BNUS ANNUAL REPORT-2015

BANGLADESH
NETWORK OFFICE FORURBAN SAFETY

BUET, DHAKA, BANGLADESH
Prepared By:

Mehedi Ahmed Ansary

CONTENTS
PART-I: LAND SUBSIDENCE BESIDE SUNDARBAN HOTEL ON BIR
UTTAM CR DUTTA ROAD IN KATHALBAGAN, DHAKA ON
27 - 29 MAY, 2015 ········································································· 1
PART-II: APPLICATION OF SEISMIC REFRACTION METHODTO INVESTIGATE SUB-SURFACE SOIL STRUCTURE ·························· 9PART-III: VALIDATION OF CORRELATION BETWEEN INSITUCONCRETE STRENGTH AND UPV ··················································· 21
PART-IV: NDT AND DESTRUCTIVE TESTS AT OAB, BUET
AND RETROFITTING PROPOSAL ···················································· 43
PART-V: FIRE INCIDENT IN READY-MADE GARMENT FACTORY‘DIGNITY TEXTILE LIMITED’, GAZIPUR ON 31 MAY, 2015 ·················· 93
PART-VI: DISTRICT WISE MULTI-HAZARD ZONING OFBANGLADESH ············································································· 97
PART-VII: WORKPLACE SAFETY COMPLIANCE OF RMG
INDUSTRY IN BANGLADESH: STRUCTURAL ASSESSMENT
OF RMG FACTORY BUILDINGS ······················································ 123
PART-VIII: COMPARISON BETWEEN WEAK AND STRONGGROUND MOTIONS AT SELECTED LOCATIONS OF BANGLADESH ······ 159

PART-I
LAND SUBSIDENCE BESIDE SUNDARBAN HOTELON BIR UTTAM CR DUTTA ROAD IN
KATHALBAGAN, DHAKA ON 27 - 29 MAY, 2015
BANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Uttama Barua
Mehedi Ahmed AnsaryMarch 2016

At around 7:30am on 27 May 2015, some parts of a bye lane beside Sundarban Hotel on Bir Uttam
CR Dutta Road in Kathalbagan near Sonargaon Intersection in Dhaka’s Karwan Bazar and several
parts of a piling structure of an under-construction building ‘National Bank Limited Twin Tower’suddenly caved in. Witnesses said the iron structure erected for pilling work of the under-constructionbuilding near the SAARC Fountain fell to ground with huge sound. After that, at around 3:45pm, thenortheast portion of the basement of the six-storey Sundarban Hotel partially fell down.

Figure 1: Boundary wall and basement of Sundarban Hotel

Figure 2: Bye lane beside the construction site
The NBL authorities contracted Korean firm, Donga, to build the 12-storey twin tower primarily witha three-storey basement on around 64 katha land. The Korean firm sub-contracted three Bangladeshi
firms — Mum Impex, BD Construction and MS Construction. On the day of incident there was no
official word on the exact reason behind the subsidence but BUET Professor Dr. Mehedi Ahmed
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Ansari, after visiting the site, said that the three-tier under construction basement of the NBL twin
tower is very weak and the method followed was not correct either. The shore piling of the underconstruction building failed due to the poorly-deigned groundwork of the under-construction building,i.e. lack of proper iron bracing to protect the piling, which is meant to protect the edge of the soil.
Chairman of RAJUK said that the National Bank Limited (NBL) obtained approval from the RAJUKin December 2013, but he assumes that the pilling work has not been done according to the approved
design. Concerns of MS Construction brushed aside poor construction measures and blamed the recent
earthquake and rain for the collapse. According to them, the boundary wall of the hotel collapsed firstand damaged the sewerage and drainage pipes beneath. When the pipes got broken, water came out
and created pressure on the surrounding earth, eventually triggering the slide. Meanwhile, Bangladesh
Bank officials said that NBL authorities did not take their permission to build their headquarters on
the site.
The incident took down several tea stalls, rickshaw vans, trees and electricity poles. But, no report of
injuries has been filed. As a result of the incident the water and gas supply system of the area collapsed.
The entire area is stated to be very risky as the sand and mud of the ground are being washed away by
the water coming out of the leakage in the water line of Hotel Sundarban. The restricted vehicular
movement on the road near the subsidence site gave rise to hours of traffic congestions in thesurrounding busy roads.
Mayors and high officials of two city corporations, RAJUK officials, officials and staff of WASA andDESCO, expert teams of Bangladesh University of Engineering and Technology (BUET) visited the
spot. The mayors held the authorities of RAJUK and the construction company responsible for theincident. They said that due to lack of monitoring by RAJUK, the construction firm got the chance toviolate the approved design. RAJUK said that they will sue the construction firm over the incident.
A team from Kalabagan Police Station and Tejgaon fire station officers rushed to the scene
immediately after being informed, although the area falls under the Mohammadpur fire station's
purview. Apart from the firefighters and police, additional law enforcers, including RAB and Ansar
members have been deployed in the area in order to prevent further damage. Afterwards, they orderedto evacuate the Sundarban Hotel. There were a total of 50 guests inside the hotel, who had been moved
away immediately afterwards. Utility authorities disconnected water, gas and power supply in theadjacent areas because some of these lines were also damaged in the incident. The authorities
concerned restricted all type of vehicular movement on the road in front of the building. Law enforcers
were deployed in the area to control an inquisitive crowd so that nobody got hurt in case there were
any further shifts in soil.
3March 2016

As an immediate step to prevent any further disaster, Dr. Ansari said that the first thing that theauthorities should do is filling up the excavated place with land. Experts said that the excavation holemust be fully filled up in the quickest possible time; otherwise the surrounding areas would also be atrisk of subsiding. Moreover a heavy downpour might cause the hotel building to collapse at any time,
which would put the nearby high-rise buildings and adjacent roads under threat. In a joint effort around12:30pm, Dhaka north and south city corporations started filling up the void created by the slide withdifferent kinds of sand and brick dust. Officials said the filling of land would continue for two days.
According to their estimation, around 1,500 trucks of sand would be required immediately to fill up
the site and save the hotel temporarily, and it would require two days to complete the work. Around
500 trucks of sand had been piled in after 10pm on the same day. The building still faces risk as several
large cracks have developed on it.

Figure 3: Land filling work

Figure 4: Land filling by truck
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Figure 5: Crack developed in Sundarban Hotel
National Bank Limited is not cooperating to make risk-free the area at Karwan Bazar after the street
caved in due to a construction of its high-rise. GM of Sundarban Hotel filed a general dairy with
Kalabagan police station narrating the incident against the construction firms. Meanwhile, RAJUK
itself filed a case with the Kalabagan police station against NBL twin tower Project Director, MS
Construction CEO, and NBL Deputy Director.
On the second day of the incident, 28 May 2015, another portion of the Bir Uttam CR Dutta Road - a
few yards north of the spot where land subsided on the previous day – caved into the excavation sitewith a loud bang at around 10pm. In the process, anser camp, row house of the workers, a part of awall, several billboards and trees, a portion of the pavement and an electricity pole also fell into the
excavation site. Later, cracks were also seen on the road of Panthpath. Moreover, the sand filling work
to prevent Sundarban Hotel from collapsing progressed at a sluggish pace on the second day of theincident due to lack of sand reinforcement in the ditch. Later the contractor MS Constructions andDevelopment's Project Director was contacted to supply the required amount of sand. Experts fear thatany untoward incident can take place in the advent of rain. In this situation, the SAARC Fountain is
now in the risk, as it may face the fate of the hotel.

5March 2016

Figure 6: Second incident of land subsidence on 28 May 2015
The second subsidence put one half of the road leading from Karwan Bazar to Panthapath at risk. The
authorities stopped vehicular movement on this half of the road, leaving the other half – adjacent to
the Basundhara City Shopping Mall – open for vehicles in order to prevent further subsidence due tovibrations created by moving vehicles. A security cordon was put in place beside the tiger sculpture,making the mouth of the Bir Uttam CR Dutta Road fully off limits for people and vehicles as hundredsof curious people gathered near the spot of the accident. Billboards, makeshift shops and hawkers fromthe site were removed in apprehension of big incident. The National Bank Limited authorities wereasked to clear the roads around Sundarban Hotel by Sunday.
Another land subsidence occurred at the Karwan Bazar construction site on 29 May, 2015 morning,
following two similar incidents on consecutive days since Wednesday. The extent and damage causedby the latest land subsidence, which happened a little before 9am in the same north-west side as
Thursday’s incident, was comparatively less than the previous days. Authorities working at the site
stayed alert throughout the day for the possibility of further rain that might trigger yet another incident.
Although there was some downpour in the afternoon, no more land subsidence happened.

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Figure 7: Third incident of land subsidence on 29 May 2015
Following the brief spell of rain, the sand-dumping trucks were parking a bit further away from thesite and maintaining caution while approaching the void left by the land subsidence at the underconstruction NBL Twin Towers. After this incident until 10 pm on Saturday around 1000 trucks ofsand have been dumped in the hole and till the third incident no other subsidence occurred. The western
portions of the hotel and the construction site are still in danger of collapse as the truck of sand cannot
reach that portion of the hotel. Commuters passing through the area continued to suffer as the adjacent
Panthapath and Bir Uttam CR Dutta roads stayed out-of-bounds for vehicles because of safety reasons.
The authorities concerned withdrew the restriction of vehicular movement on the roads four days after
the land subsidence in front of Hotel Sundarban on 31 May, 2015 stating that the lane is primarily outof risk.

Figure 8: Closure in adjacent roads after the incident of land subsidence
7

PART-IIAPPLICATION OF SEISMIC REFRACTIONMETHOD TO INVESTIGATE SUB-SURFACE SOIL
STRUCTURE
BANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Abul Khair
Pushpendue Biswas
Mehedi Ahmed AnsaryMarch 2016

1 INTRODUCTION
Seismic refraction is a commonly used geophysical technique to determine depth-to bedrock,competence of bedrock, depth to the water table, or depth to other seismic velocity boundaries. Thismethod involves the analysis of the travel times of arrivals that travelled roughly parallel to the uppersurface of a layer during their transmission through the subsurface. [1] Seismic refraction methods
provide an effective and efficient means to obtain general information about large volumes of thesubsurface in the two dimensions of depth and horizontal (or slope) distance. Information provided byseismic refraction includes compression wave (p-wave) velocities within the investigated subsurface
profile. Traditionally, these velocities are interpreted to be present within layers or horizons whose
depths are also interpreted. Newer interpretation methods are making it possible to interpret velocitychanges as gradients as well as discrete layers. Seismic refraction measurements are applicable inmapping subsurface conditions for various uses including geological, geotechnical, hydrological,
environmental, mineral and archaeological investigations.
2 STUDY BACKGROUND
The seismic refraction survey has application in a variety of geological exploration problems, where
information on the depth and strength of subsurface materials is required. These surveys provide
subsurface information over large areas at relatively low cost; locate critical areas for more detailed
testing by drilling and can readily eliminate less favorable alternative sites. Seismic surveys can also
reduce the number of boreholes required to test a particular site and improve correlation between
boreholes.
2.1 Advantages / Disadvantages
o Difficulty of interpretation in areas morphologically rough or with many underground pipes
o Open spaces is needed for cables and electrodes array, the electrodes must be planted into theground (can also be applied in paved areas or asphalt, drilling holes).
o Good vertical and lateral stratigraphic resolution.
o For best accuracy, a calibration reference stratigraphy is needed.
o Very useful for discrimination of metal, clay / sand and aquifers
2.2 Fundamentals Theory
The refraction method consists of measuring (at known points along the surface of the ground) the
travel times of compressional waves generated by an impulsive energy source. The energy source isusually a small explosive charge and the energy is detected, amplified, and recorded by special
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equipment designed for this purpose. The instant of the explosion, or "zero-time,” is recorded on therecord of arriving pulses. The raw data, therefore, consists of travel times and distances, and this timedistance information is then manipulated to convert it into the format of velocity variations with depth.
The interpretation of this raw data will be developed as we go along. The process is schematicallyillustrated in Fig. 1. The fundamental law that describes the refraction of light rays is Snell's Law (seeFig. 2), and this, together with the phenomenon of “critical incidence,” is the physical foundation ofseismic refraction surveys.

Fig 1: Schematic of seismic refraction survey
A small explosive charge is detonated in a shallow hole at A and the energy is detected by a set ofdetectors laid out in a straight line along the surface. The arrival times of the impulses are plottedagainst the corresponding shot-to-detector distances as shown in Fig. 3. The first few arrival times arethose of direct arrivals through the first layer, and the slope of the line through these points, ΔT/ΔX, issimply the reciprocal of the velocity of that layer; i.e., V1/V2. The energy that arrives at the detectors
beyond the critical distance will plot along a line with a slope of V1/V2.
The line through these refracted arrivals will not pass through the origin, but rather will project backto the time axis to intersect it at a time called the intercept time. Because both the intercept time andthe critical distance are directly dependent upon the velocities of the two materials and the thicknessof the top layer, they can be used to determine the depth to the top of the second layer.
The rock types can be found to know the seismic velocity transmitted to the soil. The verities of seismic
velocity of different layers indicated different types of soil. [5]There is an approximate range to classify
rocks depending on seismic velocities.

11March 2016

Fig 2: Snell’s law and refraction of ray transmitted across boundary between two media withdifferent velocities

Fig 3: Simple two-layer case with plane, parallel boundaries and corresponding time-distance curve.

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Table 1: Approximate seismic velocities for rocks
Rock type

Vp(km/sec)

Unconsolidated sedimentRock type

Vp(km/sec)

sandstone

2.0-5.0Clay

1.0-2.5

Sand, dry

0.2-1.0Air

0.3

Sand, saturated

1.5-2.0

Natural gas

0.43

Ice

3.4

Sedimentary Rocks

Otherslimestone

3.9-6.2

Water

1.4-1.5

Salt

4.6

Oil

1.3-1.4

3 METHODOLOGY
Measurement of subsurface conditions by the seismic refraction method requires a seismic energy
source, trigger cable, geophones, geophone cable, and a seismograph. The geophones and the seismic
source must be placed in firm contact with the soil or rock. The geophones are usually located in a line,
sometimes referred to as a geophone spread. The seismic sources may be a sledge hammer, amechanical device that strikes the ground, or some other type of impulse source. Explosives are used
for deeper refractors or special conditions that require greater energy. Geophones convert the groundvibrations into an electrical signal. This electrical signal is recorded and processed by the seismograph.
The travel time of the seismic wave (from the source to geophone) is determined from the seismic
wave form.
3.1 Study Area Selection
This machine is new one for finding soil profile. So it is needed to calibrate with another known value
which has collected by other equipments like microtremor. For our justification we selected different
locations of BUET ground as study area.
3.2 Data Collections and Results Analysis
The data of the different locations were collected using different combination of seismic impulse
source and different spacing of geophones. Some specific software based on conventional method wasneeded to process seismic refraction.

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3.2.1 Seismic refraction result analysis for soil at BUET play groundThe geophone spread and impulse source is shown in Fig. 4 and Fig. 5 respectively during seismic
refraction test at BUET. Five shot points were selected during this test named middle shot, 1st offset
shot, 1st end shot, last end shots and last offset shot. The position of two offset shots 23m away from
1st and last geophone, which is half of the total spread length 46m as shown in fig 6.

Fig 4: Spread of geophones duringrefraction test at BUET playgroundFig 5: Using 140lb with 12 feet drop heighthammer as impulse source

Fig 6: Layout of shots position during seismic refraction test at BUET

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The soil profile of the seismic refraction test is shown in Fig. 7. It shows that the investigation depthof soil profile is about 20m. The seismic velocity ranges is about to 200m/s to 400m/s which range
indicates the sub soil is dry sand according to Table 1.

Fig 7: P-wave velocity profile at BUET playground3.2.2 Seismic refraction result for Red campus play groundThe geophone spread and impulse source is shown in Fig. 8 and Fig. 9 respectively during seismic
refraction test at BUET red campus. Five shot points were selected during this test named middle shot,
1st offset shot, 1st end shot, last end shots and last offset shot. The position of two offset shots 23m
away from 1st and last geophone, which is half of the total spread length 46m as shown in fig 10.

Fig 8: Spread of geophones during

Fig 9: Using 140lb with 12 feet drop heightrefraction test at red campus playground.

hammer as impulse source15March 2016

Fig 10: Layout of shots position during seismic refraction test at BUETThe soil profile of the seismic refraction test is shown in Fig. 11. It shows that the investigation depthof soil profile is about 25m. The seismic velocity range is about to 100m/s to 500m/s which range
indicates the sub soil is dry sand.

Fig 11: P-wave velocity profile at Red campus play ground3.2.3 Seismic refraction result in front of BUET JIDPUS
The geophone spread and impulse source is shown in Fig. 12 and Fig. 13 respectively during seismic
refraction test at BUET. Five shot points were selected during this test named middle shot, 1st offset
shot, 1st end shot, last end shots and last offset shot. The position of two offset shots 12m away from
1st and last geophone, which is half of the total spread length 23m as shown in fig 14.

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Fig 12: Data collection during

Fig 13: Using 140lb hammer as impulse

refraction test at BUET JIDPUS

sourceFig 14: Layout of shots position during seismic refraction test at BUETThe soil profile of the seismic refraction test is shown in Fig. 10. It shows that the investigation depthof soil profile is about 25m. The velocity range is about to 200m/s to 1200m/s which range indicatesthe sub soil up to 3m dry sand and then clay soil.

Fig 15: P-wave velocity profile in-front of BUET JIDPUS

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4 CONCLUSION
The interpretation of the results showed that all areas having consisted of two layers with approximate
velocity 100 to 1200 m/s underlie the study area. Table 1 lists approximate ranges for velocities ofdifferent types of soil. The upper layer consists of dry sand and for in-front of BUET JIDPUS 2nd layer
consists of clay sol. The result of the investigation is therefore recommended as a useful guide for civilengineering planning and development of the area.
LIMITATIONS
A hidden layer, or blind layer, is one that is undetectable by refraction surveying. [2]A layer may
simply not give rise to first arrivals, that is, rays traveling to deeper levels may arrive before thosecritically refracted at the top of the layer in question (see Fig. 16). This may result from the thicknessof the layer or from the closeness of its velocity to that of the overlying layer. A more insidious typeof hidden layer problem is associated with a low velocity layer, as illustrated in Fig. 17. Rays cannot
be critically refracted at the top of such a layer and the layer will, therefore, not give rise to head waves.
Hence, a low velocity layer cannot be detected by refraction surveying.
.

Fig 16: Hidden layer problem inseismic refraction

Fig 17: Blind zone problem inseismic refraction

Due to lack of available impulse source the seismic refraction test is difficult in maximum places. Also
we have no sufficient financial help to buy such type of high cost impulse sources. Hence here in
Bangladesh seismic refraction test will be preferable when sufficient funding will be provided by otherto investigate subsoil characteristics.

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References[1] Alhassan, D. U., Dangana, L.M., Salako, K.A., Jonah, S.A. and Ofor, seismic refraction
investigation of the subsurface structure at the southern part of niger state college of education,
Bayero Journal of Pure and Applied Sciences, 3(2): 56 – 61
[2] Geological exploration by geophysical method (seismic refraction) —code of practice, burau ofindian standard, is 15681:2006 , pp.8-15[3] Keller G.R, Sinno Y.A, and Sbar M.L (1981). Seismic refraction in West and central Arizona,journal of Geophysical Research, New York, U.S.A, Vol. 86 ,No. 36, PP5023[4] Redpath B. B., A book of “Seismic refraction exploration for Engineering site investigations”
Explosive Excavation Research Laboratory Livermore, California, May 1973
[5] www.geo2X.com

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PART-III
VALIDATION OF CORRELATION BETWEENINSITU CONCRETE STRENGTH AND UPVBANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Fahim Ahmed
Mehedi Ahmed AnsaryMarch 2016

INTRODUCTION
Concrete is the most widely used construction materials. As a result, its quality is an important issue.
Compressive strength is the most important property of concrete as it is the main criteria to judge thequality of concrete (Aydin and Saribiyil 2010). Direct determination of compressive strength requiresthat concrete specimen must be loaded to failure. It is required to collect concrete specimen according
to ACI standards and specified requirements. This procedure may provide actual concrete strength forunder construction and existing buildings. This procedure is time consuming and troublesome forexisting buildings. Because of these problems some NDT methods have been developed to measureother properties of concrete other than strength and relate them with strength, durability or any otherproperties (Qasrawi 2000).
The nondestructive testing (NDT) is a direct method to find in situ compressive strength of concrete(Yuksel 1995). The NDT of concrete has scientific and practical importance especially for damaged
concrete constructions (Turgut 2004). Malhotra (1976) has presented a literature survey for NDT used
for evaluation and testing of concrete structures. Leshchinsky (1991) has summarized the advantages
of NDT tests as reduction in labor cost of preparation and testing of samples, minimal structural
damage, less costly, simple and quick usage, availability of test result on site, possibility of testing
concrete strength where core drilling is impossible (thin-walled, densely reinforced etc.).
NDT methods can be employed for efficient time management of large scale construction project.
Where knowing in-situ strength is necessary for removing formwork, releasing time for the wires in
pre-stressed members and post-tensioned element loading time, to avoid unnecessary delay in the nextstage of construction (Elvery and Ibrahim 1976; Karaesmen et al. 1996; Price and Hynes 1996).Theseadvantages are of no use if the results are not representative and close to the actual tested part of thestructure (Turgut 2004). The limitations of NDT are associated with material heterogeneity andanisotropy, test conduction area and its roughness, test direction, and different empirical equation fordifferent types of materials (Yilmaz 2009; Ylmaz and Sendr 2002). To overcome these limitations,the test results have to be correlated with destructive tests. (Karaesmen et al. 1996).
EVALUATION OF CONCRETE STRENGTH BY DIFFERENT NDTVarious NDT that can be used for measuring concrete strength are shown and explained in Figure 1.

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Fig 1: NDT techniques that have been or potentially can be used for in situ strength assessment of
concrete: (a) rebound hammer; (b) Ultrasonic pulse velocity (UPV); (c) Pull-out-force; (d) Penetration
Resistance ; (e) drilling resistance. (Gunes 2015)
The Rebound Hammer test, generally known as Schmidt hammer is one of the oldest, commonly used
and most simple NDT method (Gunes 2015). The test method is described in ASTM (2008), BSI(1986) and TS (1978). The test is classified as a hardness test and based on the principle that therebound of an elastic mass depends on the hardness of the surface against which the mass impinges(Aydin and Saribiyil 2010). The energy absorbed by the concrete is related to its strength (ACI
Committee 228 2003). Rebound hammer number is sensitive to local variation of concrete. For
example, if a large aggregate falls under the tip of the plunger rebound number will be very high. On
the other hand if any crack of void falls under the tip it will cause lower rebound number. Reboundnumber also varies with aggregate properties, mix proportioning, surface texture and wetness ofconcrete (Ariöz et al. 2009).
The Ultrasonic Pulse Velocity (UPV) test is a popular, fast and easy nondestructive test method (Ariöz
et al. 2009). It has been first introduced by Long, Kurt and Sandenaw in 1945 for evaluating quality ofconcrete by transmitting an irrational pulse to travel a known distance through the concrete (Mahure
et al. 2011). The ultrasonic pulse velocity (UPV) method makes use of the velocity of ultrasonic pulses
obtained from direct (opposite faces), semi-direct (neighboring faces) and indirect (same face)arrangement of the transmitter (T) and receiver (R) transducers (Fig. 1b) to estimate concrete strength(Gunes 2015).
In the laboratory, access is generally available to opposite surfaces of a test specimen, and ultrasonictests are commonly conducted using direct transmission. Direct transmission is defined as the
propagation of ultrasonic stress waves along a straight-line path between the opposite surfaces of a
specimen. In the field, however, access to opposite surfaces of a component may not be readily
available (for example, concrete pavements and bridge decks), and tests may need to be conducted23

March 2016using indirect transmission. Indirect, or surface, transmission is defined as the propagation ofultrasonic stress waves between points that are located on the same surface of the material (Yaman etal. 2001). UPV test is prescribed in ASTM (2002) and BSI (1997) . The principle of test is that thevelocity of sound in a solid material V, is a function of the square root of the ratio of its modulus ofelasticity E, to its density ρ,
V=f (g E/ρ) 1/2(1)

Where g is the gravity acceleration. In the test, the time the pulses take to travel through concrete isrecorded. Then, the velocity is calculated as:
V = L/T(2)

Where V= pulse velocity (m/s), L= Length of sample (m), and T= effective time (s), which is themeasured time minus the zero time correction. Based on experimental results, Tharmaratnam and Tan(1990) have provided the relationship between the ultrasonic pulse velocity in a concrete V andconcrete compressive strength fc as:
fc = aebV(3)

Where a and b are parameters dependent upon the material properties. The ultrasonic pulse velocity
results can be used to check uniformity of concrete, voids in concrete, quality of concrete and concrete
products by comparing results to a similar made concrete, measure condition and deterioration of
concrete, depth of surface crack, measure strength comparing with previous data (Qasrawi 2000).
Pull-out force method correlates concrete strength with the pull our force of a rod (Fig-1c). The
penetration resistance technique is based on driving a steel probe or pin into concrete by applying aknown amount of mechanical energy and the penetrated or exposed length is correlated with concrete
strength (Fig -1d). The drilling resistant method (Fig-1e) is based on the ease of drilling a hole inconcrete. It is not yet a fully established method of NDT but has the potential to become a rapid or
reliable method of measuring concrete strength (Gunes 2015).

