the model.

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2.3 Measurements
The temperature in the vicinity of the ceiling was measured atintervals of 5 sec using sheath K type thermocouples with a diameter of
1.6mm. Fig.2-1 shows the experiment model as well as the installation
positions No.1~No.16 for the thermocouples. The thermocouples were
installed at points 50mm under the ceiling at intervals of 1.0m along thecenter of the model in the longitudinal direction.

18200
4660

2
43

2700

WS

65
8 7
9
10
Fire
1211
13
1514

1620
2820

5400

116

Fig.2-1 Model used for the experiments
2.4 Experiment Cases
Experiments subjected to the simulation were carried out in case 1(where the WS was not activated) and case 2 (where the WS was activated).
As shown in Fig.2-1, the fire source was placed right under thethermocouple No.7. The WS were arranged in two lines at places 4.66m and6.28m away from the fire source in a zigzag pattern. The specifications of
the WS are as follows:
The number of sprinkler heads on one side: 11, Flow volume: 10l/min(total for both sides 220l/min), Spraying angle: 170~180゜, Mean diameterof Sauter: 200μm
2.5 Heat Release Rate
From the weight decrease value per unit time and the theoretical unit
calorific value for the fuel, obtained from the measurement of the weight ofcombustibles as well as the amount of water that had dropped into the plateusing a load cell located under the plate, the heat release rate was obtainedby equation (2-1). It is assumed that during a burning period the evaporationof the water is restrained by a film of the fuel (n-heptane).
∆G(2-1)
Q = q(− w)∆t

Where Q: Heat release rate [kW], q: Unit calorific value [kJ/kg], ΔG/
Δt: Quantity of weight decrease of fuel per unit time [kg/s],
w: Increased water volume caused by the water spraying
equipment [kg/s]

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October 2005, Singapore

By using this heat release rate, a simulation of a fire’s behavior was
carried out. Fig.2-2 illustrates the time variation in the heat release rate. Incase 1 where the WS is not activated, the value for the heat release rate
reaches 1000kW in about 120sec and attains to the maximum value in
300sec. In case 2 where the WS was activated after 90sec, the heat release
rate showed almost constant values about 180sec after the water was
sprayed.
Heat release rate (ｋW)

2500
2000

C ase1

1500
1000
C ase2
500
0

200

400

600

800

Time(sec)

Fig.2-2 Time variation in heat release rate
3. NUMERICAL SIMULATIONS
Numerical simulations were carried out by giving the same conditions
to the experimental facility and the heat release rate. The characteristics ofthe FDS used for the computations are described below.
3.1 Dominant Equation and Discrete
A physical phenomenon is dominated by 5 equations: conservationof mass, conservation of chemical species, conservation of momentum(Navier-Stokes), conservation of energy and equation of state.
3.2 Physical Model
A LES made by the standard Smagorinsky model is used for dealing
with turbulence phenomena in the FDS. The correspondence of the heattransfer rate to the material diffusion coefficient of chemical types andturbulent viscous coefficient is expressed as a 0 equation model using the
Prandtl number Pr and Schmidt number Sc.
In the simulations, the Smagorinsky constant, the Prandtl number
and the Schmidt number were set to be Cs=0.2, Pr=0.5 and Sc=0.5
respectively. The combustion model is a mixture fraction model whichburns in an instant when fuel meets with oxygen. Therefore, this model ismade so that fuel and oxygen can not exist simultaneously. Furthermore,with consideration to the heat radiation, a radiation transportation equation
for a medium radiating absorbed heat is to be solved using a finite volume
method. As for the drops of water sprayed from the WS, the combination of
the Rosin-Rammler distribution and a logarithmic normal distribution isused for the particle size distribution. The effects of the waterdrops on thethermal flow are considered as the external force term f of the NavierStokes equation. The water which drops on the floor is eliminated from the622

