No. 51 August 2017

STEEL CONSTRUCTIONTODAY & TOMORROW

http://www.jisf.or.jp/en/activity/sctt/index.html

Feature Articles

Initiatives for Enhancing Seismic
Resistance of and Damage-prevention
Technologies for Foundation Structures
1 Measures for Earthquake

Photo: Tokyo Fire Department

Resistance Enhancementof Industrial Parks in
Bay-front Areas

4 Prevention of Liquefaction-induced Damage to Existing
Bridges-Development ofSeismic Resistance
Evaluation Method andSeismic Countermeasure
Technologies for Bridge
Foundations

7 Improving Estimation Accuracy of Steel Pipe Pile Bearing
Capacity by Means of Dynamic Loading Tests

10 Evaluation of Ultimate Strength of Steel Pipe Piles in Liquefied
Soil during Great Earthquakes

13 Evaluation Method for Steel Pipe Pile Stress during Earthquakes

towards Establishing Secondary Design Method for Pile Foundations

Special Topic

16 How to Improve Social Infrastructure in Disaster-prone Areas by
Capitalizing on the Lessons Learned from the 2016 Kumamoto
Earthquake

Back cover JISF Operations

Published Jointly by

The Japan Iron and Steel Federation
Japanese Society of Steel Construction

Seismic Countermeasures for Coastal Industrial Parks

Measures for Earthquake Resistance
Enhancement of Industrial Parks in
Bay-Front Areas

Masanori Hamada: After graduating from theFaculty of Science and Engineering, Waseda
University, he entered Taisei Corporation in 1968.
Then he served as professor of Tokai University
and Waseda University, and filled the post of
professor emeritus at Waseda University in 2014.
He assumed his current position as Chairman of
Asian Disaster Reduction Center in 2014.

by Masanori Hamada
Chairman, Asian Disaster Reduction Center
During past earthquakes, industrial parks
have been repeatedly damaged by thestrong seismic motion amplified by thesoft reclaimed ground, the liquefaction of
the sandy soil, the overflow of tank oil inPhoto: Tokyo Fire Department

Photo 1 Explosion and fire of 17 spherical LPG
tanks (2011 East Japan earthquake)

Photo 2 Fire of crude and naphtha tanks by longperiod seismic motion (2003 Tokachi-oki
earthquake)

duced by the long-period seismic motion,and huge tsunamis. Heavy damages to industrial parks by future earthquakes andtsunamis will cause serious impacts on
the safety and the security of the societies
as well as the worldwide economy. Therefore, the enhancement of earthquake andtsunami resistance of industrial parks is
the most urgent subject in earthquake- andtsunami-prone countries like Japan.
The Japanese government initiated anational project for the reinforcement ofindustrial facilities around the Tokyo, Iseand Osaka Bays since 2014, by spending
about 15 billion yen per year for the financial support to oil refinery industries. This
report previews the damage to industrial
facilities caused by the past earthquakes,
and introduces the outline of the national
project for the reinforcement.
Damage to Industrial Facilities during Past Earthquakes and Tsunamis
The damage to industrial facilities causedby past earthquakes and tsunamis are
summarized as follows;• Breakages of Oil Tanks by the

Dynamic Inertia Forces Caused
by Seismic Motion
Photo 1 shows the explosion and the firesof 17 spherical LPG tanks in an oil refinery plant in the Tokyo Bay during the2011 East Japan earthquake. The causeof the damage was identified as an extensively strong seismic inertia force amplified by soft reclaimed ground.
• Overflows of Oil from Tanks andSubsequent Fires
As shown in Photo 2, during the 2003
Tokachi-Oki earthquake, a crude oil tank
and a naphtha tank were fired and burnt
down due to the sloshing vibration of thecontent oil induced by the long-period
seismic motion.
• Settlement and Inclination of Oil
Tanks Caused by Soil Liquefaction of the Foundation GroundPhoto 3 shows the inclination of anoil product tank due to the decrease of
the bearing capacity of the foundation
ground by the soil liquefaction during
the 1995 Kobe earthquake.

Fig. 1 Soil Liquefaction and Ground Displacement of a Man-made Island
Reclaimed form the Osaka Bay (1995 Kobe Earthquake)0
Photo 3 Settlement and inclination of oil producttank by soil liquefaction (1995 Kobe
earthquake)1 Steel Construction Today & Tomorrow August 2017(a) Soil liquefaction (The yellow coloredground surface shows the thick depositby the boiling of liqueﬁed sand)

100 m(b) Ground surface displacements (The vectors show thehorizontal displacements, and the numerals in theparentheses are the vertical displacements, unit: cm)

Photo 4 Floating out of oil tanks into the sea by thetsunami (2011 East Japan earthquake)• Ruptures of Pipelines of Oiland Gas, and Foundation Piles
by Liquefaction-induced Large
Ground Displacement
Fig. 1(a) is an aerial photo taken over atank yard in Kobe, two days after the Kobe earthquake. Boiled sand accumulated
all over the yard, indicating that its entire
area had liquefied (yellow colored part in
the figure). A large amount of gas leakedby the rupture of the LPG pipeline. Fig.
1(b) shows horizontal and vertical grounddisplacements on the ground surface ofthe tank yard, indicating that the seawall
displaced 3.6 m seaward at maximum,
and the whole tank yard, with about 400
× 400 m area, also moved 2-3 m seaward.
• Lift-up and Flow of Oil Tanks
The inundated tsunami lifted up oil tanks
and floated them into the sea as shownin Photo 4, and ignited the large sea surface fire at the time of the 2011 East Japan earthquake.
Assessment of Damage to Industrial Parks in the Tokyo Bay
Around the Tokyo Bay, there are huge
man-maid islands reclaimed from thebay. Most of these islands and their quay
walls have not enough resistance against
soil liquefaction, because those had been
constructed before the 1964 Niigata
earthquake, which firstly let us recognize
the phenomena of soil liquefaction andits caused damage from the viewpointof engineering. Fig. 2 shows one example of the assessment of soil liquefaction,and seawall and ground movement in thehorizontal direction of a man-made island in the Tokyo Bay by the Northern
Tokyo Bay earthquake, which has been
predicted as one of impending earthquakes in near future. The thickness of
the liquefied soil layer and the maximum seawall movement were estimated as about 10 m and 7 m, respectively.
On the reclaimed land around the Tokyo
Bay, more than 5 thousand tanks havebeen constructed for the storage of oil,oil products, high pressure gas and poison materials. A large number of them islocated on the ground which has high potential of soil liquefaction, and horizontal and vertical ground displacements.
Furthermore, there are more than 600
floating roof tanks for the storage ofcrude and heavy oil around the Tokyo
Bay. A large amount of oil is assessedto overflow from these tanks due to thelong-period seismic motion induced by
the Nankai Trough earthquake along the
Pacific coast of the western Japan.
Fig. 3 shows one example of the numerical simulations on the diffusion on
the sea surface of the oil of a volume ofabout 22,000 kl, resulting from the breakage of oil tanks due to soil liquefaction
and overflow of oil due to long-period

Fig. 2 Assessment of Soil Liquefaction and Its Induced Ground Displacement(Northern Tokyo Bay Earthquake)
Thickness ofliqueﬁed soil

seismic motion. The spilled oil from theeast coast of the Tokyo Bay will reach to
the west coast within three days under
the condition that the wind speed is 5.0
m/s in summer season. Under such condition, the maritime function of the main
sea routes of the bay may be paralyzed
and the economic activity in the metropolitan area of Tokyo will be seriously affected by the stop of sea transportation.
Measures for Earthquake Resistance Enhancement of Industrial
Facilities
The reinforcement of the seawalls is required to prevent the damage to the industrial facilities nearby the seawalls.
As shown in Fig. 4, three kinds of countermeasures were applied to protect theexisting seawalls. The first method is aconstruction of new steel sheet pile walls
behind the existing seawalls. The second
method is the soil improvement against
the liquefaction. In the third method,steel piles are driven in two rows witha proper interval behind the seawall. In
this method, the pile group is expected
to prevent the flow of the liquefied soil.
The effectiveness of each method has
been examined by experiments undercentrifuge conditions.
Fig. 5 shows an example of measuresof oil tanks against soil liquefaction andtsunamis. The steel sheet piles aroundthe tank restrain the outflow of the liqFig. 3 Diffusion of Crude Oil in Tokyo
Bay (summer season, the windspeed of 5.0 m/s in southernwest direction)
Diffusion area on the third day

Oil ﬂowing-out point

5~
6~
7~
8~
9~
10~11 m11~12 m12~13 m4 m Horizontal
displacement ofseawalls
Ground disp.
4m
Displacement of≒ 7.0 mgroundThickness of liqueﬁed soil: 10 m

