SEISMIC PERFORMANCE EVALUATION OFSCHOOL BUILDINGS CONSIDERING THE
POST-DISASTER FUNCTION: CASE STUDY FORFACILITIES OF PANGASINAN STATE
UNIVERSITY, PHILIPPINES
Rizalyn Centino IluminMEE17710

Supervisor:

Shunsuke SUGANOABSTRACTDisaster mitigation is a significant issue that must be addressed to avert the destructive impact of adisaster. Evaluation of the seismic performance of the structures is important to minimize the property
damage and eliminate loss of lives against the hazardous effect of natural phenomenon such as
earthquakes due to strength deterioration especially of the old buildings. The failure of structures
disrupted the operation particularly on the post-disaster functions of school buildings. The Japan
Building Disaster Prevention Association (JBDPA) Standard for seismic evaluation of existing
reinforced concrete buildings is a detailed inspection method where the actual capacity of the structures
to resist the seismic force can be determined. Moreover, proper retrofitting can be carried out to thevulnerable and essential structure to assure the safety of the building stakeholders. The JBDPA Standard
focuses on the reinforced concrete structures with the concrete wall. The strength index of the masonry
infill walls especially those with openings was determined from the equations of various experts. The
two target structures, namely: Engineering Building 2 and four-story Administration Building are oldand newly constructed buildings, respectively. The strength of the infill wall was added in the calculationof the seismic capacity of the school buildings. The backbone curve of the frame with reinforced
masonry infill wall presented an informative result. The structures require retrofitting based on the firstand second level screening. The result of the second level screening specified that only the first floor of
the old and new buildings’ longitudinal axis need to be strengthened. The behaviors of the structures
before and after retrofitting were analyzed in STERA 3D. Following the concept of the JBDPA Standard
was found useful in the Philippines since many existing reinforced concrete school buildings withmasonry infill wall need further evaluation. Furthermore, the proposed usage index ranges from 1.252.00 should be considered to emphasize the importance of the school buildings in post-disaster activities.
Keywords: Post-disaster functional asset value index, JBDPA Standard, Masonry infill wall.

1. INTRODUCTION
Schools must be resilient during hazardous events such as earthquakes so that their operations would
not be affected. During disasters, schools have an added value and vital function in post-disaster
activities. They are often used as evacuation centers. However, when schools are damaged, the school’s
mission of continuously providing quality education will be disrupted. Therefore, vulnerability
assessment and appropriate retrofitting must be carried out to assure that school buildings will be
operational during a disaster. Prioritization of buildings must be devised to identify the structures thatPangasinan State University, Philippines.
Professor Emeritus, Hiroshima University, and Visiting Research Fellow, IISEE, BRI, Japan.

1need immediate attention. The post-disaster functional asset value of the buildings is a vital indicator torefine the screening and ranking. A detailed inspection method following the concept of the Japan
Building Disaster Prevention Association (JBDPA) Standard for seismic evaluation of existing
reinforced concrete buildings and applying retrofitting method if necessary are effective mitigation
strategies to avert the destructive impact of a disaster. Moreover, post-disaster functional asset value
index is significant to define the usage index that ultimately ensures an earthquake-resistant schoolbuilding.
The purpose of this study is to further evaluate the seismic performance of old and newly
constructed structures, namely: Engineering Building 2 and Administration Building, respectively. The
concept of the Japan Building Disaster Prevention Association (JBDPA) Standard for Seismic
Evaluation of Existing RC buildings served as a guide to scrutinize the structural integrity of thesebuildings utilizing the first and second level of screening. According to Oreta (2011), many structureswith soft first story collapsed during the 1990 Luzon earthquake in Baguio City, Philippines. The
proposed usage indices for the two buildings were applied to emphasize their vulnerability andimportance. The post-disaster functional asset value index (PDV) was associated to define thecorresponding usage index, U, in determining the standard level of safety required for the particularlocation.

2. METHODOLOGY
The two target structures were evaluated by following the concept of the JBDPA Standard indetermining the strength capacity of the reinforced concrete and structural steel buildings. The
equivalent number of reinforcements of the steel reinforced concrete columns was considered to employ
the concept of the JBDPA Standard. The strength index of masonry infill wall was integrated to thestrength of columns to determine its contribution to the whole structural system.
The post-disaster functional asset value (PDV) was associated with the usage index toachieve the corresponding seismic demand index. The equations for the strength indices of the infill
walls taken from Alwashali et al. (2017) and JBDPA Standard were compared. The strengths of verticalmembers such as columns and walls were combined to arrive at the current strength capacity of thestructure. The vulnerable buildings were retrofitted using the reinforced concrete shear wall to increase
their strength. The seismic performance of the target buildings before and after retrofitting was analyzed
using STERA 3D and verified the structural integrity of the strengthened buildings using the second
level screening.