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computation domain. Further details of the physical model can be referred
to in the theory manual attached to the FDS4).
3.3 Computation Conditions(a) Partitioning of the Grid
The computation domain is a box type space with the same
dimensions as those for the 1/2 scale experiment model. I has a height of
2.7m, a breadth of 5.4m and a length of 18.2m. The numbers of cells for theequally spaced orthogonal grid are 36 in a vertical direction, 36 in asectional direction and 108 in a longitudinal direction. There are 139968
grid cells in all.
(b) Initial Condition and Boundary Condition
As the initial condition in the whole domain, the speed was set to be
0m/s and the temperature was set at 14℃ that is equivalent to the value forthe experiments. N-heptane was used as fuel for the fire source which was
set at the floor center in the same manner as that in the experiments. The
shape of the fire source with the same area as that for the experiments wasformed to be a square because the orthogonal grid was used. In respect of
the heat release rate, the value obtained from the experiments was used. The
heat release rate was linearly interpolated at intervals of 60sec. The speedboundary condition for the wall was set to be a half-slip and the temperatureboundary condition was insulated. As for the condition of the entrance ofthe tunnel, the boundary pressure fluctuation at the air exhaust boundary
was established to be zero and the atmospheric release condition assuming
the space at infinity being zero was applied to the air supply boundary.
(c) Condition of the WS
The values for the volume of water flowing from the WS, its
working pressure and the Sauter averaged particle size were set to beequivalent to those for the experiments. The WS was activated 90sec after
the start of combustion in the same manner as that for the experiments.

4. CONCLUSIONS AND EXAMINATIONSIn this paper, it was investigated whether or not the FDS has reached
the stage of practical use as a tool for estimating fire performance. The
value measured in the model experiments and the value computed by the
FDS were compared with each other using the moving average value
obtained from 15 points; first 7 points and last 7 points for each.
4.1 Simulations in the case of the WS not being activated(a) Temperature Behavior of the Ceiling near the Fire Source
Fig.4-1 illustrates the temperatures measured in the vicinity of theceiling near by the fire source. No.6, No.7 and No.8 in the figure correspondto the number of the thermocouple installed in the tunnel model shown in

Computational Fluid Dynamics Simulation of Thermal Behavior under Working Water Screens in a Tunnel623

October 2005, Singapore

Fig.2-2. The measurement point No.7 is located right above the fire source
and No.8 as well as No.9 is 1m away from No.7. The temperature at No.6 ishigher than at No.7 in the range from about 160sec up to 450sec. It can bethought that the flame inclines toward No.6. This is so due to the fact thatthe model was installed close to the wall of the experiment facility, adifference occurred in the amount of the air flowing in from both openingsof the tunnel model. An inclination of the flame was observed in theexperiments. On the other hand, in the computation the flame does notincline due to the same condition of both openings of the tunnel.
Temperature (DegC)

1200
No.8
No.7
No.6

1000
800
600
400
200
0

200

400

600

Time (sec)Fig.4-1 Variation in the measured temperature in the vicinity of the ceilingnear the fire source (in the case of the WS not being activated)
Fig.4-2 illustrates the variation in the temperature measured at No.7
just above the flame (Exp in the figure) and computed temperature (FDS). It
can be seen in the time variation in the computed temperature that anincrease in the temperature is caused by the heat release rate given and thatit reaches the maximum value at about 300sec. Then, the temperature falls
at about 600sec. The computation results simulate quite well the actual
measurement results in the time range up to 160sec at which the flame
inclines. The measured temperature is lower than the computed temperature
after about 160sec because the flame inclines.
Temperature (DegC)

1200
1000

Exp
FDS

800
600
400
200
0

200

400

600

Tim e (sec)Fig.4-2 Variation in the measured temperature and the computed
temperature (No.7) (in the case of the WS not being activated)(b) Behavior of the Ceiling Temperature at the WS Installation Side
Fig.4-3 shows the changes in the measured temperature and thecomputed one at No.5 located 2m away from the fire source. Figs.4-4 and 45 illustrate the variation in the measured temperature and the computed one
at No.3 and No.16 respectively. No.3 is located at a place before the WS
installation position (on the fire source side) and No.16 is on the opening
side that is beyond the WS position. Compared with the measured
temperature, the computed temperature is slightly higher, but almost thesame behavior is discernible in both temperatures.