Daily wakes ofships (about 200
ships per day)August 2017 Steel Construction Today & Tomorrow 2

uefied soil beneath the tanks, resulting
in prevention of the settlement and theinclination of the tanks. The steel pipe
piles above the ground prevent the collision of the floating objects with the tankduring tsunamis.
Recommendation for Earthquake
and Tsunami Resistance of Industrial Parks
In 2013, the Ministry of Economy, Tradeand Industry (METI) of the Japanese
government initiated the policy for theenhancement of earthquake and tsunami resistance of industrial parks. Twenty
four petroleum plants were selected fromthe areas which have high probability to
be hit by large earthquakes and tsunamis
in very near future. (Refer to Fig. 6)
The author recommended the following
advices to concerned organizations including the Japanese government for more active promotion of earthquake- and tsunamiresistance enhancement of industrial parks.
The first recommendation is that, in
addition to reinforcement of each industrial plant, the earthquake- and tsunami-resistance enhancement in larger areas such as whole areas of man-madeislands including sea areas should bestrongly promoted, because the disasterat one plant may extend to the neighbor-Fig. 4 Reinforcement of Seawalls against Soil Liquefaction and Its-Induced
Ground Displacement

10 m

Sheet pile
wall

Existingwall

Continuous wall

Soil improvement

5m

14 m

Pile grouping plants and affect the wider areas. To
achieve this, strong leadership by the central and the local governments is strongly
required to lead the group of the industrial companies. For the enhancement of disaster resilience of the larger areas, more
public investment is also required for private properties of the industries, particularly for small industries, most of which
has not enough financial foundation.
The risk information sharing is required among governments, industries
and local communities. This is essential
in order to promote the total enhancement of earthquake and tsunami resistance of wider industrial areas including
neighboring local communities. The assessment of the impact of the loss of thefunction of industrial parks on the country as well as on worldwide economy isalso required for establishment of effective national policies and strategies. ￭Fig. 5 Measures of Oil Tanks against
Soil Liquefaction and Tsunamis

10 m

Steel pipe pile
Steel sheet pileTank

4D* (pile space) 6D (pile space)*D: Diameter of pile
(Model for experiment)

Fig. 6 Survey and Practice of Earthquake and Tsunami Resistance Enhancement of Industrial Complexes-Policy by
Ministry of Economy, Trade and Industry (2013~)
Northern Tokyo Bay earthquake, earthquake resources along the Nankai Trench, and location of petroleum complexes: Industrial complexes

100 kmNorthern Tokyo Bay earthquake

The earthquake resources along
the Nankai Trench

Evaluation of tsunami height of ﬂood

Flow of survey on damage to petroleum complexes by future earthquakes and tsunamis
Soil condition
survey forassessment ofsoil liquefaction

Assessment of soilliquefaction ofartiﬁcial islands

24 petroleum industries, 16 billion yen/year (public fund)3 Steel Construction Today & Tomorrow August 2017

Assessment ofstability anddeformation of
quaywalls

Assessment ofgrounddisplacement

Assessment of disasters to petroleum
complexes due to earthquake motion,soil liquefaction, ground displacement
and tsunamis

Seismic Countermeasure Technologies for Bridge Abutments

Prevention of Liquefaction-induced
Damage to Existing Bridges-Development of Seismic Resistance Evaluation
Method and Seismic Countermeasure
Technologies for Bridge Foundationsby Toshiaki Nanazawa and Michio Ohsumi
Public Works Research InstituteToshiaki Nanazawa: After finishing the master’scourse of Graduate School of Engineering, Tohoku
University, he entered the Ministry of Construction in
1994. In 2010, he became Researcher at the Public
Works Research Institute, and assumed his current
position as Chief Researcher at the Public Works
Research Institute in 2012.

Toward Highly Resilient Highway
Networks
Among the existing bridges located onliquefiable ground, there is risk to bedamaged seriously due to great earthquakes. In order to make the highway
network resilient, it is important to extract these bridges by the use of a rational verification method and to structure a method to effectively promote
seismic countermeasures. To attain thisgoal, at the Center for Advanced Engineering Structural Assessment and Research (CAESAR) of the Public Works
Research Institute, a research project has
been underway since 2014 that aims todevelop a seismic resistance verification
method and seismic-resistant technologies for bridge foundations in liquefiableground.
This article describes the status of thisresearch project.
Outline of Research• Analysis of Examples of Damage due to Past Great Earthquakes
An analysis was made of 38 examplesof damage to bridges installed in groundwhere liquefaction occurred in past greatearthquakes. Through this analysis, theform of damages affecting the seismic
resistance of bridges was classified into three types1). Of these three forms ofdamage, the current research has targeted damage to bridge abutments forwhich comparatively many examples ofMichio Ohsumi: After finishing the master’s courseof Graduate School of Engineering, The Universityof Tokyo, he entered the Ministry of Constructionin 1996. In 2010, he served as Director of Naniwa
National Road Works Office, Ministry of Land, Infrastructure, Transport and Tourism. He assumed his
current position as Chief Researcher at the Public
Works Research Institute in 2016.

damage that might cause trouble in thetransportation function are found and forwhich examples of existing research arefew. Experiments and analytical examinations are being promoted on the damage to these bridge abutments. Photo 1
shows an example of such damage to abridge abutment.

Photo 1 Damage to bridge abutment located in
the ground where liquefaction occurred2)

Fig. 1 Example of Reinforcing Structure
for Abutment Foundation(Steel Pipe Sheet Pile Wall:
Side-integrated Type)
Filling
Occurrenceof lateral
movement
force

Steel pipe
sheet pile
wall
Existing
pile

Liqueﬁed layer
Supporting layer• Proposal of Reinforcing Meth-ods and Structures for Foundations
A proposal was made through joint research with the Japanese Association for
Steel Pipe Piles (JASPP). Specifically, a
reinforcing method and a structure forfoundations employing steel pipe piles
and steel pipe sheet piles were proposed
through examinations made from the following three aspects:• Effectiveness for seismic behavior andmechanism of the damage of foundations• Avoidance of traffic hindrance duringreinforcement work
• Applicability of construction machineryin narrow execution yards such as clear
headway under girders
Fig. 1 shows an example of reinforcing structures thus proposed for bridge
abutments.

• Verification of Seismic Behav-

ior of Foundations and Seismic
Countermeasure Technologies
through Shaking Table Tests
In order to verify liquefaction-induced
ground flow, the seismic behavior of old
foundations and the effectiveness of proposed reinforcing structures, shaking table tests were conducted on abutmentson liquefiable ground using the large
scale shaking table in the Public Works
Research Institute. Photo 2 shows the
specimens on the shaking table.
In the following, the test results of
two cases are introduced-Case 1 inAugust 2017 Steel Construction Today & Tomorrow 4

which an existing abutment built without design for liquefaction is modeled;and Case 5 in which the footing of it was
extended to the side and steel pipe sheet
pile was integrated there. (Refer to Table 1 and Fig. 2) The reduced scale of themodel bridge abutment is 1/10. The abut-

Photo 2 Specimens on the shaking table

ment model was designed by assuming
an abutment height of 8 m and a liquefiable layer thickness of 10 m in prototype
scale. In the test, an artificial seismic
wave was to be input to the bridge axial direction, and the design earthquake
ground motion (I-I-3) for dynamic analysis specified in the current Specificationsfor Highway Bridges of the Japan Road
Association4) was applied.
Photo 3 shows the ground deformation conditions after excitation in Case 1.
It is understood from the photo that almost no deformation occurred in the rearof the abutment but large deformation
occurred in front of the abutment. Fig. 3
shows the secular change of excess porewater pressure in the rear of the abutment
and at the slope toe (red circles in Fig. 2).
In both cases, while the excess pore water pressure ratio reached approximately
1.0 at the slope toe and ground liquefaction occurred, liquefaction did not occur
in the ground on the rear side of the abutment.
Fig. 4 shows the distribution of thebending strains of the piles at section
1-1 in Fig. 2 at the time when the bending strain of the piles and the displacement of the abutments reach their maximum level. In both cases, the bendingstrain surpassed the yielding strain by agreat margin at the pile head and in thepile intermediate section of the existing
piles. On the other hand, in Case 5, because the bending strain of the reinforcing pipe remained nearly within elastic
range and the shear strength of the rein-

Table 1 Test Cases for Seismic Countermeasures for
Abutments
Case

Standard
appliedCase 1Case 5

Detail offoundation

Countermeasure
structure

Configuration of
backfill

FormerPrefabricatedstandards* RC pile:φ450 mm
8×3 rows

No countermeasure

River
dike

FormerPrefabricatedstandards* RC pile:
φ450mm 8
×3 rows

Steel pipe sheet pile
wall: Side-integrated
type φ600×8 piles(one side: 4 piles)

River
dike

* Design of Pile Foundations-Guidelines to Design of Substructuresof Highway Bridges (Mar. 1964, Japan Road Association)

Photo 3 Ground deformation after excitation (Case 1)