To use the above mentioned technique (Fig 1a-c) in conjunction with cores, TS (2010) has provided aformwork. An extensive list of NDT with references and standards has been provided in TS (2013). It
is compiled from international standards and other resources. Current researches in the field of

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nondestructive evaluation of concrete strength are aimed for the improvement of the existing techniqueand developing new ones.
DIFFERENT EXISTING CORRELATIONS
Tumendemberel and Baigalimaa (2015) conducted a research to find a relation between compressive
strength of cubes and UPV values by using statistical methods. They have collected data from 126
concrete cubes with the size of 150x150 mm with different mix ratio and curing condition prepared in
the laboratory. Before determining the compressive strength of the cubes UPV test have been
conducted with 54 kHz frequency, taking the average of three readings. The range of concrete strength
is between 9.96 and 42.6 MPa for different curing conditions. The regression analysis method has beenused to find the correlation. Their proposed equation is S = 1.356*10−5V 2 − 0.076V +111.502 Where:
S = Compressive strength in MPa, V = UPV in m/ sec. The value of correlation coefficient (R2) for
this equation is 0.63. Similar study has also been conducted by Qasrawi (2000). He used linear
regression method and proposed the following equation: S (MPa) = 36.72 USPV – 129.077, where
USPV is the pulse velocity (km/s). The R2 value was found to be 0.96.
Mahure et al. (2011) has taken true concrete cube specimen from Tehri Hydro Electric Project,
Uttarakhand, India for interpreting relationship between UPV and the compressive strength of concrete.
Cubes of three different grades of concrete M15, M20 and M35 were cast. Their w/c ratio ranges from
0.42 to 0.60. 43% to 45% of the total volume of concrete has been cement mortar. The volumetric ratioof fine aggregate to coarse aggregate is 38:62, 35:65 and 37:63 respectively. Water reducing
admixtures have been used to prevent bleeding and segregation. 125 Nos. of concrete specimens forM15 grade of concrete, 200 Nos. for M20 grade of concrete and 45 Nos. for M35 grade of concrete
have been cast and tested for both UPV and compressive strength. Nominal frequency of the transducer
used for measuring UPV are 54 kHz.125 data points for M15 grade of concrete, 200 data points forM20 grade of concrete and 45 data points for M35 grade of concrete have been plotted for establishing
relation between UPV and compressive strength. Linear regression is applied for establishing therelation. The correlation equations for the simulation curves for M15, M20 and M35 grades of concrete
respectively are CS = 9.502PV - 18.89, CS = 2.701PV + 17.15, CS = 4.104PV + 19.23. Where CS andPV represent the compressive strength (MPa) and the ultrasonic pulse velocity (km/s), respectively.
Their corresponding correlation coefficient (R2) is 0.244, 0.027, and 0.025 indicating good relevance
between data points and the regression curves. To validate the relationships, additional specimen havebeen prepared in the laboratory having same grade i.e. M15, M20 and M35. A total of 15 concrete
specimens, 5 for each grade have been prepared. Pulse velocity has been measured and using the25March 2016

equation above compressive strength of concrete (M15, M20 and M35 grades) are measured. The
results show that almost all the comparison results are between 5.96% and -4.33%.
Nash't et al. (2005) covers 161 test results from 161 concrete cubes with 150x150 mm. Compressive
strength of them have varied from 15 to 25 MPa and age of them are 7 to 138 days. UPV tests havebeen carried out for each cube with the average of two reading with frequency of 54 kHz. Crushingstrength of concrete is also recorded. Power equation has been used to predict the correlation between
UPV and strength. Following exponential equation is proposed: Sc = 1.19 EXP 0.715U, where Sc=
Crushing Strength N/mm2, U= UPV (μm/sec) and R2 for this equation is 0.59. Jain et al. (2013) used
this equation to predict strength of M20, M30, M40, and M50 grade concrete in laboratory and has
found a variation of 6%.
Shariati et al. (2011) has conducted a research taking UPV values from beam, column and slab ofexisting structures. Compressive strength of concrete are determined by using specimens tested at 1,
3, 7, 14 days interval. Two specimens have been tested and average strength results have been used.
UPV values are measured in direct and semi direct method between opposite faces for column, adjacentfaces for beam and indirect method for slab. There are 36 reading for beam, 12 reading for column and
20 reading for slab. The best-fit curve that represents the relationship has the following equation: fc=15.533V - 34.358 where, V is the ultrasonic pulse velocity (Km/s) and fc is the compressive strength(MPa). The R2 value was found to be 0.92.
Turgut (2004) has made a correlation with the data obtained from previous studies which have been
produced on specimens having dissimilar concrete mix ratios in the laboratory. To develop a
correlation from existing structure, he has collected 82 cores from 30 existing concrete structures withthe age varying from 28 days to 36 years. The best fit formula is obtained from the curve of existing
reinforced structures and the curve obtained from previous studies in the laboratory. The best fit
formula is found to be: Sn = 0.3161e1.03Vn Where, Sn is in KPa and Vn is in Km/s. R2 value was foundto be 0.80.
Lin et al. (2003) has established mathematical models for predicting pulse velocity in concrete basedon aggregate content and water-cement ratio. Demirboğa et al. (2004) has developed an exponential
relationship between compressive strength and UPV for mineral admixtured concrete.
Apart from these Amin (September, 2014) has also conducted laboratory experiment on strength-UPV
relation using locally available aggregates brick and stone. He has used 3 to 180 days of concrete age
and two different testing conditions saturated and air dry conditions. He has proposed two different

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relations for brick and stone aggregate concrete and has also provided a master equation for two
different testing conditions.
Y= -64.687 + 21.411V, for brick aggregate and Saturated Condition, (R2 = 0.81)
Y= -123.65 + 32.584V, for stone aggregate and Saturated Condition, (R2 = 0.87)
Y= -34.678 + 12.648V, Combined Equation for Saturated Condition, (R2 = 0.61)
Y= -59.409 + 20.251V, for Brick aggregate and Air dry Condition, (R2 = 0.79)
Y= -120.34 + 33.414V, for Stone aggregate and Air dry Condition, (R2 = 0.87)
Y= -42.581 + 15.263V, Combined Equation for Air dry Condition, (R2 = 0.66)
The equation most commonly used is exponential form Trtnik et al. (2009) : S = a.eb.Vp Where a and b
are empirical parameters determined by the least squares method.
RESEARCH SIGNIFICANCE
Earlier researchers have conducted in finding the relation between concrete strength and UPV are
generally limited to specimens prepared in the laboratory. Only a few of those relations have beendeveloped taking mix ratio into consideration. Most of them have neglected the mix ratios. Productionof concrete in the laboratory has been done under good care, where as production of concrete in thefield may face many variations in the condition of mixing, degree of compaction or curing in the field.
In addition pulse velocity is influenced by path length, lateral dimensions of the specimen, presenceof reinforcing steel and moisture content of concrete (Jain et al. 2013). These factors need to beaddressed before using strength UPV relations developed in the laboratory, to predict field concrete
strength. In this study, relationship is developed between strength and UPV by using data obtained
from 2658 cores that are collected from elements (column, beam, and slab) of 825 reinforced concrete
structures having different ages and unknown ratios of concrete mixtures.
EXPERIMENTAL METHODOLOGY AND DISCUSSION
In this study, the relations which are produced in the laboratory are compared with relations developed
from core test of existing reinforced concrete buildings. For this process starting from June 2013 to
February 2015, 2568 cores are collected from 825 reinforced concrete buildings from all overBangladesh. The age of the buildings varied from 5 yrs. to 40 yrs. Stone chips and brick chips are thetwo types of aggregates commonly used. Fig. 2 shows the distribution of the compressive strength27March 2016

from core test results. Records containing the aggregate proportions, water-cement ratio and cylinder
strength values for tested concrete are not available. Cores have been obtained from Column, beamand slab of the structures.

500

Number of Cores

400
300

All Aggregate
Number of Buildings: 825
Number of Cores: 2654
Mean: 22 MPa
Std. Deviation: 8.72 MPa

200
100
0

Compressive Strength from Cores (MPa)Figure 2: Compressive strength of cores.
Out of the total collected cores 1561 are of brick aggregate with mean strength of 21 MPa and standard
deviation of 8.35 MPa. The diameter has varied between 44 mm and 104 mm. Length of the sample isin the range of 69 and 206 mm. Fig. 3 shows the distribution of core test result of brick aggregate.
300

Number of Cores

250
200

Brick Aggregate
Number of Cores: 1561
Mean: 21 MPa
Std. Deviation: 8.35 MPa

150
100
50
0

Compressive Strength from Cores (MPa)Figure 3: Core test result of brick aggregate

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Number of core with stone chips are 1095. They have a mean strength of 21 MPa and standard
deviation is 8.33 MPa. The diameter has varied between 44 to 112 mm. Length of the sample is in therange of 71 and 241 mm. Fig. 4 shows the distribution of core test result of stone aggregate.
250

Number of Cores

200

Stone Aggregate
Number of Cores: 1095
Mean: 21 MPa
Std. Deviation: 8.33 MPa

150
100
50
0

Compressive Strength from Cores (MPa)Figure 4: Core test result of stone aggregate
Fig. 5 shows year wise distribution of the buildings along with their storey numbers from which coresamples are tested at BUET. Out of these 825 factory buildings, 12 are built before 1980, 198 are built
between 1980 and 2000 and the rest after 2010. Approximately, 52% of those factory buildings areconstructed after 2005. Most of the buildings constructed after 2005 are made of stone chips.

Figure 5: Year wise distribution of buildings from which cores are collected29March 2016

Cores taken from column and beam have been drilled horizontally and slab has been drilled vertically.
Before the execution of destructive compressive test, pulse velocity through the cores has beenmeasured at the laboratory. The velocity of the propagating wave has been measured by directtransmission using a standard ultrasound device. The transducers used are 50 mm in diameter and had
a maximum resonance frequency of 54 khz. The values of the ultrasound pulse velocity of brickaggregate lay between 1873 to 5264 m/s and concrete strength has varied between 3 to 47 MPa. For
stone chips the pulse velocity has ranged between 1042 to 7143 m/s and concrete strength varied
between 5 to 58 MPa.
There are many factors that affect core strength such as the diameter of the core, length to diameter
ratio, presence of reinforcement, moisture condition at the time of testing, presence of reinforcementin samples. Based on these criteria some of the cores of brick and stone chips are discarded.
Experimental evidence shows there is conflicting evidence concerning the strength of cores withdifferent diameter. In practice, it is very difficult to obtain a 50mm diameter core without any defect.
Considering these factor, the authors have discarded all the cores that has a diameter less than 68mm.
Specimens with small l/d fail at greater loads because the steel loading platens of the testing machine
restrain lateral expansion throughout the length of the specimen more effectively and so provide
confinement. The end effect is largely eliminated in standard concrete compression test specimens,
which have a length to diameter ratio of two (ACI 2013). To minimize the effect of l/d ratio and tokeep them within the provided limit in ACI (2013), all the samples that had length less than 127mm
were discarded.
According to Neville (1995) Concrete strength of 40MPa or greater are high strength, 20MPa to 40MPa
are medium strength and less than 20 MPa are low strength concrete. Fig. 6 shows the cylinder test
result collected from BUET database between 2003 and 2009.

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300

Stone Aggregate
Number of Cylinders: 1254
Year: 2003-2009
Mean: 27 MPa
Std. Deviation: 8.17 MPa

Number of Cylinders

250
200
150
100
50
0

Compressive Strength from Cylinders (MPa)120

Brick Aggregate
Number of Cylinders:435
Year: 2003-2009
Mean: 23 MPa
Std. Deviation: 6.39 MPa

Number of Cylinders

100
80
60
40
20
0
0-3

4-7 8-11 12-15 16-19 20-23 24-27 28-31 32-35 36-39 40-43
Compressive Strength from Cylinders (MPa)Figure 6: Cylinder test results collected from BUET database between 2003 and 2009
According to statistical rule, it is known that 95.45% of sample fall within 2 standard deviation and99.73% of sample fall within 3 standard deviation. It can be seen from the figure that almost 95 % ofsamples have strength less than 40 MPa that are medium to low strength concrete. To remain consistent
with the record core strength greater than 40 MPa have been discarded.
After discarding sample on the basis of diameter, l/d ratio and strength, they have been sorted into
three different group column, beam and slab. They are then plotted to find a correlation between UPV
and strength. Best fit curves for each type of cores are drawn using regression analysis. Correlation
coefficient (R2) values have been used for comparing the results with previous studies.

31March 2016

Fig. 7 shows the correlation between strength and UPV for brick aggregate concrete. Figure 7(a) has
been drawn using all the cores of brick aggregate concrete after discarding the cores using the above
criteria. There are 1237 cores out of 1561 initial samples. The correlation equation has been found tobe y = 917.26e0.0003x, where X= UPV in m/s and Y is strength in MPa. R2 value for this equation is
0.17. This means that we can explain 17% of the variability for the data around the regression line and83% remained without explanation. Fig. 7(b) was drawn using the cores taken from slab made of brickaggregate concrete. It contains 147 cores. Correlation equation has been found to be y = 650.38e0.0004x,
R2 value for this equation was 0.26. It has showed a slightly good relation than the correlation fromtotal brick cores. Fig. 7(c) shows correlation for cores taken from beams only. It contains 220 cores.
Correlation equation was found to be y = 938.14e0.0003x, R2 value for this equation was 0.16. It is close
to the relation obtained from all cores. Fig. 7(d) shows correlation for cores taken from column only.
It contains 873 cores. The correlation equation has been found to be y = 981.69e0.0003x, R2 value forthis equation was 0.16 which is similar to the relation obtained from beam element and close to therelation obtained from all cores.

BRICK : All Sample

4540

y = 6.1604e0.0003x
R² = 0.1819

Strength (MPa)

35
30
25
20
15
10
5
0
0

1000

2000

3000

4000

5000

6000

UPV (m/s)(a) Strength-UPV relation for all cores of brick aggregate concrete

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BRICK : Only Slab
45
40

y = 4.4842e0.0004x
R² = 0.2604

Strength (MPa)

35
30
25
20
15
10
5
0
0

1000

2000

3000

4000

5000

6000

UPV (m/s)(b) Strength-UPV relation for slab of brick aggregate concrete

BRICK : Only BEAM45

y = 6.4683e0.0003x
R² = 0.1605

40
Strength (MPa)

35
30
25
20
15
10
5
0

0

1000

2000

3000
UPV (m/s)

4000

5000

6000

(C) Strength-UPV relation for beam of brick aggregate concrete

33

March 2016

45

BRICK : Only Column

40

y = 6.7685e0.0003x
R² = 0.1655

35
Strength (MPa)

30
25
20
15
10
5
0
0

1000

2000

3000

4000

5000

6000

UPV (m/s)(d) Strength-UPV relation for column of brick aggregate concrete
Figure 7: Strength-UPV relation for brick aggregate concreteFig. 8 shows the correlation between strength and UPV for stone aggregate concrete. Fig. 8(a) has beendrawn using all the cores of stone aggregate. There are 647 cores out of 1095 initial samples. The
correlation equation has been found to be y = 662.81e0.0004x, where X= UPV in m/s and Y is strengthin MPa. R2 value for this equation is 0.14. This means that we can explain 14% of the variability forthe data around the regression line and 86% remained without explanation. Fig. 8(b) is drawn using
the cores taken from slab made of stone aggregate concrete. It contains 54 cores. Correlation equation
is found to be y = 1333.8e0.0002x, R2 value for this equation was 0.12. It has showed a slightly lesscorrelation value than the correlation from all the cores. Fig. 8(c) shows correlation for cores takenfrom beams. It contains 142 cores. Correlation equation is found to be y = 346.19e0.0005x, R2 value forthis equation is 0.20. It is higher than the relation obtained from all cores. Fig. 8(d) shows correlation
for cores taken from column. It contains total of 453 cores. The correlation equation is found to be y
= 713.71e0.0004x, R2 value for this equation is 0.13 which is slightly higher than the relation obtained
from slab element and close to relation obtained from all cores

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Strength (MPa)

STONE : All Sample
50
45
40
35
30
25
20
15
10
5
0

y = 4.57e0.0004x
R² = 0.1446

0

1000

2000

3000

4000

5000

6000

7000

UPV (m/s)(a) Strength-UPV relation for all cores of stone aggregate concrete
STONE : Only Slab
45
40
y = 9.1961e0.0002x
R² = 0.1205

Strength (MPa)

35
30
25
20
15
10
5
0
0

1000

2000

3000
UPV (m/s)

4000

5000

6000

(b) Strength-UPV relation for slab of stone aggregate concrete

35

March 2016

STONE : Only Beam
45
40

y = 2.3869e0.0005x
R² = 0.2039

Strength (MPa)

35
30
25
20
15
10
5
0
0

1000

2000

3000

4000

5000

6000

UPV (m/s)(C) Strength-UPV relation for beam of stone aggregate concrete
STONE : Only Column
45

y = 4.9209e0.0004x
R² = 0.1345

40
Strength (MPa)

35
30
25
20
15
10
5
0
0

1000

2000

3000
4000
UPV (m/s)

5000

6000

7000

(d) Strength-UPV relation for column of stone aggregate concrete
Figure 8: Strength UPV relation for stone aggregate concreteFig. 9 shows the bar diagram of the correlation coefficient obtained from the plot of the cores of brickand stone aggregate concrete. It is clear from the diagram that brick aggregate has a higher correlation
than stone aggregate concrete. Only in case of cores obtained from beams, it has lower correlation thanstone aggregate concrete, but it is not too low. The highest coefficient obtained is 0.25 which indicatespoor correlation. It is clear from Figures 6 and 7 that there is a positive correlation between strengthand UPV, with the increase of UPV concrete strength also increases. Depending on this, it may beclaimed that for high strength concrete strength-UPV relation would be more reliable.
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0.3
Brick Aggregate Concrete

0.25

Stone Aggregate Concrete
0.2
0.15
0.1
0.05
0
all cores

slab

beam

columnFigure 9: Comparison of correlation of brick and stone aggregate
Fig. 10 shows comparison among correlation values of the previous studies of strength –UPV
established in the laboratory with the test result of cores obtained from existing reinforced concrete
structures. Qasrawi (2000) and Shariati et al. (2011), show highest degrees of correlation 0.95 and 0.92.
Kheder (1999) shows lowest value of 0.41. Among the cores obtained from existing reinforced
concrete structures, cores obtained from slab of brick aggregate concrete shows highest value of 0.26
and cores from slab of stone aggregate concrete shows the lowest value of 0.12. There is a hugevariation among correlations obtained in the laboratory and relations obtained from existing structures.
The previous studies derived good correlation between strength-UPV in the laboratory with a particularmix proportion. No clear evidence has been provided about the effect of mix proportion on thecorrelations. Each study has obtained different strength-UPV relation. Therefore there exists a large
uncertainty when one tries to use the developed relations to estimate concrete strength in the field
condition. Instead of good care in concrete production in the laboratory many variations occur in thefield such as variations of aggregate type, cement content, mixing, compaction and curing. Thesevariations are not considered in the laboratory based relations.

37March 2016

1
0.9
0.8

Degree of corelation

0.7
0.6
0.5
0.4
0.3
0.2
0.1

Turgut (2004)
Nash't et al. (2005)
Kheder (1999) (wet)Kheder (1999) (dry)Del Rio et al. (2004)
Qasrawi (2000)
Tumendemberel and Baigalimaa (2015)
Shariati et al. (2011)
Amin (September, 2014) (Brick,Saturated)
Amin (September, 2014) (Stone,Saturated)
Amin (September, 2014) (Combined,Saturated)
Amin (September, 2014) (Brick,dry)
Amin (September, 2014) (Stone,dry)
Amin (September, 2014) (Combined,Dry)
Brick (all)Brick (slab)
Brick (beam)
Brick (Column)
Stone (all)Stone (slab)
Stone (beam)
Stone (column)

0

Figure 10: Comparison of correlation with previous studies

Conclusions
The ultrasonic pulse velocity (UPV) test has a strong potential to be used for predicting insitu concrete
strength. The main problem in realizing this potential is that the correlation between compressive
strength and UPV is low in the field due to different field variations. The correlation is high for thelaboratory produced concrete specimen which cannot be directly used for the estimation of concrete
strength in the field. The relation is influenced by a number of factors which would have to be taken
in to account if a reasonable prediction of compressive strength has to be made from pulse velocity
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BNUS Annual Report-2015

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measurements. Thus the curve obtained from existing reinforced concrete structures and laboratory
specimens can be used only to measure approximate values of concrete strength. These methods canalso be employed for the efficient planning of the construction works in huge infrastructure projects,
in which it may be necessary to know in-situ strength of concrete in order to determine the removal
time of formwork, the stressing or releasing time for the wires in pre stressed members, the loading
time for the system in post-tensional elements or the time for opening the structure to service safely.
For economic and simplicity, a two stage method of concrete strength verification can be introduced
by a combination of destructive and nondestructive method. Among the various methods employed
for the assessment of concrete strength in situ, the classical method, involving compression tests on
cylindrical specimens produced from cores drilled out of the structure, should surely be recognized ashaving primary importance on account of reliability and accuracy of the result.
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ACI Committee 228 (2003). "In-Place Methods to Estimate Concrete Strength." ACI 228.1R-03,
American Concrete Institute, Famington Hills, MI.
Amin, A. F. M. S. (September, 2014). "Assessment of Concrete Strength in an Existing facility." BUET,
Dhaka, Presentation in a meeting.
Ariöz, Ö., Tuncan, A., Tuncan, M., Kavas, T., Ramyar, K., Kilinç, K., and Karasu, B. (2009). "Use of
Combined Non-destructive Methods to Assess the Strength of Concrete in Structures." Afyon
Kocatepe University Journal of Science, 147-154.
ASTM (2002). "Standard Test Method for Pulse Velocity Through Concrete." ASTM C597 - 02, ASTM
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ASTM (2008). "Standard Test Method for Rebound Number of Hardened Concrete." ASTM C805M08, ASTM International, West Conshohocken, PA,.
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Breysse, D. (2012). Non-destructive Assessment of Concrete Structures: Reliability and Limits of Single
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BSI (1986). "Testing concrete. Recommendations for surface hardness testing by rebound hammer."
BS 1881-202 : 1986,, British Standards Institution, London, U.K.
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March 2016

BSI (1997). "Recommendations for measurement of velocity of ultrasonic pulses in concrete." BS1881-203:1986, British Standards Institution, London, U.K.
Demirboğa, R., Türkmen, İ., and Karakoc, M. B. (2004). "Relationship between ultrasonic velocity andcompressive strength for high-volume mineral-admixtured concrete." Cement and Concrete
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Elvery, R., and Ibrahim, L. (1976). "Ultrasonic assessment of concrete strength at early ages."
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Elsevier,<http://www.sciencedirect.com/science/article/pii/S2214509514000321>.
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Price, W. F., and Hynes, J. (1996). "In-situ strength testing of high strength concrete." Magazine ofconcrete research, 48(176), 189-197.
Qasrawi, H. Y. (2000). "Concrete strength by combined nondestructive methods simply and reliably
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Shariati, M., Sulog, N. H. R., H, M. M. A. K., Sharif, P., and Sinaei, H. (2011). "Assessing the strength ofreinforced concrete structures through Ultrasonic Pulse Velocity and Schmidt ReboundHammer tests." Scientific Research and Essays, 6(1), 213-220.
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TS (2013). "Betonarme yaplara uygulanabilecek tahribatsz muayene (NDT) yöntemleri[Nondestructive testing methods applicable to Reinforced Concrete Structures]." TS 13543,
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Direct and Indirect Transmission." ACI Materials Journal, 98(6), 450-457.
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PART-IVNDT AND DESTRUCTIVE TESTS AT OAB, BUET
AND RETROFITTING PROPOSALBANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Pushpendue Biswas
Abul Khair
Uttama Barua
Mehedi Ahmed AnsaryMarch 2016

1.

INTRODUCTION

Men with mainly four materials built the oldest constructions and these materials lasted thousands ofyears for construction purposes. These were earth (from which bricks come from, for instance), stone,wood and natural plants fibers. With these four elements men was able to build spectacularconstructions some of which are still standing nowadays. Later in the 18th century, with the beginningof the industrial revolution in England, the iron is burnt with coal and its impurities decrease giving
rise to cast iron, to be built in great quantities. While the iron from Nature is very brittle, the cast ironis resisting well to compression, although bad to tension, and can be used as a structural resistingelement working in compression. With fewer impurities, later on, we have the forged iron/steel andlater the steel, where carbon is mixed with iron is small quantities to make it become more malleable.
The forged steel and the steel are used mainly in tension due to the phenomena of buckling. Steelstructures are common nowadays. The last great change occurring in construction materials was theintroduction of concrete.
Most unreinforced masonry (URM) buildings possess features that can threaten lives during
earthquakes. These may include unbraced parapets, walls and roofs that are not well attached to eachother, and walls that are poorly constructed. When earthquakes occur, inadequate connections in thesebuildings can allow masonry to fall. Floors and roofs may collapse leaving occupants and passers-by
in harm’s way. These risks to life can be significantly reduced with seismic retrofits.
The main objectives of the study was to make a basic structural checklist to assess the safety andvulnerability of the Old Academic Building (Masonry) of Bangladesh University of Engineering andTechnology (BUET) and to provide an earthquake resistant design for retrofitting of the Old Academic
Building.
2.

BACKGROUND

Brick masonry buildings have large mass and hence attract large horizontal forces during earthquake
shaking. They develop numerous cracks under both compressive and tensile forces caused byearthquake shaking. The focus of earthquake resistant masonry building construction is to ensure thatthese effects are sustained without major damage or collapse. Appropriate choice of structuralconfiguration can help achieve this.
2.1

Earthquake Design and Construction Basics

2.1.1 Behavior of Brick Masonry Walls
Ground vibrations during earthquakes cause inertia forces at locations of mass in the building. These
forces travel through the roof and walls to the foundation. The main emphasis is on ensuring that theseforces reach the ground without causing major damage or collapse. Of the three components of a
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masonry building (roof, wall and foundation) (Figure 1a), the walls are most vulnerable to damage
caused by horizontal forces due to earthquake. A wall topples down easily if pushed horizontally at
the top in a direction perpendicular to its plane (termed weak direction), but offers much greater
resistance if pushed along its length (termed strong direction) (Figure 1b). The ground shakes
simultaneously in the vertical and two horizontal directions during earthquakes (IITK-BMTPC
Earthquake Tip 5).
However, the horizontal vibrations are the most damaging to normal masonry buildings. Horizontal
inertia force developed at the roof transfers to the walls acting either in the weak or in the strong
direction. If all the walls are not tied together like a box, the walls loaded in their weak direction tend
to topple (Figure 2a). To ensure good seismic performance, all walls must be joined properly to theadjacent walls. In this way, walls loaded in their weak direction can take advantage of the good lateralresistance offered by walls loaded in their strong direction (Figure 2b). Further, walls also need to betied to the roof and foundation to preserve their overall integrity.

Figure 1: Basic components of a masonrybuilding

Figure 2: Advantage sharing between walls

2.1.2 How to Improve Behavior of Masonry Walls
Masonry walls are slender because of their small thickness compared to their height and length. A
simple way of making these walls behave well during earthquake shaking is by making them act
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together as a box along with the roof at the top and with the foundation at the bottom. A number of
construction aspects are required to ensure this box action. Firstly, connections between the walls
should be good. This can be achieved by (a) ensuring good interlocking of the masonry courses at thejunctions, and (b) employing horizontal bands at various levels, particularly at the lintel level. Secondly,
the sizes of door and window openings need to be kept small. The smaller the openings, the larger are
the resistance offered by the wall. Thirdly, the tendency of a wall to topple when pushed in the weak
direction can be reduced by limiting its length-to-thickness and height-to-thickness ratios. Designcodes specify limits for these ratios. A wall that is too tall or too long in comparison to its thickness isparticularly vulnerable to shaking in its weak direction (Figure 3).

Figure 3: Slender walls are vulnerable – height and length to be kept within limits.
2.1.3 Choice and Quality of Building Materials
Earthquake performance of a masonry wall is very sensitive to the properties of its constituents, namely
masonry units and mortar. The properties of these materials vary across India due to variation in raw
materials and construction methods. A variety of masonry units are used in the country, e.g. Clay bricks(burnt and unburnt), concrete blocks (solid and hollow), stone blocks. Burnt clay bricks are mostcommonly used. These bricks are inherently porous, and so they absorb water. Excessive porosity is
detrimental to good masonry behavior because the bricks suck away water from the adjoining mortar,
which results in poor bond between brick and mortar, and in difficulty in positioning masonry units.
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For this reason, bricks with low porosity are to be used, and they must be soaked in water before use
to minimize the amount of water drawn away from the mortar.
Various mortars are used, e.g. mud, cement-sand, or cement-sand-lime. Of these, mud mortar is theweakest; it crushes easily when dry, flows outward and has very low earthquake resistance. Cementsand mortar with lime is the most suitable. This mortar mix provides excellent workability for laying
bricks, stretches without crumbling at low earthquake shaking, and bonds well with bricks. The
earthquake response of masonry walls depends on the relative strengths of brick and mortar. Bricks
must be stronger than mortar. Excessive thickness of mortar is not desirable. A 10mm thick mortar
layer is generally satisfactory from practical and aesthetic considerations (IITK-BMTPC Earthquake
Tip 12).
2.1.4 Box Action in Masonry Buildings
The structural configuration of masonry buildings includes aspects like (a) overall shape and size ofthe building, and (b) distribution of mass and (horizontal) lateral load resisting elements across thebuilding. Large, tall, long and unsymmetrical buildings perform poorly during earthquakes (IITKBMTPC Earthquake Tip 6). A strategy used in making them earthquake-resistant is developing goodbox action between all the elements of the building, i.e., between roof, walls and foundation (Figure4). Loosely connected roof or unduly slender walls are threats to good seismic behavior. For example,
a horizontal band introduced at the lintel level ties the walls together and helps to make them behave
as a single unit.

Figure 4: Essential requirements to ensure box action in a masonry building.
2.1.5 Influence of Openings
Openings are functional necessities in buildings. However, location and size of openings in walls
assume significance in deciding the performance of masonry buildings in earthquakes. To understandthis, consider a four-wall system of a single storey masonry building (Figure 5). During earthquake47

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shaking, inertia forces act in the strong direction of some walls and in the weak direction of others(IITK-BMTPC Earthquake Tip 12).
Walls shaken in the weak direction seek support from the other walls, i.e., walls B1 and B2 seek
support from walls A1 and A2 for shaking in the direction shown in Figure 2. To be more specific,
wall B1 pulls walls A1 and A2, while wall B2 pushes against them. At the next instance, the directionof shaking could change to the horizontal direction perpendicular to that shown in Figure 2. Then,walls A and B change their roles; Walls B1 and B2 become the strong ones and A1 and A2 weak. Thus,
walls transfer loads to each other at their junctions (and through the lintel bands and roof).
Hence, the masonry courses from the walls meeting at corners must have good interlocking. For thisreason, openings near the wall corners are detrimental to good seismic performance. Openings too
close to wall corners hamper the flow of forces from one wall to another (Figure 6). Further, large
openings weaken walls from carrying the inertia forces in their own plane. Thus, it is best to keep all
openings as small as possible and as far away from the corners as possible.

Figure 2: Regions of force transfer fromweak walls to strong walls in a masonrybuilding

Figure 6: Openings weaken walls in a masonrybuilding

2.1.6 Earthquake-Resistant Features
Indian Standards suggest a number of earthquake-resistant measures to develop good box-type action
in masonry buildings and improve their seismic performance. For instance, it is suggested that abuilding having horizontal projections when seen from the top, e.g., like a building with plan shapes
L, T, E and Y, be separated into (almost) simple rectangular blocks in plan, each of which has simple
and good earthquake behavior (IITK-BMTPC Earthquake Tip 6).