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Temperature (DegC)

600
Exp
FDS
400

200

0

200

400

600

Tim e (sec)Fig4-3 Variation in the measured temperature and the computed
temperature (No.5) (in the case of the WS not being activated)
Temperature (DegC)

400
300

Exp
FDS

200
100

0

200

400

600

Time (sec)Fig.4-4 Variation in the measured temperature and the computed
temperature (No.3) (in the case of the WS not being activated)
Temperature (DegC)

300
Exp
FDS
200

100

0

200

400

600

Time (sec)Fig.4-5 Variation in the measured temperature and the computed
temperature (No.16) (in the case of the WS not being activated)
4.2 Simulation in the case of the WS working(a) Behavior of the Temperature at the Ceiling near the Fire Source
Fig.4-6 illustrates the variation in the measured temperature in theproximity of the ceiling near the fire source. The temperatures at No.6 andNo.8 both of which are 1m away from the fire source are lower than at No.7
located right above the fire source. The temperature behavior at No.6 isalmost equal to that at No.8. It can be judged from this that the flame
developed vertically in a different manner from that in the case of the WS
not being activated. Fig.4-7 shows the change in the measured temperatureand the computed one obtained at No.7 just above the fire source. The
computed result simulated quite well the measured result.
Temperature (DegC)

1200
1000
800

No.8
No.7
No.6

600
400
200
0

200

400

600

Time (sec)Fig.4-6 Variation in the measured temperature in the vicinity of the ceilingnear the fire source (in the case of the WS being activated)

Computational Fluid Dynamics Simulation of Thermal Behavior under Working Water Screens in a Tunnel625

October 2005, Singapore

Temperature (DegC)

1200
E xp
FD S

1000
800
600
400
200
0

2 00

40 0

60 0

Tim e (sec)Fig.4-7 Variation in the measured temperature and the computed
temperature (No.7) (in the case of the WS being activated)(b) Behavior of the Temperature at the Ceiling on the WS installation Side
Fig.4-8 illustrates the variation in the measured temperature and thecomputed one at No.5 located 2m away from the fire source. The behaviorof the computed temperature simulates well that of the measured
temperature. Figs.4-9 and 4-10 show the changes in the measured
temperatures and the computed ones at No.3 located on the near side of theWS (on the fire source side) and at No.16 located beyond the WS (on the
opening side) respectively. At any measurement point, the computed
temperature simulates quite well the behavior of the measured temperature.
The whole behavior of the computed results obtained using thethermocouples arranged in the front and rear of the WS at No.3 and No.16
correspond very well to the behavior of the measured results. It is clear fromthis that the behavior of the waterdrops as well as the amount of heat and themomentum which are exchanged between flow fields are well understood.

Temperature (DegC)

600
Exp
FDS
400

200

0

200

400

600

Time (sec)Fig.4-8 Variation in the measured temperature and the computed
temperature (No.5) (in the case of the WS being activated)

Temperature (DegC)

400
300

Exp
FDS

200
100

0

200

400

600

Time (sec)Fig.4-9 Variation in the measured temperature and the computed
temperature (No.3) (in the case of the WS being activated)

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Temperature (DegC)