Fig. 2 Outline of Abutment Model
Accelerometer
Pore water pressure meter

Earth pressure gauge
Displacement sensor
Strut

Vertical wall
BackﬁllFooting
Existing
pile
Liqueﬁable layer
Gravel layer

Pin

Accelerometer
Pore water pressure meter

Strut

Vertical wall
BackﬁllFooting
Existing
pile
Liqueﬁable layer
Gravel layer

1-1 section

Pin

Earth pressure gauge
Displacement sensor

1-1 section

Steel pipe sheet pile wall

Existing pile

Ground plan(a) Case 1

5 Steel Construction Today & Tomorrow August 2017

Strut(unit: mm)Existing pile

Ground plan(b) Case 5

Strut(unit: mm)

Fig. 6 Dynamic Analysis Using
Three-dimensional Finite
Element Model in Case 3(Tokyo Institute of Technology)1)

ExcessExcesspore waterpore waterpressure ratio pressure ratio

Fig. 3 Secular Change of Excess Pore Water Pressure
Rear of abutment (container bottom surface +0.6 m)

Slope toe (container bottom surface +0.6 m)

Time (seconds)

Fig. 4 Distribution of Bending Strains of Pile at the Time of Maximum Response

Height from container bottom surface (m)Bending strain/Yielding strain

At the time of
maximum response(38.20 seconds)

Bending strain/Yielding strain

At the time of
maximum response(38.22 seconds)

Bending strain/Yielding strain

At the time of
maximum response(38.22 seconds)

Back-row pile
Intermediate-row pile
Front-row pile

Back-row pile
Intermediate-row pile
Front-row pile

Back-row pipe
Intermediate-row pipe
Intermediate-row pipe
Front-row pipe

Case 1: Existing pile

Case 5: Existing pile

Case 5: Reinforcing pipe

Rotation angle
at the bottomof footing (rad.)Lateraldisplacement
at the bottomof footing (mm)Fig. 5 Secular Change of Lateral Displacement and Rotation Angle at the
Bottom of Footing
Case 1Case 5

Case 1Case 5Time (seconds)

forcing pipe was sufficiently large, it canbe assessed that seismic resistance is secured for the entire foundation structure.
Fig. 5 shows the secular change of lateral displacement and rotation angle atthe bottom of the footing. In both cases,
while nearly no difference of displacements of abutments was seen, if plasticization of the existing piles progresses, it
is forecasted that differences of displacement may occur.
In the future, in order to clarify the behavior of a foundation after its plasticization, it is planned to conduct a largescale verification test using a model witha reduced scale of 1/4.5.

• Structuring of Advanced Analyt-

ical Approaches
A joint research project pertaining to
the analytical technology is being promoted between CAESAR and the Tokyo Institute of Technology. Its aim is
to develop an analytical technology forfoundations in liquefied ground that can
reproduce damage examples and shaking table tests1). For that purpose, examinations are being promoted by means ofdynamic analysis using a three-dimensional finite model in which the groundand the abutment are treated as solid elements and the piles are treated as beam
elements (Fig. 6).

Dispersal into Society
CAESAR is striving to apply and disperse the attainments obtained in thecurrent research to society by capitalizing on various means-the reflectionof these attainments on the design standards of bridges and the technical support of seismic reinforcing measures bymeans of public announcements of design guidelines employing these attainments.
Acknowledgment
The current research has been supported
by Council for Science, Technology andInnovation (CSTI), Cross-ministerial
Strategic Innovation Promotion Program(SIP), “Enhancement of societal resiliency against natural disasters” (Funding agency: JST). We offer our thanks tothose of the Council for Science, Technology and Innovation who has support￭
ed our current research project.
References
1) Center for Advanced Engineering Structural Assessment and Research (CAESAR) of Public Works Research Institute:
Proceedings of 9th CAESAR Lecture
Meeting, pp. 15-35
2) Japan Society of Civil Engineers: Report on the Hanshin-Awaji Earthquake
Disaster, Damage to Civil Engineering
Structures, Dec. 1996
3) Japan Road Association: Design of Pile
Foundations-Guidelines to Design ofSubstructures of Highway Bridges, Mar.
1964
4) Japan Road Association: V Seismic Design, Specifications and Commentaries
for Highway Bridges, Mar. 2012

August 2017 Steel Construction Today & Tomorrow 6

Bearing Capacity of Steel Pipe Piles

Estimation of Bearing Capacity of SteelPipe Piles-Measures for Improving Estimation Accuracy
   Employing Dynamic Loading Testsby Takaaki Mizutani
Port and Airport Research Institute, National Institute of
Maritime, Port and Aviation Technology
Toward the Highly Accurate Estimation of Pile Bearing Capacity
Application of performance-based design in the technical standards follows aninternational trend. In light of this, performance-based design and reliabilitybased design approaches have been introduced in the Technical Standards andCommentaries for Port and Harbor Facilities in Japan1) since its revision starting in 2007. Application of the reliability-based design approach allows for
efficient structural design and an examination of advanced seismic resistance.
However, an article concerning the pile
bearing capacity (axial resistance) usedin the Standards still remains within theframework of the safety factor method,and currently falls behind the entire system of the Standards. In order to establish a system that targets pile bearing capacity and takes reliability into account,
it is necessary to collect data and prepare
statistics pertaining to a number of piles.
For that purpose, it is necessary to implement loading tests for a number ofpiles in order to obtain the related data.
However, the pile loading test is large
in scale and greatly effects the construction cost and term, and thus the numberof loading tests to be implemented is restricted. Meanwhile, dynamic loading
tests are increasingly being adopted as asimple means of testing. In the construction of port and harbor facilities in Japan,
there are many cases in which steel pipe
piles are installed using hydraulic hammers, and this pile hammering method
is well compatible with dynamic loading tests because the pile hammering device can be applied as the dynamic loading test device.
7 Steel Construction Today & Tomorrow August 2017

Takaaki Mizutani: After graduating from the Graduate Schoolof Engineering, The University of Tokyo in 2000, he entered
the Port and Airport Research Institute. Then, he worked forthe construction office, Kansai International Airport Company
for 2006-2007. He became Researcher of Port and Airport
Research Institute in 2008 and assumed his current positionas Head of Foundations Group of the Institute in 2010.

As a measure to improve the accuracyof estimates of pile bearing capacity using dynamic loading tests, loading tests
were conducted using a number of piles
to examine a method that evaluates thevariation in pile bearing capacity and applies the evaluation results in the management of pile construction work, an
example of which is introduced in thefollowing.
Outline of Dynamic Loading Tests
The dynamic loading tests subjected tothe current examination were conductedat the construction site for a coastal highway bridge located in Mizushima Port
Fig. 1 Location of Testing Site
Shin-Kurashiki
StationKurashiki City

Tamashimaarea
Bridgeconstruction site
TakahashiRiver
Mizushima Portin Okayama Prefecture. Fig. 1 shows
the location of the testing site, and Fig.
2 shows the longitudinal profile of soil
confirmed in prior ground surveys. Plans
call for the construction of a bridge near
the mouth of the Takahashi River where
it flows into Mizushima Port and of 19
bridge piers spanning the river width,
which is about 1,400 m. As can be seenin Fig. 2, the soil stratum is approximately uniform in the bridge axial direction,and it was planned to adopt gravel layer
Dg2 as the stratum to support the piles.
The dynamic loading tests were conducted at the planned construction position for the respective piers (indicated as
P1~P19 in Fig. 2) and by changing theend shape of the piles (open-ended piles
or cross-shape ended piles in which a
cruciform rib plate was weld-joined tothe inside of the ends of the open-ended
piles) and the curing days (the time justafter pile installation to 28 days) as well.
The diameter of the test piles used was
1,000 mm and, while the pile embedded
length (the length from ground surface
to the pile end) slightly differs depending on the pier position, it ranged from18 m to 24 m.
The test method followed the standard method specified by the JapaneseFig. 2 Longitudinal Profile of SoilP1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18 P19 T.P. -(m)0Asc1
Asc1N=1
5
AcAc qu=52kPa
10As N=1
As
15
N=31
Ag
Ag
20
Dg2
Dg2 N=59
25
Tamashima
Mizushima
Asc2
N=4

Evaluation of Variations in Pile
Bearing Capacity
Results of all 53 dynamic loading tests
thus conducted were organized and thensubjected to statistical treatment fromvarious aspects4). In the following, examples of the evaluation of variations in pile
point resistance are introduced.
Fig. 3 shows the distribution of pile
point resistance obtained from the respective pier positions. When examining
the figure, despite the piles being embedded in the same supporting stratum,
it can be understood that the values forpile point resistance show a certain level of variation. Meanwhile, when noticing the data in which the number of curing days and the pile end shapes coincidewith each other at an identical pier position (Fig. 3), the variations in pile point
resistance look to be slight. Then, the statistical data thus obtained were classified
by testing condition and compiled, theresult of which is shown Table 1. As seenin the table, it is understood that the coefficient of variation (C.V.) is nearly 20%
or lower when examining all piers, andnearly 10% or lower when focusing on
specific piers.
Based on these results, specific concepts were shown that pertain to thecharacteristic values of the pile bearing
capacity obtained from the loading tests,
the method for determining the safety factors to be adopted when applying
these characteristic values, and the practical application of that method. Morespecifically, it has been reported that thepartial safety factor (resistance factor)
for reliability-based design method canbe increased (the redundancy in terms ofsafety can be decreased) by conducting
the loading tests at the original pier position, compared to cases where the design
was conducted by estimating the pile
bearing capacity using common estimation formulas. To that end, it is being examined to reflect these specific results inthe next revision of the Technical Standards for Port and Harbor Facilities.

