seismic vulnerability assessment of school...

SEISMIC VULNERABILITY ASSESSMENT of

SCHOOL BUILDINGS: GAZA STRIP SCHOOLS as

a CASE STUDY S. M. Shehada 1*, S. Q. Shurrab 2

1*,2 Department of Civil Engineering, Islamic University of Gaza, Gaza Strip, Palestine

Abstract:

This study introduces a new approach for seismic assessment of existing school buildings. The proposed

approach requires minimum human effort as it can be implemented by a small team of technical

construction background. The approach is based on EMS-98 scale in addition to rapid survey of

architectural and structural elements of existing school buildings. The study uses 64 selected public school

buildings sampled from a total of 364 schools in Gaza Strip. The results showed that 50% of the surveyed

schools are classified as Vulnerability class B, while 20 % are classified as Vulnerability Class A. The

results were verified using the ‘probability matrix damage’ approach and showed good satisfying

convergence. The results of the study are beneficial for the responsible parties who are expected to take

appropriate actions related to enhancing seismic performance of Gaza Strip schools against seismic

activities, due to the fact that these school buildings not only host about 450,000 students and teachers,

but also serve as emergency shelters for those who lose their homes as a result of political instabilities in

the region.

Keywords: Damage, Vulnerability, EMS-98, Seismic risk, structural type.

1. Introduction:

School buildings have often collapsed during

earthquakes. The 2001 Bhuj earthquake in India killed

1002 students and teachers, the 2005 Kashmir

earthquake in Pakistan killed about 19,000 children,

most of them in collapses of school buildings, and the

2008 Sichuan, earthquake in China destroyed about

6,898 schools killing thousands of students and

teachers (López et al., 2008). In Palestine, earthquakes

occur frequently where some Palestinian cities were

damaged during the past hundred years. Seismicity in

Palestine is mainly affected by the geodynamic

processes acting along the Dead Sea Transform. The

Dead Sea Transform is a left-lateral fault between the

Arabia and the Sinai tectonic plates (Al-Dabbeek and

El-Kelani, 2008, Fruend et al., 1968, Garfunkel, 1981,

Ginsburg et al., 1981, Quennell, 1959 and 1983).

Seismic vulnerability is a measure of how susceptible a

building is to damage for a given severity of the ground

shaking (Borzia, B., Pinhob, R. and Crowleya, H.,

2008). The building vulnerability is due to older

building design codes, poor design practices and poor

code enforcement (Solomn and Zheng, 2010 and

Jalayer et al., 2010).A number of procedures have been

outlined in the literature. The simplest and quickest

way, called walk-down survey, requires only

superficial data collected from a brief inspection of the

building. The number of stories, vertical and plan

irregularities, location of the building, age of the

building, its structural system and apparent material and

workmanship quality are typical parameters that are

used. The purpose of rapid evaluation is to identify or

rank highly vulnerable buildings that deserve further

investigation. The screening method is performed

without any structural analysis and takes little time to

complete. Basic structural hazard scores for various * Samir Shihada, Professor at department of Civil Engineering, The Islamic

University of Gaza, Gaza, Palestine, (e-mail: [email protected]).

Sallam Shurrab, Infrastructure Engineer at Qatar Ministry of Foreign Affairs,

Gaza, Palestine, (e-mail: [email protected]).

IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 3 Issue 10, October 2016ISSN (Online) 2348 – 7968 | Impact Factor (2015) - 4.332

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mailto:[email protected]

mailto:[email protected]

building types are provided on the Rapid Visual

Screening form (Aftabur and Shajib, 2012). More

refined methods which include detailed analysis and

take more time than Rapid Visual screening are used for

the evaluation of individual buildings only. In addition,

these methods can be used for rapid screening of

hazardous buildings (Grandori, 1982 and Yakut, 2004).

Al-Dabbeekand El-Kelani (2008) carried out a rapid

seismic vulnerability study of three Palestinian refugee

camps in the West Bank, based on EMS, 1998 and

FEMA 310 provisions. The results of the study showed

that very heavy structural and non-structural damages

to buildings in these camps are expected under the

influence of moderate to strong seismic activities. Al-

Dabbeek (2007) studied vulnerability, and expected

seismic performance of buildings in the West Bank.