100
Exp
FDS

50

0

200

400

600

Time (sec)Fig.4-10 Variation in the measured temperature and the computed
temperature (No.16) (in the case of the WS being activated)
4.3 Visualization of Flow and Temperature
Fig.4-11 shows the vector of the air flowing from the fire source
position through the opening of the tunnel when the WS is not activated.
The flow vector in the case of the WS working is shown in Fig.4-12. The
vector figure indicates the resultant sum vector values for the flow speed indirections X,Y and Z. Both figures show the results obtained from thevisualization of the central cross-section composed of a sectional direction
and a vertical direction.
(a) Results in the case of the WS not being activatedWhen the WS is not operated, fire plumes generated from the firesource reach the ceiling surface and form a high temperature layer as aceiling jet, which flows out through the upper part of the opening.
Furthermore, the air flowing into the tunnel through the lower part of the
opening is caught in the fire plumes in the vicinity of the fire source, and alarge convective flow is formed. As a result, it can be seen that a thermal
profile with a high temperature layer in the upper part and a low temperature
TEMP
in the lower part has been produced.
400℃

Fire
10℃

Fig.4-11 Figure of vector flow (central cross-section of the surface composed oflongitudinal and vertical directions) (in the case of the WS not being activated)
TEMP

200℃

Fire

WS

Fig.4-12 Figure of vector flow (central cross-section of the surface composedof longitudinal and vertical directions) (in the case of the WS being activated)

Computational Fluid Dynamics Simulation of Thermal Behavior under Working Water Screens in a Tunnel

10℃

627

October 2005, Singapore(b) Results in the case of the WS working
Fig.4-12 in respect to the flow vector clarifies the following
characteristics. Namely, at the WS installation point on the fire source side
the air flow thrusts through the WS, but at the WS installation point on the
opening side the flow is controlled to run from the upper part to the lower
part and the longitudinal flow is cut off. Two large convective flows areproduced with the WS on the opening side as a boundary. When the WS
works, the flow of the high temperature layer in the upper part of the spacepartitioned by the WS is isolated. Then, the direction of the flow changes
toward the floor due to the water sprinkling from the WS and a circulating
flow running toward the fire source is again formed. As a result, it caneasily be understood that the WS plays an important role in the partitioning
system.
5. CONCLUSIONS
The following items have been obtained by comparing theexperiment results with the computation results from the FDS.
(a) In the case of the WS not being activated, since the boundary condition
was not faithfully simulated, the computation result with regard to thetemperature at the center of the fire source obtained using the FDS showed ahigher value. The temperature distribution behavior of the whole space wassimulated with accuracy.
(b) In case of the WS working, the temperature distribution behavior of thewhole space was simulated with very high accuracy.
(c) In the case of the WS working, the formulation of the partitioning was
simulated.
(d) In the case of the WS working, it can be estimated that the ceiling jet isintercepted due to the partitioning and that a circulating flow is formed in
the partitioned space.
There are few reports on the estimation of thermal behavior based on
the partitioning with water sprinkling equipment such as water screens using
the CFD. In this study, computational results obtained from the CFD
showed a favorable conformity to the measured values. Although conditions
for experiments are often limited, in numerical simulations various
phenomena can be studied comparatively with ease. It can be judged that the
FDS will be effective for the narrowing down of experiment cases inadvance and for the estimation of the behavior which can not be obtained inexperiments under the restriction of costs and environmental matters.
REFERENCES
1)Kohyo Satoh,K.T.Yang ： Simulations of Swirling Fires controlled Self-generated Entrainment Flows, Fire
Safety Science Proceedings of the fifth International Symposium,1997
2)W.K.Chow,N.K.Fong：Numerical Simulation on Cooling of the Fine-induced Airflow by Sprinkler Water
Sprays, Fine Safety Journal 17,1991
3)William Mell,Mcgattan KB,Borm HR ： Large Eddy Simulation of Fine-Driven Flows, ASMEHTD
Vol.304,National Heat Transfer Conference Vol.2,1995
4) Kevin B,McGrattan at el ： Fire Dynamics Simulator (Version3) Technical Reference Guide,
http://www.bfrl.nist.gov/
5)Reiko Amano at el：Water Screen Fire Disaster Prevention System in Underground Space, 6th Asia-Oceania
Symposium on Fire Science and Technology, 20046)G.Su ,J.G Quintiere,N.Schultz：Physical Scaling of Fire
Suppression By Water Mist, Proceeding of 2001ASME International Mechanical Engineering Congress andExposition November 11-16,2001,HTD-Vol.369-4, MECE2001/HTD-24238