Application of Dynamic Loading
Test Results in Management of
Piling Works
When steel pipe piles are driven bymeans of hammering in the construction of port and harbor facilities in Japan, there are many cases in which thepile driving work is managed employing
Hiley’s pile driving equation. While theaim of the equation is to estimate not on-ly the pile penetration resistance from thepenetration amount and rebound amountof the driven piles but also the pile bearing capacity, its estimation accuracy isvery low. To remedy the situation, it is
proposed that Hiley’s equation be corrected based on the pile bearing capacity
obtained from the dynamic loading tests
and that the corrected equation then be
applied in managing the piling work5).

Photo 1 Condition of dynamic loading testing

Photo 2 Condition in which sensors are pasted on
test pileFig. 3 Pile Point Resistance Obtained from Dynamic Loading Tests
4.0
3.5
3.0
2.5

Rp/MN

Geotechnical Society2), and the waveform matching analysis using CAPWAP
was conducted for the data obtained using PDA to calculate the pile bearing capacity. Photo 1 shows the condition for
dynamic loading testing, and Photo 2
the condition where sensors are pasted
on the test pile (section encircled using
while line). As regards the testing conditions, please refer to the existing literature3).

2.0

Open-ended 0-1 day
6-7 days

1.5

9-12 days
13-14 days

1.0

28 days
Other piles 0-1 day

0.5
0.0

5-7 days
9-12 days
1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19Pier #

Table 1 Statistical Amount of Pile Point ResistancePier #

Pile type

Curing days

Sample size

Mean (kN)

C.V. (%)

Standard errorAll

All cases

All cases

53

2650

19.2

69.9

All

Open-ended

All cases

33

2570

18.4

82.2

All

Cross-shaped

All cases

20

2790

19.6

122

11

Open-ended

6

4

3040

9.93

151

14

Open-ended

7

4

2310

5.02

58.0

17

Open-ended

6

4

2670

4.91

65.5

13

Open-ended

14

4

2760

1.18

16.4

16

Open-ended

14

4

3200

7.34

118

6

Cross-shaped

6

4

2220

7.75

86.0

7

Cross-shaped

6

4

3370

0.190

3.20

August 2017 Steel Construction Today & Tomorrow 8

Fig. 4 shows the relation between thepile bearing capacity Rt obtained fromthe dynamic loading tests and the pile
bearing capacity Rth calculated using Hiley’s equation. As can be seen from thefigure, both the loading test results and
Hiley’s equation calculation results havea nearly proportional relation. In the figure, while regression lines are shown that
conform to the kind of hammers applied
and the shapes of the pile ends adopted,
the coefficient of variation (Rt/Rth) exactly exceeds 20%, thereby resulting in agreat variation in the data. Accordingly,
it is considered difficult to apply a corrected coefficient for Hiley’s equation in
all the bridge piers.
On the other hand, when we look attests conducted at specified pier positions, many data comparatively come together at these specified pier positions as
seen in Fig. 4, and accordingly it is considered feasible that a corrected coefficient for Hiley’s equation can be applied
to the piles of specified piers. That is, incases when one loading test is conducted
at a respective pile position, it is possible
to conduct piling work management withhigh accuracy by making use of the dataobtained from the loading tests.
Development of Simpler Pile Testing Methods
In this article, diverse examinations are
introduced on improving the accuracyof estimated pile bearing capacities andto manage piling work by making use ofloading tests, which are being promoted toward the revision of Technical Stan-

Photo 3 The Kurashiki Minato Bridge under construction at the testing site was completed and opened to traffic in March 2017 (foreground)dards for Port and Harbor Facilities inJapan. In order to enhance the reliability of the examination, it is effective tocollect a large number of data pertaining
to pile loading tests. Meanwhile, even if
the accuracy of pile bearing capacity estimates can be enhanced, we can neverforget that there is no method to confirm
the pile bearing capacity with high accuracy other than to conduct a pile loading
test at the original piling position.
Anyway, the development of a simple
pile testing method like dynamic loading tests will offer a greater contribution
to the structural design and constructionof piles, and expectations are high for increasing adoption of dynamic loading
tests and other simple pile testing methods.

Fig. 4 Comparison between Dynamic Loading Test Resultsand Calculation Results Employing Hiley’s Equation
12000

NH open
10000

IHC

Rt/kN

8000

6000

4000

2000

0

NH cross

0

2000

4000

6000
Rth/kN

9 Steel Construction Today & Tomorrow August 2017

8000

10000

12000

Meanwhile, at the site where the dynamic loading test introduced above wascarried out, construction of a coastal highway bridge has made steady progress.
Then, the completed bridge was named
the Kurashiki Minato Bridge and opened￭
to traffic in March 2017 (Photo 3).
References
1) Ports and Harbours Bureau, Ministryof Land, Infrastructure, Transport andTourism; National Institute for Land andInfrastructure Management; and Portand Airport Research Institute, Technical standards and commentaries for port
and harbour facilities in Japan. Overseas
Coastal Area Development Institute ofJapan, 2009, Part III, ch. 2.
2) Japanese Geotechnical Society, Method for dynamic load test of single piles.
JGS 1816-2002, 2002.
3) Mizutani, T. Axial resistances of openended piles driven into gravel layers:
Dynamic loading tests of piles at roadbridge construction site in Mizushima
port. Geotechnique, Construction Materials & Environment, Vol.5(1), Proc.
of 5th Intl. Conf. - GEOMATE 2015,
pp. 389-394, 2015.
4) Mizutani, T. Variance of dynamic load
test results of piles at a single construction site, Journal of Japan Society of
Civil Engineers, Ser. C (Geosphere Engineering), Vol. 71, No. 3, pp. 228-240,
2015 (in Japanese).
5) Mizutani, T and Matsumura, S. Correction of Hiley’s equation and its applicability based on dynamic loading tests at
Mizushima port. Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean
Engineering), Vol. 72, No. 2, pp. I_396I_401, 2016 (in Japanese).

Ultimate Strength of Steel Pipe Piles

Evaluation of Ultimate Strength of SteelPipe Piles in Liquefied Soil
-Ultimate Strength of Pipe Piles Used for High-rise
Buildings in Liquefied Soil during Great
Earthquakes-

Yoshihiro Kimura: After finishing the doctor’s course at the Tokyo Institute of Technology in 1995, he served as professor at the Nagasaki
University and the Tohoku University. He assumed his current position as Professor, Tohoku University (New Industry Creation Hatchery Center) in 2012. Among his recent awarding are Paper Awardsof JSSC (Japanese Society of Steel Construction) 2009, 2014, Best
Paper Award and Keynote Paper Award of GEOMATE 2012, 2016 and
The Prize of AIJ (Architectural Institute of Japan) 2017.

by Yoshihiro Kimura
Professor, Tohoku University
Clarification of Pile’s Dynamic
Buckling Phenomenon
In the Great East Japan Earthquake of2011, soil liquefaction occurred in a wide
area including the Tokyo Bay coastal area more than 500 km from the focus of
the earthquake1). Due to the soil liquefaction caused by the earthquake, many buildings suffered inclination damage. Meanwhile, in the upper stories ofhigh-rise buildings, horizontal displacement measuring several meters occurredin the earthquake. And, the overturning moment of these high-rise buildings
caused by the inertia force amounted to avalue several times that of medium- andlow-rise buildings, which means that reversed axial forces not assumed in thedesign stage occurred in the foundation
piles used for these high-rise buildings.
In the coastal areas of big cities, manyhigh-rise buildings are constructed on reclaimed land and soft ground near rivers.

In cases when these buildings are subjected to a great and long-period earthquake such as the one mentioned above,
the building and the liquefied soil cause
resonance, and as a result, large reversed
axial force works on the foundation piles(refer to Fig. 1). And, when the piles installed on a liquefied layer that has lost
horizontal stiffness of the soil are subjected to a high axial compression force,
flexural buckling of the piles is likely tooccur.
In the current research, the flexural
buckling phenomenon of steel pipe piles
beneath high-rise buildings constructedon soil liquefied due to an earthquake isclarified by means of centrifugal loading
experiments, and at the same time, theultimate strength of these piles is evaluated by the use of buckling curves employing the modified equivalent slenderness ratio.