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During earthquakes, separated blocks can oscillate independently and even hammer each other if they
are too close. Thus, adequate gap is necessary between these different blocks of the building. The
Indian Standards suggest minimum seismic separations between blocks of buildings. However, it may
not be necessary to provide such separations between blocks, if horizontal projections in buildings are
small, say up to ~15-20% of the length of building in that direction. Inclined staircase slabs in masonrybuildings offer another concern. An integrally connected staircase slab acts like a cross-brace between
floors and transfers large horizontal forces at the roof and lower levels (Figure 7a). These are areas ofpotential damage in masonry buildings, if not accounted for in staircase design and construction. To
overcome this, sometimes, staircases are completely separated (Figure 7b) and built on a separate
reinforced concrete structure. Adequate gap is provided between the staircase tower and the masonrybuilding to ensure that they do not pound each other during strong earthquake shaking (IITK-BMTPC
Earthquake Tip 13).

Figure 7: Earthquake-resistant detailing of staircase in masonry building

2.1.7 Role of Horizontal Bands
Horizontal bands are the most important earthquake-resistant feature in masonry buildings. The bands
are provided to hold a masonry building as a single unit by tying all the walls together, and are similar
to a closed belt provided around cardboard boxes. There are four types of bands in a typical masonrybuilding, namely gable band, roof band, lintel band and plinth band (Figure 8), named after theirlocation in the building. The lintel band is the most important of all, and needs to be provided in almost
all buildings. The gable band is employed only in buildings with pitched or sloped roofs. In buildings49

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with flat reinforced concrete or reinforced brick roofs, the roof band is not required, because the roof
slab also plays the role of a band.
However, in buildings with flat timber or CGI sheet roof, roof band needs to be provided. In buildings
with pitched or sloped roof, the roof band is very important. Plinth bands are primarily used when
there is concern about uneven settlement of foundation soil. The lintel band ties the walls together andcreates a support for walls loaded along weak direction from walls loaded in strong direction. Thisband also reduces the unsupported height of the walls and thereby improves their stability in the weak
direction. During the 1993 Latur earthquake (Central India), the intensity of shaking in Killari village
was IX on MSK scale. Most masonry houses sustained partial or complete collapse (Figure 9a). On
the other hand, there was one masonry building in the village, which had a lintel band and it sustained
the shaking very well with hardly any damage (Figure 9b) (IITK-BMTPC Earthquake Tip 14).

Figure 8: Horizontal Bands in masonry Figure 9: The 1993 Latur Earthquake (Central
building
India)

2.1.8 Design of Lintel Bands
During earthquake shaking, the lintel band undergoes bending and pulling actions (Figure 10). To
resist these actions, the construction of lintel band requires special attention. Bands can be made ofwood (including bamboo splits) or of reinforced concrete (RC) (Figure 11); the RC bands are the best.
The straight lengths of the band must be properly connected at the wall corners. This will allow theband to support walls loaded in their weak direction by walls loaded in their strong direction. Small
lengths of wood spacers (in wooden bands) or steel links (in RC bands) are used to make the straightlengths of wood runners or steel bars act together. In wooden bands, proper nailing of straight lengths
with spacers is important. Likewise, in RC bands, adequate anchoring of steel links with steel bars isnecessary. The Indian Standards IS: 4326-1993 and IS: 13828 (1993) provide sizes and details of the
bands. When wooden bands are used, the cross-section of runners is to be at least 75mm×38mm and50

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of spacers at least 50mm×30mm. When RC bands are used, the minimum thickness is 75mm, and at
least two bars of 8mm diameter are required, tied across with steel links of at least 6mm diameter at a
spacing of 150 mm centers (IITK-BMTPC Earthquake Tip 14).

Figure 10: Bending and pulling in lintel bands

Figure11: Horizontal Bands in masonrybuildings

2.1.9 Response of Masonry Walls
Horizontal bands are provided in masonry buildings to improve their earthquake performance. Thesebands include plinth band, lintel band and roof band. Even if horizontal bands are provided, masonrybuildings are weakened by the openings in their walls (Figure 12). During earthquake shaking, themasonry walls get grouped into three sub-units, namely spandrel masonry, wall pier masonry and sill
masonry.
Consider a hipped roof building with two window openings and one door opening in a wall (Figure13a). It has lintel and plinth bands. Since the roof is a hipped one, a roof band is also provided. Whenthe ground shakes, the inertia force causes the small-sized masonry wall piers to disconnect from themasonry above and below. These masonry sub-units rock back and forth, developing contact only atthe opposite diagonals (Figure 13b). The rocking of a masonry pier can crush the masonry at thecorners. Rocking is possible when masonry piers are slender, and when weight of the structure above
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is small. Otherwise, the piers are more likely to develop diagonal (X-type) shear cracking (Figure 13c);
this is the most common failure type in masonry buildings.
In un-reinforced masonry buildings (Figure 14), the cross-section area of the masonry wall reduces atthe opening. During strong earthquake shaking, the building may slide just under the roof, below thelintel band or at the sill level. Sometimes, the building may also slide at the plinth level. The exact
location of sliding depends on numerous factors including building weight, the earthquake-induced
inertia force, the area of openings, and type of doorframes used (IITK-BMTPC Earthquake Tip 14).

Figure 12: Sub-units in masonry building

Figure 14: Horizontal sliding at sill level in amasonry building

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Figure 13: Earthquake response of a hippedroofmasonry building

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2.1.10 How Vertical Reinforcement Helps
Embedding vertical reinforcement bars in the edges of the wall piers and anchoring them in thefoundation at the bottom and in the roof band at the top (Figure 15), forces the slender masonry piers
to undergo bending instead of rocking. In wider wall piers, the vertical bars enhance their capability
to resist horizontal earthquake force sand delay the X-cracking. Adequate cross-sectional area of these
vertical bars prevents the bar from yielding in tension. Further, the vertical bars also help protect thewall from sliding as well as from collapsing in the weak direction (IITK-BMTPC Earthquake Tip 15).
2.1.11 Protection of Openings in Walls
Sliding failure mentioned above is rare, even in unconfined masonry buildings. However, the mostcommon damage, observed after an earthquake, is diagonal X-cracking of wall piers, and also inclined
cracks at the corners of door and window openings. When a wall with an opening deforms during
earthquake shaking, the shape of the opening distorts and becomes more like a rhombus- two opposite
corners move away and the other two come closer. Under this type of deformation, the corners thatcome closer develop cracks (Figure 16a). The cracks are bigger when the opening sizes are larger.
Steel bars provided in the wall masonry all around the openings restrict these cracks at the corners(Figure 16b). In summary, lintel and sill bands above and below openings, and vertical reinforcement
adjacent to vertical edges, provide protection against this type of damage (IITK-BMTPC Earthquake
Tip 15).

2.1.12 How to make Stone Masonry Buildings Earthquake Resistant(a) Ensure proper wall construction: The wall thickness should not exceed 450mm. Round stoneboulders should not be used in the construction. Instead, the stones should be shaped using chisels andhammers. Use of mud mortar should be avoided in higher seismic zones. Instead, cement -sand mortar
should be 1:6 or richer) and lime-sand mortar 1:3 (or richer) should be used.(b) Ensure proper bondin masonry courses: The masonry walls should be built in construction lifts not exceeding 600mm.
Through-stones (each extending over full thickness of wall) or a pair of overlapping bond -stones (eachextending over at least ¾ths thickness of wall) must be used at every 600mm along the height and at a
maximum spacing of 1.2m along the length (Figure 17). (c) Provide horizontal reinforcing elements:
The stonemasonry dwellings must have horizontal bands (IITK-BMTPC Earthquake Tip 14for plinth,lintel, roof and gable bands). These bands can be constructed out of wood or reinforced concrete, andchosen based on economy. It is important to provide at least one band (either lintel band or roof band)in stone masonry construction (Figure 18). (d) Control on overall dimensions and heights: The
unsupported length of walls between cross-walls should be limited to 5m; for longer walls, cross53

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supports raised from the ground level called buttresses should be provided at spacing not more than
4m. The height of each story should not exceed 3.0m. In general, stone masonry buildings should not
be taller than 2 stories when built in cement mortar, and 1 story when built in lime or mud mortar. The
wall should have a thickness of at least one -sixth its height. Although, this type of stone masonry
construction practice is deficient with regards to earthquake resistance, its extensive use is likely tocontinue due to tradition and low cost (IITK-BMTPC Earthquake Tip 16)

Figure 15: Vertical reinforcement in masonry
walls

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Figure 16: Cracks at corners of openings in amasonry building

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Figure 17: Use of “through stones” or “bondstones” in stone masonry walls

2.2

Figure 18: Horizontal lintel band is essential
inrandom rubble stone masonry walls

NON-DESTRUCTIVE TESTING EQUIOMENT

2.2.1 Ferroscan
Ferroscan is portable, non-destructive steel reinforcement detection system using electromagnetic
pulse. It can reduce costly effort to drill, cut or physically break concrete surface to find out the bar.
Ferroscan has been used for determining the position, depth and diameter of rebar in existing structure.
This is a portable, quick and simple-to-operate system carrying out structural analysis quickly andexactly in a non-destructive manner. This also determines coverage coverage over the entire surfaceof the structure. The key element of the system is the scanner and the monitor. After scanning a
structure data has been transferred to the monitor. Collected data can be analyzed by monitor or in a
PC using the software PS 200. Maximum depth of scanning is 180 mm (at 36 mm rebar diameter)where rebar diameter range 6-36 mm. Accuracy of depth measurement for rebar is േ 1 mm, dependingon the depth range and Scan mode used. Three types of scanning can be checked out by using Ferroscan
device. Line scan is simple way to detect position and depth of rebar where Image scan provides detail

information (diameter of bar, concrete cover, location etc.) with scanned image (2ft x 2ft grid) of any
structure. Block scan is a combination of a set of image scan for a comparatively large area (Rahman
et. Al, 2010). Figure 19 shows monitor and scanning device.

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Figure 19: Monitor and scanning device of Ferroscan
2.2.2 Microtremor Instrument
Microtremor measurement has been done with five component of sensor. At each site microtremor
ground motions were measured for five minutes. Each accelerometer recorded data in the direction
two horizontal (N-S and E-W components) and one vertical direction (up-down). For free two fields
near to building, First Fourier Transform (FFT) has been done in order to calculate H/V spectral ratio
for microtremors. At the top and ground floors of the both buildings, horizontal X- and Y-component
microtremor motions, which are in longitudinal and traverse direction of the buildings, were observed.
Figure 20 shows the microtremor testing equipments.

Figure 20: Microtremor testing equipments

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2.2.3 Ultrasonic Pulse Velocity (UPV) Instrument
Principle and Crack Depth Estimation
The ultrasonic pulse transmits a very small amount of energy through air. Therefore, if a pulse travelingthrough the concrete comes upon an air filled crack or a void whose projected are perpendicular to thepath length is larger than the area of the transmitting transducer; the pulse will get diffracted aroundthe defect. Thus, the pulse travel time will be greater than that through a similar concrete without any
defect. The pulse velocity method, therefore, is effective in locating cracks, cavities, and other such
defects. It should be pointed out that the application of this technique in locating flaws has serious
limitations. For example, if the cracks and flaws are small or if they are filled with water or otherdebris, thus allowing the wave to propagate through the flaw, the pulse velocity will not significantly
decrease, implying that no flaws exist.

Vertical crack depth
The experimental set up for estimating the vertical crack is as shown in the Figure 21.
The depth of an air filled crack can be estimated by the pulse velocity method.
The depth, h, is given by equation (1),h

2xT12  T22
T2





(1)

Where
x = distance of transducer from the crack (note that both transducers must be placed equidistant fromthe crack);
T1= transmit time around the crack;
T2= transmit time along the surface of the same type of concrete without any crack (note that surface
path length for T1 and T2 must be equal).
It should be pointed out that for the above equation to be valid; the crack must be perpendicular tothe concrete surface. A check should be made to determine if the crack is perpendicular to thesurface or not. This can be done as follows. Place both the transducers equidistant from the crack andobtain the transit, time. Move each transducer, in turn, away from the crack. If the transmit timedecreases, then the crack slopes towards the direction in which transducer was moved.

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Figure 21: Experimental set-up for vertical crack depth estimation

Figure 22: Ultrasonic Pulse Velocity Instrument
2.3 Moisture Content Analysis of OAB building
2.3.1 Introduction
Moisture, in all its physical forms, is commonly regarded as the single greatest threat to durability andlong-term performance of the building stock. Excessive exposure to moisture is not only a common
cause of significant damage to many types of building components and materials, it also can lead tounhealthy indoor living environments (Dacquisto et al., 2004). Bangladesh lies in the sub-tropicalmonsoon zone and receives approximately 2000 mm of rainfall annually, of which more than 80%
occurs during the monsoon season (from June to September) (Dewan et al., 2007; Dewan andYamaguchi, 2009a). So, climate of the city is characterized by subtropical, high rainfall, humid
condition with cool and short winter; and long, humid and hot summer. Moreover, the buildings in thiscountry are not constructed complying with the national building code. Due to such climatic conditionand structural condition, excessive exposure to moisture is a common phenomenon in Bangladesh.
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This study aims to assess building moisture content by detecting thermal or infrared radiation throughthermal imaging or infrared (IR) camera. The Old Academic Building (OAB) in Bangladesh
University of Engineering and Technology (BUET) was selected as the study area for this study.
2.3.2 Background of the study
2.3.2.1 Moisture Assessment
Some of the more serious effects resulting from moisture problems in houses include: decay of
corrosion of metals, infestation by termites, carpenter ants and other insects, negative impacts on
indoor air quality, the growth of mold, mildew and other biological contaminants, reduced strength inbuilding materials, expansion/contraction damage to materials, reduced thermal resistance of wet
insulation, premature failures of paints and coatings, damage to building contents, negative effects onbuilding aesthetics, etc (Dacquisto et al., 2004). Considering the consequences several studies
regarding moisture assessment have been undertaken. Colantonio (2008) discussed moisture detection
methodologies for interior inspections in the paper. Dacquisto et al. (2004) carried out a project todevelop a set of recommendations for future research on moisture problems in housing that will help
to prevent such problems or resolve them once they have occurred through a review and analysis of
the extensive technical literature concerning the problems created by bulk water and excessive water
vapor in houses, and the solutions to those problems.
Some case studies providing information on specific occurrences of moisture problems in different
courtiers are also found in the literature. Most case studies are anecdotal in nature and deal with a
specific construction or a select group of structures that have experienced moisture-related
performance problems (Dacquisto et al., 2004). Marshall Macklin Monaghan Limited (1983) studied
indications of moisture problems in CMHC-financed housing built between the years of 1973 and 1981
(689,000 total housing units representing about 35% of housing production in Canada during that
period). Later in 1998, 1999, and 2000, CMHC carried out similar studies for moisture assessment in
British Columbia, Seattle, WA, Vancouver, B.C., and Alberta in Canada (Survey of Building Envelope
Failures in the Coastal Climate of British Columbia, 1998; Comparative Analysis of Residential
Construction in Seattle, WA and Vancouver, B.C., 1999; Wall Moisture Problems in Alberta
Dwellings, 2000). Chouinard and Lawton (n.d.) revealed that in Canada, the primary source ofmoisture leading to performance problems was rainwater intrusion rather than interior sources of
construction moisture. May (1991) demonstrated through several examples that moisture damage ismore dependent on management of rainwater. Similar conclusion was drawn in the studies of U.S.
Department of Housing and Urban Development (Assessing Housing Durability: A Pilot Study, 2001),
Crandell (1996), Crandell (2003), Crandell and Kenney (1996), and Tsongas et al. (1998).

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2.3.2.2 Thermal Image for Moisture Assessment
2.3.2.2.1 The Thermal Imaging Camera and How It Works
Infrared thermographic imagers have been used in the building industry since the 1980's, mainly forbuilding envelope and heat loss analysis, which are now vital tools to determine performance
characteristics of walls and roofs for both energy and structural integrity (Colantonio, 2008). A thermal
imaging camera is a unique and non-contact tool utilizing infrared thermography which is the art oftransforming an infrared image into a radiometric one allowing temperature values to be read from theimage. Infrared radiation is an energy wave that lies between the visible and microwave portions of
the electromagnetic spectrum where heat or thermal radiation is its primary source (Holland, 2008;
FLIR, 2011a & 2011b). As a diagnostic technique, thermography captures two-dimensional images of
the apparent temperatures of equipment and structures (FLUKE, n.d.). On the electromagnetic
spectrum infrared has a lower frequency than the red part of the visible light, thus the designation infra(below) red (Holland, 2008). The tool produces thermal image indicating the exact location of energy
losses through scanning and visualizing the temperature distribution of entire surfaces quickly andaccurately providing precise and convincing argumentation (FLIR, 2011a & 2011b). It is also well
suited to identifying wet spots in building envelopes (FLUKE, n.d.). Figure 1 shows thermal and visual
image showing wet area of wall.

Figure 23: Thermal and visual image showing wet area of wall (Source: Hopkins, 2011a)
2.3.2.2.2 Use of Thermal Image for Moisture Assessment
The presence of moisture in building envelopes, whether from leakage or condensation, can haveserious consequences. For example, moisture in insulation reduces its insulating capability, causing
heating and/or cooling losses and wasting energy. Moisture can also cause structural deterioration and
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foster the growth of mold, while a serious roof leak can damage or destroy a building's contents(FLUKE, n.d.). The true culprits of moisture damage are design flaws, construction defects andmechanical or plumbing mistakes which allow for the intrusion of water. And a structure’s age isdefinitely a factor too as components start to wear, like caulking and mastic, and in these cases deferred
maintenance would be the true cause of a leak (Hopkins, 2011b). There are a number of areas where
moisture can accumulate that are often overlooked in typical inspection processes, or require extensive
damage to the property to find them. That is why many are turning to thermal imaging as part of theirbuilding inspection regimen (FLUKE, n.d.).
An infrared camera can see and measure heat differences in building materials on ceilings, walls andfloors. Wet or moist areas and objects usually have a different temperature than dry areas (Hopkins,
2011b). Usually, the temperature of the damp areas are colder then dry ones (a), because of surface
evaporation, or warmer (b), because of the higher thermal inertia of water versus building materials(Rosina and Ludwig, 1999). Infrared camera can be used to detect presence and extent of moisture bymeans of variances in heat transfer brought on by this capacitance of water and phase change heat loss
or gain (Colantonio, 2008). The principle that allows locating moisture on the interior walls is
evaporative cooling. Evaporative cooling can be very slight; there may only be a 1ºF temperature
difference from wet to dry. A good IR camera easily shows even that slight temperature difference(Holland, 2008). Accordingly, the wet areas will appear relatively darker or lighter than the dry areas
on an infrared picture, enabling us to locate them (Hopkins, 2011b). The process of finding all areas
with moisture issues can be a long and tedious task when using only a moisture meter. The thermal
imaging camera quickly and accurately shows all relevant thermal differences. The investigation
results in the preliminary determination of the problem (Holland, 2008). Moreover, unlike othermoisture-detecting technologies, such as meters, thermography requires no physical contact with roofs,
ceilings, walls or floors. In addition, it is possible to check inaccessible areas and cover a large area ina single image (FLUKE, n.d.). Thus the infrared camera can be readily utilized to detect the extent ofmoisture intrusion in building structures in a much faster and convenient way than conventional
moisture detection devices (Colantonio, 2008).
Using infrared cameras (or thermal imagers) to detect moisture is a relatively new but rapidly growing
practice in inspection and insurance circles (FLUKE, n.d.). Realizing the importance of thermal
imaging camera in building moisture assessment, several studies have been carried out on relevant
subject. Hopkins (2011a and 2011b) showed the use of thermal imaging camera for identifying theindoor moisture content problems due to condensation leaks, slab leaks, poor roof design, etc. Rosina
and Ludwig (1999) described optimal procedures to obtain reliable maps of moisture in building
materials, at different environmental and microclimatic conditions, and the related energetic
phenomena, which cause temperature discontinuities, and that are detected by thermography.
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2.4

Direct Shear Test

Ancient masonry structures are partially vulnerable to dynamic actions, especially seismic actions.
This building, as structure planned and constructed at past, is vulnerable to dynamic loads, which may
unpredictably induce a collapse of a portion of the building or derive the whole structure to rapid
failure. However, the high vulnerability of ancient masonry buildings to seismic actions is mostly due
to insufficient connections between the various parts.
The old academic building of BUET, the bonding material is lime mortar so it was required to checkthe shear stress of the bonding mortar of masonry. And direct shear test has been carried out to findthe best result for mortar strength.
3

METHODOLOGY OF THE STUDY

The study has been conducted with the following methodology:
3.1 Study Design
Masonry is the building of structures from individual units laid in and bound together by mortar; theterm masonry can also refer to the units themselves. The common materials of masonry construction
are brick, building stone such as marble, granite, travertine, and limestone, cast stone, concrete block,glass block, and cob. Masonry is generally a highly durable form of construction. However, thematerials used, the quality of the mortar and workmanship, and the pattern in which the units areassembled can significantly affect the durability of the overall masonry construction.
Seismic retrofitting is the modification of existing structures to make them more resistant to seismic
activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic
demand on structures and with our recent experiences with large earthquakes near urban centers, theneed of seismic retrofitting is well acknowledged. Prior to the introduction of modern seismic codesin the late 1960s for developed countries (US, Japan etc.) and late 1970s for many other parts of theworld (Turkey, China etc.), (NZSEE Bulletin 39(2)-June 2006), many structures were designed
without adequate detailing and reinforcement for seismic protection. In view of the imminent problem,
various research works has been carried out. State-of-the-art technical guidelines for seismic
assessment, retrofit and rehabilitation have been published around the world - such as the ASCE-SEI
41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines (NZSEE 2006).
These codes must be regularly updated; the 1994 Northridge earthquake brought to light the brittlenessof welded steel frames, for example (Reitherman, Robert (2012).
The retrofit techniques outlined here are also applicable for other natural hazards such as tropical
cyclones, tornadoes, and severe winds from thunderstorms. Whilst current practice of seismic
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retrofitting is predominantly concerned with structural improvements to reduce the seismic hazard ofusing the structures, it is similarly essential to reduce the hazards and losses from non-structuralelements. It is also important to keep in mind that there is no such thing as an earthquake-proof
structure, although seismic performance can be greatly enhanced through proper initial design or
subsequent modifications.
In many parts of developing countries such as Bangladesh, Iran and China, unreinforced or in somecases reinforced masonry is the predominantly form of structures for rural residential and dwelling.
Masonry was also a common construction form in the early part of the 20th century, which implies
that a substantial number of these at-risk masonry structures would have significant heritage value.
Masonry walls that are not reinforced are especially hazardous. Such structures may be more
appropriate for replacement than retrofit, but if the walls are the principal load bearing elements instructures of modest size they may be appropriately reinforced. It is especially important that floor andceiling beams be securely attached to the walls. Additional vertical supports in the form of steel orreinforced concrete may be added.
In the western United States, much of what is seen as masonry is actually brick or stone veneer. Current
construction rules dictate the amount of tie–back required, which consist of metal straps secured tovertical structural elements. These straps extend into mortar courses, securing the veneer to the primarystructure. Older structures may not secure this sufficiently for seismic safety. A weakly secured veneer
in a house interior (sometimes used to face a fireplace from floor to ceiling) can be especially
dangerous to occupants. Older masonry chimneys are also dangerous if they have substantial verticalextension above the roof. These are prone to breakage at the roofline and may fall into the house in asingle large piece. For retrofit, additional supports may be added; however, it is extremely expensive
to strengthen an existing masonry chimney to conform to contemporary design standards. It is best to
simply remove the extension and replace it with lighter materials, with special metal flue replacing theflue tile and a wood structure replacing the masonry. This may be matched against existing brickwork
by using very thin veneer (similar to a tile, but with the appearance of a brick).
3.2 Study Area Selection
The Old Academic Building of Bangladesh University of Engineering and Technology (BUET) was
selected as the study area.

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Figure24: Ground Floor plan of Old Academic Building BUET
3.3 Preparation of Structural Checklist
A basic Structural checklist of masonry structure has been made by following the ASCE-SEI 31 andASCE-SEI 41. To prepare this checklist, a detailed field survey was conducted.
3.4

Non-Destructive Tests

To assess the actual scenario of the of the masonry structure of Old Academic Building BUET, somebasic Non-destructive tests were performed which includes Ferroscan, Microtremor, Ultrasonic Pulse
Velocity (UPV), Thermal Imaging for Assessment of Moisture.
3.5

Direct Shear Test

Direct shear test is a destructive test. It has been conducted to measure the shear stress due to mortar
bond only.
3.6

Data processing and analysis

The data collected from the survey have been analyzed with the relevant software to prepare the final
report.

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3.7

Preparation of Final Report

All information and findings were gathered and presented by tables and figures to prepare the final
report.
4

ANALYSIS AND RESULTS

4.1 Structural Checklist
The following checklist has made based on ASCE-SEI 31 and ASCE-SEI 41. The checklist is given
belowi.

Building Usage Type

Academic buildingii.

Fire and Electrical Safety

Not in the scope of the reportiii.

Structural System

Unreinforced Masonry Bearing Walls with Stiff
Diaphragms (Building Type 15 according to
ASCE/SEI 31-03)

iv.

Floor Systemv.

Floor Area

First floor (2nd story) is slab supported on masonrywalls, Ground floor (1st story) is slab on grade
36000 svi.

No. of Stories

2-storiedvii.

Construction Year

Early 1940’s (as reported)viii. Construction by

Owner of the buildingix.

Floor Load

Academic cum office loadxFoundation Typexi.

Design Drawings

Shallow masonry strip foundation (assumed according
to the usual practice)
Not available (only architectural plan is available)

xii.

Soil Boring Report

Available

xiii. Site ClassClass Dxiv. Adjacent buildings or others

Adequate distance is maintained with otherbuildings
Unreinforced burnt clay brick masonry with lime
mortarxv

Construction Materials

Building plan dimension of the Academic building is roughly about 150 ft x 240 ft. Wall thickness ismostly 25 inches.
Reported Distress History:
Cracks in various positions both in ground floor and first floor of the building were reported.
Observations:
The observations of the visiting team members on the general physical condition of the superstructure,65March 2016

based on visual inspection of the exposed parts, are as follows:

There is deviation in the arrangement of walls from the approved drawing.

Both horizontal and vertical cracks in masonry wall were observed in the ground floor and firstfloor which is much greater than the permissible crack width 0.3mm.

Dampness was observed in the wall which has mentioned in the moisture content analysis of
the OAB.

The non-structural members were not found in disordered or in distressed condition.
The walls are not properly anchored with the concrete slabs.



Bottom story has some portion as weak-story as well as a soft-story.

GENERAL RECOMMENDATIONS:Anchorage should be provided between masonry walls and the concrete slabs.



Flexible couplings should be introduced in the fluid and gas piping.



No construction beyond existing level should be made without any detail investigation.

Concluding Remarks:The building may be regarded safe for its present level (gravity load) of use. There is no
immediate threat or risk in using the building at its normal working condition with existingloading status.

However, measures mentioned in the General Recommendations should be taken to reduce
seismic vulnerability.

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Figure 25: Major cracks in the wall67

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4.1.1

Seismic Performance Evaluation as per ASCE 31-03 Tier-1 Analysis

Level of Investigation
Only architectural plan is available. A site visit was made to verify the plan information and to assess
the condition of the building.
Level of Performance
The building is evaluated to the Life Safety Performance Level (L.S).
Level of Seismicity
The building is located in the region of moderate seismicity. The parameters of level of seismicity
are described in belowAccording to BNBC (1993) and based on geotechnical investigation report
1. Zone coefficient for Dhaka = 0.15
2. Site Class = S3 (as per BNBC 1993)
Therefore,
Design short period response acceleration SDS = 2.5×0.15g= 0.375g
Design spectral response acceleration at 1 sec. SD1 = 2×0.15g = 0.300g
Where, g = acceleration due to gravity
Building TypeAs the description of types of building, the evaluated buildings are classified as URMA
(Unreinforced Masonry Bearing Walls with Stiff Diaphragms).
Screening Phase (Tier 1)
The buildings are URMA type and the site is in a high seismicity zone. Thus the following checklists
are associated for Tier 1 evaluation.