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PLANNING OF EMERGENCY RESCUEROUTES AFTER STRONG EARTHQUAKES
CHIN-HSUN YEH1, WEI-CHANG CHEN2, WEN-YU JEAN1 and
LAP-LOI CHUNG1
1
Research Fellow, 2Assistant Research Fellow
National Center for Research on Earthquake Engineering, Taiwan
chyeh@ncree.org.tw, wcchen@ncree.org.tw, wychien@ncree.org.tw andchung@ncree.org.tw
ABSTRACT
Buildings, bridges, buried pipelines and so on are vulnerable instrong earthquakes. The damages of these infra-structures may interrupt
the rescue routes and reduce the effectiveness of live-saving efforts. The
main purpose of this study is to provide a systematic way to plan emergency
routes for the rescue vehicles immediately after strong earthquakes in themetropolitan areas. It is expected to minimize the mean travel-time or to
maximize the mean speed of rescue vehicles. To achieve the goal, several
significant nodes of the road-network in each district are identified firstbased on the quantities of neighboring populations, the capacities ofneighboring hospitals and fire stations, the accessibility of the selected
nodes, and so on. Seismic performance index (SPI) of each road segment
has been defined in this study according to the width and the design speedof the road segment, and the damage-state probabilities of bridges orelevated-highways which are either on the road, pass-over the road orparallel to the road. In short, the SPI is intended to reflect the mean
velocity of rescue vehicles on the road segment immediately after strong
earthquakes. The damage assessment of infra-structures considering the
ground excitation intensity and ground failure extent can be carried out by
applying software such as Taiwan Earthquake Loss Estimation System,
which is developed by the National Center for Research on Earthquake
Engineering, Taiwan. Based on the results of seismic scenario simulation,
the emergency rescue routes connecting all the significant nodes in each
district are then selected by the shortest path algorithm using mean
travel-time as the cost. It is noted that an analyzable road-network must
be constructed before applying Dijkstra algorithm to identify the minimum
travel-time routes. In this paper, Taipei City serves as the pilot study
region and the emergency rescue routes of different priorities in Taipei City
have been identified.
Keywords: emergency rescue routes, seismic scenario simulation, shortest
path problem
1. BACKGROUND
Since Taiwan is located in seismic active region and has many active
faults, as shown in Figure 1, in the past decades, several devastating629

October 2005, Singapore

earthquakes, such as the 1999 Chi-Chi earthquake in Taiwan, have caused
serious losses and casualties, especially in the metropolitan areas. In viewof the fact that highway systems play important roles in economy andemergency responses; however, some of the components in the highway
systems, such as tunnels, bridges and elevated-roads, are vulnerable instrong earthquakes. Once some of the components or the neighboringbuildings/pipelines are damaged, they may block the roads and significantlyinterrupt the functionality of highway systems, such as convenient
communications, shipment of rescue and medical resources, etc.
Therefore, it is important to plan emergency rescue routes in advance basedon considerations of seismic safety and transportation rapidity.
Taipei City
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# # # ####
# ## ## # ## ####the 1999 Chi-Chi
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Earthquake
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## # #### # # #
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Fig. 1 Distribution of the historical seismic events with magnitude exceed
6.0 and the active faults in Taiwan
Figure 2 shows the flow chart which is used in this study to plan
emergency rescue routes. The detail procedures will be explained step bystep in the succeeding sections. Taipei City, not only the capital but also
one of the economic centers in Taiwan, is chosen as the pilot study region to
examine the feasibility of proposed planning scheme.
2. DATA COLLECTION AND PROCESSING
There are many factors that can influence the effectiveness oflife-saving efforts immediately after earthquakes. It is necessary to collectthe entire related database and to identify some of the important factors andcharacteristics in the database which can be used in planning emergency
rescue routes. In this study we collected and processed database ofadministration boundaries, river basins, populations, highway transportation

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systems, schools, hospitals, fire stations, and so on. Some of the data werecollected from Taipei City government or other resources. Some of thedata were investigated in field, if the existing database could not be found.
All the data were stored in GIS format so that the spatial distribution andinter-relationship of objects could be visually displayed and analyzed.

