Citation: Iqbal N.S., S. Nakai (2023), Soil type dependency on the seismic performance of RC precast
government residential building, Synopsis of IISEE-GRIPS Master's Thesis.

SOIL TYPE DEPENDENCY ON THE SEISMICPERFORMANCE OF RC PRECAST GOVERNMENTRESIDENTIAL BUILDING
Nur Shajihan Binti MOHAMED IQBAL1
MEE22706

Supervisor: Shoichi NAKAI2

ABSTRACT
Malaysia is known to have less seismic activities as it is located in the intraplate region and is far frommajor plate boundary faults. Besides, Malaysia also experiences frequent tremors and has recorded adevastating tsunami due to the active seismic activities in neighboring countries. The latest occurrenceof earthquake in Ranau on June, 5 2015 that had caused casualties and damages to properties, triggered
Malaysia to take immediate actions to deal with all the issues. Following that, the national seismic code
and National Annex were introduced in 2015 and 2017 respectively. However, buildings constructed
before both documents were established do not consider seismic requirements. This study is conducted
to evaluate the seismic performance of the target building and improves it with suitable seismic retrofit
methods. A 5-story RC precast government residential building is selected to be evaluated based on theseismic hazard level at Bentong, Pahang with 𝑎𝑔 = 0.106 g and Lahad Datu, Sabah with 𝑎𝑔 = 0.192
g considering soil profile models available in Malaysia. Capacity spectrum method is carried out toestimate the performance points based on specific seismic hazard levels with different soil profile
models. The seismic performance of the building is then evaluated based on the performance level ofplastic hinges formation observed at the performance points. Finding indicates that the target building
can survive based on the seismic hazard level at Bentong, Pahang with soil profile model 1 without
requiring any seismic retrofitting. Nonetheless, it cannot survive concerning the soil type E of soil profile
model 2. For the seismic hazard level at Lahad Datu, Sabah, the target building cannot survive
concerning the soil types C, D and E of soil profile model 1 and 2. Seismic retrofit plan is applied to thetarget building, and the seismic performance of the retrofitted building is re-evaluated. The findingshows that the retrofitted building can survive based on both seismic hazard levels with soil profile
models 1 and 2.
Keywords: seismic performance, plastic hinge, pushover, capacity spectrum method, seismic retrofit.
1. INTRODUCTION
Most of the private and government buildings in Malaysia constructed before the establishment of thenational seismic code and National Annex in 2015 and 2017 respectively, are seismic-vulnerable due tono consideration of seismic requirements during the design stage. Those buildings also include thegovernment buildings that have been constructed using the Pre-Approved Plan (PAP) designs

12

Public Works Department of Malaysia (PWD), Kuala Lumpur, Malaysia.
Professor Emeritus, Chiba University.

1established within 2015 until before May 21, 2018. All the existing buildings are potentially exposed toearthquakes and at risk of experiencing structural damage, which require seismic performance review.
2. TARGET BUILDING SELECTION
For this study, a five-story reinforced concrete (RC)precast government residential building from thePAP design collection that was established in April2016 is selected as the target building (see Figure 1).
This building was designed using MS EN 19921:2010 without considering seismic requirements
during the design stage. It also has an irregular planand elevation layout, equipped with cast-in-situ loadbearing RC walls in the X and Y directions. Most ofits beams, columns and slabs are precast.
3. METHODOLOGY
Modelling of the target building and seismic analysis
are carried out by using the software SAP 2000 v22.
Figure 1: Analytical model of the target
The evaluation on the seismic performance of thebuilding.
target building is carried out by using the Capacity
Spectrum Method (CSM) of ATC 40 (1996). The limit states for the seismic performance of the target
building are determined based on the performance level of plastic hinge (FEMA-356 (2000)) and thecolumn failure mode (JBDPA (2001)). The plastic hinge conditions are observed at the intersection
points between the two main components of CSM; the capacity spectrum (obtained from the pushover
analysis) and the demand spectrum (represented by the reduced elastic response spectrum).
3.1. Provision of the elastic response spectra(a) Bentong, Pahang with soil profile model 1.

(b) Bentong, Pahang with soil profile model 2.

(c) Lahad Datu, Sabah with soil profile model 1. (d) Lahad Datu, Sabah with soil profile model 2.
Figure 2. Elastic response spectra according to the selected locations and soil
profile models.

2Based on thirty-six site locations randomly selected from the PWD project database, Bentong, Pahangis the site location in the Peninsular region with the highest peak ground acceleration, 𝑎𝑔 of 0.106 gwith a population density of 63 people/km². Meanwhile, Lahad Datu is the site location in the Sabah
state with the highest peak ground acceleration, 𝑎𝑔 of 0.192 g with a population density of 30
people/km². Bentong, Pahang (Peninsular Malaysia) and Lahad Datu, Sabah were selected for this study
to define seismic hazard levels. The elastic response spectra as shown in Figure 2 above represent theseismic hazard levels at both locations considering the soil types available in Malaysia.
3.2. Seismic retrofit plan
To improve the seismic performance of the existingbuilding, suitable seismic retrofit methods are chosen andapplied to the building. The details of the seismic retrofit
plan are as per below:a) Demolition of the existing parts of the buildingb) Retrofitting of the existing columns with RC jacket(RC1 and RC2)c) Provision of the new RC shear walls (NSW200)d) Extension of the existing RC walls (RSW200)e) Provision of the new RC slabs (NS150)
Figure 3. Three-dimensional view of thef) Provision of the new steel structures
retrofitted building.