Basic Structural Checklist
Geologic Site Hazards and Foundation Checklist
Basic Nonstructural Checklist

The mentioned checklists are given belowBasic Structural Checklist for Building Type URMA: Unreinforced Masonry Bearing Wallswith Stiff Diaphragms
The following is the General Basic Structural Checklist with relevant clauses. Each of the evaluation
statements on this checklist shall be marked Compliant (C), Non-compliant (NC) or Not
Applicable (N/A) for a Tier 1 Evaluation. Compliant statements identify issues that are acceptableaccording to the criteria of this standard, while non-compliant statements identify issues that require
further investigation. Certain statements may not apply to the buildings being evaluated. For non68

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compliant evaluation statements, the design professional may choose to conduct further investigation
using the corresponding Tier 2 Evaluation procedure; corresponding section numbers are inparentheses following each evaluation statement.
Criteria
Load Path

Description of Conditions
Remark Comments
The structure shall contain a minimum ofC
one complete load path for Life Safety and
Immediate Occupancy for seismic force
effects from any horizontal direction thatserves to transfer the inertial forces fromthe mass to the foundation

Mezzanines

Interior mezzanine levels shall be braced N/Aindependently from the main structure, or

There ismezzanine.

noshall be anchored to the lateral-forceresisting elements of the main structure.
Weak Story

The strength of the lateral-force-resisting NC
system in any story shall not be less than 80
percent of the strength in an adjacent story,

Some part of thebuildinghas
weak story.

above or below, for Life Safety and
Immediate Occupancy.
Soft Story

The stiffness of the lateral-force-resisting NC
system in any story shall not be less than70 percent of the lateral-force-resistingSome part of thebuilding has softstory.

system stiffness in an .adjacent story above
or below, or less than 80 percent of theaveragelateral-force-resisting

systemstiffness of the three stories above or below
for Life Safety and Immediate Occupancy.
Geometry

There shall be no changes in horizontal NC
dimension of the lateral-force-resisting
system of more than 30 percent in a story
relative to adjacent stories for Life Safety
and Immediate Occupancy, excluding onestory penthouses and mezzanines.

VerticalDiscontinuities

There is morethan 30 percent
change in lateraldimensionoflateralforceresisting systemof building.

All vertical elements in the lateral-force- NC
resisting system shall be continuous to the69March 2016

foundation.
Mass

There shall be no change in effective mass C
more than 50 percent from one story to thenext for Life Safety and Immediate
Occupancy. Light roofs, penthouses, andmezzanines need not be considered.

TorsionThe estimated distance between the story C
center of mass and the story center ofrigidity shall be less than 20 percent of thebuilding width in either plan dimension forLife Safety and Immediate Occupancy.

Deterioration
Of Concrete

There shall be no visible deterioration of C
concrete or reinforcing steel in any of thevertical- or lateral force-resisting elements.

Masonry Units

There shall be no visible deterioration of C
masonry units

Masonry Joints

The mortar shall not be easily scraped C
away from the joints by hand with a metal
tool, and there shall be no areas of erodedmortar.

Unreinforced
Masonry Wall
CracksThere shall be no existing diagonal cracks Cin wall elements greater than 1/8 inch for

Observed crack are
not diagonal.

Life Safety and 1/16 inch for Immediate
Occupancy or out-of-plane offsets in the
bed joint greater than 1/8 inch for Life
Safety and 1/16 inch for Immediate
Occupancy, and shall not form an X
pattern.

LATERAL FORCE RESISTING SYSTEM
Criteria
Redundancy

70

Description of Conditions
Remark Comments
The Building does
The number of lines of shear walls in each NC
principal direction shall be greater than or

not haveequal to 2 for Life Safety and Immediate

redundancy
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Occupancy.
Shear
Check

Stress The shear stress in the unreinforced masonry C
walls, calculated using the Quick Checkprocedure shall be less than the greater of 30
psi for clay units and 70 psi for concrete
units for Life Safety and Immediate
Occupancy.

Wall

Exterior concrete or masonry walls that are NC

Anchorage

dependent on the diaphragm for lateralproperly anchoredsupport shall be anchored for out-of-planewith theforces at each diaphragm level with steel

diaphragms.

Walls are notanchors, reinforcing dowels, or straps thataredeveloped

into

the

diaphragm.

Connections shall have adequate strength toresist the connection force.
Transfer

to Diaphragms shall be connected for transfer NC

Walls aren’t

Shear Wallsof loads to the shear walls for Life Safety

properly connected

and the connections shall be able to develop

to the diaphragms.

the lesser of the shear strength of the walls
or diaphragms for Immediate Occupancy.
Girder/Column There shall be a positive connection N/AConnection????

utilizing plates, connection hardware, or
straps between the girder and the column
support.

Geologic Site Hazards and Foundation Checklist
The following is a geological site hazards and foundations checklist. Each of theevaluation statements on this checklist shall be marked Compliant (C), Non-compliant (NC)or Not Applicable (N/A) for a Tier 1 Evaluation. Compliant statements identify issues that are
acceptable according to the criteria of this standard, while non-compliant statements identify issues
that require further investigation. Certain statements may not apply to the buildings being
evaluated. For non-compliant evaluation statements, the design professional may choose to
conduct further investigation using the corresponding Tier 2 Evaluation procedure; corresponding
section numbers are in parentheses following each evaluation statement.
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Geologic Site Hazards
The following statements are completed as the building is in the high seismicity level.
Criteria

Description of Conditions

Liquefaction

Liquefaction-susceptible,
loose

granularjeopardize

the

soils

Remark Comments
saturated, C
thatbuilding's

could

Liquefaction
susceptible soils do

seismicnotperformance shall not exist in the

exist

in

the

foundation soils.

foundation soils at depths within 50 feetunder the building for Life Safety and
Immediate Occupancy.
Slope Failure

The building site shall be sufficientlyC

The building is on

remote from potential earthquake-arelatively

induced slope failures or rock falls to

site.

flat

be unaffected by such failures or shallbe capable of accommodating any
predicted movements without failure.
Surface Fault

Surface fault rupture and surface

C

Surfacefault

Rupturedisplacement at the building site is

rupture and surface

not anticipated.

displacements are
not anticipated.

Conditions of Foundations
The following statements shall be completed for Tier 1 building evaluation
Criteria
Foundation
Performance

Description of Conditions
RemarkThere shall be no evidence of excessive C
foundation movement such as settlement
or heave that would affect the integrity
or strength of the structure.

Deterioration

There shall not be evidence that C
foundation elements have deteriorated
due to corrosion, sulfate attack, material

Comments
The structure does
not show evidenceof excessive
foundation
movement

No evidences arefoundbreakdown, or other reasons in a mannerthat would affect the integrity or
strength of the structure

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Capacity of Foundation
The following statements shall be completed for Tier 1 building evaluation
Criteria
Pole
Foundations

Description of Conditions
Pole foundations shallRemarka N/Ahave

minimum embedment depth of 4 feet
for

Life

Safetyand

Immediate

Comments
Foundation
embedment depth ismore than 4 feet.

Occupancy.
Overturning

The ratio of horizontal dimension of C

The

the lateral-force-resisting system athorizontal dimension

the foundation level to the buildingof the lateral-force-height (base/height) shall be greater

resisting system atthan 0.6Sa.

the foundation level

ratio

of

to the building height(base/height)

isgreater than 0.6Sa.
Ties between The foundation shall have ties C
Foundation
adequate to resist seismic forces where
Elements
footings, piles, and piers are not

Strip foundation

restrained by beams, slabs, or soils
classified as Class A, B, or C.
DeepFoundations

Piles and piers shall be capable of N/AThe

transferring the lateral forces between

evaluated for Lifethe structure and the soil. This

Safety Performancestatement shall apply to the Immediate

Level.

buildingisOccupancy Performance Level only.
Sloping Sites

The

differenceinfoundation

N/A

The

building

isembedment depth from one side ofevaluated for Lifethe building to another shall not

Safety Performanceexceed one story in height. This

Level.

statement

shall

apply

to

the

Immediate Occupancy Performance
Level only.

73March 2016

Basic Nonstructural Component Checklist
This following is the Basic Nonstructural Component Checklist with relevant clauses. Each of theevaluation statements on this checklist shall be marked Compliant (C), Non-compliant (NC)or Not Applicable (N/A) for a Tier 1 Evaluation. Compliant statements identify issues that are
acceptable according to the criteria of this standard, while non-compliant statements identify issues
that require further investigation. Certain statements may not apply to the buildings being
evaluated. For non-compliant evaluation statements, the design professional may choose to
conduct further investigation using the corresponding Tier 2 Evaluation procedure; corresponding
section numbers are in parentheses following each evaluation statement.
Partitions
Criteria

Description of Conditions

Remark Comments

Unreinforced

Unreinforced masonry or hollow clay tile N/A

The masonry walls

Masonry

partitions shall be braced at spacing equal

are load bearing

to or less than 10 feet in levels of low or

structural elements.

moderate seismicity and 6 feet in levels ofhigh seismicity.
Ceiling System
Criteria

Description of Conditions

Remark Comments

Support

The integrated suspended ceiling system

N/Ashall not be used to laterally support thetops of gypsum board, masonry, or
hollow clay tile partitions. Gypsum
board partitions need not be evaluated
where only the Basic Nonstructural
Component Checklist is required
Lighting Fixture
Criteria

Description of Conditions

Remark Comments

Emergency

Emergency lighting shall be anchored orCLightingbraced to prevent falling during anearthquake.

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Cladding and GlazingCriteria
Cladding
Anchors

Description of Conditions
Cladding components weighing more

RemarkC

Comments

than 10 psf shall be mechanicallyanchored to the exterior wall framing at
a spacing equal to or less than 4 feet. A
spacing of up to 6 feet is permitted
where only the Basic Nonstructural
Component Checklist is required.

Deterioration There shall be no evidence of deterioration, C
damage or corrosion in any of theconnection elements.
Cladding

For moment frame buildings of steel or C

Isolation

concrete, panel connections shall be
detailed to accommodate a story drift ratioof 0.02. Panel connection detailing for astory drift ratio of 0.01 is permitted where
only the Basic Nonstructural Component
Checklist is required.

Multi-Story

For multi-story panels attached at each N/A

Panelsfloor level, panel connections shall be
detailed to accommodate a story drift ratioof 0.02. Panel connection detailing for astory drift of 0.01 is permitted where only
the

Basic

Nonstructural

Component

Checklist is required.
Bearing

Where bearing connections are required, N/A

Connections

there shall be a minimum of two bearing
connections for each wall panel.

Inserts

Where

insets

are

used

in

concrete N/Aconnections, the inserts shall be anchored toreinforcing

steel

or

other

positiveanchorage.
Panel

Exterior cladding panels shall be anchored C

Connections

out-of- plane with a minimum of 475

March 2016

connections for each wall panel. Twoconnections per wall panel are permitted
where

only

the

Basic

Nonstructural

Component Checklist is required.

Masonry Veneer
There is no masonry veneer; statements in this section are Not Applicable (N/A).
Parapets, Cornices, Ornamentation, and Appendages
Criteria

Description of Conditions

Remark Comments

URM Parapets There shall be no laterally unsupported C
unreinforced masonry parapets or cornices
with height-to-thickness ratios greater than
1.5. A height- to-thickness ratio of up to 2.5
is permitted where only the Basic
Nonstructural Component Checklist isrequired.
Canopies

Canopies located at building exits shall be N/Aanchored to the structural framing at a
spacing of 6 feet or less. An anchorage
spacing of up to 10 feet is permitted where
only the Basic Nonstructural Component
Checklist is required
Masonry Chimneys

There is no masonry chimney; statement in this section is Not Applicable (N/A).
StairsCriteria

Description of Conditions

Remark Comments

URM Walls

Walls around stair enclosures shall not C
consist of unbraced hollow clay tile or
unreinforced masonry with a height-tothickness ratio greater than 12-to-1. A
height-to-thickness ratio of up to 15-to-1 is76

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permitted

where

only

the

Basic

Nonstructural Component Checklist isrequired.
Stair Details

In moment frame structures, theN/Aconnection between the stairs and thestructure shall not rely on shallow anchorsin concrete. Alternatively, the stair details
shall be capable of accommodating thedrift calculated using the Quick Checkprocedure of Section 3.5.3.1 without
including tension in the anchors.
Building Contents and FurnishingCriteria

Description of Conditions

RemarkComments

Tall Narrow Contents over 4 feet in height with a height- C
Contents

to- depth or height-to-width ratio greaterthan 3- to-l shall be anchored to the floorslab or adjacent structural walls. A heightto-depth or height-to-width ratio of up to 4to-l is permitted where only the Basic
Nonstructural Component Checklist isrequired

Mechanical and Electrical Equipment
Criteria

Description of Conditions

Remark Comments

Emergency

Equipment used as part of an emergency C

Powerpower system shall be mounted to maintaincontinued operation after an earthquake.

Hazardous

HVAC or other equipment containing C

Material

hazardous material shall not have damaged

Equipment

supply lines or unbraced isolation supports.

Deterioration

There shall be no evidence of deterioration, C
damage, or corrosion in any of theanchorage or supports of mechanical or77March 2016

electrical equipment.
Attached

Equipment weighing over 20 lb that is

Equipment

attached to ceilings, walls, or otherC

supports 4 feet above the floor level shallbe braced.

PipingCriteria

Description of Conditions

Remark Comments

FireFire suppression piping shall be anchored C

Suppression

and braced in accordance with NFPA-13

Piping(NFPA, 1996)

Flexible

Fluid, gas, and fire suppression piping shall NC

Fluid and gas piping

Couplings

have flexible couplings

does not haveflexible couplings.

Hazardous Materials Storage and Distribution
Criteria

Description of Conditions

Remark Comments

Toxic

Toxic and hazardous substances stored in N/A

Substances

breakable containers shall be restrained
firm falling by latched doors, shelf lips,
wires, or other methods.

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4.2 Ferroscan
Though the Old Academic Building of BUET is basically masonry but it has columns in various
positions in similar pattern of RC column. That why the Ferroscan test was performed to check if
there’s any reinforcement present in the column. The line scan has confirmed that few columns havesteel channel inside the masonry column.

Figure 25: Line scan operation of masonry column of OAB, BUET

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4.4 Ultrasonic Pulse Velocity (UPV)
Using the UPV the depth of the cracks were measured which have given belowTest point 01:
Point
Location
t1 (µs)t2 (µs)Depth (mm)Type of Crack
Crack Width(mm)
Comments
Crack Image

80

01
Slab
88.90
161.4052 mm
Linear Crack
0.45 mm

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Test point 02:
Point
Location
t1 (µs)t2 (µs)

02
Slab
91.90
158.40Depth (mm)Type of Crack
Crack Width (mm)Comments
Crack Image

57 mm
Linear Crack
0.51 mm81

March 2016

4.5 Moisture Content Analysis of OAB building
Figure 26, Figure 27, Figure 28, Figure 29, and Figure 30 show the moisture content in different
portions of OAB building.

Figure 26: Damped arch at the back of OAB building

Figure 27: Damped wall in OAB building82

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Figure 28: Possible leakage in OAB building

Figure 29: Damped wall in OAB building83March 2016

Figure 30: Damped wall OAB building
4.6 Direct Shear Test
As the Old Academic Building, BUET has to be retrofitted, the direct shear test was required tomeasure the shear stress due to mortar bond only. Destructive test has been performed using HiForce Hydraulic Jack. The result has given below. Figure 31 shows application of Direct Shear Test.
Direct Shear Test of Masonry
Jack diameter

35

mm

Area

962.12
Length
25477419.2
P (bar)
190

mm^2
Width
114.3

Height76.2

Force (N)18280.19

Shear Stress N/mm^20.236119528

Brick Size
Contact Area
Dial Gauge Reading
Shear Strength of the Sample, τNos. of bricks above testing brick
Height of wall above testing brick
Unit weight of wall
Vertical Pre-stress on testing brick, σσ* μShear Stress due to mortar bond only

84

0.236121009.15
19173.850.17385τ-σ* μ0.06227mm

N/mm^2m
KN/m^3
KN/mm^2

N/mm^2

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Figure 31: Application of Direct Shear test
5. Conclusions
The building has recommended for retrofitting after observing and analyzing all Destructive and Nondestructive test results. The proposed design of retrofitting has been presented below:

85March 2016

Figure 32: Vertical wall section for retrofitting

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Figure 33: Vertical cross section of wall for retrofitting

87March 2016

Figure 34: Typical section of slab for retrofitting

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Figure 35: Recommended retrofitted column layout

89March 2016

Figure 36: Typical section of column with retrofitted

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REFERENCES
ASCE-SEI 41-13: Seismic Evaluation and Retrofit of Existing Buildings

Assessing Housing Durability: A Pilot Study. (2001). U.S. Department of Housing and Urban
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Crandell, J.H. (2003). Exterior Insulation Finish Systems (EIFS): Lessons Learned, Advancements,

and Challenges. Prepared for Institute for Business and Home Safety (IBHS), Tampa, FL.
Crandell, J.H., & Kenney, T.M. (1996). Investigation of Moisture Damage in Single-Family DetachedHouses Sided with Exterior Insulation Finish Systems in Wilmington, NC, 2nd Edition, NAHB
Research Center, Inc., Upper Marlboro, MD, January 1996.
Crandell, J.H. (1996). Investigation of Moisture Damage in Insulating Concrete Form Homes Sided

with Exterior Insulation Finish Systems in Eugene, Oregon. Portland Cement Association, Skokie, IL.
Chouinard, K.L., & Lawton, M.D. (n.d.). Rotting Wood Framed Apartments – Not Just a Vancouver

Problem. Morrison Hershfield Limited, Canada
Colantonio, A. (2008). Detection of Moisture and Water Intrusion within Building Envelopes By

Means of Infrared Thermographic Inspections. Presented at Building Enclosure Science &Technology (BEST1) Conference, 1 April.

Comparative Analysis of Residential Construction in Seattle, WA and Vancouver, B.C. (1999).
Technical Series 99-111, CMHC, Ottawa, Canada.
Dacquisto, D. J., Jay H. Crandell, J. H., & Lyons, J. (2004). Building Moisture and Durability: Past,

Present and Future Work. Newport Partners, LLC Davidsonville, Maryland.
Dewan, A. M., Islam, M. M., Kumamoto, T., & Nishigaki, M. (2007). Evaluating flood hazard forland-use planning in Greater Dhaka of Bangladesh using remote sensing and GIS techniques. Water

Resources Management, 21(9), 1601-1612.
Dewan, A. M., & Yamaguchi, Y. (2009). Land use and land cover change in Greater Dhaka,Bangladesh: Using remote sensing to promote sustainable urbanization. Applied Geography, 29(3),390-401.
Earthquake Tip- Indian Institute of Technology Kanpur, BMTPC
FLIR. (2011a). Thermal Imaging Guidebook for Building and Renewable Energy Applications. FLIR
Systems AB.
FLIR. (2011b). Thermal Imaging Guidebook for Industrial Applications. FLIR Systems AB.
FLUKE. (n.d.). Moisture in Building Envelopes. Retrieved on 14 November 2015, from:http://www.fluke.com/fluke/chde/losungen/warmebildkamera/thermal-imaging-moisture-in-buildingenvelopes
Holland, J. (2008). Infrared or Thermal Imaging Cameras - Finding Moisture Using Infrared Light.
Cleaning Industry Research Institute (CIRI).
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Hopkins, P. (2011a). Chasing water with thermal imaging. InfraMation 2011 Proceedings, Infrared
Training Center.
Hopkins, P. (2011b). Demystifying the Art and Science of Finding Moisture in Buildings Using
ThermalImaging.

Retrievedon

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2015,

from:

http://www.unitedinfrared.com/files/2_1_2011_hopkins.pdf
Marshall Macklin Monaghan Limited. (1983). Moisture Induced Problems in NHA Housing: 3 Parts.
Canada Mortgage and Housing Corporation, Cat. No. NH20-1/2-1983-IE, ISBN 0-662-12662, Ottawa.
May, J.C. (1991). Moisture Problems: From Case Studies and Home Inspections. Proceedings of Bugs,

Mold, and Rot I, BETEC, BSSC, Washington, DC.
NZSEE 2006NZSEE Bulletin 39(2)-June 2006
Rahman, M.S., Islam, B. and Ansary, M. A.. (2010), “Diagnosis of the Seismic Vulnerability of
Buildings at Dhaka using Non-Destructive Testing”, 9th proceedings of New Technologies for Urban
Safety of Mega Cities in Asia, Kobe, Japan.
Reitherman, Robert (2012). Earthquakes and Engineers: An International History. Reston, VA: ASCE
Press.
Rosina, E., & Ludwig, N. (1999, September). Optimal thermographic procedures for moisture analysis
in building materials. In Industrial Lasers and Inspection (EUROPTO Series), pp. 22-33. International
Society for Optics and Photonics.

Survey of Building Envelope Failures in the Coastal Climate of British Columbia. (1998). Technical
Series 98-102, CMHC, Ottawa, Ontario, Canada.
Tsongas, G.A., Govan, D.P., & McGillis, J.A. (1998). Field observations and laboratory tests of water

migration in walls with shiplap hardboard siding. Thermal Performance of the Exterior Envelopes of
Buildings VII, Clearwater Beach, FL.

Wall Moisture Problems in Alberta Dwellings. (2000). Technical Series 00-112, CMHC, Ottawa,
Canada.

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PART-V

FIRE INCIDENT IN READY-MADE GARMENTFACTORY ‘DIGNITY TEXTILE LIMITED’,GAZIPUR ON 31 MAY, 2015

BANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Uttama Barua
Mehedi Ahmed AnsaryMarch 2016

On 31 May 2015 Sunday at around 1:45pm a fire broke out at a ready-made garment factory ‘Dignity
Textile Limited’ Betjuri area of Sreepur upazila of Gazipur. The fire was originated at the warehouseon the third floor of the seven-storey factory building and engulfed the whole floor. It is a complete
composite factory owned by Deel Hue, a Mauritius citizen, where some 3000 workers were working
in different units included knitting, dyeing, cutting and finishing section. The fire was sensed when thesmoke began to pour through the window of the warehouse in the south of the third floor.
On information, 14 units of firefighters from Tongi, Mawna, Joydebpur, Kaliakoir and Bhaluka of
Mymensingh rushed to the spot. The building is made of metals like iron and steel. So the efforts todouse the fire using water were not working accordingly. The firefighters were also facing difficulties
as they could not go near the building due to excessive heat and the boundary wall was too strong to
be bulldozed. The fire was finally brought under control after twenty hours of frantic efforts at around9.30am on the next morning.

Figure 1: Before and after scenario of the RMG factory building, Gazipur
The cause of the fire and extent of damage could not be known immediately. It was initially suspectedthat the fire originated from an electric short circuit. There were flammable products on all floors
which resulted in rapid spread of fire in the building. There were modern and sufficient fire
extinguishing systems available in the factory building, but they lacked trained persons for the purpose.
As a result immediate actions to douse fire could not be taken. Moreover the fire fighters did not haveany experience to douse fire in metal structured building. This kind of metal structured building require
concrete jacketing, fire proof painting and other preventive measures as metals become heated andthus melts rapidly. In case of this factory building, these measures were absent which resulted in greater
consequence due to fire.
Huge amount of thread, cotton, clothes and others equipments were gutted in the fire. Administrative
Manager of the factory said that the machines and other equipments on the third floor were completely
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burnt in the fire. The extreme heat, generated by prolonged fire, melted the steel-frame of the building,triggering its collapse at 11:00am. The blaze gutted most parts of the factory building. Some people
sustained minor injuries but no worker was reported to be killed in the incident as all 3,000 workers offactory were out at lunch hours when the fire broke out.

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PART-VI
DISTRICT WISE MULTI-HAZARD ZOANING OFBANGLADESHBANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Uttama Barua
M. Shammi Akhtar
Mehedi Ahmed AnsaryMarch 2016
1. Introduction
Bangladesh is a developing country with numerous problems like overpopulation, poverty, complex socio economic
structure, low level industrial base, and resource constrains, lack of appropriate infrastructural and institutional facilities,
dearth of trained manpower, etc. These problems are complicated and compounded with the occurrences of regular andfrequent disasters impeding the overall socio-economic development efforts of the country (Haque 1997). The geographicalsetting of Bangladesh makes the country vulnerable to natural hazards (Karim and Mimura 2008). Major factors responsible
for natural hazards in Bangladesh are flat topography, heavy monsoon rainfall, rapid run-off and drainage congestion,
enormous discharge of sediments, low relief of the floods plains, low river gradients, funnel shaped and shallow Bay of
Bengal etc. The mountains and hills bordering almost three-fourths of the country, along with the funnel shaped Bay of
Bengal in the south, not only make the country a meeting place of life-giving monsoon rains, but also make it subject tothe catastrophic ravages of natural hazards. Its physiography, river morphology, abnormal rainfall condition, andearthquakes in the adjacent Himalayan range also contribute to recurring disasters. For all these conditions Bangladesh isstated as one of the most natural disaster prone countries in the world (Choudhury 2002; Karim and Mimura 2008; Ali,
Rahman and Chowdhury 2012).
Natural hazards become disasters when they intersect with the human environment. In Bangladesh, historical natural
disasters have left a profound imprint causing devastating loss of life, property, economy and community. From historicalevidences it can be observed that, different types of disasters like flood, cyclonic storm, tidal surge, drought, tornado,riverbank erosion, earthquake, etc. occur in Bangladesh regularly and frequently causing devastating consequences (Karim
1995). The 1988 flood killed 1517 people and nearly half of the population were affected (Hossain 2004). The 1970 cyclone
killed almost 500,000 people (Karim 1996). About 1300 people were killed by tornado at Saturia of Manikganj district inBangladesh in 1989 (EIA, 2004). The 1897 Great Indian Earthquake with a magnitude of 8.7 killed 1542 people andaffected almost the whole of Bangladesh, which is one of the strongest earthquakes in the world (Oldham 1899). Drought
is a recurrent phenomenon in some parts of Bangladesh, which leaves a permanent damage, i.e. damages agricultural
production and encourages the desertification process that is going on in some parts of North Bengal (Shahid and Behrawan2008). River erosion takes away thousands of hectares of land every year in the country resulting in displacement of huge
number of people (Mutton and Haque 2004). Depending upon their potential to cause damage to human life and property,
these natural calamities may be broadly grouped into major and minor types. Natural hazards like earthquake, drought,
flood, tornado and cyclone can be regarded as major for their greater impact, whereas, landslide, riverbank erosion,
groundwater contamination, fire, tsunami etc. can be categorized as minor hazards, whose impacts are localized andintensity of the damages are much less. Thus, based on historical occurrences and potential damage of these hazards in
Bangladesh, tornado, flood, earthquake, and cyclone are considered as focused hazards.
Total elimination of risks is difficult and impractical. So disaster management through proper hazard assessment is very
essential to reduce loss of lives and sufferings of people. UNISDR (2007) defined hazard as “…..A dangerous phenomenon,
substance, human activity or condition that may cause loss of life, injury or other health impacts, property damage, loss of
livelihoods and services, social and economic disruption, or environmental damage…..” . According to UNISDR (2007),
quantitatively hazards in different areas are determined by “the likely frequency of occurrence of different intensities as
determined from historical data or scientific analysis”. So hazard scores can be calculated for identifying hazards throughconsideration of historical disaster data and their potential damage levels (Granger and Trevor 2000; Munich Reinsurance
Company 2003; Bell and Glade 2004; UNDP 2004; Lavalle et al. 2005; Dilley 2005; Khatsu and Westen 2005; Schmidt-