Fig.2 Flow chart of planning emergency rescue routes in metropolitan area
2.1 Establishment of Analyzable Road-Network
Generally speaking, a highway system should be transformed into a
logical network, which is composed of links and nodes, before it can berecognized or analyzed by digital computers. A link represents a roadsegment, while a node represents an intersection of several road segments.
Some of the links represent bridges or elevated highways, which may bedamaged or even collapsed under strong excitations. These links should be
identified and their seismic design parameters used in damage assessment
should be associated with them.
Most of the links in a highway system are not influenced by otherlinks in case of damage or collapse. However, some of the links may beover passed by other links (e.g. bridges or overpasses) or adjacent to otherlinks (e.g. ramps or elevated roadways). The aforementioned three typesof inter-relationships of links are demonstrated in Figure 3 and are denoted
as normal type, overpass type and adjacent type, respectively. The
attributes of each link includes information of one-way/two-way, number oflanes or width of the link, overpass or adjacent elevated link ID if they
exists, design speed or speed limit of the link, and so on.

Planning of Emergency Rescue Routes after Strong Earthquakes

631

October 2005, Singapore• Normal Type• Adjacent Type

X002
B012

1
X00
B012

X001
B012

F-3

A-3

X002
B012
F-1

F-2

A-3

A-2

S001
B012
F-1

A-1

A-2

S002
B012

A-1

F-2

A-3

F-3
N001
B012

02
2X0
B01

• Overpass Type

N002
B012

A-2

A-1

01
2X0
B01

F-9
F-8

F-7

F-6

F-5

2
3S00
B01

F-4

1
3S00
B01
02
3N0
F-3
B01

F-2
F-1

01
3N0
B01

H-1

Fig. 3 Three relationships between transportation components, i.e., (1)normal (2) adjacent (3) overpass
2.2 Selection of Significant Nodes in Each District
In this study, the planning of emergency rescue routes in metropolitan
areas can be roughly divided into three steps. The first step is to choose
several significant nodes in each district. These nodes represent the mostimportant or convenient places to access in the district when disasters occur.
The second step is to build an inner-district network connecting thesignificant nodes in each district; and the final step is to complete theinter-district network connecting the entire set of significant nodes.
Therefore, it is essential to select significant nodes in each district.
Since there are thousands of nodes in Taipei City, it is difficult toselect the significant nodes based solely on intuition or experience. Hence,a significance index I r was proposed to evaluate the accessibility andrescue capacity of each node based on the quantities of neighboring
populations, hospitals, schools and fire stations, and the widths of roads
connected to the node. The significance index I r ranges between 0 and 1
and is defined as follows.

I r = 0.3Rw + 0.2 Rh + 0.2 R f + 0.1Rs + 0.2 Rv
where Rw is a factor reflecting the number of roads connected to thenodes; Rh is a factor reflecting the number of beds in hospitals within a
specified region; R f is a factor reflecting the number of firefighters withina specified region; Rs is a factor reflecting the shelter spaces within a
specified region; and Rv is a factor reflecting the number of populations
within a specified region. All the factors are scaled to range between 0 and
1; and the specified region is a circular buffer region with 500-meter radius.

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The thematic map of index I r is shown in Figure 4. There were 40 nodes
chosen as the significant nodes in this study.