3. THEORY AND METHODOLOGY
3.1 Post-disaster functional asset value (PDV) index
A case study was conducted in the Pangasinan
State University, Urdaneta City campus in thePhilippines to guide the school administrators indetermining which of the school facilities need
immediate action as presented in Figure 1. The
two-dimensional screening was applied to eleven(11) buildings which are built for different
purposes. The facilities of the school werescreened and ranked based on the post-disasterFigure 1. Satellite image of Pangasinan State
function and rapid visual screening. The quick
University, Urdaneta City Campus showing theinspection was conducted to identify thetwo target buildings.
seismically hazardous buildings. The seismic
hazard of the area was determined using PSHA which refers to the maximum PGA at the site and2matched to the seismic hazard index. Moreover, the structures’ post-disaster functional asset values were
calculated and were used to define the most important building in a post-disaster scenario.
The prioritization matrix was utilized to figure out the corresponding usage index for eachbuilding. Ilumin and Oreta (2011) divided this matrix into four quadrants that represent the Priorities I,
II, III, and IV. For each quadrant, letters A, B, C, and D indicate the order of priority where A="VeryHigh", B="High", C="Moderate", and D="Low" as shown in Figure 2. The Post-disaster functional asset
value (PDV) refers to the combined values obtained from educational and emergency functions of theschool. It is a numerical representation for buildings with different levels of importance to signify theuses of space which are excellent in post-disaster activities.
The vulnerable buildings were determined to employ the detailed evaluation and retrofit. In
this study, the seismic performance of the two target structures, namely: Engineering Building 2 andAdministration Building which also corresponds to Bldg 2 and Bldg 10, respectively were evaluatedusing the JBDPA Standard as shown in Figure 1. The former is an old two-story reinforced concretebuilding with 9.5m width and 57.5 m length which was built in the year 1985. The latter is a four-story
building constructed last 2015 with the dimensions of 20m wide and 35m long. This steel structure witha soft story part in its ground floor is utilized as a parking area.
The usage index, U, of the JBDPA Standard and NSCP 2015 were modified. In this study,
the usage index with the range of 1.25-2.0 was proposed. The corresponding value of U based on theschool buildings’ vulnerability and importance can easily be traced due to the evenly distributed indices.
The PDV index and seismic index are plotted as shown in Figure 2 to determine the structure’s
equivalent Usage index as presented in Table 1. The outcome shown below proved that school buildings
have a different level of importance in times of disaster. Moreover, it can be utilized to anticipate thedegree of disruption of the school operations when these buildings are damaged.
Table 1. Proposed Usage Index, U, of theschool buildings in the Philippines.

Figure 2. Seismic risk scores are plotted against
the PDV values in x and y axis, respectively.
3.2. Following the concept of the JBDPA Standard
Seismic index of structure, Is, connotes the actual lateral loads resisting capacity of an existing building
and can be calculated using Eq. (1). The basic seismic index, Eo, of all the stories are calculated using
Eqs. (2) and (3) wherein the largest value should be taken into account. Irregularity indices (SD) equal
to 1.0 and 0.90 for the old and newly constructed buildings, respectively denote the effect of structural
shape and distribution of unbalanced stiffness. On the other hand, the time index, T, of values 0.8 and
1.0 defines the age and deterioration of the target buildings. The story-shear modification factor,(n+1)/(n+i), changes based on the earthquake lateral force along the story height. In judging the seismic
safety of a structure, this index should be equal to or greater than the seismic demand index, Iso, toconclude that the building is structurally sound.
The seismic demand index of structure, Iso, was determined using Eq. (5). The values of basic
seismic demand index of structure, ES, for both first and second level screening are 0.8 and 0.6,