Fig. 1 Concept for Flexural Buckling of Steel Pile in Liquefied Soil
Inertial force

Dead load

Steel piles are believed to be able to sustain strong
lateral and compressive forces and to feature that no
pile experiences ﬂexural buckling because of soil
resistance against lateral deformation of piles.
Design codes have no prescription for
limitations of piles’ slenderness ratio.
The horizontal stiffness of the grounddecreases drastically when liquefaction occurs
during an earthquake.
Moreover, slender steel piles beneathbuildings experience high axial compression
forces caused by the overturning moment of
the superstructure, which are generated by theinertial force of the building.

Force couple due tooverturning moment
Horizontal force due
to inertia force
Liqueﬁed
soil

Soil reaction

Flexural buckling of piles may occur.

Centrifugal Loading Experiments
for a Superstructure, Steel Pipe
Pile-Liquefied Soil Model
The specimens are composed of a superstructure, steel pipe piles and soil asshown in Fig. 2. The dimensions of thespecimens and the measurement positions
are shown in the figure. The pile length
in the model measures 265 mm (10.6 m
in full-scale size). The specimen parameters cover the initial axial force of thepiles, the plate spring length of the superstructure, the input seismic waves,and their maximum values (Table 1). The
soil of the specimens was prepared by anair dropping method in which dry Toyoura silica sand is air-sprayed and accumulated. In order to saturate the soil, the“Metolose” solution (nonionic water-soluble cellulose) is adopted in which its viscosity is adjusted to 40 times that of water.
Fig. 2 Specimen and Instrumentation
Strain gauge
Accelerometer
Water pressuregaugeSuperstructure
Bending plate
Pile cap

Laminar box

Piles A, C
Piles B, D
Unit: mm(a) Side
Laminar box Superstructure
Pile C

Pile D

Pile A

Pile B(b) Top

August 2017 Steel Construction Today & Tomorrow 10

Two waves are adopted as the input
seismic waves: the coastal seismic wave
as the simulated wave and the wave observed at Urayasu in the Great East Japan Earthquake of 2011. The centrifugal
loading experiment was conducted at a
40g site using a centrifugal loading apparatus at the Disaster Prevention ResearchInstitute of the Kyoto University. (Refer
to Photo 1)
Fig. 3 shows examples of the centrifugal loading experiment results-(a) in
the figure, response of the accelerationof the superstructure; (b): response of theexcess pore water pressure ratio; (c): response of the axial force working on thepiles; and (d) response of the bendingstrain of the piles.
In Fig. 3-(b), it can be understoodfrom the water pressure gauges installedin three locations to the depth directionthat soil liquefaction occurred throughthe entire layer in the neighborhood of
the 16th second. In Fig. 3-(c), the maximum axial force working on the piles
reached 1,582 kN in the neighborhoodof the 22nd second (reversed axial forceof 307 kN due to the response of the superstructure). In Fig. 3-(d), as regards thebending strain of the pile heads, the maximum bending increment strain reached
its maximum level in the neighborhood

Table 1 Specimen Parameters
Specimen Initial axial force, Plate length
N0 (kN) (N0 /Ny)h (mm)
Case1-1
Case1-2
Case1-3
Case1-435
1275(0.33)

55
70

Case1-5
Case1-6856(0.33)

Case1-9Input wave

Maximum input
wave (m/s2)

30

4.5

60
30
60

Coastal wave

3.0

4.5
35

Case1-7
Case1-8

Relative density
Dr (%)

1275(0.49)

45
35

Case1-10

3.0

30

45

Urayasu wave

6.0

Coastal wave

3.0

of the 21st second, then the bendingstrain showed an upward trend in one direction to reach the maximum level in
the neighborhood of the 26th second,which caused the collapse of the piles.
Photo 2 shows the condition of the final deformation of the pile specimens.
Regardless of the length of the superstructure plate spring and the differences in the relative density of the soil, thesteel pipe piles underwent large bending
deformation underground, and the crosssection of the piles caused yielding.
It was shown from the above experiment results that the steel pipe piles beneath the building are likely to cause collapse due to soil liquefaction occurring
during a great earthquake2).
Evaluation of Ultimate Strength of
Steel Pipe Piles
In order to evaluate the ultimate strengthof steel pipe piles during dynamic buckling, firstly a formula for elastic flexural buckling loads applied to steel pipe
piles in liquefied soil that are subjected
to compression axial force is led using
a variational principle based on the energy method, and secondly the modified
equivalent slenderness ratio to which thiselastic flexural buckling load formula isapplied is adopted as a parameter to evaluate the ultimate strength3).

Fig. 3 Response Time History of Case 1-1
Soil liquefaction

Possible to work thecentrifugal force(40~60 g) by rotating
the arm
Shear soil tank(a) Superstructure acceleration
Soil liquefaction

Water pressuregaugesPhoto 1 Centrifugal loading apparatus(b) Excess pore water pressure ratio
Soil liquefaction
Reversed axial force
307 kN

Maximumcompressiveforce(c) Pile's axial force
Soil liquefaction
h=35 mm
Dr=30%

h=35 mm
Dr=60%

h=70 mm
Dr=30%

Case 1-1

Case 1-2

Case 1-4

Photo 2 Bending deformation of piles

11 Steel Construction Today & Tomorrow August 2017(d) Bending strain of piles

Maximum bending
increment strain
Maximum bendingstrainThen, the elasto-plastic flexural buckling strength of the steel pipe piles, obtained by means of the finite element elasto-plastic large deformation analysis andthe centrifugal loading experiment mentioned above, are evaluated using the buckling stress curve (Fig. 4) that applies themodified equivalent slenderness ratio4), 5).
Further, not only the centrifugal loading
experiment results2) are applied but numerical analysis is conducted for the single pipe pile model and the superstructurepipe pile model3) in order to evaluate theultimate strength mentioned above.
As regards the dynamic bucklingstrength obtained from the experimentand numerical analysis, the buckling
stress curve that applies the modified
equivalent slenderness ratio can practically be evaluated as the lower limit forsuch dynamic buckling strength.

Further, in Fig. 5, the ultimate strengthof the steel pipe piles in liquefied soilthat are subjected to horizontal force andcompression force is evaluated6). The
vertical axis shows the ratio of the maximum compression force to the elastoplastic buckling strength obtained fromthe buckling stress curve in Fig. 4, andthe horizontal axis, the ratio of the maximum bending moment to the full plastic
bending strength.
The respective curves in the figure
show the M-N interaction allowablestrength curve shown in the currently prevailing design guidelines in Japan andthe ultimate strength curve obtained fromexisting research6). The mark + shows
the numerical analytical results for a single pipe pile and other plots, the centrifugal loading experiment results; theseplots are the major values from the time-

Fig. 4 Dynamic Buckling Strength and Buckling Stress Curves
Nc/Ny

Design Standard for
Steel Structures in Japan4)

1
0.8
0.6

Limit State Design Standard for
Steel Structures in Japan5)

0.4

Static analyses results

Numerical analysis
Piles with
Experiment
Piles
superstructures
No soil

0.2
0

Soil
0

0.5

1

1.5
λc

Fig. 5 Estimation of Axial Force and Bending Moment of Piles Using
M-N Interaction Curves and Ultimate Strength Curves

Nc/Ny

Maximum bending increment strain
Maximum bending strain

1

0.8

Ultimate strengthof Steel Piles in Ref. 6)

0.6

0.4
Limit State Design Standard
for Steel Structures in Japan5)0.2

0Recommendation for Designof Building Foundation7)

history response of the piles to their collapse and are excerpted from the guidelines and experiment results. Of thesevalues, the green plots are the values foraxial force and bending moment in thecase of the maximum bending increment
strain found by the use of the strain gauges pasted to the pile heads, and the redplots are the values for axial force andbending moment in the case of the maximum bending strain at identical positions. (Refer to Fig. 5)
The strength in the case of the maximum bending increment strain (greenplot) is held within the M-N interaction
allowable strength curve shown in thecurrently prevailing design guidelines,
and the ultimate strength in the case of
the maximum bending strain (red plot) isheld within the ultimate strength curve inexisting research6). To these ends, the allowable strength of steel pipe piles andtheir ultimate strength can be evaluatedusing these M-N interaction allowable￭strength curves.
References
1) Architectural Institute of Japan, Preliminary Reconnaissance Report of the2011 Tohoku-Chiho Taiheiyo-Oki Earthquake, Jul. 2011
2) Kimura Y, Goto T., Matoba M., Tamura S. “Dynamic Collapse Mechanism
And Ultimate Strength Circular Tube
Pile Based on Centrifuge Tests of Superstructure-Pile-Liquefied Soil System“,Jour. of Structural and Construction Engineering, Vol.81, No.730, Dec. 2016,
pp.2079-2089
3) Kimura Y, Tokimatsu K, “BucklingStress of Steel Pile with Vertical Loadin Liquefied Soil”, Jour. of Structural
and Construction Engineering, No.595,
Sep. 2005, pp.73-79
4) Architectural Institute of Japan, DesignStandard for Steel Structures, 2005
5) Architectural Institute of Japan, Limit
State Design of Steel Structures, 2010
6) Kimura Y, Tokimatsu K, Ultimate Vertical Strength and Ultimate Flexural Moment of Steel Pile subjected to Verticaland Horizontal Load in Liquefied Soil.
Jour. of Structural and Construction Engineering, Vol.77, No.675, May 2012,
pp.775-781
7) Architectural Institute of Japan, Recommendation for Design of Building
Foundations, 2001