(a) 1st story plan view.

(b) Elevation view at grids A and J.

(c) 5th story plan view.

(d) Elevation view at grids 1 and 7.

Figure 4. The locations and arrangement of the retrofitted and new structuralmembers.

3

4. RESULTS AND DISCUSSION
The pushover results asshown in Figure 5
demonstrate that theexisting building has a
weakcolumn-strong
beam design and a soft
first-storyfeatures.
Based on the review ofthe column failure mode(b) X direction.
(a) -X direction.
according to the JBDPA(2001), most existingcolumns fail in a shear
manner. All of thesefeatures
shouldbeavoided in buildingdesign as they will lead tosudden
andglobal
collapseduringtheearthquake.
The retrofitted(d) Y direction.
(c) -Y direction.
building is subjected toFigure 5. Formation of plastic hinges on structural
the same procedures usedmembers of the existing building in different pushover
to evaluate the seismic
directions.
performanceoftheexisting building. Figure
6 shows that plastic
hinges with various
performance levels arestill formed on the firststory columns even after
being
retrofitted.
However,
thetotal
number of green plastic
hinges at the first story(b) X direction.
(a) -X direction.
has reduced and appear atamore
significant
spectral
displacementcompared to the pushover
results of the existingbuilding. The seismic
retrofit plan implemented
on the existing building isable to delay theformation of plastic(d) Y direction.
(c) -Y direction.
hinges and has improved
the spectral capacity ofFigure 6. Formation of plastic hinges on structural
the SDOF system in all
members of the retrofitted building in different
pushover directions. The
pushover directions.
review on the failuremode of the retrofitted columns results in a shear manner.

4

(a) -X direction.

(b) X direction.

(c) -Y direction.

(d) Y direction.

Figure 7. Maximum inelastic displacement of the existing building based on
the seismic hazard level at Bentong, Pahang and Lahad Datu, Sabah withdifferent soil profile models in different pushover directions.

(a) -X direction.

(b) X direction.

(c) -Y direction.

(d) Y direction.

Figure 8. Maximum inelastic displacement of the retrofitted building based on
the seismic hazard level at Bentong, Pahang and Lahad Datu, Sabah withdifferent soil profile models in different pushover directions.

5Referring to the CSM results of the existing building as shown in Figure 7, based on the seismichazard level at Bentong, Pahang (Peninsular Malaysia) with soil profile model 1, the existing building
can survive during the earthquake under the influence of soil types A, B, C, D and E with theperformance level of plastic hinges within Immediate Occupancy (IO) limit observed at most of theperformance points. However, the existing building cannot survive during the earthquake under theinfluence of soil type E for soil profile model 2. Meanwhile, based on the seismic hazard level at LahadDatu, Sabah with soil profile models 1 and 2, the existing building can survive during the earthquake
under the influence of soil types A and B only with the performance level of plastic hinges within IO
limit observed at all the performance points. However, the existing building cannot survive during theearthquake under the influence of soil types C, D and E for both soil profile models.
Referring to the CSM results of the retrofitted building as shown in Figure 8, based on theseismic hazard levels at Bentong, Pahang (Peninsular Malaysia) and Lahad Datu, Sabah considering all
the soil types of soil profile models 1 and 2, the retrofitted building is able to survive during theearthquake.
5. CONCLUSIONS
From the above outcomes, the seismic performance of the building is significantly affected by theinfluence of different soil types. The irregularity of the building with the unfavorable features also
contribute to the poor seismic performance of the existing building. The proposed seismic retrofit planmanages to improve the seismic performance and the capacity of the existing building to withstand theseismic forces from each direction. However, the plan cannot eliminate the weak column-strong beam,
the soft first-story, and the shear column failure mode features.
ACKNOWLEDGEMENTS
This research was conducted during the individual study period of the training course “Seismology,Earthquake Engineering and Tsunami Disaster Mitigation” by the BRI, GRIPS, and JICA. I want toexpress my sincere gratitude to my supervisor, Dr. Shoichi Nakai, as well as my advisors, Dr. Hiroto
Nakagawa (Senior Research Engineer, IISEE, BRI) and Dr. Moeko Matoba (Research Engineer, IISEE,BRI) for supervising and giving the invaluable ideas, advice and suggestions for my study and also thecontinuous support from the beginning of this program.
REFERENCES
ATC 40 (1996). Seismic Evaluation and Retrofit of Concrete Buildings, Volume 1, ATC-40 Report,
Applied Technology Council (ATC), Redwood City, California.
CSi (2020). SAP2000 V-22, Computers and Structures Inc., Berkeley, California.
FEMA-356 (2000). Prestandard and commentary for the seismic rehabilitation of buildings, Federal
Emergency Management Agency (FEMA), Washington D.C., United States.
JBDPA (2001). Standard for Seismic Evaluation of Existing Reinforced Concrete Buildings, 2001,
Guidelines for Seismic Retrofit of Existing Reinforced Concrete Buildings, 2001 and Technical
Manual for Seismic Evaluation and Seismic Retrofit of Existing Reinforced Concrete Buildings, 2001,
Japan Building Disaster Prevention Association (JBDPA), Tokyo, Japan.

6