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respectively were based on the JBDPA Standard. Zone index, Z, equal to 1.0 is a modification factor forthe target buildings since they are located at zone 4 which is the highest seismicity zone in thePhilippines. Ground index, G, is a numerical representation of the soil amplification, geologicalconditions, and interaction between soil and building based on earthquake ground motion. The value of
1.0 was assumed for the site with a very dense type of soil. The proposed usage index, U, which indicatesthe use and importance of the building was applied. The usage indices equal to 1.7 and 1.4 were used
for the Engineering Building 2 and Administration Building, respectively.
The strength index, C, of the vertical members such as columns and walls were computed byusing Eqs. (6), (7), and (8). Moreover, aging of the concrete, βc, for the column was determined byutilizing the √(Fc/20) where Fc is equal to 20.7 MPa. In the first level screening, the ductility index of
the column is equal to 1.0 while the extremely short column is 0.8. The ductility index of the wall was
assumed as 1.0 to include its contribution to the whole structural system.
𝐼𝑠 = 𝐸𝑜 · 𝑆𝐷 · 𝑇
𝑛+1
𝐸𝑜 =(𝐶𝑤 + 𝛼1 𝐶𝑐 ) · 𝐹𝑤
𝑛+𝑖
𝑛+1
𝐸𝑜 =
(𝐶𝑆𝐶 + 𝛼2 𝐶𝑤 + 𝛼3 𝐶𝑐 ) · 𝐹𝑠𝑐𝑛+𝑖
𝑆𝐷 = 𝑞1𝑎 𝑥 𝑞1𝑏 𝑥 … 𝑞1𝑗
𝐼𝑠𝑜 = 𝐸𝑆 · Z · 𝐺 · 𝑈
𝜏𝑤1 · 𝐴𝑤1 + 𝜏𝑤2 · 𝐴𝑤2 + 𝜏𝑤3 · 𝐴𝑤3
𝐶𝑤 =
· 𝛽𝑐
𝛴𝑊
𝜏𝑐 · 𝐴𝑐
𝐶𝑐 =
· 𝛽𝑐
𝛴𝑊
𝜏𝑠𝑐 · 𝐴𝑐
𝐶𝑠𝑐 =
· 𝛽𝑐
𝛴𝑊
𝑛+1
√𝐸12 + 𝐸22 + 𝐸32
𝐸𝑜 =
𝑛+𝑖
𝐸𝑜 =

𝑛+1
( 𝐶1 + ∑ 𝛼𝑗 𝐶𝑗 ) · 𝐹1
𝑛+𝑖

(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)

𝑗

The strength index of reinforced masonry infill wall is determined using the two formulas
which are from JBDPA Standard and Alwashali et al. (2017) as shown in Eqs. (11) and (12),respectively. The Aw denotes the area of a wall while ΣW connotes the weight of the story concerned.
The value of βc was derived by using f’m/20 from the study of Naqi (2017).
Based on Alwashali et al. (2017), Vinf is the ultimate lateral load carrying capacity of eachmasonry infill wall and can be computed using Eq. (13). The f’m, tinf, linf, and λop indicate the compressive
strength of masonry, thickness, length, and reduction factor due to openings such as doors and windows,
respectively. Their statement pertaining to the calculation of the reduction factor using Eq. (14) from
Al-Chaar et al. (2003) was adopted. The Ao and Ap are the areas of opening and masonry infill wall,
respectively. Moreover, the shear stress of reinforced masonry infill wall, τw, was presumed as 1.0 MPa
for the second level screening. Results from the two equations gave the same values. Therefore, Eq. (12)was preferred in determining the strength index, C, of the reinforced masonry infill wall.
𝜏𝑤 · 𝐴𝑤
· 𝛽𝑐
𝛴𝑊
𝑉𝑖𝑛𝑓
𝐶=
∑𝑊
𝑉𝑖𝑛𝑓 = 0.05𝑓 ′ 𝑚 · 𝑡𝑖𝑛𝑓 · 𝑙𝑖𝑛𝑓 · 𝜆𝑜𝑝
𝐴𝑜𝐴𝑜𝜆𝑜𝑝 = 0.6( )2 − 1.6 ( ) + 1
𝐴𝑝
𝐴𝑝
𝐶𝑤 =

4

(11)
(12)
(13)
(14)

3. RESULTS AND DISCUSSION
3.1. Seismic Evaluation
The Engineering Building 2 has forty-two (42) reinforced concrete columns. The strength index of all
the columns was calculated. Majority of columns failed in shear in both directions. The strength of wallsin the transverse direction was added to the columns because they have the same ductility index.
However, the walls in its longitudinal direction with large openings were neglected. The Administration
Building has a total of sixty-two (62) steel reinforced concrete (SRC) columns. Majority of its SRC
columns failed in shear in both directions. The strengths of its walls and columns were incorporated in
the computation of Eo.
The first level screening revealed a conservative result wherein the longitudinal andtransverse directions of the Engineering Building 2 need retrofitting. Moreover, the first, second andthird floors of the Administration Building require strengthening. The second level screening is a moredetailed method of evaluation. It exposed that only the first story of these two buildings along thelongitudinal direction need to be retrofitted.
The equations based on experimentsfrom Sugano (2018) were applied to plot the
backbone curve of the frame with reinforced
masonry infill wall of the Bldg 2 showing thethree deformation stages which are in cracking,maximum, and ultimate as presented in Figure 3.
The equation in determining the shear force at
maximum
denotedthatthelateralreinforcements specifically the distance between
the two horizontal reinforcing bars significantly
influenced the result where the contribution ofreinforcements was emphasized. The force at theultimate stage was defined by considering 80%of the shear force at maximum.