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Thomé 2006; Thierry et al. 2008; Kunz and Hurni 2008; SCEMDOAG 2009; Wipulanusat et al. 2009; Shi 2011; Siddiqueand Schwarz 2015).Thus, the first step for hazard assessment is the identification of hazards along with their intensity andtheir potential damage levels through analysis of historical data for evaluation of disaster condition. Here intensity refers
to the damage generating attribute of a hazard (Deyle et al. 1998). Intensity scales represent the damage severity of disasters,
which are subjective and dependent upon social condition and construction status of a country along with regional effects.
Intensity scales are important and informative for decision makers as the scales give them ideas about the level of disasterand their magnitude of damage at a glance.
In any disaster management programme, the first and the foremost task is to identify the areas where hazards are probableto occur at disastrous magnitude (Cutter et al., 2000). Hazard maps provide clear and attractive pictures of the geographic
distribution of potential hazards which play a key role in disaster risk identification (Tran et al., 2009). Some literatures
focused on development of hazard specific zoning maps, i.e. flood (Büchele et al. 2006; Fuchs et al. 2009; Maantay andMaroko 2009; Meyer, Scheuer and Haase 2009; Tran et al. 2009; Pradhan 2010; Porter and Demeritt 2012), earthquake(Anbazhagan et al. 2010), and landslide (Abella and Westen 2007; Pourghasemi, Pradhan and Gokceoglu 2012;
Pourghasemi et al. 2012; Xu et al. 2012; Tremblay, Svahn and Lundström 2013). Use of historical data in preparation of
hazard specific zoning maps is the most common method in these literatures (Büchele et al. 2006; Abella and Westen 2007;
Fuchs et al. 2009; Maantay and Maroko 2009; Meyer, Scheuer and Haase 2009; Tran et al. 2009; Anbazhagan et al. 2010;
Pradhan 2010; Pourghasemi, Pradhan and Gokceoglu 2012). Some literatures adopted probabilistic analysis (Meyer,
Scheuer and Haase 2009; Xu et al. 2012; Tremblay, Svahn and Lundström 2013) or statistical analysis (Fuchs et al. 2009)or both (Büchele et al. 2006; Pradhan 2010) to analyze different dataset and criteria. Some of the literatures utilized
Geographic Information System (GIS) based methodology for preparation of hazard map (Büchele et al. 2006; Abella andWesten 2007; Meyer, Scheuer and Haase 2009; Tran et al. 2009; Anbazhagan et al. 2010; Pradhan 2010; Pourghasemi etal. 2012; Xu et al. 2012).
Although, some countries or regions may be highly vulnerable to specific hazard, but consideration of one hazard at a time
is not sufficient for the purpose of disaster management. Multi-hazard zoning maps identify the vulnerable areas for
multiple hazards considering their threat levels, which is important to aid and orient the authorities’ decisions regarding
hazard mitigation and preparedness (Thierry et al. 2008; Mahendra et al. 2011). Thus, multi-hazard zoning maps arepractical tools in disaster management, which give a good indication on the extent of expected hazardous areas for overall
natural disaster. The importance of addressing hazards collectively is now recognized in several literatures (Liu et al. 2014).
According to Liu et al. (2014), two approaches exist to assess multiple-hazards, e.g. the index or scoring method and themathematical statistics method. The index or scoring method identifies hazards and their potential damage levels (Granger
and Trevor 2000; Munich Reinsurance Company 2003; Bell and Glade 2004; UNDP 2004; Lavalle et al. 2005; Dilley
2005; Khatsu and Westen 2005; Schmidt-Thomé 2006; Thierry et al. 2008; Kunz and Hurni 2008; SCEMDOAG 2009;
Wipulanusat et al. 2009; Shi 2011; Siddique and Schwarz 2015). The mathematical statistics method integrates
observations of past losses attributed to each hazard type (FEMA 2004; Grünthal et al. 2006; Westen 2008; Mahendra etal. 2011; Schmidt et al. 2011; Linares-Rivas 2012; Frolova et al. 2012; Liu et al. 2013). Thus, the task of multi-hazard
assessment is dependent on the country’s past disaster records and their characteristics.
In Bangladesh, studies for multiple-hazard assessment have not been done so far in Bangladesh. Moreover, there are no
existences of individual hazard intensity scales to identify the characteristics of particular hazards. The zoning maps forsome individual hazards are available for Bangladesh, but historical database for different hazards are not well organized.
To make the information readily available to the planners, administrators and disaster managers, it is necessary to prepare99March 2016
multi-hazard map on larger scale (district-wise) for easy identification of the vulnerable districts. In this background, themain aim of this paper is the preparation of district wise multi-hazard zoning map for Bangladesh. To achieve this aim, theobjectives of this paper are: firstly to organize the historical database for four major hazards in Bangladesh, i.e. tornado,
flood, earthquake, and cyclone; secondly to propose suitable intensity scales and damage risk levels for those four major
hazards; and finally to calculate district wise individual and multi-hazard scores based on historical data, intensity scales
and damage risk levels to produce a district wise multi-hazard zoning map for whole Bangladesh presenting the relative
estimate of multiple hazards. This study is done integrating scoring and mathematical statistics methods, where hazards
scores are calculated based on historical database. The map will assist decision makers to determine areas susceptible toindividual hazards or multiple hazards and take initiatives accordingly.
2. Methodology of the Study
Every community has unique or unusual hazards that need to be considered. So, for preparation of multi-hazard map ofBangladesh for four natural disasters, i.e. cyclone, tornado, flood and earthquake, were considered based on the disaster
context of Bangladesh and their potential damage. Steps followed for the purpose of preparation of multi-hazard zoning
map of Bangladesh were: organization of the historical database, development of intensity scales and damage risk levels,
calculation of district wise individual and multi hazard scores, and preparation of district wise multi-hazard zoning map ofBangladesh. These steps are described in details below:
2.1. Organization of the Historical Database
The available historical database of the four hazards in Bangladesh were collected and compiled from different secondary
sources. The secondary data sources were: Bangladesh Meteorological Department (BMD), Bangladesh Space Research& Remote Sensing Organization (SPARRSO), Disaster Management Bureau (DMB) and concerned non-governmentorganizations (NGO), Cyclone Preparedness Programme (CPP), and geological information from the Geological Surveyof Bangladesh (GSB). Moreover, information from local and environmental organizations, international journals, local
newspapers and many study reports were collected. Frequency is the occurrence of a disaster in a particular area, which
was defined based on the organized historical database of hazards in Bangladesh.
2.2. Development of Intensity Scales and Damage Risk Levels
Comparing scenarios of four hazards in Bangladesh and their corresponding scales all over the world, suitable intensity
scales and their corresponding damage risk levels were proposed for four major hazards in Bangladesh for district wise
hazard assessment in Bangladesh. For the purpose of decision making in this regard considering experts’ opinion, key
informant interviews were carried out.
2.3. Calculation of District Wise Hazard Scores
Hazard specific zoning maps considering disaster levels or intensities are suitable to represent district wise scenario of
Bangladesh for particular hazard. But consideration of historical occurrences, i.e. frequency of that particular hazard, alongwith intensity provides true representation of hazard scenario. So, district wise hazard scores for four major hazards in
Bangladesh were calculated by multiplying district wise hazard factors and weighting factors for particular hazards which
represent the hazard scenario considering disaster context. Hazard factors for particular hazard in particular district were
defined comparing district wise historical disaster database with corresponding intensity scales and damage risk levels.

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Hazard factors were defined on the scale from one to five, where one was assigned for zones with no hazards and five was
assigned for high risk zones. It was decided in consultation with the experts from relative fields through key informant
interview. Weighting factors for particular hazards in particular district were defined based on frequency of particulardisasters in different districts of Bangladesh. This was done through relative priority scoring system (higher scores forhigher hazard prone areas), where the base point is considered 1.0 for locations with no occurrence of a disaster and increasein frequency of disasters adds a point, i.e. 0.1 (NOAA 2007). For the purpose of decision making regarding weighting
factors, key informant interviews were carried out. Thus, for calculation of district wise hazard scores for individual hazards,
equation (1) was followed.
TH (c/ f/ t/ e) = WT × H(1)

Where,TH (c/ f/ t/ e) = Hazard score of a particular district (for particular hazard e.g. Cyclone(c)/ Flood (f)/ Tornado (t)/Earthquake (e))
H

= Hazard factor

WT= Weighting factor = f (fr)fr = frequency of particular disaster2.4. Preparation of District Wise Multi-Hazard Zoning Map of Bangladesh
After calculation of district wise scores for four individual hazards in Bangladesh, combined hazard scores were calculatedusing equation (2).
�� � � ∑���� ���

Where,
TH= Total hazard score of a particular district

THk= Hazard score of a particular district for individual hazard(2)

k= 1 is for Cyclone
k=2 is for Tornado
k=3 is for Earthquake
k=4 is for FloodTo prepare a multi-hazard zoning map of Bangladesh, the district wise multi-hazard scores were categorized into threegroups to classify the districts of Bangladesh into three multi-hazard zones, i.e. high, moderate and low. The classificationof combined multi-hazard scores was done through equal interval classification method in consultation with experts from101

March 2016
related fields through key informant interview. Then, districts corresponding to each hazard zones were classified
accordingly.
3. Results and Discussion
3.1. Historical Database of Major Disasters in Bangladesh
Disaster Management Bureau (DMB) prepared a map identifying the areas affected by Tornadoes, where the basis of the
map is not clear (DMB 1993). Moreover, data on district wise wind speeds during different tornados occurred in
Bangladesh are not available. So, frequency of tornado is considered in this study for hazard assessment. Frequency of
tornado in different districts of Bangladesh were organized based on the historical database of tornado from 1875-2007.
Table 1 shows frequency of tornado in different districts of Bangladesh. Here maximum frequency is eight representingthat the districts have been affected by tornado eight times within the time frame, and minimum is zero representing thatthe districts were not affected by tornado within the time frame.
In the history of flood in Bangladesh, the 1998 flood is the extreme. Thus, 1998 flood map prepared by Flood Forecasting& Warning Centre (FFWC) and Bangladesh Water Development Board (BWDB), is used as a reference in this study(FFWC 1998). In the map the districts of Bangladesh are divided in four zones based on water level, i.e. severe flooding
area (above 50cm above DL), moderate flooding area (up to 50cm above DL), normal flooding area (within 50cm DL) andnon flooding area (below 50cm DL). Again, data of seven years’ historical floods, i.e. 1955, 1974, 1987, 1988, 1991, 1998
and 2004, of Bangladesh are considered for calculation of district wise flood frequency in Bangladesh. From the flood
maps of 1955, 1974, 1987, 1988, 1991, 1998 and 2004 of Bangladesh, and from different data source (BWDB 1987 &
1991; WFP 2004; FFWC 2007), the flood affected area of different districts of Bangladesh of seven flood year are
calculated (Islam & Sado 2000). Based on the calculated flood affected area of different districts, frequencies or
occurrences of flood in corresponding districts of Bangladesh are determined in this study. Table 1 shows district wise
flooding area zones based on water level data and frequency of flood occurrences in Bangladesh. Here maximum frequency
is seven representing that the districts have been affected by flood during all of the seven flood events, and minimum iszero representing that the districts were not affected by floods during any of the seven flood events considered in this study.
Ansary and Sharfuddin (2001) proposed a seismic-zoning map for Bangladesh, where the districts of Bangladesh are
divided into three zones based on Peak Ground Acceleration (PGA), i.e. zone 1 (0.075g), zone 2 (0.15g), and zone 3 (0.25g).
Table 1 shows district wise earthquake zones based on PGA and frequency of earthquake (with earthquake magnitude
greater than 5 Mw) in Bangladesh.
The cyclone map of Bangladesh prepared by SPARRSO in 1993 is considered as the basis of hazard assessment in thisstudy, where the districts of Bangladesh are grouped into three zones based on height of storm surge, i.e. high risk area(above 1m), high wind area (storm surge buffer), and non affected area (SPARSO, 1993). The maximum extent of thehazard does not realistically include the entire country and is limited to proximity to coastal waters. Frequency of cyclone
in different districts of Bangladesh are calculated based on the historical database of cyclone from 1584-2004. Table 1
shows district wise cyclone zones based on height of storm surge and frequency of cyclone in Bangladesh.
3.2. Intensity Scales and Damage Risk Levels for Major Disasters

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In Bangladesh no tornado scale exists. Again, though damage risk due to tornado depends on wind speed (Fujita 1978),data on district wise wind speeds during different tornados occurred in Bangladesh are not available. So, frequency of
tornado is considered in this study for hazard assessment. Thus, intensity scales and damage risk levels depending on windspeed are not considered for tornado hazard assessment in this study.
In this study, 1998 flood map prepared by FFWC and BWDB based on water level is used for hazard assessment. So, in
this study it is considered that intensity of flood depends on flood level, i.e. water level during flood. Again, detailedbuilding damage reports for flooding have not recorded so far in Bangladesh. So, flood intensity scale with damage risk
for Bangladesh is prepared comparing the 1998 flood map and the Vulnerability Atlas of India developed by the BMPTC(1997), based on understanding of material behavior under submergence. Table 2 shows flood intensity scale withcorresponding damage risk for Bangladesh.
Earthquakes are measured in terms of their magnitude and intensity. Magnitude is measured using the Richter scale, an
open-ended logarithmic scale that describes the energy release of an earthquake through a measure of shock wave amplitude.
There are several scales available for measuring earthquake intensity, i.e. Modified Mercalli Intensity (MMI) Scale (12level scale), Japanese seismic intensity Scale (0-VII levels), MSK 1964, EMS 1998 (updated scale of MSK scale), etc.
Among these, MMI Scale is considered suitable for Bangladesh. Table 3 shows MMI scale for earthquake. For Bangladesh,
Ansary and Sharfuddin (2001) proposed a seismic-zoning map based on Peak Ground Acceleration (PGA). The PGA, i.e.,
maximum acceleration experienced by the ground during shaking, is one way of quantifying the severity of the groundshaking. To translate PGAs in terms of MMI scale, the approximate empirical correlations between the MMI and the PGA
is considered in this study which is explained in Table 4 (Bolt 1993).
Cyclone map of Bangladesh based on height of storm surge prepared by SPARRSO in 1993 is considered for hazard
assessment in this study. So, in this study it is considered that intensity of cyclone depends on storm surge. Debsarma’s
Storm Surge Forecast (SSF) model predicts highest storm surge based on Reid (1956) and Breitschneider (1966) empiricalformula utilizing maximum expected wind speed, Expected Central Pressure (ECP) of the cyclone, point of intersection of
the storm track and 200m bathymetric contour (Debsarma, 1993, 1995a & 1995b). Again, Saffir-Simpson Hurricane Scaleis a 1-5 rating scale based on a hurricane's present intensity, which is used to give an estimate of the potential property
damage and flooding expected along the coast from a hurricane landfall. Thus, to develop cyclone intensity scale for
Bangladesh, firstly highest storm surges were predicted for Chittagong, Cox’s Bazar, Kutubdia, Sandwip, Hatia, andKhulna utilizing Debsarma’s Storm Surge Forecast (SSF) model. The storm surge height obtained in the model is valid forthe shoreline, which will decay as the surge advances into the coastal localities. Then comparing Saffir Simpson Hurricane
Scale with the predicted highest storm surges, a cyclone intensity scale for Bangladesh is proposed (Table 5). Again basedon intensity, damage risk levels were required to be defined for Bangladesh from previous damage study, which could not
be done in this study for limitation of data. So Saffir-Simpson Hurricane Scale is adopted for Bangladesh with somemodification suggested by experts based on cyclone damage data of 1991 (LGEB 1991). Table 5 shows cyclone intensity
scale and damage risk levels for Bangladesh.
3.2 District Wise Scores for Individual Hazards in Bangladesh
3.2.1 District Wise Tornado Scores
Considering available database, hazard factors and weighting factors were decided based on the frequency or number ofoccurrence of tornado (Table 1). Tornado may always have damaging consequences for all the tornado prone areas. So,

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hazard factor is considered “five” for all districts which have been affected by tornado at least once, and “one” for the
districts with no occurrence of tornado. Then, weighting factors are defined for corresponding frequency classes. Herehighest frequency of tornado events is “eight”, so highest weighting factor is considered “1.8”. Table 6 shows frequency
or number of occurrence of tornado and their corresponding hazard factors and weighting factors. Thus district wise tornado
hazard factors and weighting factors are assigned considering corresponding frequency or number of occurrence of tornado(Table 1) based on Table 6.
Combining corresponding tornado hazard factors and weighting factors using equation (3), tornado hazard scores for all
districts of Bangladesh are calculated (Table 13).
Tornado Hazard Factor, Ht = f (fr)andTornado Weighting Factor, WTt = f (fr)
Where,
fr = Frequency.
Tornado hazard score of a district, THt = Ht × WTt(3)

3.2.2 District Wise Flood Scores
Considering the flood intensity scale and damage risk levels (Table 2), flood hazard factors are defined for corresponding
flood zones in Bangladesh. Table 7 shows flood zones and their corresponding hazard factors. Then, weighting factors aredefined for corresponding frequency classes. Here highest frequency of flood events is “seven”, so highest weighting factor
is considered “1.7”. Table 8 shows frequency or number of occurrence of floods and their corresponding weighting factors.
Thus district wise flood hazard factors and weighting factors are assigned considering corresponding flooding area zones,
and frequencies or number of occurrence of floods (Table 1) based on Table 7 and Table 8.
Combining corresponding flood hazard factors and weighting factors using equation (4), flood hazard scores for all districtsof Bangladesh are calculated (Table 13).
Flood Hazard Factor, Hf = f (fz)
Where,
fz= Flood zone
Flood Weighting Factor, WTf = f (fr)
Where,
fr = Frequency

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Flood hazard score of a district, THf = Hf × WTf(4)

3.2.3 District Wise Earthquake ScoresComparing the seismic zones according to the seismic-zoning map for Bangladesh proposed by Ansary and Sharfuddin(2001), with MMI seismic intensity scale (Table 4), corresponding intensities are defined. Considering the intensities andtheir damage risk levels (Table 3), earthquake hazard factors are defined for corresponding seismic zones in Bangladesh.
Table 9 shows seismic zones and their corresponding hazard factors. Then, weighting factors are defined for corresponding
frequency classes. Here highest frequency of earthquake events is “21”. So the frequencies are classified through equalinterval classification, where the interval is considered three. It is decided in consultation with experts through key
informant interview. Thus, highest weighting factor is considered “1.7”. Table 10 shows frequency or number of occurrenceof earthquakes (with magnitude greater than 5 Mw) and their corresponding weighting factors. Thus district wise
earthquake hazard factors and weighting factors are assigned considering corresponding seismic zones and frequencies(Table 1) based on Table 9 and Table 10.
Combining corresponding earthquake hazard factors and weighting factors using equation (5), earthquake hazard scoresfor all districts of Bangladesh are calculated (Table 13).
Earthquake Hazard Factor, He = f (sz)
Where,
sz = Seismic zone
Earthquake Weighting Factor WTe = f (fr)
Where,
fr = Frequency
Earthquake hazard score of a district, THe= He × WTe(5)

3.2.4 District Wise Cyclone Scores
Considering the cyclone zones with cyclone intensity scale and damage risk levels for Bangladesh (Table 5), hazard factors
are defined for corresponding zones. From the cyclone intensity scale and damage risk levels for Bangladesh (Table 5), it
can be observed that, storm surges with height greater than one meter are categorized into different intensity levels whichcause different levels of damage in the affected areas. Again, the areas affected by storm surges with height below one
meter are also risk prone areas for cyclone. Thus, hazard factor is considered “five” for the cyclone surge high risk and risk
areas for their high risk, “two” for the high wind areas for their lower risk, and “one” for the locations with no considerationof risk for cyclone (Table 11). Table 11 shows cyclone zones and their corresponding hazard factors. Then, weighting
factors are defined for corresponding frequency classes. Here highest frequency of cyclone events is “32”. So thefrequencies are classified through equal interval classification, where the interval is considered four. It is decided in

105March 2016
consultation with experts through key informant interview. Thus, highest weighting factor is considered “1.8”. Table 12shows frequency or number of occurrence of cyclone and their corresponding weighting factors. Thus district wise cyclone
hazard factors and weighting factors are assigned considering corresponding cyclone zones and frequencies (Table 1) basedon Table 11 and Table 12.
Combining corresponding cyclone hazard factors and weighting factors using equation (6), cyclone hazard scores for all
districts of Bangladesh are calculated (Table 13).
For Cyclone:
Cyclone Hazard Factor, Hc = f (cz)Where,
cz= Cyclone zone
Cyclone Weighting Factor, WTc = f (fr)
Where,
fr = Frequency
Cyclone risk score of a district, THc = Hc × WTc(6)

3.3 Multi-Hazard Risk Map of Bangladesh
Total multi-hazard scores for each of 64 districts are estimated by adding corresponding hazard scores for four individual
hazards (tornado, cyclone, earthquake, and flood). Table 13 summarizes district wise individual hazard scores for tornado,
cyclone, flood earthquake, and flood, as well as the combined multi-hazard scores. Table 14 shows an example illustrating
the calculation of individual hazard scores for individual hazards, as well as the combined multi-hazard scores for“Chittagong” district. Table 15 shows districts corresponding to multi-hazard zones based on combined multi-hazard score.
Fig 1 shows the proposed district wise multi-hazard zoning map of Bangladesh representing multi hazard scenario (cyclone,
flood, tornado and earthquake) of Bangladesh at a glance.
4. Recommendation
The findings of this study can be used by decision makers as a reliable basis for district wise decision making considering
individual hazards, as well as a multi-hazard approach. To disseminate and utilize the results regarding district wise
individual hazard assessment and multi-hazard map of Bangladesh, the former Disaster Management Bureau (DMB) andnow Department of Disaster Management (DDM) can make the results available in their website for all the respective
decision makers including planners, administrators and disaster managers, and guide them to incorporate the informationin their decision making and plan making process. Policy makers at the national and regional levels can use the multihazard map for formulation of development strategies in multi-hazard active zones, i.e. land use management, revision andenforcement of appropriate building codes, and formulation of plans for mitigating measures against hazard risks affecting
the region considered. Moreover, the map can be used as a guideline by planners, administrators and disaster managers to

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make decisions regarding layout planning, updating building construction regulation for reducing probable damage,suggesting improvements for the building types, planning for disaster preparedness and response, etc., for different districts
considering the different aspects of respective multiple hazards. The district level administrators can be made aware of theoutcomes regarding their corresponding administrative units, so that they can disseminate the information to the local
people to take preparedness measures according to the hazard condition of their locality.
Due to unavailability of historical records or database on past disasters in Bangladesh, some important factors could not be
incorporated in this study. This includes but not limited to district wise variation of wind speed in case of tornados, district
wise variation of flood duration, district wise wind disaster data in case of cyclones, etc. Moreover, the multi-hazard map
is time-dependent and might be subjected to changes due to future events. So, updates and refinements to the database arenecessary for updating the multi-hazard map. For the purpose, it is required to develop, maintain and update, recording andanalysis system of historical disasters in Bangladesh by the Government of Bangladesh (GoB) involving respective
agencies, institutions, departments and working levels ranging from districts and the central government. Also
methodologies for rapid assessment of damage caused by hazards (earthquake, cyclone, tornado, and flood) considering
more variables, i.e. duration, probability etc should be developed. For the purpose of recording of disaster information,
intensity scales and damage risk levels for different disasters considering international standards should be followed
ensuring compliance with local context. In this case, the intensity scales developed and proposed in this study for different
hazards (earthquake, cyclone, tornado, and flood) can be considered by respective authorities with adequate adjustments
and improvements. In this study, intensity scale for tornado is not proposed due to lack of historical database, but for futurestudies and data management Fujita-Pearson Tornado Scale can be utilized which measures the damage severity of a
tornado with respect to wind speed (FEMA 1997). Proper historical data recording will open the scope for the preparationof sub-district based multi-hazard micro-zoning mapping of Bangladesh. Moreover, incorporation of vulnerability
assessment with multi-hazard zoning map will result in multi-hazard risk map.
5. Conclusion
Bangladesh has suffered from some major natural disasters in the last decade. Among the hazards, earthquake, cyclone,
tornado and flood, are most notable based on historical occurrences and their potential damage. An effort has been madeto develop a multi-hazard zoning map of Bangladesh, considering earthquake, cyclone, tornado and flood. As a basic
requirement in this regard, a complete database of those disasters of Bangladesh has been prepared. Then comparing theorganized disaster database with international scales, damage scenario and models, intensity scales and damage risk levels
for earthquake, flood, cyclone and tornado for Bangladesh have been developed and proposed. Then, district wise hazard
scores of earthquake, cyclone, tornado and flood hazards have been calculated for Bangladesh. After that the districts of
Bangladesh have been subdivided into three zones based on multi-hazard scores. Finally a district wise multi-hazard zoning
map of Bangladesh has been prepared and proposed. The research findings are crucial and an important aspect for policy
makers to take decision regarding disaster management strategy for planning disaster prevention, mitigation, andpreparedness actions by identifying districts in high multi hazard zone. It can guide policy makers at the national andregional levels in the formulation of development strategies in multi-hazard active zones, i.e. land use management,
revision and enforcement of appropriate building codes, and formulation of plans for mitigating measures against hazard
risks affecting the region considered. It can guide planners, administrators and disaster managers to make decisions
regarding layout planning, updating building construction regulation for reducing probable damage, suggesting
improvements for the building types, planning for disaster preparedness and response, etc., for different districts

107March 2016
considering the different aspects of respective multiple hazards. It can be helpful for the general people to take preparedness
measures according to the hazard condition of their locality.
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Table 1 Historical database for four major hazards in Bangladesh

District
Name
Bagerhat
BandabanBarguna
Barishal
Bhola
Bogra
Brahmanbaria
Chandpur
Chittagong
Chuadanga
ComillaCox’s bazar
Dhaka
Dinajpur
Faridpur
Feni
Gaibandha
Gazipur
Gopalganj
Habiganj
JamalpurJessoreJhalkati
Jhenaidah
Joypurhat
Khgrachari
KhulnaKishoreganj
Kurigram
Kushtia
Lakshmipur
Lalmonirhat
Madaripur
MaguraManikganj
Meherpur
Moulvibazar
Munshiganj
Mymensingh
NaogaonNarailNarayanganj
Narsingdi
NatoreNawabganj
Netrokona
Nilphamari
NoakhaliPabanaPanchagarh
PirojpurPotualkali
Rajbari
Rajshahi

Tornado
Fr
2
0
0
3
2
1
0
1
1
0
4
1
8
0
5
1
4
4
3
0
4
2
0
0
0
0
3
5
1
2
1
2
1
2
4
1
1
2
8
0
4
1
0
0
0
1
2
6
2
1
1
0
1
1

Historical database (Fr represents frequency)
Flood
Earthquake
CycloneFlooding area
Earthquake
Cyclone zones
zones based on
Frzones based
Fr
based on height ofwater level data
on PGA
storm surge
Non flooding area
3
Zone 1
3
High risk area
Severe2
Zone 38
High wind area
Non flooding area
2
Zone 1
3
High risk area
Severe6
Zone 1
3
High risk area
Moderate
4
Zone 1
3
High risk area
Severe6
Zone 310
Non affected area
Severe6
Zone 35
Non affected area
Severe7
Zone 2
4
High wind area
Severe5
Zone 2
6
High risk area
Moderate
1
Zone 2
3
Non affected area
Severe5
Zone 2
4
High wind area
Severe3
Zone 3
6
High risk area
Severe6
Zone 2
4
Non affected area
Severe3
Zone 2
3
Non affected area
Severe6
Zone 2
4
Non affected area
Moderate
4
Zone 2
3
High risk area
Severe6
Zone 313
Non affected area
Moderate
6
Zone 38
Non affected area
Moderate
6
Zone 1
3
High wind area
Severe7
Zone 312
Non affected area
Severe7
Zone 319
Non affected area
Non flooding area
1
Zone 1
2
Non affected area
Non flooding area
1
Zone 1
3
High wind area
Non flooding area0
Zone 22
Non affected area
Moderate
3
Zone 38
Non affected area
Non flooding area0
Zone 3
5
High wind area
Non flooding area0
Zone 1
3
High risk area
Severe7
Zone 310
Non affected area
Severe7
Zone 316
Non affected area
Severe2
Zone 25
Non affected area
Severe5
Zone 2
1
High risk area
Moderate
4
Zone 39
Non affected area
Severe6
Zone 2
3
High wind area
Moderate
5
Zone 2
4
Non affected area
Severe6
Zone 2
6
Non affected area
Non flooding area
1
Zone 2
4
Non affected area
Moderate
7
Zone 317
Non affected area
Severe5
Zone 2
4
Non affected area
Moderate
7
Zone 311
Non affected area
Severe6
Zone 2
4
Non affected area
Normal6
Zone 1
4
Non affected area
Severe6
Zone 2
3
Non affected area
Severe6
Zone 35
Non affected area
Severe6
Zone 2
6
Non affected area
Severe5
Zone 22
Non affected area
Moderate
6
Zone 319
Non affected area
Moderate
5
Zone 33
Non affected area
Moderate
4
Zone 2
2
High risk area
Severe6
Zone 28
Non affected area
Non flooding area
2
Zone 33
Non affected area
Normal2
Zone 1
3
High wind area
Non flooding area0
Zone 1
3
High risk area
Severe6
Zone 2
7
Non affected area
Severe5
Zone 2
4
Non affected area

Fr
6
0
1
21
5
0
0
2
32
0
1
25
0
0
0
1
0
0
0
0
0
0
0
0
0
0
19
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
18
0
0
0
12
0
0

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Rangmati
Rangpur
Satkhira
Shariatpur
SherpurSirajganj
Sunamganj
SylhetTangailThakurgoan

0
4
0
3
1
4
0
0
2
0

Non flooding area
SevereNon flooding area
SevereModerate
SevereSevereSevereSevereNon flooding area

1
6
1
6
6
6
7
7
7
1

Zone 3
Zone 3
Zone 1
Zone 2
Zone 3
Zone 3
Zone 3
Zone 3
Zone 3
Zone 3

6
7
3
3
21
8
18
16
9
3

High wind area
Non affected area
High risk area
High wind area
Non affected area
Non affected area
Non affected area
Non affected area
Non affected area
Non affected area

0
0
5
0
0
0
0
0
0
0

Table 2 Intensity scale and damage risk levels for flood in Bangladesh

Flood
zone
No
Flooding
Area
NormalFlooding
Area
Moderate
Flooding
Area

SevereFlooding
Area

Water
level (DLrepresents
DangerLevel)
Below
50cm
DL
Within
50cm
DL
Up to
50cm
Above DL

Above
50cm
above DL

Intensity
scale

Damage risk

Description

1

Very Low
Damage Risk

Fine cracks in plaster; fall of small pieces ofplaster.

