Citation: Nasuha, M. Z., T. Azuhata (2023), Seismic performance evaluation of a hybrid RC frame –precast wall building in Malaysia, Synopsis of IISEE-GRIPS Master's Thesis.

SEISMIC PERFORMANCE EVALUATION OF AHYBRID RC FRAME–PRECAST WALL BUILDING IN
MALAYSIA
Nurul NASUHA1
MEE22707

Supervisor: Tatsuya AZUHATA2*ABSTRACTThis study evaluates the seismic performance of a hybrid reinforced concrete (RC) frame–precast wallbuilding in Malaysia to assess the building’s response to seismic forces, identify potential vulnerabilities,
and propose strategies to enhance its seismic resilience. To do this, various methodologies, including
modal analysis, first and second screening methods based on the Japan Building Disaster Prevention
Association (JBDPA) guidelines, and response history analysis (RSA) are employed. The building’s
behavior under different seismic scenarios is investigated through comprehensive evaluations. The
findings reveal critical insights into the building’s seismic capacity. The original design exhibits certain
shortcomings, particularly in withstanding higher peak ground acceleration levels. However, thebuilding’s seismic performance can significantly be enhanced with the careful consideration andimplementation of specific design improvements. This work highlights the importance of incorporating
the best practices in structural design and retrofitting to better withstand the potential seismic events inMalaysia. The results obtained herein contribute valuable knowledge to the seismic engineering field,
offering practical implications for the construction and safety standards of hybrid RC frame–precast wallbuildings in seismic-prone regions.
Keywords: seismic performance, Hybrid RC Frame-Precast Wall Building, JBDPA, RSA
1. INTRODUCTION
Malaysia is geographically located in a tectonically inactive seismic region which deals very lowly withthe risk of tremors or earthquakes. Over the past decades, it is common for Malaysians to think Malaysia
is safe from holocaust tremor. The trend has been rapidly changing, and numerous studies have provedthat Malaysia is vulnerable to the risk of tremors. According to Amir et al. (2016), Peninsular Malaysia
is specifically exposed to Sumatra’s fault and subduction zones, where the Malaysia Meteorology
Department (MMD) has documented numerous instances of minor localized earthquakes occurring
within Peninsular Malaysia.
The presence of non-seismic reinforcing details in Malaysian structures highlights theinadequacy of incorporating sufficient seismic considerations during the design phase. Consequently,
this issue emerges as a substantial concern, as it not only poses the potential for extensive structural
damage but also carries the risk of tragic loss of life for occupants. Therefore, in this study, it is importantto evaluate the seismic performance of RC buildings especially and therefore propose suggestions forbetter seismic performance. This study will evaluate the mode shapes of the structure by using ETABS
software, study the strength and ductility of vertical members by using JBDPA, and verify those results
by using response history analysis.

1

Public Works Department, Malaysia.
International Institute of Seismology and Earthquake Engineering, Building Research Institute (BRI), Japan.
* Chief Examiner21

2. DATAFor the purpose of this study, a residential building
comprising eight stories has been specifically chosen.
Notably, this building was designed without considering
any seismic considerations. The architectural configurationof this structure employs a hybrid system, featuring areinforced concrete moment-resisting frame at the first story
and a precast wall system in the upper stories. Furthermore,this construction exhibits irregularities both in its floor planand vertical alignment. The height of the first story
measures 5.3 meters, while subsequent stories are 3.3
meters each, encompassing overall dimensions of 48.2
meters longitudinally and 31.5 meters transversely. The
concrete's material strength (fc) is rated at 30N/mm², while
the steel (fy) possesses a strength of 500N/mm².
Figure 1. 3D view of the target building
Table 1. Description of sites
Location
Lahad Datu, SabahSoil TypeBagR = PGA
0.16(%g)/100
Importance Class,II,1.2
Factor0.192
ag = agR. γiag. S
Depth of Soil
DepositColumn
Size
Main
bar
Hoop

0.2688

Table 2. Column Types
C1C2C3300 x800
10D20450 x 800

250 x 500

12D20

6D16

D10175mm

D10175mm

D10175mm

Not exceed 30m
3. METHODOLOGY

3.1. Modal Analysis
Within the context of this investigation, the modal
analysis was effectively conducted by employing thestate-of-the-art ETABS software that enabled acomprehensive
examinationof
thedynamic
characteristics of the studied building. The structure wassubjected to a uniform unit weight of 12 kN/m2 across all
floors, reflecting realistic loading conditions. The
intricate structural behaviour was captured by modellingthe beams and the columns using frame elements. The
concrete shear wall surrounding the lift was represented
by utilizing shell elements. A layered and membranetype modelling approach was applied to accommodate
the precast wall intricacies.
Figure 2. Numerical model of the buildingin ETABS software