Static analyses results
0

0.2

0.4

0.6

0.8

1

M/Np
August 2017 Steel Construction Today & Tomorrow 12

Stress of Steel Pipe Piles during Earthquakes

Study of Evaluation Method for Pile
Stress during Earthquakes-Towards Establishment of Secondary Design
Method for Steel Pipe Pile FoundationsKatsuichirou Hijikata: He graduated from the
Department of Architecture of Graduate School ofEngineering, The University of Tokyo in 1981, andin 1991 received a doctor’s degree (engineering)from The University of Tokyo. He assumed his
current position as professor at the Department ofArchitecture and Building Engineering, Shibaura
Institute of Technology in 2013.

by Katsuichirou Hijikata
Professor, Shibaura Institute of Technology
Purpose of the StudyIn the construction of energy-related facilities and other similar important facilities, demand is growing for steel pipe
piles that are high in toughness and offer high strength. In the seismic designof these piles that support such important facilities, it is necessary to confirm
the safety of their application against twolevels of seismic motions: level 1 seismic motion that has an occurrence probability of once or twice during their service period and level 2 seismic motionthat has an extremely rare occurrence
probability.
Because examinations of the safety for level 2 seismic motion are madefrom the standpoint of the ultimate limit of structural strength, it is necessary toappropriately evaluate nonlinearity up
to the occurrence of large deformationof the ground and piles. However, at thecurrent stage, it cannot be said that an approach for these examinations has been
established. Targeting steel pile piles
and other pile foundations having hightoughness, the current study aims at establishing a method to evaluate the stressoccurring in piles during earthquakes
and the seismic response of structures bymeans of seismic response analysis.
Composition of Analytical Models• Outline of Seismic Response
Analysis Method
Fig. 1 shows an outline of the seismic response analysis method (EENA-MultiPILE) for pile groups that was developedin the current study. This method adopts
an integrated model that evaluates theground−pile group−structure coupling
effect. Herein, the pile group is modeled
13 Steel Construction Today & Tomorrow August 2017by every pile using a beam element, towhich a horizontal ground spring is added that reflects the reaction force characteristics of the peripheral ground aroundthe piles.
The horizontal ground spring serves
as a model that can evaluate ground non-linearity even with a large deformationof the piles. The seismic motion of thefree ground at the pile’s respective depth
position in the ground is calculated, andthe pile response is calculated by applying these calculated motions from outside of the horizontal ground spring.

Fig. 1 Outline of EENA-Multi-PILE (Seismic Response Analysis Method)

Structure

Base matHorizontal
soil spring

Input motion
Pile• Study of Soil Spring aroundPiles
In examining the load-deformation relation of horizontal ground springs, whichindicates the characteristic property ofthe peripheral ground around a pile, aKishida-Nakai method1) of the bilinear type was adopted. With this method, the initial rigidity of pile peripheral ground is evaluated using a Francis
ground spring to which an appropriate
modulus of deformation is given, and thesize of the ultimate ground reaction force(Pmax) is evaluated using the so-called“wedge formula.”
In the Kishida-Nakai method, themethod is not shown that applies theelastic wave exploration (PS logging) results that can precisely evaluate the dynamic characteristic of the ground. Then,
we noticed the following description
shown in the Design Standards of Railway Structures and CommentariesFoundation Structures and settled themodulus of deformation to be used for
the Francis ground spring.
→“The modulus of deformation equivalent to E50 (secant rigidity at the position 50% of maximum stress) is thevalue 0.1 times the modulus of deformation obtained from PS logging.”
In the pile group, it is known that aphenomenon occurs in which the pilerigidity/pile is lowered due to reciprocal effects between piles. This phenomenon is a group effect of the piles, andthe level of the effect is evaluated using
the pile group coefficient of formula (1).
In the current study, evaluation formula(2) using the pile group coefficient was
proposed based on a recently conducted “three-dimensional nonlinear analysis” and on an “actual site experiment”
for pile groups. In the formula (2), N indicates the number of piles, B the diameter of the piles, and S the space between
the piles.

Pile head rigidityof pile groupe=sition. Then, targeting pile groups having an equal pile-to-pile spacing and arranged in a square form and based on
the three-dimensional nonlinear analytical results for pile groups, we proposeda simple evaluation method for the standardized reaction force η indicated in thedefinition of formula (3)2). With the proposed evaluation method, the difference
between Pmax of the aft pile to the vibration direction and that of the anterior pilecan simply be evaluated, and as regards
the Pmax distribution, the distribution in
the proposed method is to be applied.
Fig. 3 shows an example of the evaluation of η.
Pmax of respective pile
positions of pile groupη=Pmax of single pile
・・・・(3)

No. of piles×Pile headrigidity of single pile
・・・・(1)B/S
e= 1/Ｎ ＋0.2 (e≦1.0)
・・・・(2)
Fig. 2 shows an example of a comparison of pile group coefficients between
the proposed formula (2) and the threedimensional nonlinear analytical results in the case of pile-to-pile space ratio (S/B) at 2.5. As seen in the figure, thepile group coefficient obtained from formula (2) coincides well with that of theexisting analytical research.
Further, it is known that in the pilegroup, the difference in the value of “ultimate ground reaction force (Pmax)”occurs depending on the plane pile po-

Fig. 2 Evaluation Formula for Pile Group Coefficient (S/B=2.5)
1.2e

S/B=2.5

3-D nonlinear analysis
× Sandy soil
◯ Clay soil
△ Intermediate soil

1
0.8

The proposed formula

0.6
0.4
0.2
0

1/N0.5

0

20

40

60

80

100 N

Fig. 3 Comparison of Standardized Coefficient η between Proposed
Evaluation Formula and 3-D Analysisη1.2Standardized coefﬁcient η

In the pile group, reciprocal effects between piles occur via the ground, and it
is known that a phenomenon occurs inwhich the stress of the aft pile in the vibration direction becomes larger than the
stress of the anterior pile.
In EENA-Multi-PILE, a method isadopted in which the pile stress, which
differs depending on the position of eachof the piles, is directly calculated by imparting a ground spring having different
characteristics by pile.

3‐D nonlinear analysis:

S/B2.5

S/B4.0S/B6.0The current study:

S/B2.5

S/B4.0S/B6.0Vibration direction

1.0
0.8
Aft pile

0.6
0.4

Anterior pile

0.2
0.0

0

1

2

3
Pile position

4

5

6

August 2017 Steel Construction Today & Tomorrow 14

• Proposal of Soil Spring around

Piles
From the above, the soil spring aroundpiles is proposed as shown in Fig. 4, andthe evaluation is made based on the following:• The skeleton curve of a single pile isbased on the Kishida-Nakai method of
the bilinear type. For the skeleton curvein the figure, a revision that considers
the group effect of the piles is made using ξ and η.
• The modulus of deformation used for theFrancis ground spring is evaluated using(0.1×EPS) based on PS logging.
• The rigidity of the horizontal ground springof the pile group is decreased using thefollowing formula.
ξ=(1/ＮB/S＋0.2)4/3• The difference of Pmax depending on theposition of each pile is evaluated using
the proposed simple evaluation methodfor η. Meanwhile, as regards the Pmax ofidentical pile, a different value is adopted
depending on the vibration direction: thevalue in the case of the aft pile (η+) andthat in the case of the anterior pile (η−).
Analytical Results Obtained byMeans of EENA-Multi-PILE
A seismic response analysis was conducted targeting an important energyrelated facility of RC structure with aheight of 8 m. The facility is supported
using 25 steel pipe piles (600 mm in diameter) arranged in a square form andwith a pile-to-pile spacing ratio (S/B)
of 3.3. The ground is sandy two-layer
ground composed of the surface groundlayer with a thickness of 22 m and about
Vs 200 m/s and the solid ground that
supports the piles. For the input seismic
motion, seismic motion was adopted thatwas obtained by multiplying by 2.5 themain shock at the Ofunato-bochi-S in the1978.6.12 Miyagiken-Oki Earthquake(observed by Port and Airport ResearchInstitute: Observation of Port/Harbor Area Strong Motion Earthquake).
Fig. 5 shows the maximum shear
force and the maximum moment respectively for the center and corner piles. As
can be seen from the figure, it was confirmed that the moment differs depending on the pile position.
Appropriate Evaluation of Pile
Stress by Means of EENA-MultiPILEIn the current study, we developed a seismic response analytical method (EENAMulti-PILE) for foundations composed
15 Steel Construction Today & Tomorrow August 2017of pile groups. This method can appropriately evaluate the stress of piles andthe response of structures. In the future,
we plan to undertake a parametric studyof the proposed method and the improvement of the codes necessary for this￭study.