Seven regions that represent the West Bank were

investigated by collecting information based on site

conditions, regularity and configuration of structural

and architectural elements of buildings, adjacency,

construction material conditions, etc. The collected data

and analysis were determined according to European

Macroseismic scale 1998 (EMS) and calibrated using

Japanese qualitative method. The results showed that

one third of the investigated buildings belong to seismic

vulnerability of class A (heavy damage), whereas about

40 percent of the buildings indicate class B (moderate

damage ( . Lazzali and Farsi (2012) used the European

Macroseismic Scale EMS-98 to define the relationship

between damage and macroseismic intensity to assess

the seismic vulnerability of buildings in Algiers area.

Results lead to the conclusion that Algiers buildings

have an average vulnerability class B. Panahi et al.

(2014) evaluated the seismic vulnerability of school

buildings in Tehran city based on the analytic hierarchy

process (AHP) and geographical information system

(GIS). The results indicated that only in 3 % of the

school buildings in the study area the destruction rate

will be very high and therefore need to be reconstructed.

Sobaih and Nasif (2012) evaluated the seismic

vulnerability of existing reinforced concrete school

buildings in Egypt using a methodology that is based

mainly on questionnaire forms and a computer program

in order to execute the methodology.

In this study, a new approach for seismic assessment of

existing school buildings in Gaza Strip has been

developed, based on European Macroseismic Scale

(EMS-98) scale and available literature and depends

mainly on rapid survey of school building architectural

and structural elements. The importance of this study

stems from the fact that Gaza Strip school buildings not

only host more than 450,000 students and teachers, but

also serve as emergency shelters for those who lose

their homes as a result of political instabilities in the

region.

2. Topology of existing school buildings in

Gaza Strip

There are 364 school buildings in Gaza Strip hosting

about 450,000 students. The distribution amongst the

directorates of Gaza Strip is shown in Table 1. These

schools are mainly administered by the Ministry of

Education and Higher Education (MEHE) and the

United Nations Relief and Works Agency (UNRWA)

and limited number of schools are considered private

schools. Gaza city, being the largest city in Gaza Strip,

holds the largest number of existing school buildings

(135 Buildings),Khan-yonis directorate includes 73

schools, Middle Area directorate includes 52 schools,

North Gaza directorate includes 60 schools and Rafah

directorate includes 44 schools. Figure 1 shows the

distribution of these school buildings in Gaza Strip

education directorates, (MEHE,2012).

Table 1: Student distribution in Gaza Strip

directorates

Directorate MEHE

students

UNRWA

students

Total

number

North Gaza 41,012 40,929 81,941

Gaza 99,435 57,615 157,050

Middle

Area 24,320 44,168 68,488

Khan-yonis 44,670 39,737 84,407

Rafah 20,236 35,156 55,392

Total 229,673 217,605 447,278


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Figure 1: Distribution of school buildings in Gaza

Strip directorates

3. School building structural systems:

Gaza Strip school structural systems fall into three

types; concrete block bearing walls, RC building

frames (Ordinary moment frames) and RC moment

resisting frames (Intermediate moment frames).

MEHE Schools

RC Building frames, which represent 78.15 % of

the total number of schools.

Concrete block bearing walls, which represent

17.23 %of the total number of schools.

Precast frames, which represent 4.62 % of the

total number of schools.

UNRWA Schools

RC Building frames which represent 70 % of

the total number of schools.

Concrete block bearing walls which represent 12

% of the total number of schools.

RC moment resisting frames which represent 18

% of the total number of schools.

4. Proposed Approach for Rapid Seismic

Survey of School Buildings

The new proposed approach for seismic evaluation of

existing school buildings is based on the European

Macroseismic Scale (EMS-98) and data collected from

field survey of school buildings. Fifteen structural and

architectural parameters that create vulnerability are

included within the survey forms. The method is

summarized in the following steps.

A. Preparing the field survey forms that take into

account the structural and architectural

parameters, which are listed below

1. Falling hazards (El.01).

2. Adequacy of entrance and distance of staircases (El.02).

3. Vulnerable sites / poor soil condition (El.03).

4. Short columns (El.04).

5. Plan irregularity in general (El.05).

6. Vertical irregularity in general (El.06).

7. Cantilever system (El.07).

8. Seismic joint (El.09).

9. Building construction material (El.10).

10. Seismic design (El.11).

11. Maintenance (El.12).

12. Large windows on one side of the classroom (El.13).

13. Standard building plans with seismic deficiencies (El.14).

14. Vulnerable forms of vernacular construction (El.15).

B. Defining school building names and their locations.

C. Selecting selected school building (64 building over Gaza

Strip), using a GIS software model.