2

Low Damage
Risk

Small cracks in walls; fall of fairly large
pieces of plaster.

3

Moderate Damage
Risk

4

Source: Adapted from BMPTC 1997

114

High Damage
Risk(<3m above 50cm
DL)
Very High
Damage Risk(>3m above DL)

Large and deep cracks in walls; bulging ofwalls; loss of belongings; damage toElectric fittings.
Gaps in walls; punching of holes through wallby flowing water; parts of buildings may
collapse; light roofs float away; erosion offoundation, sinking or tilting; undercutting offloors, partial roof collapse.
Total collapse of buildings; roof and somewalls collapse; floating away of sheets,
thatch, etc; erosion of foundation; severe
damage to lifeline structures and systems.

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Table 3 Modified Mercalli Intensity (MMI) scale for earthquake
Intensity
level

Intensity
level

Explanation

I

Only felt by instruments.

VII

II

Felt by people at rest, especially on
upper floors. Suspended objects may
swing.

VIII

III

Felt indoors. Vibrations like passing
traffic.

IX

IV

Many people feel it indoors, a few
outdoors. Crockery and windows
rattle. Standing cars rock. Somesleepers awake.

X

V

Felt by nearly everyone. Tall objects
rock. Plaster cracks.

XI

VI

Most people run outdoors. Damage
to weakly constructed buildings. Feltby people in moving vehicles.

XII

Explanation
Most people run outdoors. Damage to
weakly constructed buildings. Felt bypeople in moving vehicles.
Considerable damage to most buildings.
Heavy furniture overturned. Some sandfluidized.
Even well-designed and sturdy buildings
badly damaged, moved from theirfoundations. Ground cracks. Pipes break.
Most masonry destroyed. Landslides occur.
Water slops from reservoirs and lakes.
Railway lines bend.
Few structures remain upright. Bridges fall.
Extensive fissures in the ground.
Underground pipes totally out of action.
Total destruction. Ground thrown into
waves. Objects flung into the air. You would
be lucky to survive this one.

Table 4 Peak Ground Accelerations (PGAs) during shaking at different intensities
MMI
PGA (g)V
0.03-0.04

VI
0.06-0.07

VII
0.10-0.15

VIII
0.25-0.30

IX
0.50-0.55

X>0.60

Table 5 Intensity scale and damage risk levels for cyclone in Bangladesh

Intensity

Maximum
possible
Expected central
Wind speed
Stormpressure
Surge
(MSL)
(mbar)(in)(mph) (kph) (m) (ft)Category 1>=976>=28.94

74-95

119153Category 296697528.5028.91

96110

154177

Damage
risk
level

<7

<22

Very
Low
Damage
Risk
(VL)

8-9

2329

Low
DamageRisk (L)

Description

No real damage tobuilding structures.
Damage primarily tofishing boats, trees
near coastal. Somedamage to poorly
constructed signs.
Also, some coastalroad flooding andminor pier damage.
Some roofing material,door, and windowdamage of buildings.
Considerable damage
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Intensity

Maximum
possible
Expected central
Wind speed
Stormpressure
Surge
(MSL)
(mbar)(in)(mph) (kph) (m) (ft)Category 394896527.9128.47

1111301782091011

3032

Category 492394727.1727.88

131155210249

1213

3342

116

Damagerisk
level

Description

to trees with sometrees blown down.
Some fishing boats
missing. Considerable
damage to poorly
constructed signs, andpiers. Small craft in
unprotectedanchorages breakmoorings.
Tin roof, wooden
supports blown off.
Tin shed cottage
industry totally
damage. Crack in walland beam and floor
settled of somegodown. Somestructural damage tosmall residences andutility buildings with
RCC roof and wall
crack. Extensive
damage to doors andwindows of one storey
Moderate buildings and General
Damagedamage of doorsRisk (M) windows of some twostorey residentialbuildings. Somedamage of boundary
wall and steel gate.
Some retaining wall
washed away andsome damage to toe ofwall. Wooden jetty
totally damage. Someelectrical works
damage. Major
damage to lower floorsof structures near the
shore.
More extensive curtainHigh
wall failures with
Damagesome complete roof
Risk (H)structure failures on
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ICUS Report 81

Intensity

Category 5

Maximum
possible
Expected central
Wind speed
Stormpressure
Surge
(MSL)
(mbar)(in)(mph) (kph) (m) (ft)<924

<27.17

>155

>249

>13

>42

Damage
risk
level

Very
High
DamageRisk(VH)

Description

small residences. Semi
pucca tin roof totally
destroyed. Roofs
blown away andwindows-doors
damaged of dormitory
and community centre.
Single storey buildings
totally collapse.
General damage tointerior of cyclone
shelter. RCC pillars
crack. Doors andwindows of two storey
cyclone shelter
destroy. Complete roof
failure of many
residential andindustrial buildings.
Trees and all signs areblown down. Major
damage to lower floorsof structures near the
shore.
Complete roof failure
on many residences
and industrial
buildings. Some
complete building
failures with small
utility buildings blown
over or away. All trees
and signs blown down.
Severe and extensive
window and door
damage. Stairs,
auditorium and toilet
block severely
damage. Some onestorey buildings andboundary walls
collapse. Some twostorey buildings
destroy.

117

March 2016
Table 6 Tornado hazard factors and weighting factors based on frequency

No. of occurrence/ Frequency of tornado
0
1
2
3
4
5
6
7
8

Weighting factor
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8

Hazard factor
1

5

Table 7 Flood zones and their corresponding hazard factors for Bangladesh
Flood zone
No Flooding Area
Normal Flooding Area
Moderate Flooding Area
Severe Flooding Area

Intensity
12
3
4

Hazard factor
12
45

Table 8 Flood weighting factor with respect to frequency

Frequency/ No. of occurrence
0
1
2
3
4
5
6
7

Weighting factor
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7

Table 9 Seismic zones and their corresponding hazard factors

118

Zone

PGA

Intensity

Hazard factor

Zone-1
Zone-2
Zone-30.075g
0.15g
0.25g

VI
VII
VIII

3
4
5

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ICUS Report 81
Table 10 Earthquake weighting factor with respect to frequency

Frequency/ No. of Occurrence
0
1-3
4-6
7-9
10-12
13-15
16-18
19-21

Weighting Factor
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7

Table 11 Cyclone zones and their corresponding hazard factors

Cyclone zone

Intensity

Hazard factor

Non Affected Area
High Wind Area
Risk Area

Category 1
Category 2
Category 3
Category 4
Category 5

1
2High Risk Area

5

Table 12 Cyclone weighting factor with respect to frequency

Frequency/ No. of
occurrence
0
1-4
5-8
9-12
13-16
17-20
21-24
25-28
29-32

Weighting factor
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8

119

March 2016
Table 13 District wise individual hazard and multi-hazard scores
District name
Jhalkati
Jhenaidah
Thakurgoan
Khgrachari
Rangmati
Chuadanga
Barguna
JessoreSatkhira
Potualkali
Meherpur
Dinajpur
Panchagarh
Pirojpur
Joypurhat
Nawabganj
NarailNaogaonNatoreBandabanBrahmanbaria
Narsingdi
Bagerhat
Habiganj
kushtia
MaguraGopalganj
KhulnaNilphamari
Sunamganj
SylhetRajshahi
Narayanganj
Lalmonirhat
Munshiganj
RajbariMadaripur
PabanaManikganj
Bhola
Gazipur
Shariatpur
Chandpur
Feni
Faridpur
Moulvibazar
Netrokona
Sherpur
Bogra
Comilla
Tangail
Lakshmipur

120

Tornado
(T)
1
1
1
1
1
1
1
6
1
1
5.5
1
5.5
5.5
1
1
7
1
1
1
1
1
6
1
6
6
6.5
6.5
6
1
1
5.5
5.5
6
6
5.5
5.5
6
7
6
7
6.5
5.5
5.5
7.5
5.5
5.5
5.5
5.5
7
6
5.5

Score for individual hazards
CycloneEarthquake (E)
(C)
1.1
3.3
1
4.4
1.1
5.5
1
6
1.1
6
4.4
4.4
1.2
3.3
1.1
3.3
1.1
3.3
1
3.3
1.1
4.8
6.5
4.4
1.2
5.5
2.4
3.3
5.2
6.5
7.5
4.4
3.2
3.6
8
4.8
8
4.8
6
6.5
8
6
8
6
1.3
3.3
8.5
7
6
4.8
6
4.8
6.4
3.3
1
3.3
6
5.5
8.5
8
8.5
8
7.5
4.8
8
4.4
5.6
6.5
7.5
4.8
8
5.2
8
4.4
8
5.2
8
4.8
5.6
3.3
6.4
6.5
8
4.4
8.5
4.8
5.6
4.4
8
4.8
6.8
8
6.4
8.5
6.4
8.5
8
7
7.5
4.8
8.5
6.5
7.5
4.4

Flood (F)
2
1
1
2
2
1
5.5
1
6
6.5
1
1
1
2
1
1
1
1
1
2
1
1
6
1
1
1
2
7.5
1
1
1
1
1
1
1
1
2
1
1
6
1
2
2.2
5.5
1
1
1
1
1
2.2
1
5

Multi-hazard score(T + E + C + F)
(increasing order)
7.4
7.4
8.6
10
10.1
10.8
11
11.4
11.4
11.8
12.4
12.9
13.2
13.2
13.7
13.9
14.8
14.8
14.8
15.5
16
16
16.6
17.5
17.8
17.8
18.2
18.3
18.5
18.5
18.5
18.8
18.9
19.1
19.3
19.7
19.9
20.2
20.8
20.9
20.9
20.9
21
21
21.3
21.3
21.4
21.4
21.5
21.5
22
22.4

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ICUS Report 81
Rangpur
RangpurSirajganj
Sirajganj
Dhaka
Dhaka
Kurigram
Kurigram
Gaibandha
Gaibandha
Mymensingh
Mymensingh
Kishoreganj
Kishoreganj
Jamalpur
Jamalpur
Noakhali
Noakhali
Barishal
BarishalCox’s
Cox’s bazar
bazar
Chittagong
Chittagong

7
7
7
7
9
9
5.5
5.5
7
7
9
9
7.5
7.5
7
7
8
8
6.5
6.5
5.5
5.5
5.5
5.5

8
8
8
8
8
8
8.5
8.5
8
8
6.8
6.8
8.5
8.5
8.5
8.5
5.6
5.6
8
8
6.5
6.5
7.5
7.5

6.5
6.5
6.5
6.5
4.8
4.8
8
8
7.5
7.5
7
7
7
7
8.5
8.5
4.4
4.4
3.3
3.3
6
6
4.8
4.8

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
7.5
7.5
8
8
8.5
8.5
9
9

22.5
22.5
22.5
22.5
22.8
22.8
23
23
23.5
23.5
23.8
23.8
24
24
25
25
25.5
25.5
25.8
25.8
26.5
26.5
26.8
26.8

Table 14
14 Calculation
Calculation ofof individual
individual andand multi-hazard
multi-hazard scoresscores forfor “Chittagong”“Chittagong” district
district
Table

TornadoTornadoFlood
Flood
Earthquake
Earthquake
CycloneCycloneHazardHazard factor
factor(H)(H)

HazardHazard zone
zone

Frequency
Frequency-SevereSevereZone
Zone 22High
High risk
risk area
area

11
55
66
32
32
Multi-hazard
Multi-hazard score
score

55
55
44
55

Weighting
Weightingfactorfactor (WF)
(WF)
1.1
1.1
1.5
1.5
1.2
1.2
1.8
1.8

HazardHazard Score
Score
(TH
(TH =
=H
H×
×
WT)
WT)
5.5
5.5
7.5
7.5
4.8
4.8
99
26.8
26.8

Table
Table 15
15 Districts
Districts corresponding
corresponding toto multi-hazard
multi-hazard zones
zones based
based onon multi-hazard
multi-hazard score
score
Multi-hazard
Multi-hazard
score
score
1-10
1-10

Multi-hazard
Multi-hazard
zones
zones
Low
Low

10-20
10-20

Moderate
Moderate

20-30
20-30

High
High

Districts
Districts
Jhalkati,
Jhalkati, Jhenaidah,
Jhenaidah, Thakurgoan,
Thakurgoan, KhgrachariKhgrachari
Rangmati,
Chuadanga,
Rangmati, Chuadanga, Barguna,Barguna, Jessore,
Jessore, Satkhira,Satkhira,
Potualkali,
Meherpur,
Dinajpur,
Panchagarh,
Potualkali, Meherpur, Dinajpur, Panchagarh, Pirojpur,
Pirojpur,
Joypurhat,
Joypurhat, Nawabganj,
Nawabganj, Narail,
Narail, Naogaon,
Naogaon, Natore,
Natore, Bandaban,
Bandaban,Brahmanbaria,
Brahmanbaria, Narsingdi,
Narsingdi, Bagerhat,
Bagerhat, Habiganj,
Habiganj, Kushtia,
Kushtia,
Magura,Gopalganj,
Khulna,Nilphamari,
Magura, Gopalganj, Khulna, Nilphamari, Sunamganj,
Sunamganj,
Sylhet,Sylhet, Rajshahi,
Rajshahi, Narayanganj,
Narayanganj, Lalmonirhat,
Lalmonirhat, Munshiganj,
Munshiganj,
Rajbari,Madaripur
Rajbari, Madaripur
Pabana,Pabana, Manikganj,
Manikganj, Bhola,
Bhola, Gazipur,
Gazipur, Shariatpur,
Shariatpur, Chandpur,
Chandpur,
Feni,
Faridpur,
Moulvibazar,
Netrokona,Feni, Faridpur, Moulvibazar, Netrokona, Sherpur,
Sherpur, Bogra,
Bogra,
Comilla,Comilla, Tangail,Tangail, Lakshmipur,
Lakshmipur, Rangpur,
Rangpur, Sirajganj,
Sirajganj, Dhaka,
Dhaka,
Kurigram,
Gaibandha,
Mymensingh,
Kishoreganj,
Kurigram,
Gaibandha,
Mymensingh,
Kishoreganj,
Jamalpur,
Noakhali,
Barishal,Cox’s
bazar,
Chittagong
Jamalpur, Noakhali, Barishal, Cox’s bazar, Chittagong

121March 2016

Source: Prepared by authors

Fig. 1 Multi-hazard risk map of Bangladesh

122

BNUS Annual Report-2015

PART-VII
WORKPLACE SAFETY COMPLIANCE OF RMG
INDUSTRY IN BANGLADESH: STRUCTURALASSESSMENT OF RMG FACTORY BUILDINGSBANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Uttama Barua
Mehedi Ahmed AnsaryMarch 2016

1. Introduction
Accidents in industry effect on the safety of workers, livelihood of the workers’ families, those livingin the vicinity of the industry and on the environment. Thousands of people are killed and injured inindustrial accidents every year (Jaiswal, 2012). According to ILO, occupational accidents and workrelated diseases cause over 2.3 million fatalities annually, of which over 350,000 are caused byoccupational accidents, which result in immeasurable human suffering to victims and their families
along with major economic losses for enterprises and economies as a whole, e.g. around 4 per cent of
the world’s gross domestic product (GDP), or about US$2.8 trillion, is lost annually in direct andindirect costs (ILO, 2014e). Among different types of hazards in textile industry, physical hazards i.e.
fire, building collapse, etc, are dependent on the structural and workplace safety compliance issues.
Different industrial hazards resulted in several initiatives worldwide to protect human life and reducematerial damage from industrial accidents, both nationally and internationally.
Occupational hazards are common in China with the dramatic economic development over the past 20
years (Zhang, Wang, and Li, 2010). For the prevention of occupational hazards, especiallyoccupational diseases several legislative measures have been promulgated in China. Other initiatives
included enforcement and implementation of occupational health and safety research, capacity
building, supervision team formation, basic occupational health services in collaboration withinternational organizations, etc (Zhang, Wang, and Li, 2010). The occupational hazards in Japan arecharacterized by health issues and industrial accidents resulting in several laws and acts (JISHA, 2010;
Takahashi, and Ishii, 2013).
Manmade industrial disasters happen frequently in Europe, resulting in adoption of minimum
requirements for safety and health protection at the workplace to prevent accidents and occupational
diseases in Member States of European Union (EU), i.e. policies, legislation, convention, etc(European Commission, 2014a; Chambers, 2015; European Agency for Safety and Health at Work,n.d.). Among the industrial accidents influencing adoption of preventive measures, Seveso chemical
accident in Italy (1976), Baia Mare industrial accident in Romania (2000) etc are significant (European
Commission, 2014b; Ludwiczak, 2014; European Commission, 2015; Eves, 2015). The earlier poor
working condition in industries of United Kingdom (UK) resulted in initiation of factory inspection
and imposition of Factory Act in 1833, which amended several times afterwards to address industrial
accident issues. Several initiatives were undertaken in response to industrial accidents, i.e. industrial
explosion in Silvertown, East London killing 73 workers (1917), explosion and fire at Flixborough,
Lincolnshire killing 28 workers and injuring 36 workers (1974), collapse of a four-storey factorybuilding in Glasgow caused by a liquefied petroleum gas (LPG) explosion killing nine and injuring
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thirty three workers (2004), massive explosion and fire at the Buncefield Oil Storage Depot, Hemel
Hempstead (2005), etc (McQuaid, 1991; Eves, 2015). In USA, unhealthy working conditions andfrequent serious accidents with resulting economic and social losses influenced the government toundertake different actions, e.g. in 1877 the first Factory Act along with factory inspection initiative
were enacted in Massachusetts in response to the tragic fire at the Granite Mills in Fall River (1875)(MacLaury, n.d.).
In 1919, following the end of the First World War, the International Labour Organization (ILO) wasestablished in order to address all conceivable aspects of labor rights internationally. Occupational
health and safety (OHS) is one of the ILO Constitution’s main objectives, the concept of which wasdeveloped by the ILO and the World Health Organization (WHO) in 1950 as a building block forlabour legislation (Muller, 2013; Nations Encyclopedia, n.d.).
The Ready Made Garment (RMG) industry in Bangladesh has been facing challenges regarding
compliance with the international standard to ensure workplace safety and better working conditions
for the millions of garment workers resulting in worst safety record in the world (CCC, 2012).
Neglecting the importance, many employers did not comply with the basic regulations in Bangladesh,
despite extensive global legislation on occupational health and safety and other workers’ rights. Most
garments factories in Bangladesh paid little attention to labor standards and labor rights, many of which
did not meet the minimum standards prescribed in building and construction legislation (Ahmed, 2013).
Such non-compliance resulted in numerous industrial accidents in RMG factories of Bangladesh likefire and building collapse resulting in the enormous sufferings to the workers and their families(Ahmed, 2013). One of the most deadly fire accidents in RMG sector Bangladesh is Tazreen Fashion
fire on November 24, 2012, which resulted in death of 112 workers (ILO, n.d.a). Since Tazreen Fashion
Factory fire to April 17, 2015, about 84 fire incidents have occurred in the sector leading to at least 31
deaths and 903 injuries (Solidarity Center, 2015). In 2005 Spectrum factory collapsed causing deathof 64 garment workers and injury of 80 (CCC, 2012). In 2006, 22 workers died due to collapse of
Phoenix Garments building. Just months after the fatal fire at Tazreen Fashions, Rana Plaza collapsed
on 24 April 2013 resulting in 1134 deaths and more than 2500 injuries. It is the last most alarming
accident in RMG sector in Bangladesh stated as one of the deadliest industrial disasters in the world,which resulted due to the reluctant attitude of the stakeholders towards the compliance issues.
Without workplace safety compliance, it is almost impossible to ensure business sustainability andthus to survive in global market competition (Rajon, 2014). Despite the challenges in RMG sector in
Bangladesh McKinsey, a global management consulting firm, described Bangladesh as the next hot
spot in apparel sourcing (Berg et al., 2011). The firm forecasted that the export-value growth will be
125March 2016

7-9% annually resulting in increase of apparel export double by 2015 and nearly triple by 2020, if thesector in Bangladesh can ensure total compliance with the international standard. Even after the Rana
Plaza collapse, a study jointly conducted by the United States Fashion Industry Association (USFIA)
and the University of Rhode Island (URI) revealed that, the US-based fashion companies are expected
to boost their sourcing from Bangladesh by 2016 (Lu, 2014).
Considering the potentiality of RMG industry in Bangladesh, several and diverse national andinternational commitments and initiatives resulted as part of the reform and restructuring of the
Bangladesh RMG sector aiming at improvement of workplace safety in Bangladesh’s garment
factories to safeguard the lives of over four million RMG workers and to retain the confidence of
global buyers following the Rana Plaza accident (ILO, 2015a; Moazzem, & Islam, 2015). The
initiatives include but not limited to, National Tripartite Action Plan (NTPA), the European Union
Sustainability Compact, and the United States Trade Representative (USTR) Plan of Action. Though
the targets and objectives of these initiatives are same, but they share some common courses of action(Moazzem, & Islam, 2015). Among the common actions considered in three initiatives, structuralassessment of RMG factory buildings is significant to ensure a safe working environment for all in the
sector preventing further accidents.
In this background, this paper aims firstly to discuss the history, potentiality and challenges of RMG
industry in Bangladesh to bring out the importance of this industry in the economy of the country alongwith the challenges, secondly to review the initiatives taken after Rana plaza accident to overcome thechallenges along with their progress in terms of achievement within two years, and finally to review
and discuss in detail about the action regarding structural assessments of buildings housing RMG
factories in Bangladesh including its progress, implementation mechanism, and outcomes within two
years after Rana Plaza collapse. Assessment of buildings is not an end in itself, which requires further
study to take corrective measures accordingly. So, along with the discussion, some recommendations
have been suggested in this study to be incorporated in the structural assessment initiative to make theweak factory buildings resilient by addressing the structural issues. This study was done on the basisof review of secondary resources and field experiences of the authors.
2. Ready Made Garment (RMG) Industry in Bangladesh: History, Potentiality and Challenges
Ready Made Garment (RMG) industry sector of Bangladesh commenced its journey in late 1970s due
to global garment chain and outside pressure rather than local demands and has come to the position
it is in today (Rahman, 2004; Hasan, 2013). The industry emerged in Bangladesh at a time when it
began its struggle for achieving economic emancipation after independence to lead the country toprosperity with its limited resources. At that time jute was the major foreign exchange earner of126

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Bangladesh contributing more than 50% of the country’s total export earnings (Chowdhury, Ahmed,
and Yasmin, 2014). But the jute market collapsed due to consequent decline in global demand for jute.
The growth in the RMG sector has been a welcome change for Bangladesh’s export market
diversifying the economy of the country which has historically been dependent on agricultural sector.
It has indeed emerged as a niche market for Bangladesh’s export sector.
The history influencing the commencement of RMG industry in Bangladesh initiated in 1950 whencost of production increased in Western World due to increase in labour wage in RMG sector(Chowdhury, Ahmed, and Yasmin, 2014). As a result, retailers started searching for places where thecost of production was cheaper, i.e. Hong Kong, Taiwan and South Korea (Hasan, 2013; Chowdhury,
Ahmed, and Yasmin, 2014). In 1974, Multi Fiber Agreement (MFA) was made by General Agreement
on Tariffs and Trade (GATT) to control the level of imported RMG products from developing
countries into developed countries, imposing six percent increase in export rate every year from adeveloping country to a developed country and quotas on countries that exported at a higher rate
(Chowdhury, Ahmed, and Yasmin, 2014). Bangladesh was able to escape the MFA quotas as it was
not perceived to be a particular threat to the industries of those countries (Khan, 2002). The MFA
agreement led the producers to search for countries that were outside the umbrella of quotas andhad cheap labour like Bangladesh. Thus, exemption of Bangladesh from MFA and cheap labour
influenced the instigation of RMG sector in the country, when South Korean company Daewoo signed
a five-year collaboration agreement with Desh, a Bangladeshi garment in 1974. Further thedevelopment and improvement of communication system and networking, flexible government policy
toward the sector, and other factors persuaded the expansion and success of Bangladesh’s entire
garments export sector (Rahman, 2004; Yunus, and Yamagata, 2012; Chowdhury, Ahmed, andYasmin, 2014). By late 1980s, the sector became the main export sector and a major source of foreignexchange in Bangladesh (Rahman, 2004; Chowdhury, Ahmed, and Yasmin, 2014). Thus, the MFA
quota was a blessing to the RMG industry of Bangladesh. In 2005, phase out of the quota wascompleted under the Uruguay round of GATT (1994) (Razzaue and Eusuf, 2007; Yunus, andYamagata, 2012; Hasan, 2013). At the end of the quota, it was predicted by many that the phase out
would greatly affect the export of the country. However, the post MFA era is another storey of successproving all predictions wrong (Razzaue and Eusuf, 2007; Yunus, and Yamagata, 2012; Hasan, 2013).
In the recent years, RMG exports from Bangladesh have been growing at an impressive rate. In
FY 1984-‘85 the value of RMG export of Bangladesh was 116.20 million USD which was 3.89% of
total export (BGMEA, 2014). It is now the biggest export earner in Bangladesh with an export earningof around 25 Billion USD which is 84.1 percent of the total export earnings of the country in FY201415 (May). Due to such growth in RMG export earning, Bangladesh became the second largest apparel127

March 2016

exporting country in the world in 2010 just within a course of three decades despite other challenges
in the sector (Islam, 2014; ILO, 2015b; Rahman and Hossain, 2010). Figure 1 shows comparative
statement on share of different sectors in total export earning of Bangladesh, which represents theincreasing superiority of export earnings of RMG sectors in Bangladesh in last eight fiscal years.
Except its contribution in export earning, the RMG industry emerged as an important player in theeconomy in terms of employment generation, poverty alleviation and empowering of women (Rahman
and Hossain, 2010). In 1978, there were only 9 export-oriented garment manufacturing units
employing 0.12 million workers, which shot up to around 3500 employing more than 4.2 million
workers in 2014 (BGMEA, 2014; ILO, 2015b). At present, European Union (EU including UK) andNorth America (the US and Canada) are the main buyers of RMG products of Bangladesh, where sixty
percent of export contracts of western brands are with European buyers, and about 30 percent with
North American buyers (Hasan, 2013; Hasan, 2014). Bangladesh is a participant in General System ofPreferences (GSP) programs of both the EU's as well as that of the US.