References
1) Pile horizontal resistance that takes into account the ground destruction: Proceedings of Architectural Institute of Japan, Sept. 1979
2) A proposal concerning the simple evaluation method for ultimate ground reaction force distribution of pile group,
Proceedings of Architectural Instituteof Japan, July 2016

Fig. 4 Skeleton Curve Considering Group Effects of PilesP
K０: Francis (0.1 EPS)
Pmax: Wedge formula

Skeleton curve of a single pile
K０

Pmax
Pmax＋
K０

η+

0

Pmax－

δ

η−

Skeleton curve of a group pile

Pmax

Fig. 5 Stress of Piles Evaluated Using EENA-Multi-PILE
0

10

20

tonf
30

0

0.00

0.00

−5.00

−5.00

−10.00−10.00−15.00−15.002040Corner pile
Center pile−20.00−20.00
Shear force−25.00m

Moment−25.00m

tonf×m60

Special Topic

How to Improve Social Infrastructure in
Disaster-prone Areas-Disaster Resilience and Lessons Learned from the2016 Kumamoto EarthquakeYoshiaki Kawata: After finishing the doctor’scourse at the Graduate School of Engineering, Kyoto University in 1971, he became
Professor in 1993 and Director of Disaster
Prevention Research Institute in 2005, Kyoto
University. He assumed his current position
as Director of Research Center for Societal
Safety Science, Kansai University in 2012.

by Yoshiaki Kawata
Director of Research Center for Societal Safety Science
Kansai University
Actual State of Infrastructure
Damage due to the Recent Kumamoto Earthquake
When disasters occur, the most important measures are the restoration andreconstruction of damaged social infrastructure. As shown in Fig. 1, social
infrastructure covers various kinds of“lifelines” (critical infrastructure), communications, logistics, public services
and financial services.
In the recent Kumamoto Earthquakethat occurred in March 2016, many pressing concerns arose particularly about logistics. Based on reflections of the Great
East Japan Earthquake of 2011, the Japanese government extended push-type
support and delivered 2.62 million meals
to Tosu in Saga Prefecture, which is adjacent to Kumamoto Prefecture. Whilethese relief supplies were supposed to
be delivered from Tosu to 855 specified
refuge sites in Kumamoto Prefecture bymeans of home delivery services, traffic
congestion occurred in a wider area than
anticipated and their delivery did not gosmoothly.
The most notable reason for this adverse situation was that the expressways running from north to south andthe trunk lines running from east to west
in the Saga and Kumamoto areas weredamaged so badly that traffic had to besuspended. In particular, highway networks were cut off and bridges gave way
due to the large-scale collapse of slopesthat occurred on the hillsides of Mt. Aso,a volcano in Kumamoto Prefecture (seePhoto 1). This greatly hindered the practical execution of disaster countermeasures and the promotion of restoration
work.

Furthermore, in this earthquake, eventhough traffic on ordinary roads was
passable and congestion information wasavailable on a real-time basis throughcar navigation systems, traffic congestion spread to a wider area and became

Fig. 1 Kinds of Social Infrastructure (once suffered from disasters,social functions come to a standstill.)
The following items are cited as social infrastructure:● Lifelines (critical infrastructure)
Electricity, gas, waterworks, sewage, garbage, fossil fuel, transport(expressway, ordinary road, railway and air route)● Communications
Communication (telephone, Internet), broadcasting, social network service● Logistics
Supply of food, water and daily necessities● Public service
Education, medical treatment, administration, crime prevention● Financial service
Electronic transactions

Photo: Geographical Information Authority of Japan

After earthquake

Before earthquake

Hohi-honsen
Railway

Hohi-honsen
RailwayAso
BridgeAso
BridgeNational Highway
Route 57
National Highway
Route 325

Photo 1 Suspension of traffic services at National Highway Routes 57 and 325 and Hohi-honsen
Railway during Kumamoto Earthquake
August 2017 Steel Construction Today & Tomorrow 16

worse than expected. As a result, many
trucks that were loaded with relief supplies could not arrive at their target destinations for a long time.
Mainstreaming of Disaster Resilience and Reduction, and the Assumption of Worst Damage Scenarios
There is a word “disaster resilience.”
The term was translated by the Japanese
government into “Building National Resilience.” The translation is not quite
appropriate, but the term “disaster resilience” has eight meanings and a wide
context involved in social infrastructure
improvement in disaster-prone areas.
Fig. 2 shows the eight specific elements
covered by that term.
Fig. 2 What Is “Disaster
Resilience”?
“Disaster resilience” means not only
the disaster control that reduces
damages but an earlier recovery fromdisasters. The resilience relates to thefollowing eight specific terms.
Flexibility

Responsiveness

Adaptability

Redundancy

Innovation

Rapidity

Robustness

Resourcefulness

Herein, what is important is how theeight elements are satisfied. When eachof the eight elements are individuallysatisfied with social significance, it iscalled partial optimization, but when alleight are together satisfied, disaster resilience is totally optimized for the firsttime. Particularly in assessing benefits
in the cost benefit (B/C) analysis of social infrastructure, it is necessary to assess new benefits to social infrastructurefrom the aspect of these eight elements.
In addition to the above, it is necessary to recognize that Japan has entered a
new stage with regard to disasters. As regards storm and flood disasters, the characteristic features of typhoons and rainfall have recently shown notable changes
due to global warming. The characteristics of earthquakes are also undergoingsome changes.
Although these changes are not attributable to the time-like background,
there have arisen many unknown andunclear factors in the earthquake phenomenon itself. Whenever an earthquake occurs, it shows a new fact. For
17 Steel Construction Today & Tomorrow August 2017

example, in the recent Kumamoto Earthquake, aftershocks registering 1+ on theJapanese seismic intensity scale occurred 4,200 times in the year since theoccurrence of the main shock on April
16, 2016, but the cause of these shocks
has yet to be clarified. Accordingly, we
may experience new earthquake tremorsthat we have not experienced with pastearthquakes, which may bring about
new hazards to us.
Given this situation, how should theimprovement of social infrastructure inareas frequently struck by disasters bepromoted? Specific measures to effectively deal with such tasks is organizedin Fig. 3.
First, to capitalize on disaster resilience or assumption that a disaster will
occur, measures should be implemented that prevent disasters to social infrastructure from occurring. To attain thisgoal, the concept of “mainstreaming disaster resilience” should be promoted.
This is the greatest lesson learned fromthe Great East Japan Earthquake of 2011.
On top of this, the concept of mainstreaming disaster resilience is trending
toward global diffusion. Both the International Monetary Fund and the WorldBank are supporting the economic development of developing countries on theassumption of mainstreaming disaster
resilience. The reason why is that, evenwhen economic development is attainedwith the support of these agencies, certain problems may have already occurredin which economic development investment comes to nothing if a disaster occurs.
To prevent such a problem from occurring, it is widely known that it is necessary to pay due consideration to disaster-reduction investment right from thestart of the planning stage. There is aninternational verity that an early investment of one dollar in disaster reduction
yields six dollars in profit.
Then, it is also important to hold aroundtable conference with the participation of those working in the field ofsocial infrastructure improvement and tofind out the worst disaster scenarios inface of disasters. That is, it is required towrite the scenario that practically images
the worst disaster cases. Next, it is necessary to discuss how disaster risks can
be avoided, mitigated or passed to, forexample, insurance; and, to attain thesegoals, it is also necessary to quantify therisks.
To these ends, it is necessary to hold aroundtable conference with the participation of all stakeholders in order to sharerisk information, and then to identify therisks after the implementation of disaster countermeasures in order to guarantee the sustainable development of local
communities.
Concepts Required for Improving
Social Infrastructure in Areas ofFrequent Disasters
The following measures are required
to maintain expressway traffic in volcanic areas or in tsunami areas during
earthquakes like the recent one in Kumamoto:• Assumption of the scale of disasters,such as ground damage, that are likely to occur• Change of transportation routes in cases when a large-scale disaster occurs• Provision of transition sections in cases
when medium- and small-scale disasters
occur: for example, additional installation of interchanges, passing separationof the in and out bound lanes, advanceinstallation of temporary roads on theassumption of disaster occurrence

Fig. 3 Prior Consultations Required for Promoting Social Infrastructure
Improvement in Disaster-prone Areas● In the disaster resilience conceived by assuming that disasters will occur,

disaster-preventive measures aiming to improve social infrastructure are
implemented right from the start of the planning stage (mainstreaming of disaster
reduction).

● Not only the worst damage scenario but also all the scenarios of damages thatare likely to occur are extracted to prepare specific damage images (scenario
writing).

● Examinations are made of how a risk can be avoided, mitigated or passed to,for example, insurance (quantification of risks).

● A roundtable conference is held with the participation of all stakeholders to sharerisk information and to guarantee the sustainable development of local
communities (identification of risks).