D. In situ survey of school buildings.

E. Organizing and analyzing collected data.

F. Assigning vulnerability classes for each school

separately, according to the defined magnitude levels;

High (H), Medium (M) and Low (L).

G. Defining damage degree for corresponding vulnerability

classes of each surveyed school building.

H. Arranging expected damage grades, according to EMS-

98 scale.

Selection of school building samples for purposes

of field survey

Studying all of (364) existing school buildings in

Gaza Strip requires immense effort and long time.

GIS tool (Desktop Arc GIS software) is used in order

to locate the school building samples in each

directorate of Gaza Strip. A soil texture map

classifies Gaza Strip for six soil texture types (Figure

North Gaza17%

Gaza37%Middle

Area14%

Khanyonis20%

Rafah12%


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114

2); each soil texture is defined in specified terrain

area on Gaza Strip map. Existing school buildings

(MEHE and UNRWA administration) locations are

projected on the soil map. Then, school buildings

which are enclosed in each specific texture terrain

are listed in separate sheets (based on the

intersection between projected soil texture map and

school building locations by adopting a GIS model

as shown in Figure 3.

School buildings considered in the study

As discussed earlier, the selection is based on

building structural system, building age and

founding soil properties. Sixty four schools are

chosen as shown in Figure (4).

Assigning vulnerability classes

According to the Vulnerability Classes shown in

Table 2 (European Macroseismic Scale EMS-98),

most of Gaza Strip schools are considered as

vulnerability classes (B) to (C). For RC frame

buildings without earthquake resistant design (ERD)

and with serious defects (such as soft story, weak

columns, lack of stiffening elements, long or very

long cantilevers with heavy loads at the end, etc.),

vulnerability class (B) or even (A) may be

appropriate. Seismic vulnerability classes used in

EMS-98 scale (A, B, C, D) are assigned for each

school separately according to building structural

system. Rapid survey forms are used to assign

classes of vulnerability (see Table 3 in an appendix).

The analysis of the considered school buildings

provides the following vulnerability classes: 50% of

school buildings are classified as class (B), and

classes (A), (C) and (D) represe nt 20%, 22% and

8% respectively (As shown in Figure 5).

Figure(2) : Classification of soil texture

profile in the Gaza Strip

Figure (3) : Projection of existing school buildings

locations (vertical and horizontal coordinates) on Gaza

Strip soil texture map, using Arc GIS software (ArcGIS

9.3/9.3.1, ESRI Software, 2013)

NorthGaza

directorate

Gazadirecto

rate

Middledirecto

rate

Khanyonis

directorate

Rafahdirecto

rate

MEHE 5 10 5 9 3

UNRWA 7 8 5 7 5

17.5%

30%

14%

26%

12%

02468

101214161820

Nu

mb

er

of

scch

oo

ls

Figure 4: Selected school samples


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The information collected from the field survey

sheets is to identify most parameters that affect

identifying the attribution of the vulnerability class

(Adequacy of entrance and distance of staircases,

Short columns, Cantilever system...).The results

show that the most observed element in surveyed

schools are short columns (El.04), cantilever system

(E.07) and soft story (E.08) , (See Fig 6).

Estimate of Damage

The distribution of damage varies from directorate

to another. For each vulnerability class, the

percentages of damage grade for each of the

different degrees of macroseismic intensity is

described. According to many studies (Dabek,

2007), (Kahane, 1988)and (Yankelevsky, 2008),

Palestine could be exposed to strong earthquake

once or twice during each 50 years and the intensity

would be on Modified Mercalli of “VII” and

“VIII”).The distribution of damage degrees (D1 to

D5) for various EMS-98 intensities (V, VI, VII and

VIII) for the school buildings under study are shown

in (Fig. 7, 8and 9).