3.2. Implementation of the JBDPA

Based on guidelines, evaluating how well a building(1)
𝐼𝑠 = 𝐸𝑜 . 𝑆𝐷 . 𝑇
can withstand an earthquake is done by considering
its seismic capacity, which is measured using a seismic index, Is. It is calculated by multiplying the2building's strength and ductility (Eo), irregularity (Sd), and time indices (T). It represents the amount ofenergy the building can handle during an earthquake. Essentially, the seismic index, Is indicates theintensity of an earthquake that the building is capable of resisting in each primary direction of impact.
The seismic index of structure, Is is expressed as Eq. (1) and should be compared with the demand index,
Iso. For this study, Iso for Malaysia is adjusted by multiplying with the modification factor of 0.65 to theIso Japan (0.8 for the first screening, 0.6 for the second screening). Therefore, Iso Malaysia for the firstscreening method is 0.52 and the second screening method is 0.39.
3.2.1. First and Second Screening Method by JBDPA
The initial level screening methodology provides a rapid evaluation of the seismic resilience ofreinforced concrete (RC) structures, focusing solely on the cross-sectional areas of vertical members
while disregarding their reinforcement details. In the first screening procedure, when assessing the index,
Eo for the structure, a crucial step involves comparing and selecting the greater value obtained from bothEq. 2 and Eq. 3.
𝑛+1( 𝐶𝑤 + 𝛼1 . 𝐶𝑐 ). 𝐹𝑤
𝑛+𝑖(2)

where n denotes the number of stories of abuilding, i signifies the number of story for𝑛+1(3) evaluation, 𝐶𝑤 , 𝐶𝑐 , 𝐶𝑠𝑐 are strength index( 𝐶𝑠𝑐 + 𝛼2 . 𝐶𝑤 + 𝛼3 . 𝐶𝑐 ). 𝐹𝑠𝑐
𝐸𝑜 =of the wall, columns, and extremely short𝑛+𝑖columns. α1, α2 and α3 represent theeffective strength factor of the columns at the ultimate deformation of the wall, short columns, extremely
short columns, Fw and Fsc represent the ductility index of the walls and extremely short columns
respectively.
𝐸𝑜 =3.2.2. Second Screening Method by JBDPA
The classification of the structure involves dividing it into two distinct groups: ductility-dominant
structures and strength-dominant structures. In order to determine the basic seismic index of the structure,
denoted as Eo, the larger value between Eq. 4 and Eq. 5 is selected. The evaluation of this index, Eo, issubject to the constraints imposed by the minimum ductility index of the second-class prime elements.
By considering these criteria, the classification and determination of the seismic index provide acomprehensive framework for assessing the structural behavior and response to seismic forces.

𝐸𝑜 =𝑛+1𝑛+𝑖(4)√𝐸1 2 + 𝐸2 2 + 𝐸3 2𝑛+1(𝐶 + Σ𝛼𝑗 𝐶𝑗 ). 𝐹1
𝑛+𝑖 1

3.3 Non-Linear Response History Analysis
The meticulous analysis is carried out utilizing
Dr. Azuhata's custom-developed software,
named IISEE Analysis Tools. The approach
employed in this methodology encompasses anextensive assessment of the building's direct
response, encompassing the scrutiny of its
behavior under distinct seismic scenarios,
comprising one actual earthquake (Ranau) and
four artificial ground motion earthquakes (withphase angle of El-Centro, Kobe, Northridge,and Random). Spectral matching is done basedon the target spectra from Eurocode 8,
Malaysian annex.

(5)where αj is an effective strength factor inthe j-th group at the ultimate deformation
R1 corresponding to the first group.

Simulated and Target Acceleration

1000 Spectra

El- Centro
Kobe
NorthridgeRandom
Target Spectra
Ranau_RealSa (gal)

𝐸𝑜 =

00

1

Time (s)23

4Figure 3. Spectrum Matching based on El-Centro,
Kobe, Northridge earthquakes and Random Phase34. RESULTS AND DISCUSSION
4.1. Results and Discussion on Modal Analysis
Figure 4 shows the first mode shape of the building
containing four blocks connected to each other. The
first mode shape exhibits a rotational behaviour,wherein individual blocks of the building respondindependently. This rotational behaviour raises
significant concerns, particularly when the building issituated in a seismic region. Further evaluation is
crucial because excessive rotational behaviour during
seismic events can pose risks of structural instability
and potential damage to the building’s integrity.
Therefore, Block 3 is investigated in detail in thefollowing parts of the study.

Figure 4. First mode shape in plan layout

4.2. Results and Discussion on the First Screening
MethodFigures 5 and 6 show the first screening evaluation for
x and y directions. Upon analysis, the irregularityindex (Sd) was determined as 0.9 and 0.8 for the x andy directions, respectively, with the classification
associated with the elevation balance to account for thepotential soft story effects adhering to the guidelines
set forth by the JBDPA. A careful examination of thefindings revealed that, if this building were located inMalaysia, all stories would possess a sufficient andsecure seismic capacity, except for the first story,
depicting the shortcomings in both directions. Certain
enhancements must be implemented to the structuraldesign, with a special emphasis on addressing crucial
aspects, particularly concerning the first floor’s
resilience and stability, to successfully erect thisparticular building type within any seismic region in
Malaysia. However, in the case of a location likeJapan, the seismic capacity of this building from thefirst to fourth stories is considered insufficient for thehorizontal direction. This highlights the importance ofassessing the building’s structural strength and safety
against seismic events, especially in earthquake-proneregions.