北投區

士林區

蘆洲鄉
內湖區

三重市

中山區
大同區

松山區

南港區

萬華區

中正區

大安區

信義區

永和市

板橋市

深坑鄉
中和市

文山區

Fig. 4 Thematic map of the significance index of nodes in Taipei City
3. EFFECTIVENESS OF LINKS AFTER EARTHQUAKES

Evaluation of post-earthquake effectiveness of each link is an
important issue in planning emergency rescue routes.
As far as
effectiveness is concerned, the expected speed that rescue vehicles can haveafter strong earthquakes is the most important parameter to assess, because
time is always the most precious thing to save in rescue actions. There areseveral factors which may influence the vehicle speed on a link, such as theroad width and seismic safety performance of the link. To evaluate theexpected rescue vehicle speed V p on a link immediately after strong
earthquakes, the following equation is proposed

VP = Ce ⋅ I p ⋅ V(1)where V is the design speed of the link; Ce is the coefficient considering
non-seismic effects such as the road width; and I p is the speed
modification factor considering seismic performance of the link itself andthe neighboring links if they exist.

Planning of Emergency Rescue Routes after Strong Earthquakes633

October 2005, Singapore

3.1 Non-Seismic EffectIf the width of link is large enough, no only it will not be blocked byfallen buildings or damage pipelines, but also it may provide a reserved lane
for rescue vehicles. Therefore, it is reasonable to assign Ce a larger value
for links with more than two lanes on each side. On the other hand, every
link has its design speed; and there might be more traffic on wider links.
So, the Ce can not increase unlimitedly. In this study, Ce is set to 1
when there is one lane on each side of the link. The Ce is set to 1.1 or 1.2
depending on the number of lanes on each side of link is two or larger thantwo, respectively.
3.2 Seismic Safety Performance of Links

Assume the expected rescue vehicle speed on a link after strong
earthquakes is proportion to the seismic safety performance of the link. In
other words, if the link is seismic designed or it will not be blocked out byother damage links, not only it is safe to drive after strong earthquakes, butalso the design vehicle speed of the link can be ensured. Since the impactof an earthquake can not be predicted accurately beforehand, the seismic
safety performance of links should be evaluated in a probabilistic sense. In
this study, the seismic safety performance of the link is expressed as afunction of damage-state-probabilities of the link itself and the neighboring
links which may influence the link when damaged or collapsed. The speed
modification factor I p in Eq. (1) can be expressed as follow:

I p = Fs ⋅ Fo ⋅ Fa ⋅ Fb

(2)

where Fs indicates the success probability of the link itself. The term
success means that vehicles can pass through the link. If there is someprobability that the link will fail after strong earthquakes, the expected
speed is reduced and assumed to be proportional with the successprobability. Similarly, the factors Fo , Fa and Fb are the successprobability to be influenced by the overpass link, the adjacent link and theneighboring buildings/pipelines, respectively.
All the ground motion intensity estimates, soil liquefaction potential
and settlement estimates, and the damage-state-probabilities of roads,
bridges, overpasses and elevated highways, etc are evaluated by using
TELES. There are five damage states defined for bridges and elevatedroads, i.e., none ( d1 ), slight damage ( d 2 ), moderate damage ( d 3 ), extensive
damage ( d 4 ) and complete damage ( d 5 ). The probability in each damage
state is denoted by p1 , p2 , p3 , p4 and p5 , respectively. The successprobability of the link itself Fs can be evaluated as
5

Fs = ∑ pi ⋅ si

(3)

i =1

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where si is the success probability given specific damage state d i of thelink. Eq. (3) is one of the applications of total probability theorem.
Similarly, the success probabilities due to indirect effects of overpass
and adjacent link damages are expressed as follows:5

Fo = ∑ pi ⋅ oi
i =15

Fa = ∑ pi ⋅ ai
i =1

where oi and ai are the conditional success probabilities that vehicles
can pass through the link given the overpass link and the adjacent link,respectively, being in damage state d i . The values of coefficients si , oi
and ai are given subjectively and listed in Table 1. Due to lack of
information, Fb is set to 1 temporarily. The seismic safety performanceand the expected rescue vehicle speed of the links in Taipei City are shownin Figures 5 and 6, respectively, based on the assumption that peak groundacceleration (PGA) equals 0.23g everywhere.