Table 2: Vulnerability Classes (European

Seismological Commission, 1998)

Class A20%

Class B50%

Class C22%

Class D8%

Vulnerability Classes of Building

Class A

Class B

Class C

Class D

Figure 5: Vulnerability classes for existing school

buildings in Gaza Strip

EL.1, 72.81%

EL.2, 89.69%

EL.3, 94.69%

EL.4, 90.63%

EL.5, 87.34%

EL.6, 85.16%

EL.7, 88.59%

EL.8, 91.09%

EL.9, 51.25%

EL.10, 79.69%

EL.11, 51.25%

EL.12, 83.44%

EL.13, 83.13%

EL.14, 85.00%

EL.15, 85.47%

0.0% 20.0% 40.0% 60.0% 80.0% 100.0%

EL.1

EL.2

EL.3

EL.4

EL.5

EL.6

EL.7

EL.8

EL.9

EL.10

EL.11

EL.12

EL.13

EL.14

EL.15

Figure 6: Fifteen structural and architectural elements

observed in existing school buildings


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EMS-98 damage probability matrix

The damage probability matrix is a matrix which

expresses the statistical distribution of the degrees of

damage for a given Macroseismic intensity (Lazzali

and Farsi, 2012). For purpose of convergence,

damage probability is generated for class (B), which

is the most dominant vulnerability class of

investigated existing school building, see Fig (10).

Conclusion:

The proposed approach for assessment existing

school building is based on simple procedure for the

evaluation of vulnerability classes and damage

distribution using a Macroseismic method (EMS-

98).

Based on the results of this study, about 70 % of

Gaza Strip school buildings are highly vulnerable to

seismic risk (categories A and B). Moreover, about

20 % are classified as category C. Therefore,

existing school buildings in Gaza Strip are

vulnerable to severe damages in case of minor

seismic activities. In addition, existing school

buildings in Gaza Strip are highly exposed to

seismic damage (EMS-98 damage grade) at low

grade, where 30.0 % of school building expected to

be classified as degree (2) damage. The most

Intensity (V)Intensity (VI)

Intensity (VII)Intensity (VIII)

0.00%

10.00%

20.00%

5 4 3 2 1

DA

MA

GE

PR

OP

AB

ILIT

Y



0.00%

20.00%

40.00%

5 4 3 2 1

Da

ma

ge

pro

ba

lity

Figure 7 :Distribution of damage degrees for

Vulnerability class (A)

Intensity (V)

Intensity (VI)

Intensity (VII)

Intensity (VIII)

0.00%

20.00%

40.00%

Da

ma

ge

pro

ba

bilit

y

Figure 8: Distribution of damage degrees for

Vulnerability class (B)



0.00%

10.00%

20.00%

5 4 3 2 1

Da

ma

ge

pro

ba

bilit

y

Figure 9: Distribution of damage degrees for

Vulnerability class (C)

Figure 10: Damage probability matrix degrees

for Vulnerability class (B)


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117

vulnerable forms of existing school building in Gaza

Strip are short columns, soft storey and adequacy of

entrance and distance of staircases. These forms tend

to increase seismic risk of school building

(Vulnerability).

References:

1- Aftabur, R. and Shajib, U., 2012, Seismic

vulnerability assessment of RC structures:

a review, Int. J Sci. Emerging Tech, 4(4),

171-177.

2- Al-Dabbeek, J. and El-Kelani R., 2008,

Rapid assessment of seismic vulnerability

in Palestinian refugee camps, Journal of

Applied Sciences, 8(8), 1371-1382.

3- Al-Dabbeek, J., 2007, Vulnerability, and

expected seismic performance of buildings

in West Bank, Palestine, The Islamic

University Journal (Series of Natural

Studies and Engineering), 15(1), 193-217.

4- Borzia, B., Pinhob, R. and Crowleya, H.,

2008, Simplified pushover-based

vulnerability analysis for large-scale

assessment of RC buildings, Engineering

Structures 30(3), 804–820.

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(EMS-98)-Working Group M.S., European

Seismological Commission, Luxembourg,

Cahiers du Center Européen de

Géodynamiqueet de Séismologie, Vol. 15.

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Age and rate of the sinistral movement

along the Dead Sea Rift, Nature 220, 253-

255.

7- Garfunkel, Z., 1981, Internal structure of

the Dead Sea leaky transform (rift) in

relation to plate kinematics,

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Prodhel, C., 1981, the structure of the crust

and upper mantle in the Dead Sea

Transform, Tectonophysics, 80, 109-119.

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earthquake engineering, Proceedings of the

Seventh European Conference on

Earthquake Engineering, Athens, Greece.

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of existing RC structures, Structural Safety,

32(3), 220-228.

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vulnerability assessment of buildings in

Algiers area, World Academy of Science,

Engineering and Technology, 61, 796-800.