• New construction of ordinary roads withmultiple traffic routes as a substitute forexpressways; simultaneous maintenanceand management of both newly-installed
roads and ordinary roads with backup
functions in a compatible system
In areas that are frequently struck by
disasters, implementation of these measures is required in order to maintainhighway traffic. (For more details, refer
to Fig. 4)
Fig. 5 shows how to improve social
infrastructure on the assumption thatdisasters on a national scale will occur, such as an inland earthquake in themetropolitan Tokyo area and a Nankai
Trough mega earthquake that are both
forecasted for the near future. Once sucha mega-scale disaster occurs, it is widely
accepted that the Disaster Relief Act thatwas enforced 70 years ago will fail. Thisact denotes a system in which the national or local or municipal governments
will distribute all the necessities to people who temporarily reside in places ofrefuge just after the occurrence of a mega disaster. It is impossible for the current Disaster Relief Act to respond tosuch a request.
When large-scale disasters occur, selfhelp and mutual assistance are inevitably
required for reconstruction and restoration after a disaster. And, even when the
promotion of restoration and reconstruction efforts requires the use of public assistance, the financial and human resources are all too short. Meanwhile, it isregrettable to say that a national disasterwill certainly occur. To cope with sucha situation, it is absolutely required thata system of self-help, mutual assistanceor industry assistance be routinely introduced in the course of social infrastructure improvements. That is, it should berecognized that the time has passed whensocial infrastructure improvement is undertaken by counting on public assistance.
As mentioned above, disaster resilience is a concept devised on the assumption that disasters will occur. To
that end, it is essential to make a priorassessment of disaster risks particularly
in areas that are frequently struck by orvulnerable to disasters. Another essential
means is to dispel bottlenecks that willhinder the management of social infra￭
structure facilities during disasters.

Fig. 4 Example of Expressway Reinforcement in Areas Vulnerable toDisasters such as Volcanic Area and Tsunami Attacking Area
The scale of ground damages and other disasters that are likely to occur isassumed.
When large-scale disasters occur, the transportation route is changed.
When medium- and small-scale disasters occur, transition section is provided.
To illustrate: increase of interchanges, passing separation of the in and out
bound lanes, advance installation of temporary roads on the assumption ofdisaster occurrenceInstead of expressways, ordinary roads with plural routes are newly constructedto substitute for expressways.
These newly-constructed roads and the ordinary roads with back-up functions
are maintained and managed in a compatible system.

Fig. 5 How to Improve Social Infrastructure on the Assumption of National
Crisis-scale Disasters
1 The spirit of the Disaster Relief Act established 70 years ago has failed, andwhen disasters occur, it is no longer the times in which all these disasters arerestored by the use of public assistance.

2 Even if restoration of great disasters are planned by the use of public assistance,

all of financial resources, human resources and information are entirely scarce.

3 However, national crisis-scale disasters will certainly occur in the near future.
4 Given such situations, a mechanism for applying self-help, mutual assistanceand industry assistance (enterprise cooperation) systems should be routinely
introduced in the improvement of social infrastructure.

5 Disaster resilience denotes a measure devised on the assumption of disasteroccurrence.

6 It is indispensable to evaluate disaster risks especially in areas frequently

attacked by disasters and vulnerable to disasters.

7 During disaster attacks, it is necessary to dispel the bottlenecks that lead tohindrance in management of social infrastructure facilities.

8 If these bottlenecks are to be dispelled, it is necessary to promote tie-ups andcoordination among related administrative organs, but at the current stage it isnearly impossible to promote them and further new financial resources areunavailable.

9 It is therefore inevitable that those who will benefit should, as a basic principle,

bear the expense to dispel the bottlenecks.

10 For expressways responsible for logistics in particular, it is inevitable to extend

an industry assistance (private enterprise cooperation), but the current toll
system is very political. To this end, a new benefit/cost concept is introduced.

11 The above can also be applied to the case of home delivery services in which

highways are utilized as a virtual warehouse (because the road of an area
equivalent to the size of a truck is occupied by a truck).

12 Further, because the delivery tax for light oil is cheaper than that for gasoline(a policy peculiar to Japan), truck transport becomes profitable in terms of cost.

13 An extremely high dependence (maldistribution) of logistics on highway transportoffers a great risk during disasters.

14 It is necessary to change the policy so that the logistics be appropriately shiftedto aviation, railway and shipping transport (uniform sharing of transport cost).
However, the current application condition does not conform to a move toimprove social infrastructure (ship transport particularly by means of coastal
shipping is in a slump).

15 Currently, the increased cost required to pursue convenience is covered by anincreased transport volume. It is necessary for us to recognize that this situation
ultimately brings about an excess over-concentration in Tokyo.

August 2017 Steel Construction Today & Tomorrow 18

JISF Operations

Two Events for the Steel Cooperation Program of the JapanThailand EPA
As a link in the Japan-Thailand Economic Partnership Agreement: Steel Cooperation Program, the Japan Iron and Steel Federation (JISF) in collaboration with the Iron and Steel Institute ofThailand (ISIT) held two events at the beginning of 2017 in Japan.
• Program for Linkage between Steel Standards andTechnological Regulation/CodeIn order to enhance the capability to draft and certify standards
in Thailand and to promote the application advantages of highperformance steel products for bridge construction, JISF car-ried out two programs in five days starting from March 6, 2017:lecture presentations and related site visits to a steel-frame fabrication plant of Tokyo Tekkotsu Kyoryo and to the National Institute for Materials Science.
A total of 16 persons participated in the programs, including people from the Thai Industrial Standards Institute, the Department of Rural Roads and the Department of Highways in
Thailand, and steel companies in Thailand as well. The Thai
participants highly rated the lectures and site visits regarding
the application practices of steel product standards in Japan and“High-performance Steels for Steel Bridges.”• Program on Production and Safety Control

Scenes of the Program for Linkage between Steel Standards and Technological Regulation/CodeDuring 10 days starting from February 22, 2017, JISF held lecture meetings on diverse aspects of the Japanese manufacturingindustry: the concept of monodzukuri (product making), equipment control, cost control, cost improvement and solutions forindustrial safety and health and other tasks arising on the production floor. In addition to the lectures, a tour of related sites
was held. They were attended by a total of 10 engineers fromThai steelmakers.
In the second week, a two-day study tour was made to threemanufacturing plants in the Kita-Kyushu area, whereby the participants gained first-hand experience of production floors in theJapanese manufacturing industry. On the final day, a group discussion and report meetings were held to confirm the practicalachievements of the various training courses mentioned above.

Fourth Steel Structure Conference in Cambodia
The Japan Iron and Steel Federation held a conference titled “Recent Technologies for Steel Structures 2016” in Phnom-Penh,
Cambodia on December 9, 2016. It was jointly held by the Ministry of Public Works and Transport of Cambodia and the Instituteof Technology of Cambodia, and was supported by the Embassyof Japan in Cambodia, the JICA Cambodia Office, JETRO PHNOMPENH and the Japanese Business Association of Cambodia.
The opening ceremony of the conference was held with theparticipation of the Acting Minister of Public Works and Transport and other distinguished guests. Subsequent to the ceremony, five lectures with themes on ports and harbors, bridges
and building construction were delivered by experts from both
Cambodia and Japan and were attended by about 160 engineers
and university students from Cambodia.
Subsequent to the lecture, a small group session was held

STEEL CONSTRUCTION TODAY & TOMORROW
Published jointly by

The Japan Iron and Steel Federation
3-2-10, Nihonbashi Kayabacho, Chuo-ku, Tokyo 103-0025, Japan
Phone: 81-3-3669-4815 Fax: 81-3-3667-0245
URL http://www.jisf.or.jp/en/index.html
Japanese Society of Steel Construction
3F Aminosan Kaikan Building, 3-15-8 Nihonbashi, Chuo-ku, Tokyo 103-0027, Japan
Phone: 81-3-3516-2151 Fax: 81-3-3516-2152
URL http://www.jssc.or.jp/english/index.html

with the participation of key persons from both nations, where
views were exchanged on the prospects for the diffusion ofsteel-structure applications in Cambodia. And, an introduction
was also made regarding the support system for students studying in Japanese universities.
This conference was the fourth in the series, following those
held in 2012, 2014 and 2015.

Scenes of the Fourth Steel Structure Conference in Cambodia© 2017 The Japan Iron and Steel Federation
Edited byCommittee on Overseas Market Promotion, The Japan Iron and Steel Federation
Chairman (Editor): Hiroyuki Tanaka
P u b l i s h e d t h r e e t i m e s p e r y e a r, S T E E L C O N S T R U C T I O N TO D AY &TOMORROW is circulated to interested persons, companies and publicorganizations to promote a better understanding of steel products and theirapplication in the construction industry. Any part of this publication may be
reproduced with our permission. To download content (PDF format), please go
our website at: http://www.jisf.or.jp/en/activitity/sctt/index.html. We welcome yourcomments about the publication and ask that you contact us at: sunpou@jisf.or.jp.