Figure 1: Share of different sectors in total export earning of Bangladesh (Source: Export Promotion
Bureau, 2015)
It is apparent from Figure 1 that that the growth rate of RMG sector in Bangladesh has been aroundnine percent over the FY2013-14 which is slightly lower than the earlier five years average of around
12 percent (Anwar, 2014). This reduction has resulted due to several factors including image smearing
due to industrial accidents, political turmoil, energy crises, physical distribution, and discriminatory
treatment by some major global buyers. Industrial accidents are common in RMG factories of
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Bangladesh due to lack of compliance with the international standard. Many of the factories did notmeet the minimum standards prescribed in building and construction legislation causing different
accidents like fire and building collapse causing enormous suffering to workers and their families(Ahmed, 2013). One of the most deadly fire accidents in RMG sector Bangladesh is Tazreen Fashion
fire on November 24, 2012. Just months after the fatal fire at Tazreen Fashions, Rana Plaza collapsed
on 24 April 2013 at around 8:30 am, which was located at Dhaka-Aricha highway near Savar bus stand(Figure 2). It is the last most alarming accident in RMG sector in Bangladesh, which resulted due tothe reluctant attitude of the stakeholders towards the compliance issues.
Rana Plaza housed five garment factories employing around 5,000 people, 300+ shops, and a bank. It
was a 9-storied industrial building with a single basement. Figure 2 shows the schematic diagram, of
the building and a photo before it collapsed. Instead of RAJUK (Capital Development Authority), local
municipality (Savar) gave permission to the owner of Rana Plaza to construct a five storey commercial
building with one basement in 2005 and later allowed the owner to extend it up to nine storey, without
considering the structural design, though the foundation of the building was of 5 storey (Rahman, andAnsary, 2013). Moreover, the building was converted from commercial to industrial use, and power
generators were placed at the higher floors. As a result of such violation in building construction,
cracks developed on some pillars and a few floors of the building following a jolt on 23 April 2013, a
day prior to the fateful day. After inspection of industrial police, they requested the building authorities
to close the building and to suspend operations of the factories on that day. However, the building
owner and top-management of the garment factories ignored the warning and forced the workers towork in the next morning of 24th April, 2013. As a consequence, the collapse resulted in the high death
toll of 1,134 and more than 2500 people to be badly injured at the end of the rescue operation on 14
May 2013 (Osman et al., 2013; CPD, 2014a). It was a global tragedy emphasizing the importance ofissues concerning millions of workers, employers, brands and consumers – the entire supply chain in
the RMG sector of Bangladesh (ILO, 2014a).
After Rana Plaza accident, the US President suspended Bangladesh from participating in the GSP
program on June 27, 2013, and the suspension order was to be implemented within 60 days after theannouncement (Brooks, 2013). Many in the international community had wondered if the EU would
soon follow suit, or if it would pursue a different approach toward spurring policy changes in the
country (ICTSD, 2013). Convinced by ILO, the EU confirmed that it will be keeping Bangladesh in
its Everything But Arms (EBA) scheme of GSP, which grants least developed countries, such as
Bangladesh, duty-free, quota-free access to the EU market for all goods exports, with the exception ofarms and ammunition (ILO, 2014d; ICTSD, 2013). Thus, the initial reaction of the trading partners

129

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and global business and investors after Rana Plaza collapse weakened confidence in Bangladesh (ILO,
2014c).
To safeguard the lives of over four million RMG workers and to retain the confidence of global buyers
following the Rana Plaza accident, several and diverse national and international commitments andinitiatives resulted as part of the reform and restructuring of the Bangladesh RMG sector aiming at
improving workplace safety in Bangladesh’s garment factories (ILO, 2015a; Moazzem, & Islam, 2015).
The initiatives include but not limited to, National Tripartite Plan of Action (NTPA), the European
Union Sustainability Compact, and the United States Trade Representative (USTR) Plan of Action.
Though the targets and objectives of these initiatives are same, but they share some common coursesof action (Moazzem, & Islam, 2015).
After Rana Plaza accident, the Government of Bangladesh (GoB) put in place a number of incentives
to ease the difficulties faced by RMG entrepreneurs, i.e. bringing down the advance income tax from
0.8 per cent of f.o.b. value to 0.3 per cent, arrangement of low-cost credit for struggling RMG units,etc (CPD, 2014b). But these incentives were not enough to satisfy the requirement of global buyers.
Thus, tripartite partners, i.e. GoB, RMG workers, and RMG employers, signed a Joint Statement built
upon NTPA on May, 2013 (ILO, n.d.b). The NTPA on Fire Safety was first outlined on March 2013
after Tazreen Fashion fire accident (Ahmed, n.d.). Afterwards, without altering the content, the NTPA
on Fire Safety was merged with the Joint Statement to form the NTPA on Fire Safety and Structural
Integrity in the RMG Sector of Bangladesh on July 2013 (ILO, n.d.b). The NTPA on Fire Safety and
Structural Integrity includes 25 commitments divided into the three categories, i.e. legislation andpolicy, administration, and practical activities, among which 16 have been fully or substantiallycompleted and nine of the commitments have been partly completed within two years (Moazzem, &Islam, 2015). The National Tripartite Committee (NTC) was established in 2013 under NTPA
commitment to ensure and monitor implementation of the NTPA (ILO, n.d.b; CPD, 2014a). The
committee chaired by Labour Secretary includes Government agencies, employers, i.e. Bangladesh
Employer's Federation (BEF), Bangladesh Garment Manufactures & Exporters Association (BGMEA)
and Bangladesh Knitwear Manufacturers & Exporters Association (BKMEA), and trade unions.

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ICUS Report 81(a) Rana Plaza(b) Rana Plaza before collapse(c) Rana Plaza after collapse

Figure 2: Rana Plaza before and after its collapse on April 24, 2013 (Source: bdnews24.com)

131

March 2016

3. Initiatives after Rana Plaza Collapse: Workplace Safety Compliance Issues
Based on NTPA; the EU, GoB and ILO issued an agreement of time-bound actions, “The Sustainability
Compact: Compact for Continuous Improvements in Labor Rights and Factory Safety in the ReadyMade Garment and Knitwear Industry in Bangladesh” on July 2013 to promote improved labor
standards and responsible business conduct in the RMG and knitwear industry in Bangladesh (ILO,
n.d.b; Joint Statement, 2013; Moazzem, & Islam, 2015). A total of twenty nine activities are listed in
the EU Sustainability Compact, among which 15 actions have been fully or substantially completed,
13 actions have been partly completed, and one action regarding encourage retailers and brands toadopt and follow a unified factory audit code of conduct in Bangladesh has not been initiated yet(Moazzem, & Islam, 2015). The United States Trade Representative (USTR) requested GoB to
implement a sixteen-point action plan within one year in order to reinstate Bangladesh’s GSP status in
the US market (Moazzem, & Islam, 2015; Brooks, 2013). The USTR Action Plan endorsed the EU
Sustainability Compact particularly for trade union related activities. Substantial progress has been
made in regards to twelve of the actions and greater progress is required in regards to four actions(Moazzem, & Islam, 2015). Table 1 shows the status of actions under three initiatives. From this review
it is realized that Bangladesh has progressed a lot in terms of the achievement or completion of actions
initiated under plans of actions.
Table 1: Status of actions under three initiatives
Initiative
NTPA

Fully or substantially completed

Partly completed

1. Submit the Bangladesh Labour

1. Review relevant laws,

Law Reform Package torules and regulations

Parliament.

regarding fire, building

2. Adopt a National Occupationaland chemical safety.

Health and Safety Policy.

2. Review and adjust factory

3. Establish a Task Force on

licensing and certification

Building and Fire Safety under
the Cabinet Committee for the
RMG sector.
4. Establishing a single resource for
information on fire safety
licensing and certification.
5. Recruitment of 200 labour

procedures.
3. Develop a transparent andaccountable industry subcontracting system.
4. Develop and implement afactory fire safety
improvement programme.

inspectors
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ICUS Report 81

Initiative

Fully or substantially completed

Partly completed

6. Upgrade the Department of the

5. Develop and deliver fire

Inspection for Factories andsafety training to factory

Establishments (DIFE) to ainspectors.

Directorate.
7. Strengthen the capacity of theDIFE
8. Establish a publicly accessible

6. Develop and deliver fire
safety training to union
leaders.
7. Assess the structural

database on safety issues in RMG

integrity of all active

factories.

RMG factories.

9. Develop and introduce a unified

8. Develop and deliver massfire safety checklist to be used byworker education tools.

all relevant government agencies.

9. Develop a tripartite and10. Conduct a factory level fire safety
needs assessment.
11. Deliver a fire safety “crashcourse” for mid-level factory

protocol forcompensation of thefamilies of deceased andinjured RMG workers.

managers and supervisors.
12. Establish a fire safety hotline forworkers.
13. Strengthen the capacity of the
Bangladesh Fire Service and Civil
Defence (FSCD).
14. Develop guidelines for theestablishment of labour
management committees on
occupational safety and healthand/or fire safety.
15. Develop and disseminate fire
safety self-assessment andremediation tools.
16. Redeploy RMG workers thatwere rendered unemployed by the133March 2016

Initiative

Fully or substantially completed

Partly completed

incident, as well as rehabilitateddisabled workers.
EU

1. Amend the Bangladesh Labour Law

Sustainability 2. The ILO is to provide technicalcompact

assistance to Bangladesh towards
implementation and follow-up
concerning freedom of associationand the right to collective bargaining

monitor the Labour Law
2. Issue and implement all rules
required by law
3. Develop and adopt additionaldomestic legislative

3. Ensure freedom of association,

proposals to address freedom

collective bargaining and theof association and protection

application of the Bangladesh Labourof the Right to Organise andLaw

Collective Bargaining

4. Register independent trade unions

4. Establish Joint Committees

and ensure protection of unions andfor the improvement of

their members from anti-union

occupational safety anddiscrimination and reprisals.

health

5. Conduct a diagnostic study of the

5. Deliver education andLabour Inspection System, followed

training programmes onby the development andfundamental principles, rights

implementation of an action planat work and occupationalwith appropriate measures.

safety and health

6. Conduct regular visits to assess

6. Extend technical assistance toindustrial establishments

address labour standards

7. Upgrade the Department of the Chief

7. The ILO is to assist

Inspector of Factories andBangladesh in reviewing theEstablishments to a Directorate.

adequacy of reforms in

Recruit 200 additional inspectors bymeeting ILO requirements

the end of 2013.
8. Implement the National Action Plan

134

1. Implement, enforce and8. Align actions with the ILO
Programme Outline 2013-

on Fire Safety and Structural

2016, ‘Improving Working

Integrity in the RMG industry in

Conditions in the RMG

Bangladesh, with the support of the

Sector in Bangladesh’, andILO, in accordance with established‘Better Work’; to be
BNUS Annual Report-2015

ICUS Report 81

Initiative

Fully or substantially completed

Partly completed

milestones and timelines as stipulated

supported technically orin the Programme of Action.

financially by the EU under

9. Assess the structural and fire safety

the next programming cycleof all active export-oriented RMG
and knitwear factories and initiate
remedial actions(2014-2020).
9. Explore further funding
possibilities within the

10. Create a publicly accessible database

upcoming programming

11. Achieve eligibility for the ‘Better

period (2014-2020),

Work Bangladesh’ (BWB)

including through theprogramme‘Thematic Programme Global

12. Explore the possibility of reallocating

Public Goods andfunds under the current EU-funded

Challenges’ programme‘Technical and Vocational Education

10. Rehabilitate those who are

and Training’ (TVET) projectpermanently disabled as a

implemented by the ILO. Implement

result of the Rana Plaza

the existing EU-funded ‘Better Work

Tragedy

and Standard’ (BEST) cooperation
programme.
13. Extend the social compliancecomponent in the ongoing EU BEST
programme with Bangladesh

11. Ensure a focus on skills
development in future EU
assistance to Bangladesh
12. Encourage other companies
to expeditiously join the

14. Underline the importance of engaging

Accord within theirwith stakeholders to ensure effective

respective capacities.

implementation of and consistency

13. Take note of the steps taken

among various initiatives

by European social partners

15. Implement the ILO’s skills andin the RMG sector to update

training programme for injured

their 1997 and 2008 Codes ofworkers. Rehabilitate and reemploy

Conduct on Fundamental

affected workers.

Rights, within the frameworkof the European SectoralSocial Dialogue Committee
for Textiles and Clothing135

March 2016

Initiative
USTR

Fully or substantially completed
1. Develop a plan to increase thePartly completed
1. Enact and implement labour

Bangladesh

number of labour, fire and building

law reforms to address key

Action Plan

inspectors, improve their training,

concerns related to freedom

establish clear procedures forof association and collective

independent and credible inspections

bargaining.

and expand resources and their

2. Develop and implement

disposal, so as to conduct effective

mechanisms to prevent

inspections

harassment, intimidation and

2. Increase fines and other sanctions forviolence against labour

failure to comply with labour, fire or

activists and unions

building standards to levels sufficient
to deter future violations
3. Develop and implement a plan toassess the structural building and fire
safety of all active RMG/knitwear

3. Actively support the ILO andother worker-employer
initiatives in the shrimp
sector
4. Publicly report on complaints

factories in consultation with thereceived of anti-union

ILO. Initiate remedial actions, or

discrimination or other unfair

close or relocate inadequate factories,

labour practices in the shrimp

as appropriate.

sector

4. Create a publicly accessible databaseof all RMG/knitwear factories as aplatform for reporting labour, fire andbuilding inspections
5. Establish an effective compliant
mechanism
6. Continue to register unions to ensure
protection of unions and theirmembers from anti-union
discrimination and reprisal
7. Publicly report information on thestatus and final outcomes ofindividual union registration
applications

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BNUS Annual Report-2015

ICUS Report 81

Initiative

Fully or substantially completed

Partly completed

8. Register non-governmental labour
organizations
9. Publicly report any complaints
received of anti-union discriminationor other unfair labour practice
10. Bring the EPZ law into conformity
with international standards
11. Issue regulations to ensure theprotection of EPZ workers' freedomof association until the EPZ law has
been repealed or overhauled
12. Issue regulations to ensuretransparency in the enforcement of
the existing EPZ law until the EPZ
law is repealed or overhauled

Source: Prepared by author on the basis of Moazzem, & Islam, 2015
In addition to these initiatives, two different factory inspection programmes have been established tomake work place safer in Bangladesh: the Bangladesh Accord on Fire and Building Safety in
Bangladesh, and the Alliance for Bangladesh, where ILO fulfills the role of neutral chair. The Accord
on Fire and Building Safety in Bangladesh (the Accord) was signed by over 190 apparel companies
from over 20 countries in Europe, North America, Asia and Australia; two global trade unions,
IndustriALL and UNI Global; and eight Bangladeshi trade unions on May 15th 2013. It is a five year
independent and legally binding agreement designed to build a safe and healthy Bangladeshi RMG
Industry (Bangladesh Accord, 2015a; Bangladesh Accord Secretariat, 2015). The Alliance for
Bangladesh Worker Safety (the Alliance) officially launched its local operation in Dhaka on December
9, 2013, which is also a five year independent and legally binding agreement founded by a group of
North American apparel companies and retailers and brands (26 North American retailers and brands)
to develop and launch the Bangladesh Worker Safety Initiative (Alliance for Bangladesh, 2013).
The initiatives and their achievements indicate that Bangladesh RMG sector is not only trying hard tomaintain required global standards but in fact in some cases it was far exceeding the standards set by
the competing countries (Anwar, 2014). Thus, despite the challenges, the RMG sector still held a137

March 2016

competitive position in global RMG market showing impressive export performance afterwards in FY
2013-14 and FY 2014-15 (Figure 1).
4. Structural Assessments of Buildings Housing RMG Factories in Bangladesh
4.1 Progress of the Structural Assessment Initiative
After Rana Plaza accident, work-place safety was considered one of the most important challenges tosustain RMG industry in Bangladesh. Thus actions regarding structural and fire safety assessment of
all active export-oriented RMG factories were addressed in all the action plans. The supporting actions
included up-gradation and strengthening of the Chief Inspector of Factories and Establishment office
to a department, recruitment of additional labour, fire and building inspectors, arrangement of training
programs to increase capacity of the inspectors, development of plan in consultation with the ILO to
conduct effective inspections, initiation of remedial actions or close or relocate factories as appropriate,and creation of a publicly accessible database of all RMG/knitwear factories as a platform for reporting
labour, fire and building inspections. All of these actions are either fully or partially completed (Table
1).
The GoB has already upgraded Chief Inspector of Factories and Establishment office to Departmentof the Inspection for Factories and Establishments (DIFE), sanctioning 679 new staff positions
including 392 new inspectors and also started organizing training program for the newly recruitedinspectors for capacity building. Bangladesh University of Engineering and Technology (BUET) andtwo private engineering firms TUV SUD Bangladesh (Pvt.) Ltd and Veritas Engineering & Consultant
on behalf of the NTC, the Accord, and the Alliance are responsible for conducting the assessments ofthe structural integrity and fire safety of RMG factory buildings. To undertake the structuralassessment of factory buildings with common approach, Guidelines for Assessment of Structural
Integrity and Fire and Safety including harmonized standards were developed the technical experts(structural engineers, fire safety experts, etc.) from the BUET on behalf of the NTC, the Accord, and
the Alliance. A review panel along with a review mechanism was also established to handle urgent
safety issues in garment factories. Finally on November 2013, assessments of the structural integrity
and fire safety of RMG factory buildings officially commenced led by engineers from BUET (ILO,
n.d.b; ILO, 2013; ILO, 2014b; ILO, 2014c). The BGMEA and BKMEA agreed to share necessary
documents related to factory design and layout with the Committee to facilitate a smooth assessment
process (ILO, 2013). A publicly accessible database of all RMG factories has also been created as aplatform for reporting labour, fire and building inspections.

138

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ICUS Report 81

Among a total of 1,400 Accord member factories, 1,250 have been inspected till March, 2015.
Moreover, among newly listed factories initial inspections of 250 factories have already completed.
As of March 2015, the Accord has received and handed over 950 Corrective Action Plans (CAPs) tothe respective factories. So far 683 CAPs have been published on the website (Bangladesh Accord,
2015c). The Alliance has already inspected all of its 647 factories (Alliance for Bangladesh, 2015).
The NTPA has set a target to inspect around 1,500 factories that are neither part of the Accord or the
Alliance with the support of the ILO. The Bangladesh University of Engineering and Technology(BUET) has inspected 471 factories, and rest of the factories in the initiative are to be inspected by
two private sector companies, TUV SUD Bangladesh (Pvt.) Ltd and Veritas Engineering & Consultant(ILO, 2014c; ILO, 2015a; ILO, 2015b). Despite such progress in the assessment, the initiative iscurrently facing a number of difficulties in conducting the inspections. The difficulties include listingwith incorrect address, factories in the list missing as a result of previous closures, and incomplete
listing of factories (Moazzem, & Islam, 2015).
4.2 Implementation Mechanism of the Structural Assessment
To undertake the structural assessment of factory buildings with common approach and standard, ILO
brought together the technical experts (structural engineers, fire safety experts, etc.) from the BUET
on behalf of the NTC, the Accord, and the Alliance. NTC endorsed ‘Guidelines for Assessment ofStructural Integrity and Fire and Safety’ including harmonized standards developed by technicalexperts from the BUET, the Accord and the Alliance. The common steps for structural assessment ofbuildings housing RMG factories by team of expert are: visual inspection for identification of existenceof any distress in the structure of a building, review of structural design drawings and soil investigation
reports to assess the current use and loading pattern (if available), and assessment of immediate threatof collapse from current building use.
Firstly the columns for brick or stone aggregate concrete in the buildings were checked and recorded.
In case of unknown column material, brick aggregate was assumed. For initial assessment of thecolumn, equivalent concrete strengths for Stone Aggregate Concrete and Brick Aggregate Concrete
were assumed 16.3 MPa (2365 psi) and 14.1 MPa (2045 psi) respectively. These two equivalentconcrete strengths were estimated on the basis of the cylinder test results conducted at BUET Concrete
Laboratory between 2003 and 2009 using equation (1). Figure 3 shows cylinder test results collectedfrom BUET database between 2003 and 2009. Then the order of reinforcement is checked with aferroscanner. In case of unknown number of reinforcement bar, it was assumed 1%.
݂௖௘௤ ൌ ‫ݐ݁ݏܽݐܽ݀݄݁ݐ݂݋݊ܽ݁ܯ‬Ȃ ͳǤ͵Ͷ‫……………ݐ݁ݏܽݐܽ݀݄݁ݐ݂݋݊݋݅ݐܽ݅ݒ݁݀݀ݎܽ݀݊ܽݐܵݔ‬..… (1)139

March 2016250

Number of Cylinders

200
150

Stone Aggregate
Number of Cylinders: 1255
Year: 2003-2009
Mean: 3963 psi
Std. Deviation: 1186 psi

100
50
0

Compressive Strength from Cylinders (psi)(a) Cylinder test results for stone aggregate
100
90

Number of Cylinders

80
70
60

Brick Aggregate
Number of Cylinders:435
Year: 2003-2009
Mean: 3288 psi
Std. Deviation: 927 psi

50
40
30
20
10
0

Compressive Strength from Cylinders (psi)(b) Cylinder test results for brick aggregate
Figure 3 Cylinder test results collected from BUET database between 2003 and 2009140

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ICUS Report 81

For the assessment of immediate threat of collapse from current building use, the surveyors highlighted
key columns and carried out simple calculations of working stresses to find out Factor of Safety (FOS).
The FOS is Column Ultimate Strength divided by the Column Working Stress, where Column Ultimate
Strength of the columns were calculated using equation (2) according to Bangladesh National Building
Code (BNBC) (1993) and the Column Working Stresses were calculated comparing data set values
and trigger points developed.
P� = 0.8ϕ[0.85f�� (A� − A�� ) + f� A�� ] ……………………………………………………. (2)Here,Pn = Ultimate Strength of a column
Φ = strength reduction factor (= 0.7)f́c = compressive (cylinder) strength of concrete
Ag = gross area of concrete section
Ast = area of reinforcement
fy = assume 40 ksi (276 MPa) for steel before 2005 and 60 ksi (414 MPa) for steel after 2005
Based on FOS, four color codes have been proposed to be used indicating the required actions withincertain time frame. After assessment if any factory is notified as hazardous, the respective assessment
teams let the review panel of Bangladesh government know about the factories to carry on further
assessment by inspection team and take final decision regarding the closure of the factory. Table 1
shows the color codes based on FOS of columns along with required actions within time frame.

141

March 2016

Table 2: Color codes based on FOS of columns along with required actions within time frame
structural assessment of buildings housing RMG factories
Factorof
Safety

Color

(FOS)

codes

Description

Required action

Time frame ofactionofcolumnRequirecarefulreview.

Take actions to increase
Critical
Below
1.25

visible FOS by reducing load lessdefects resulting in than the minimum load onRed

immediate danger any floor, i.e. 1kN/m² ortostructureand 20psf. If FOS is still below

workers.

1.25, then evacuate thefacility

Start

Detailed

Engineering
Assessment (DEA)
immediately.

immediately

considering expert opinion.
No

reasontosuspendSignificant visible operations in the facility.
Betweendefects

with

1.50 and Amber

immediate danger subject to agreement to

1.25

to

structureno Production may continue

Require DEA within
six weeksor address issues raised andworkers.

actions prioritized locally inreport.

LimitedvisibleBetweendefects

1.86 and Yellow

immediate danger

1.5

to

structure

workers.

Betterthan 1.86

142

with

no
or

Production may continue
subject to agreement to Actions and core test
address issues raised and within 6 months
actions prioritized in report.

No critical visible Generally all clear subject
defectsor to agreement to address
Greenstructures and no prioritized comments.
visible immediate
Production can continue.
risks to workers.

No

immediateactions required.

BNUS Annual Report-2015

ICUS Report 81

Requirement of Detailed Engineering Assessment is decided based on FOS values of factory buildings.
Other issues triggering DEA are: concerns with structural issues, i.e. extensions, lateral system, flat
plate punching capacity and slender columns, and state of documentation and approvals. Core tests are
essential actions for factory buildings falling under red, amber and yellow category to gradually
improve the state of building and reach to green category. For the purpose of core test at least four,
three inch diameter core samples have to be collected and tested, and ACI 562 (2013) will be used toestimate equivalent concrete strength from those core data.
After each inspection, preliminary assessment reports are prepared including the findings along withrequired recommendations for the building owner and user according to the assessment results, i.e.
Detailed Engineering Assessment (DEA) of the building involving soil investigation, other nondestructive tests and 3D building modeling.
4.3 Findings from RMG Factory Buildings’ Structural Assessments
Starting from June 2013 until February 2015, 4552 core samples of 825 factory buildings werecollected and tested at BUET’s Concrete Laboratory. Figure 4 shows year wise distribution of thebuildings along with their storey numbers from which core samples are tested at BUET. Out of these825 factory buildings, 12 are built before 1980, 198 are built between 1980 and 2000 and the rest after
2010. Approximately, 52% of those factory buildings are constructed after 2005. Figure 5 shows
representative of factory buildings by their construction year. This represents the types of the factorybuildings constructed at different time frames. Again, Figure 6 shows distribution of these core test
results. Out of these data, 2673 are of brick aggregate with mean strength of 2805 psi (19.3 MPa) andstandard deviation of 1231 psi (8.5 MPa), and 1823 are of stone aggregate with mean strength of 3312
psi (22.8 MPa) and standard deviation of 1320 psi (9.1 MPa).

143

March 2016

Number of Buildings140

1961-1970120

1971-1980100

1981-1990

80

1991-2000
2001-2010

60

>2010

40

Unknown

200Construction Year of the Factory Buildings

Figure 4: Year wise distribution of factories from which cores are collected(a) Construction Year: 1984

144(b) Construction Year: 1992

BNUS Annual Report-2015

ICUS Report 81(c) Construction Year: 2002(d) Construction Year: 2012

Figure 5: Representative of Factory Buildings by their Construction Year
800
700
Number of Cores

600
500

All Aggregate
Number of Buildings: 825
Number of Cores: 4552
Mean: 3009 psi
Std. Deviation: 1290 psi

400
300
200
100
0

Compressive Strength from Cores (psi)(a) Core test results for all aggregates
450

Number of Cores

400
350
300
250

Brick Aggregate
Number of Cores: 2673
Mean: 2805 psi
Std. Deviation: 1231 psi

200
150
100
50
0

Compressive Strength from Cores (psi)(b) Core test results for brick aggregate
145March 2016

300

Number of Cores

250
200

Stone Aggregate
Number of Cores: 1823
Mean: 3312 psi
Std. Deviation: 1320 psi

150
100
50
0

Compressive Strength from Cores (psi)(c) Core test results for stone aggregates
Figure 6: Core tests performed at BUET Laboratory between 2013 and 2015
Figure 7 shows the structural assessment results conducted by different team and Table 3 shows
Review Panel decisions to different cases. A total 65 factories were referred to Review Panel, out of
which 29 factories located in 12 buildings were closed, 17 factories located in 10 buildings werepartially closed and 19 factories located in 12 buildings were allowed to operate (Table 3). Till March
2015, summary reports of 474 RMG factories assessed by the Accord were available in DIFE website,
among which majority (274) fall under amber category, and 11 fall under red category (Figure 7). The
Accord brought 38 immediate risk cases to the review panel, elected to fully close eight factories,
partially close 24 and allow six to operate with reduced loads (Table 2). Again, till March 2015,
summary reports of 122 RMG factories assessed by the Alliance were available in DIFE website,
among which majority (93) fall under amber category, and nine fall under red category (Figure 7). The
Alliance brought 25 immediate risk cases to the review panel, elected to fully close four factories,
partially close eight and allow 13 to operate with reduced loads (Table 2). Till December 2014,assessments of 618 factories have been conducted under the National Initiative by BUET covering 471
factory buildings. Among those, majority of the buildings (279) fall under green category, and four
fall under red category (Figure 7). Among the immediate risk cases two were brought to the Review
Panel which elected fully close one factory and partially close one (Table 2).

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300

No. of Factories

250
200
Green
Yellow

150

Amber
Red

100
50
0

NTC

AccordAlliance

Figure 7: Structural assessment results by different team
Table 3: Review Panel decisions to different cases of Building Assessment
NTC
No.

Decisionoffactor

AccordAlliance

Total

No. ofNo. ofNo. ofNo. ofNo. ofNo. ofNo. ofNo. ofBuildinfactori

Buildinfactori

Buildinfactori

Buildin

gs

es

gs

es

gs

es

gs

ies

worke
rs
affected

Referredto

Review

2

2

38

18

25

14

65

34

20724

1

1

8

5

8

4

17

10

1530

1

1

24

9

4

2

29

12

15093

0

0

0

0

0

0

0

0

0

Panel
Partially closed
ClosedDecisionpending147

March 2016

Inspecti
on

0

0

0

0

0

0

0

0

0

0

0

6

4

13

8

19

12

4101

pending
AllowedoperationSource: Adopted from DIFE, 2014
4.4 Recommendation Regarding Structural Assessment
According to the assessments by different parties, the common problems faced by the factories
regarding safety hazards are: lack of fire doors and fire exits, inadequate fire alarm systems, inadequate
fire separations and protected exits, lack of lateral stability in structure, lack of accurate structural
drawing, inadequate space for electrical installations (i.e. substations), etc. To make the weak factorybuilding resilient by removing the problems, the Corrective Action Plan, Detailed Engineering
Assessment and Retrofitting have to be undertaken immediately in accordance with the initialassessment report under the NTC.
4.4.1 Corrective Action Plan (CAP)
Corrective Action Plan (CAP) is the plan for action to be prepared by each factory to address andcorrect the problems found out in the initial structural assessment of the factory building. It is very
important to eliminate or reduce the problems within significant extent to ensure structural safety.
Figure 7 shows comparative status of different issues of Accord, Alliance and NTC and Figure 9 shows
the Assessment Workflow of Alliance. The Accord and The Alliance have already started this process.
By now 598 CAP have been approved by Accord (Bangladesh Accord, 2015b). All factories under the
Alliance are now in the process of addressing safety concerns and updating safety equipment and close
to 300 factories have approved CAPs (Alliance for Bangladesh, 2015). Alliance has also published a
protocol regarding this issue (Alliance for Bangladesh, 2014).