Figure 5. First Screening Evaluationaccording to JBDPA for x direction

4.3. Results and Discussion on the Second
Screening Method
The impact of ductility on each column was assessedby performing a thorough evaluation using the second
screening method prescribed by the JBDPA. Bothdirections were carefully analyzed to determine the4

Figure 6. First Screening Evaluationaccording to JBDPA for y direction

failure type (i.e., extremely brittle column, flexural failure, or shear failure) exhibited by each column.
All columns in the x direction experienced flexural failure, with only column N/9 showing signs of shear
failure. Conversely, the majority of columns in the y direction experienced shear failure, while theremaining columns exhibited flexural failure. The two following methods are recommended herein toenhance the column ductility: 1) increasing the column size and 2) elevating the value of the shear
reinforcement ratio. Increasing the shear reinforcement ratio specifically involves reducing the spacing
between the reinforcement bars from 175 to 100 mm. A substantial improvement in column ductility
was observed when both methods were employed. A strength–ductility index graph was created (Fig. 78) to facilitate a clearer comprehension of the original and newly proposed designs. This graph illustrates
the relationship highlighting the substantial enhancement in the seismic index (Is) for both directions.

Figure 8. Strength-Ductility Index
Relationship for y direction

Figure 7. Strength-Ductility Index
Relationship for x direction
4.4. Results and Discussion on Response History
Analysis
Figures 9-12 illustrate the maximum displacement
values in both the x and y directions for the original
and proposed designs under various PGA sets. In
the case of the x and y directions in the original
design, the structure remained in a safe condition
when subjected to 0.03g PGA. However, at ahigher PGA of 0.16g, only the real Ranau
Earthquake resulted in displacements within apermissible limit. The other artificially simulated
earthquakes with similar PGA values exceeded thislimit. The displacement limit was calculated using
the second screening method to assess how
different PGA sets would affect the resulting
displacements. The findings led to the conclusionthat the original design lacks adequate seismic
capacity for handling such scenarios. An analysis of
the revised design revealed that, in the x direction,
all artificially generated earthquakes exceeded thedisplacement limit at a 0.4g PGA, with only the real
Ranau Earthquake remaining within the allowablerange. This poses a significant concern because thestructure may suffer from severe damage or collapse
if subjected to similar PGA levels occurring inMalaysia. In the y direction of the revised design,
however, only the artificially simulated

5

Figure 9. Maximum Displacement for
Original Design (x-direction)

Figure 10. Maximum Displacement for
Revised Design (x-direction)

earthquakes with arandom phase andtheKobeEarthquake
exceeded
thedeflection limit. In
other words, after
the revised design
was implemented,
the y direction
exhibited greater
strengthandresilience
compared to the xdirection.

Figure 11. Maximum Displacement
for Original Design (y-direction)

Figure 13. PGA vs annual exceedance
probability for Japan and Malaysia

Figure 12. Maximum Displacementfor Revised Design (y-direction)

Fig. 13 serves as a highly informative tool forunderstanding the probabilities associated withdifferent PGA levels in the two regions. The likelihoodof a 0.4 g PGA earthquake transpiring in Malaysia
during any given year is exceedingly low, measuring
only less than 0.01% (Noor, 2013). The occurrence ofsuch a formidable earthquake in the region appears tobe highly improbable, which provides reassurance thatbuilding construction in Malaysia is safe, even if itsurpasses the prescribed displacement limit, given theremote possibility of encountering a seismic event withsuch a magnitude.
5. CONCLUSIONSIn modal analysis, this building shows rotational behaviour has occurred. The JBDPA's initial screening
identifies a soft-story effect in the building, both x and y directions. The second screening evaluation
reveals the original design had weak seismic capacity in the columns, prompting two methods toimprove it: increasing column size and raising the shear reinforcement ratio. After evaluating diverse
earthquake scenarios, it was found that the structure could not withstand a seismic impact of 0.4g PGA.
However, it was noted that the probability of experiencing such high PGA values in Malaysia isremarkably low. Considering this, the revised design ensures the building's safety for construction inMalaysia, as the rarity of extreme seismic events provides substantial reassurance for its overall stability.
ACKNOWLEDGEMENTS
This research was conducted during the individual study period of the training course “Seismology,Earthquake Engineering and Tsunami Disaster Mitigation” by the Building Research Institute, JICA,and GRIPS. I would like to express my sincere gratitude to my supervisor Dr. Tatsuya Azuhata and Dr.
Zaurbek Abaev for their valuable support in completing my research successfully.
REFERENCES
Amir, N., et al (2016), Estimation of Peak Ground Acceleration (PGA) for Peninsular Malaysia using
geospatial approach, 8th IGRSM International Conference and Exhibition on Remote Sensing
Noor S.,(2013) et. al., Seismic Hazard Assessment of East Malaysia Region, USM
Nagae, T. et. al. (2006). Performance Assessment for Reinforced Concrete Buildings with Soft First
Stories. Annuals of Disaster Prevention Research Institute, Kyoto University6