Table 1 Conditional success probabilities in various damage statesclassificationsi (road)si (bridge)oi (overpass bridge)oi (pedestrian overpass )ai (adjacent highway)

d1

d2

d3

d4

d5

1.0

1.0

0.9

0.8

0.7

1.0
1.0
1.0
1.0

1.0
1.0
1.0
1.0

0.6
0.8
1.0
0.9

0.3
0.5
0.9
0.8

0.0
0.2
0.8
0.7

4. PLANNING OF EMERGENCY RESCUE ROUITESAs explained previously, significant nodes in each district wereselected first. The expected rescue vehicle speed on each link wasevaluated by using Eq. (2), and the expected travel time on each link could
be obtained accordingly. The shortest (travel time) path connecting eachpair of significant nodes could be identified by using the Dijkstra (1959)
algorithm, e.g., the inner-district rescue routes in Daan are shown in Fig. 7.
The next step was to select rescue routes connecting significant nodes
in different districts. Since there were more than one significant node ineach district, it was necessary to identify the shortest paths for all possiblecombinations of significant nodes and to select the rank-one path withminimum travel time. When the rank-one rescue routes had been
identified, they were removed from the road-network temporarily. Using asimilar approach in finding the rank-one rescue routes, rank-two rescue
routes were obtained. In turn, the rank-one and rank-two rescue routes
were removed from the road-network temporarily to find rank-three rescue
routes.

Planning of Emergency Rescue Routes after Strong Earthquakes

635

October 2005, Singapore

Fig. 5 Seismic safety performance of links in Taipei City

Fig. 6 Expected vehicle speed of links after earthquakes in Taipei City

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New Technologies for Urban Safety of Mega Cities in Asia

ICUS Report 11

Ν Φ

(

Ν

Ν

新生南路一 段南路

敦化南路 一段

大安區

二段

(

(

(

和平 東路 三段

Φ

(

Ν
(
Φ

敦化南路二段

二段

和平東路(
敦化南路二段

南路二

段金 山

南路

新生南路一 段新生南路一段((敦化南路二段

( (

Φ (

維

(

-四

(
Φ

(

金山南

南路

Φ

(
B

Ν
(

(

敦化

Φ

新生

路 二 段金
山

(

A

路-

C

忠 孝 東 路 三 忠孝東 路三段 忠孝東
路四段
段
Φ
仁愛

一段

(

敦化南路一段

金山

南路

Ν

一段

(

一段

路一段

(

C

(
(
(

((

(

Fig. 7 The rescue route of Daan district in Taipei City
Through this approach, it is guaranteed that no rescue routes will
overlap with each other. After comprehensive network analysis andparameter sensitivity study, there were 615 links served as inner-district
rescue routes, 461 links as the rank-one rescue routes, and 1,057 links as therank-two or rank-three rescue routes. The inner- and inter-district rescue
routes in Taipei City are shown in Figure 8.
5. CONCLUDING REMARKS

In order to evaluate the seismic performance of transportation systems
and to plan the optimal rescue routes in a metropolitan area, a systematic
approach, which includes GIS data processing, seismic hazard analysis,
structural damage assessment and shortest-path network analysis, has been
proposed and demonstrated in this paper. Using the proposed method, theemergency rescue routes are classified into three priorities and no overlap
among each rescue route. The proposed approach to select rescue routes isbased on the link width as well as the seismic safety performance of the link
and its neighboring links. So, it is expected that the selected rescue routes
will perform better in strong earthquakes and the approach can be easily
applied in other metropolitan areas.

Planning of Emergency Rescue Routes after Strong Earthquakes

637

October 2005, Singapore

6. REFERENCES

Dijkstra, E.W., 1959. "A Note on Two Problems in Connection with
Graphs," Numerische Mathematik, vol. 1, pp. 269-271.
區內救援道路一級救援道路二級救援道路三級救援道路重要路網節點

Fig. 8 The inter-district rescue routes in Taipei City

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New Technologies for Urban Safety of Mega Cities in Asia