Figure 3. Backbone curve of the frame withreinforced masonry infill wall based on
Sugano (2018).

3.2. Retrofitting by Installing Reinforced Concrete Shear Panel
The vulnerable buildings wereretrofitted using the reinforced
concrete shear wall to upgrade
their seismic capacity. The
contributions of the infilledshear panels to the verticalmembers of structures were Figure 4. Rear elevation of the Engineering Building 2 showing thelocation of shear walls.
verified utilizing the second
level screening. Furthermore,they were modeled in STERA 3D and the technical manual version 5.8 which was also produced by
Saito (2017) was used to fully understand the notion behind the gathered results. Figures 4 and 5 show
the location of the four and three RC shear panels of the Engineering Building 2 and Administration
Building, respectively. According to Sugano (2018), the connection failure with assumed ductility index
equal to 1.0 will cause the concrete shear panel to have a shear sliding failure at the connection. The
existing boundary columns will also experience the failure mode such as punching failure, flexural or
shear failure. The 16mm diameter anchors served as connectors to be installed around the existing framewith the effective embedment length of 160mm. Figure 6 shows the improved strength of the structuresindicating the effectiveness of RC shear wall.

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Figure 5. Rear elevation showing the location ofshear walls.

Figure 6. Maximum inter-story driftsof Bldg 2 (left) and Bldg 10 (right).

4. CONCLUSIONS
Detailed investigation of the facilities of Pangasinan State University with reinforced masonry infill wallis very effective to scrutinize their actual seismic capacity. The equation applied to the soft story building
with an irregularity index, SD, equal to 0.90 considerably influenced the outcome. It resulted into asmaller value of the seismic index, Is, which affects its actual seismic performance. Moreover, the usage
index, U, equal to 1.4 and 1.7 increased the seismic demand index, Iso, of structures. Retrofitting thevulnerable building using RC shear wall ensures an earthquake-resistant structure. Therefore, the safetyof the building stakeholders is guaranteed where school buildings can also be used as a temporary shelter.

5. RECOMMENDATIONSThe efficacy of following the concept of the JBDPA Standard to evaluate in detail the seismic
performance and retrofit the vulnerable buildings has been proven. Therefore, this should be carried out
in all the reinforced concrete structures instead of the rapid visual screening. This detailed inspection isa vital tool to trace a more precise usage index for each structure where it can give an accurate standard
level for a building to be safe. Post-disaster functions of the school building should be considered todefine the appropriate Usage index, U, to be used. Moreover, buildings with reinforced masonry infill
wall need further study. Sufficient laboratory experiment is necessary on the different types of wallswith openings to have adequate information on their real behavior.

ACKNOWLEDGEMENTS
I would like to express my heartfelt gratitude to my supervisor Dr. Shunsuke SUGANO and to myadvisers, Dr. Tatsuya AZUHATA, Dr. Haruhiko SUWADA, and Mr. Mizuo INUKAI for their guidance,
comments, and suggestions which served as my guide to improve and finish my study.

REFERENCES
Al-Chaar, G., Lamb, GE., Issa, MA., 2003, ACI Special Publication. SP-211-12; 247–261.
Alwashali, H., Suzuki, Y., and Maeda, M., 2017, 16th World Conf. on Earthq., Santiago, Chile, 788.
Ilumin, R., and Oreta, A.W. C., 2018, Procedia Engineering, 212, 230-237.
Naqi A., 2015, Toyohashi University of Technology, Japan.
Oreta, A.W.C., 2011, Proc. of the Ninth Pacific Conf. on Earthq. Eng., Auckland, New Zealand.
Sugano, S., 2018, Lecture notes on Masonry Structures II, IISEE/BRI (2017-2018).
Saito, T., 2017, STERA 3D, Toyohashi University of Technology, Japan.
The Japan Building Disaster Prevention Association (JBDPA), 2001, Translated by BRI, Japan.

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