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Figure 9: Assessment Workflow of Alliance (Source: Alliance for Bangladesh, 2014)
In contrary, no CAP has been prepared under National Initiative by now. Recently a task force has
been formed at the beginning of January 2015 headed by Inspector General (Additional Secretary) of
DIFE along with two professors from BUET, one director from RAJUK, and one director from Fire
Service and Civil Defense (FSCD). The Terms of Reference (ToR) includes regular inspection of thefactory buildings to inspect whether the factories follow the recommendations accordingly, Detailed
Engineering Assessment (DEA), and preparation of CAP. The time limit has been bound to 30 March,2015 for short listing of the firms or companies to undertake the activities.

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NTC has also approved a CAP process for the NTC assessed factory buildings composed of five main
steps. Firstly, the inspection reports will be shared with factory owners to propose an outline CAP andfirm for DEA (within the short-listed DEA firms by the DIFE Task Force) after review of theinspection report within maximum two weeks. Secondly, the outline of the CAP will be approving
with two weeks through joint meeting between Factory Technical Team and the Initial Assessment
Team. Thirdly, the approved firm will conduct DEA to prepare report containing detail remediation
scheme within six to twelve weeks and submit it for review and comments by the DIFE Task Force.
Fourthly, the DIFE Task Force will review the DEA along with remediation scheme and sendcomments to the factory owner within two weeks after receiving the DEA report. After revision of
DEA and remediation scheme by the approved firm, it will be submitted to DIFE Task Force for final
approval within maximum two weeks.
4.4.2 Detail Engineering Assessment (DEA)
Detail engineering assessment is required to have in-depth understanding of the condition of thestructure. It also identifies inadequate structural members (if any) with respect to capacity as per code.
In addition to that the condition of the structure can be assessed for different loading conditions. As
per Alliance, Accord, and NTC guideline (NTPA, 2013) DEA is required if the visual or initialassessment found structural distress in main load-carrying members, apparently inadequate main
structural members for both vertical and lateral load, or extension beyond design drawing or
permission. Accord (2014) and Alliance (2014) have published their own protocol regarding DEA.
The typical Steps for the assessment are shown below. The steps may vary according to the level ofassessment and information available.
 Prepare As-built Architectural and Structural drawings, if not available already. The as-built
drawing shall show the structural, non-structural elements with dimensions at all levels,
foundations and framing on plan, section and elevation, and cross-sectional drawings showing
reinforcements in foundations, columns, beams, slabs etc. If as-built drawings are available –verify if it truly represents the structure. As-built drawing shall be prepared/ checked as per
NTC Guideline (NTPA, 2013)
 Scanning of rebars in main structural elements of lower tiers to confirm as-built condition.
 Confirm bar size by drilling 50mmx 50mm holes at rebar location.
 Arrange confirmatory soil test (2 to 3 borings).
 Spot check of foundation by excavation, if necessary.
 Identify causes of any physical distress, dampness or any other abnormalities and suggest
remedial measures.
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 Work on specific items of concern identified in the initial structural assessment report Identify any overloading, additions, extensions, presence of water tanks, towers. Study theireffect on the structure and suggest remedial measures.
 Arrange for core test by taking 4 Nos. 3 inch cores (preferably from columns) to assess in situ
strength ensuring sample reliability, testing of cores in approved laboratories only, and properinterpretation of core test results considering various factors as per ASTM C42-90.
 Use ACI 562 to find equivalent concrete strength to be used in design checking
 UPV tests may also be conducted with proper calibration.
 Prepare structural model as per As-built drawing using appropriate software by following thestandard practice and building code.
 Obtain reliable data on steel grade or arrange testing of steel rebar (if possible) or assume 40
grades conservatively for using in all analysis/design adequacies.
 Use loading and Load factors as per standard (NTPA, 2013).
 Check strength and serviceability requirements as per Bangladesh National Building Code(BNBC, 1993).
 Make recommendation(s) based on results of DEA– including restriction of loading, restriction
on vertical extension.
 In case of deficiency in structural integrity of the structure(s), appropriate retrofitting scheme is
to be designed.
 Prepare Load Plan and arrange posting of load plan and approve it.
 Submit report for review by the Engineering Team4.4.3 Retrofitting
Retrofitting is the modification of existing structures to make them more resistant and safe. In case offactory buildings, retrofitting will have to be carried out as per the DEA. The DEA of factory buildings
will incorporate a full structural evaluation of the building, as well as investigation of ways to improve
the factory buildings based on several defining criteria (Accord, 2014). In case of retrofitting, therequirements of BNBC are to be adhered to as much as possible, although it recognized that in somecases a fair judgment must be made as to how much a building can be improved based on its existing
condition, as well as how economical it will be to satisfy every design criteria as stipulated by code
requirements. The overall strategy will be generally as follows based on a hierarchical principle ofincreasing compromises:a) Follow strictly the code design requirements to assess the actual deficiency of the building underanalysis.
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March 2016b) Determine all possible requirements, and which compliant factors can be relaxed in order to achievea minimum level of compliance of another factor which does not comply (for example, the relaxationof floor loading in order to achieve a reasonable level of punching shear resistance when taking into
account lateral loads which cause unbalanced forces within the structural system)c) Propose a comprehensive remedial plan based on the extent of works and the practicality of carrying
them out cost-effectively. Prepare alternative retrofitting schemes to remedy the structural deficiency.
Discuss with the owner about construction issues and cost. Decide the most optimum retrofitting option.
d) Submit Retrofitting Scheme for review by the Assessment Team.
e) Supervise retrofitting work during construction for quality control and certify the structural
integrity/safety after construction as per the provision of the Remediation and Oversight Protocol.
In some cases, situation may arise at which the results of the analysis may have the possibility ofrendering certain buildings completely unfit for purpose, and the extent of remedial works may be toomuch and too complicated to implement. In such cases, it should be decided whether or not partial orcomplete demolition and reconstruction should be considered as a single viable option.
5. Conclusions:
There is no denying that Bangladesh has progressed a lot since two years after Rana Plaza collapse interms of achieving workplace safety compliance issues in RMG industry, under three plans of actions- National Tripartite Action Plan (NTPA), the European Union Sustainability Compact, and the UnitedStates Trade Representative (USTR) Plan of Action. Among 25 commitments under the National
Tripartite Plan of Action on Fire Safety and Structural Integrity (NTPA), 16 have been fully or
substantially completed and nine have been partly completed. Among a total of twenty nine listed
activities in the EU Sustainability Compact, 15 actions have been fully or substantially completed, 13
actions have been partly completed, and one action regarding encourage retailers and brands to adopt
and follow a unified factory audit code of conduct in Bangladesh has not been initiated yet. The UnitedStates Trade Representative (USTR) proposed a sixteen-point action plan, where substantial progresshas been made in regards to twelve of the actions and greater progress is required in regards to four
actions.
In all three plans of actions, structural assessments of buildings housing RMG factories have been
given importance, with regard to which substantial progress has been made, i.e. up gradation of Chief
Inspector of Factories and Establishment office to DIFE, sanction of 679 new staff positions including
392 new, organization of training program for capacity building of the newly recruited inspectors,
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development of Guidelines for Assessment of Structural Integrity and Fire and Safety including
harmonized standards, establishment of a review panel along with a review mechanism to handle
urgent safety issues in garment factories, initiation of assessments of the structural integrity and fire
safety of RMG factory buildings, and creation of publicly accessible database of all RMG factories asa platform for reporting labour, fire and building inspections. Till December 2014, assessments of 618
factories have been conducted under the National Initiative by BUET covering 471 factory buildings.
By March 2015, assessment of approximately 1500 factories have been done among 1600 factories by
the Accord which houses approximately 1.9 million workers and 507 factory assessment summary
reports are available in DIFE website which are housed in 474 buildings. To date, every factory
producing for Alliance Members, i.e. 647 factories have been inspected which houses approximately
1.1 million workers. Among these 122 factory assessment summary reports are available in DIFE
website which are housed in 113 buildings.
Still there are nearly 1000 factories remaining for assessment under national initiative. The reason forsuch delay is that NTC is facing a number of difficulties in conducting the inspection. The maindifficulty remains in the list of factories provided by BGMEA and BKMEA, based on which theassessments have been carried out. The list contains factories with wrong address causing delay inlocating the factories and some enlisted factories do not even exist. Moreover, there remain somefactories which are not member of any organizations such as BGMEA and BKMEA. So, the list offactories is required to be updated and verified internalizing the remaining factories to ensure quickcompletion of the assessment.
On the other hand, structural assessment alone is not enough to ensure a safe working environment for
all in the sector. The weak factory buildings are required to be strengthened to ensure resilience throughdifferent initiatives, i.e. preparation on Corrective Action Plan based on the assessment findings,
Detailed Engineering Assessment as proposed in the initial assessment report, and retrofitting as
requirement. The Accord and the Alliance have showed much progress in preparation of CAP, but no
CAP has been prepared under National Initiative so far. So, immediate actions are required by NTC to
address the issues.
After Rana Plaza tragedy, there was a strong apprehension that RMG sector would confront achallenging time, but the sector has performed better than other competing countries in post Rana Plaza
Tragedy period. In the long run, the challenge is to maintain momentum already created for achieving
sustainability in RMG sector in Bangladesh. The future competitiveness in the sector will depend on
adjustment with rising operational cost towards maintaining compliance. If the industry wants to153

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achieve the export target of USD $50 Billion by 2021, all the factory buildings identified to be
structurally unsound will have to be structurally strengthened within the next five years.
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PART-VIIICOMPARISON BETWEEN WEAK AND STRONGGROUND MOTIONS AT SELECTED LOCATIONSOF BANGLADESHBANGLADESH NETWORK OFFICE FOR URBANSAFETY (BNUS), BUET, DHAKA

Prepared By: Md Samsur Rahman
Mehedi Ahmed AnsaryMarch 2016

DATA COLLECTION AND ANALYSIS

Damage in recent earthquakes showed that local site conditions have a significant effect on groundmotion. Site response studies play an important role in seismic microzonation studies. The applicationof microtremor is to determine dynamic characteristics (predominant frequency and amplification
factor). Microtremor measurements are usually used in site characterization due to their simplicity,
low cost and minimal disturbance to other activities.
In the traditional spectral ratio method, ‫ܪ‬ௌ /‫ܪ‬௥ , site and source effects are estimated from observation

at a reference site. In practice, adequate reference site are not always available especially in flat areas
where exposed rock is not available. Therefore, methods have been developed that do not needreference sites (Bard 1994). Several recent applications of this technique have proved to be effectivein estimating predominant frequency (Field and Jacob 1993; Ohmachi et al. 1994) and amplification
factors (Lermo and Chavez-Garcia 1994; Konno and Ohmachi 1995).
Several methods have been proposed for spectral calculation of ground motions including
microtremor. Fourier spectrum is the most convenient one that is used widely. Some investigations
showed that different methods give similar results (Dimitriu et al. 1998). However some researchers
declare that a suitable spectral method gives more reliable results (Ghayamghamian and Kawakami1997). That’s why five segments of spectra have been selected to compute the mean segmental crossspectra. Standard deviation of mean has also been calculated to show the deviation of mean value
from Fourier spectra in East-West and North-South direction. Among these locations, empirical soil
correlations developed by Ansary et al. (2010) and other empirical correlations (After TC4, ISSMFE,
1993) have been used to convert SPT-N value to shear-wave velocity.
STUDY LOCATIONS
29 SMAs have been deployed by BUET from 2003 to 2005 and all these digital seismic measuring
device are located free-field stations around Bangladesh as shown Figure 3.1. Out of these 29
locations, 6 are selected for this research. Microtremor Array of six points have been collected.

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Figure 3.1 Location of Digital Seismic Measuring Devices (29-ETNA) in and around of Bangladesh
Location of Digital Seismic Measuring Device free-field Station (ETNA) as shown Table.1
Table 1 Location of Digital Seismic Measuring Device Station (ETNA)
SL.No

Model

Location

LatitudeLongitude*1

ETNA (BUET)

LGED, Bogra

23.320N

88.450E **2

ETNA (BUET)

LGED, Natore

23.220N

88.350E *3

ETNA (BUET)

Jamuna Bridge West-End

23.280N

88.250E*4

ETNA (BUET)

Jamuna Bridge East-End

23.250N

88.200E *5

ETNA (BUET)

LGED, Mymensingh

25.430N

90.650E
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SL.No

Model

Location

LatitudeLongitude*6

ETNA (BUET)

BUET-Dhaka

23.920N

90.250E *7

ETNA (GSB)PWD Office, Satkhira23.850N

88.520E **8

ETNA (GSB)

PWD, Ashkona-Hajji camp

23.710N

90.380E **9ETNA (GSB)

Pollice Staff College

23.720N

90.250E

10ETNA (GSB)

GSB-Dhaka

23.750N

90.350E

11

ETNA (GSB)

GSB-Chittagong

22.150N

91.800E

12

ETNA (GSB)

PWD, Cox’s-bazar

21.420N

91.890E

13

ETNA (GSB)

PWD, Bandarban

22.250N

92.320E

14

ETNA(JIDPUS)

PWD, Rangamati

22.720N

92.380E

15

ETNA (GSB)

PWD, Sunamganj

25.070N

91.320E

16

ETNA (GSB)

PWD, Sylhet

25.150N

91.250E

17

ETNA (GSB)

PWD, Moulvibazar

24.350N

91.720E

18

ETNA(JIDPUS)

PWD, Comilla

23.220N

91.350E

19

ETNA (GSB)

PWD, B.Baria

23.920N

91.250E

20

ETNA (GSB)

PWD, Kishoreganj

24.350N

90.920E

21

ETNA (GSB)

PWD, Netokona

24.720N

90.650E

22

ETNA(JIDPUS)

Haluaghat, Mymensingh

25.050N

90.250E

23

ETNA(GSB)

PWD, Jamalpur

25.150N

90.120E

24

ETNA(GSB)

PWD, Rangpur

25.800N

89.200E

25

ETNA (GSB)

PWD, Lalmonirhat

25.900N

89.350E

26

ETNA(JIDPUS)

PWD, Kurigram

25.600N

89.800E

27

ETNA (GSB)

PWD, Panchagarh

26.150N

88.250E

28

ETNA(GSB)

PWD, Meherpur

23.750N

88.620E

29

ETNA(JIDPUS)

Ruppur, Pabna

23.420N

88.750E*Microtremor observations have been made162

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SOME EARTHQUAKES HAVE AFFECTED BANGLADESH OF THE LAST DECAYOn May 25, 2015 the major “Nepal earthquake” occurred in Pokhara province, Nepal. Its Magnituteis 7.8 and distance 741 km from Dhaka, Bangladesh. This earthquake been recorded by the free-fieldstations at Kurigram, Bogra, Natore, Sylhet, Ruppur at Pabna, Jamuna Bridge at Sirajganj, Police Staff
College, at Mirpur, and BUET-Dhaka at 12:15:45 hrs BST (06:15:45 hrs GMT, May 25, 2015). The
maximum acceleration of this earthquake recorded in Bogra with a values of 23.56 cm/sec.2 in Eastwest direction. Some major earthquakes that have affected Bangladesh recently is shown in Table 2
Table 2 Some earthquakes that have affected in and around BangladeshDate14-02-2006
16-11-2006
11-09-2010
18-03-2012
25-04-2015

Name

Epicentre

Magnitude (M)Sikim Earthquake

Bihar, India

5.9

Jessore, Bangladesh

5.5

Shillong Plateau

5.1

Jantia Hill, Assam

7.1

Pokhara, Nepal

7.8

Bengal Earthquake
Assam Earthquake
Sikim Earthquake
Nepal Earthquake

METODOLOGY OF EARTHQUAKE AND MICROTREMOR DATA ANALYSIS
At first, site is selected for data collection. There are six selected locations Bogra, Natore, Jamuna Bridgeat Sirajganj, Haji-Camp at Ashkona, Police Staff College at Mirpur and BUET. Both microtremoe andearthquakes data have been recorded along three directions (x, y and z directions). Fast Fourier
Transformation (FFT) along x, y, and z directions and their H/V Ratio analysis with frequency are
conducted. Ultimate target is to etimation of predominant frequency of these site from HVR of
Microtremor and Earthquakes analysis. The following flow chart (Figure 2) shows the outline of the
Metholodogy.

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Figure 2 Flow Chart for Microtremor and Strong Motion Data Analysis.

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MICROTREMOR AND EARTHQUAKE DATA ANALYSIS, RESULTS AND DISCUSIONSThe transfer function of the shear wave (the surface motion versus the incidental motion at depth) has
been calculated using the soil models. For the calculation of transfer function of shear-wave and adamping ratio of 2% has been used, assuming input motion at the outcrop. Comparision between
predonant frequency and H/V ratio six selected locations at Bogra as shown Figure 4.1. Similarly
Natore, Jamuna Bridge East at Sirajganj, Haji-Camp at Ashkona, Police Staff College at Mirpur and
BUET-Campus as shown Figure 4.2 to 4.6
Figure 4.1 and Figure 4.2 show the typical graphs for comparison of amplitude ratio between
predominant frequency and H/V ratio of microtremor and earthquake. On the other hand, microtremorand earthquake H/V ratio curve has been found from the Horizontal to Vertical spectral ratio (H/V) of
Fourier spectra.
From the comparison of microtremor and earthquake, four types of characteristics curves have been
observed. These curves are classified as similar, dissimilar, right side shifted and left side shifted andcompared to the microtremor and earthquake H/V ratio curve. Among four models two transfer
function have been shifted in the right side of microtremor and only one has been shifted in the left
side. There are two sites curves have similar pattern. The rest one site have been found where no
similarity between microtremor within earthquake H/V ratio.
Figure 4.1 shows the comparison of amplitude ratio between predominant frequency and H/V ratio of
microtremor and earthquake microtremor at Bogra. The amplitude ratio of earthquake is similar to
microtremor H/V ratio. However, peak of H/V has been moved into right side slightly. The amplitude
ratio of both curves is around 3.36 and 6.67. The predominant frequency of microtremor is 1.68 Hz
and H/V ratio is 3.36. Similar curves between earthquake and microtremor have been found in four
locations which are shown in Figure 4.1.
Figure 4.2 demonstrates that the peak amplitude ratio has been moved toward right side of microtremor
at Natore. But, the peak value of transfer function is lower amplified than microtremor H/V ratio. The
predominant frequency of microtremor is 1.07 Hz and H/V ratio is 3.68. On the other hand, peak H/Vratio of earthquake is 6.67 and predominant frequency is 2.10 Hz. The similar types of right shifted
and lower amplified locations have been observed.
Figure 4.3 shows that amplitude ratio of microtremor is higher than earthquake at Jamuna Bridge East
site. The predominant frequency of microtremor is 1.04 Hz whereas the earthquake is 0.83 Hz. The
H/V ratio of microtremor is 4.66 and earthquake is 8.44.The similar pattern of curves between
microtremor and earthquake have been observed.
The dissimilarity between earthquake and microtremor H/V ratio has been found in Figure 4.4 at
Ashkona Haji-Camp, Dhaka. The predominant frequency and amplitude ratio of microtremor is 2.84
165

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Hz and earthquake is 1.71 Hz where as H/V ratio is 3.02 and 11.41. Figure 4.5 demonstrates that
amplitude ratio of transfer function is right shifted at Police staff college, Mirpur-Dhaka. The
predominant frequency and H/V ratio of microtremor is 1.35 Hz and earthquake is 1.25 Hz. The H/Vratio of microtremor and earthquake have been found 3.24 and 7.65.
The similar predominant frequency but higher amplification has been found in Figure 4.6 at BUETCampus. The predominant frequency in microtremor is 1.21 Hz and earthquake is 0.90 Hz. The peak
H/V ratio of microtremor is 5.46 Hz whereas the earthquake is 6.32..
From these result, it can be said that although amplitude values of the ratios are close, the predominantfrequency for the two cases differs slightly. The reason of this difference is that microtremor consistsof different types of waves, but the earthquake based on shear-wave velocity only. Microtremor results
may be more similar pattern of earthquake but more different its H/V ratio. Compare of average andsmoothed HVR in Microtremor and Earthquake at Bogra as shows Figure 4.1 and Similarly at Natore,
Jamuna Bridge East at Sirajganj, Haji-Camp at Ashkona, Police Staff College at Mirpur and BUETCampus as shown in Figure 4.2 to 4.6

20

H / V Ratio

10

1

MT1 (date:21.11.2014)
EQ1 (date:14.02.2006, M=5.3 D=227 km)
EQ3 (date:16.11.2006, M=5.5 D=204 Km)
EQ2 (date:23.02.2006, M=4.7 D=170 Km)
EQ4 (date:25.04.2015, M=7.9 D=741 Km)

0.1
0.1

1

10

20

Frequency (Hz)Figure 4.1 Compare of Average and Smoothed HVR in Microtremor and Earthquake at
Bogra LGED office, Bogra.

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20

H / V Ratio

10

1MT2 (date:21.11.2014)
EQ1 (date:14.02.2006, M=5.3 D=227 Km)
EQ2 (date:23.02.2006, M=4.7 D=211 Km)

0.1
0.1

1

10

20

Frequency (Hz)Figure 4.2 Compare of Average and Smoothed HVR in Microtremor and Earthquake at
Natore20

H / V Ratio

101

EQ1 (Date:14.02.2006, M=5.3 D=227 km)
EQ3 (Date:27.07.2008, M=4.8 D=247 Km)
MT3 (Date:24.11.2014)

0.1
0.1

1

10

20

Frequency (Hz)Figure 4.3 Compare of Average and Smoothed HVR in Microtremor and Earthquake in the
Jamuna Bridge East at Sirajganj

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H / V Ratio

10

1

MT4 (17.11.2014)
EQ2 (11.09.2010, M=5.1 D=278 Km)
EQ3 (18.03.2012, M=4.9 D=220 Km)

0.1
0.1

1

10

20

Frequency (Hz)Figure 4.4 Compare of Average and Smoothed HVR in Microtremor and Earthquake in theHaji-Camp at Ashkona.

20

H / V Ratio

101MT5 (16.11.2014)
EQ2 (11.09.2010, M=5.1 D=278 Km)
EQ3 (18.03.2012, M=4.9 D=220 Km)
EQ4 (25.04.2015, M=7.9 D=741 Km)

0.1
0.1

1

10

20

Frequency (Hz)Figure 4.5 Compare of Average and Smoothed HVR in Microtremor and in the Police Staff
College at Mirpur.

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20

H / V Ratio

101

MT6 (Date:16.11.2014)
EQ2 (Date:18.09.2005, M=5.1 D=250 Km)
EQ3 (Date:18.03.2012, M=4.9 D=220 Km)
EQ4 (Date:25.04.2015, M=7.9 D=741 Km)

0.1
0.1

1

10

20

Frequency (Hz)Figure 4.6. Compare of Average and Smoothed HVR in Microtremor and Earthquake at
BUET-Campus.

VULNERABILITY ASSESSMENT
Earthquake and Microtremor data analysis and their vulnerability assessment of selected
locations. Microtremor observation and earthquake data has been carried out at sixt selected
locations of Bangladesh which has been discussed in Chapter 3. The Horizontal to Vertical
spectra ratio (H/V) of these locations have been compared with the predominant frequency of
selected site in EW and NS direction, respectively. The mean square root of H/V ratio (RM)
obtained from microtremor observations and earthquakes data analysis and found that which
nearby soils has been compared with Fourier spectra at the sites soils. The damage assessmentof consolidated soil using Nakamura’s Seismic Vulnerability Index (Kg) has been included inarticle 4.3.1.

169March 2016

Seismic Damage assessment of soil using Nakamura’s Technique
Seismic vulnerability index (Kg) is an index indicating the level of vulnerability of a layer of soil todeform. Therefore, this index is useful for the detection of areas that are weak zone (unconsolidated
sediment) at the time of occurrence of earthquakes. Some studies like Daryono (2009) and Nakamura(2000) showed a good correlation between seismic vulnerability index (Kg) and the distribution ofearthquake disaster damage. This index is obtained from the peak value of HVSR squared, divided by
the value of the predominant frequency. For this research area (Kg) values for six locations are shownin Table 4.1.
The seismic vulnerability index has been classified into four major types. Article 2.9.1 Vulnerability
Index (Kg) of Loma Preta Earthquake (after Nakamura et al., 1990). These are Low (0-5), Moderate(6-10), High (11-20) and Very High (>20). Table 4.1 demonstrates the highest (Kg) value in the
Jamuna Bridge East at Sirajganj, Police Staff college at Mirpur and Haji-Camp at Ashkna. Most of
the zones having higher Vulnerability Index (Kg) are situated in reclaimed areas
Table 4.1 Damage assessment of site soil using Nakamura’s empirical formula

SL.
No

1
2

3

4

5

170

Predomina
ID LocationtnFrequency(MT),
Fg(Hz)

Predominan H/Vt Frequency Ratio(MT)(EQ), Fg(Hz),Ag

H/V Vulnerabilit Vulnera
bilityRatio y Index,
���Index,
(EQ),
�� =
���
��
Ag
�� = ,
��
(MT)
(EQ)

MT1 LGED& Office at
EQ1 Bogra

1.68

2.06

3.36

9.02

MT2 LGED& Office at
EQ2 Natore

1.07

2.09

3.68

6.56

1.77

4.66

MT3 Jamuna& Bridge
EQ3 East Sideat
Sirajganj
MT4 Haji& Camp at
EQ4 Ashkona
MT5& Police
EQ5 Staff
Collegeat Mirpur

1.04

6.72

12.65
11.52

39.49
20.59

1.45

2.99

7.75

Moderat
e to
Very
High

41.42

Moderat
e to
High

39.74

Mediumto High

10.64
1.35

1.48

3.24

7.67

7.77

Low toModerate
Low toModerat
e

74.97
20.88

0.84

Remarks

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SL.
No

6

Predomina
ID LocationtnFrequency(MT),
Fg(Hz)MT5&
EQ6

BUETCampus

1.21

Predominan H/Vt Frequency Ratio(EQ), Fg
(MT)
(Hz)
,
Ag
2.06

3.41

H/V Vulnerabilit Vulnera
bilityRatio y Index,
���
(EQ),
Index,
�� =
���
�
Ag
�
�� = ,
��
(MT)
(EQ)
4.16

9.61

8.40

Remarks

Low toModerate

Table 4.1 shows the classification of vulnerability site at six locations using Nakamura’s Vulnerability
Index (Kg). Figure 4.3 demonstrates three major and three minor in between vulnerability type. The
number of low vulnerability type locations, which is 3, is the most common among 3 locations. The
second most predominant number of vulnerability type is moderate type which varies between 10 and
15. The number of very high type vulnerable site is Jamuna Bridge East site at Sirajganj, Haji-Camp
at Ashkona and police staff college at Mirpur, Dhaka.
To further ensure this, research on the acceleration of seismic waves in the basement need to be
estimated. Vulnerability Index together with the acceleration of seismic waves in the basement has
been suggested by Nakamura (2000) to calculate the value of shear strain (γ) of surface soil layers.
Damaging earthquakes will occur when the limits are exceeded due to the shear strain deformation
surface layer of soil. Soil is plastic at γ = 1000 x10�� , whereas at γ > 10.000 x 10�� , the ground will

deform. Only predominant frequency is not effective to classify a site due to Nakamura’s vulnerability
index. Both predominant frequency and H/V ratio are required to estimate vulnerability type.
CONCLUDING REMARKSThis chapter shows the comparison of theoretical analysis with microtremor observation andearthquake data analysis results. The theoretical analysis and has been compared with the microtremorand earthquake ground motion of H/V ratio. From these result, it can be said that although amplitude
values of the ratios are close, the predominant frequency for the three cases differs slightly. The reasonof this difference is that microtremor and earthquake consists of different types of waves, but the H/Vratio based on shear-wave only.
In addition to this, the seismic vulnerability of soil has been analyzed at the study points using the
Nakamura’s (2000) Vulnerability Index (Kg). The Vulnerability Index of six selected locations has
been classified into four types which are Low, medium, high and very high vulnerable. Most of thereclaimed sites fall within high medium to high vulnerability range.
.

171