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R., Fernandez N., Dominquez J., Bala T.,

Cornel G., Safina S., and Vielma R., 2008,

Seismic evaluation and retrofit of school

buildings in Venezuela, The 14th World

Conference on Earthquake Engineering,

October 12-17, 2008, Beijing, China.

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Education (MEHE), 2012, Statistics about

the reality of education sector for

2011/2012, Gaza Strip, Palestine.

14- Panahi M., Rezaie F. and Meshkani, A.,

2014, Seismic vulnerability assessement of

school buildings in Tehran city based on

AHP and GIS, Natural Haza

15- rds and Earth System Sciences, 14, 969-

979.

16- Shurrab, S., 2013, Evaluating seismic

performance of existing school buildings in

Gaza Strip, M.Sc. Thesis, Islamic

University of Gaza, Palestine.

17- Sobaih, M. and Nasif, M, 2012, A proposed

methodology for seismic risk evaluation of

existing reinforced school buildings,

HBRC Journal, 8, 204-211.

18- Solomon, T. and Zheng, L., 2010,

Earthquake induced damage classification

for reinforced concrete buildings,

Srtructual Safety, 32(2), 154-164.

19- Quennell, A., 1959, Tectonic of the Dead

Sea Transform, International Geological

congress, Mexico City, 22, 385-405.

20- Quennell, A., 1983, Evolution of the Dead

Sea Transform, A in Proc. 1st Jordanian

Geological Conference, Abed and Khaled

(Editors), Amman, Jordan, 460-482.

21- Yakut, A.,M2004, Preliminary seismic

performance assessment procedure for

existing RC buildings, Engineering

Structures, 26(10), 1447-1461.

22- Yankelevsky. (2008). SEISMIC

ARCHITECTURE AS AN ESSENTIAL

COMPONENT of the Structural Integrity

of Apartment Buildings in Israel. The 14th

World Conference on Earthquake

Engineering (p. 8). Beijing, China:

Technion- Israel institute of Technology.

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Insurance - Policy Considerations:The

Israeli Case. The Geneva Papers on Risk

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for-desktop.


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http://www.esri.com/software/arcgis/arcgis-for-desktop

http://www.esri.com/software/arcgis/arcgis-for-desktop

Appendix

Existing School building name: Banat El Khansa' Elem school Banat El Khansa' Elem school

#

Structural/ architecture parameter

Influence Degree

Rapid Field

survey evaluation

Vulnerability Classes Rapid Field

survey evaluation

Vulnerability Classes

A' B' C' D' A' B' C' D'

Structural System Type R.C Frame R.C Frame

1 Falling Hazards (H,M,L) WE,WH

L-WE

sch

oo

l bu

ildin

g is

clo

sed

to

be

clas

sifi

ed a

s (B

') c

lass

Inti

ial

vuln

erab

ilit

y c

lass

as

stru

ctura

l sy

stem

of

exis

ting

sch

oo

l b

uil

din

g, ac

cord

ing

to

Eu

ropea

n S

eism

olo

gic

al M

acro

seis

mic

,

199

8 T

able

(2

)

L-WE

sch

oo

l bu

ildin

g is

clo

sed

to

be

clas

sifi

ed a

s (B

') c

lass

Inti

ial

vuln

erab

ilit

y c

lass

as

stru

ctura

l sy

stem

of

exis

ting

sch

oo

l b

uil

din

g, ac

cord

ing

to

Eu

ropea

n S

eism

olo

gic

al M

acro

seis

mic

,

199

8 T

able

(2

)

2Adequacy of Entrance

(E,V.G,G,B) N.G N.G

3Vulnerable Sites / Poor Soil Condition

(H,M,L) L L

4 Short Columns (H,M,L) H H

5Plan Irregularity, General

(H,M,L) L L

6Vertical irregularity, General

(H,M,L) L L

7 Cantilever System (H,M,L) WE,WH

H H

8 Soft Storey (H,M,L) H H

9 Seismic Joint dis/ Nor - -

10Building Construction Material

(E,V.G,G,B) G G

11 Seismic Design with

/without Without Without

12 Maintenance (E,V.G,G,B) N.G N.G

13

Large Windows on One Side of 18-22% of surface area of Wall

(E,V.G,G,B) N.G N.G

14Standard building plans with seismic deficiencies

(H,M,L) H H

15Vulnerable forms of Vernacular construction

(H,M,L) H H

Table 3: An example of using Rapid survey forms (fifteen structural and architectural elements applied to

two selected existing school buildings)


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