IRJET- Seismic Response of Flat Slab Buildings with Shear Wall

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 07 | July 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 2266
Seismic Response of Flat Slab Buildings with Shear Wall
Amit Arvind Yadav1, Prof J. P. Patankar2
1PG Scholar, Applied Mechanics Department, Government College of Engineering, Karad,
Maharashtra-415124, India
2Adjunct Professor, Applied Mechanics Department,
3Government College of Engineering, Karad, Maharashtra-415124, India
----------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - In the present study, the seismic behavior of flat
slab building is carried out. For this purpose response
spectrum analysis and static pushover analysis of flat slab
building and regular frame structure has been carried out for
study. All the models are analyzed using Etabs 2016 software.
Different parameters like performance point, base shear, roof
displacement etc. have been compared. Thecomparisonshows
that the flat slab building have low base shear capacity and
large deflection. Also linear and nonlinear analysis of flat slab
building with shear wall and regular framed structure
building has been carried out. It is found that theperformance
of flat slab building under seismic load improves much better
with the use of shear wall.
Key Words: Flat slab, Response spectrum analysis,
Pushover analysis, Etabs2016 etc.
1. INTRODUCTION
Flat slab system is being adopted in many buildings
as they have major advantages over traditional slab-beam-
column structures such as speedy construction, reduced
floor heights to meet the economical and architectural
demands, less loss of energy incoldstoragebuildings,simple
formwork and more unobstructed space etc.
Flat slab system also known as a beamless slab is
one in which RCC slabs directly rests on columns without
the agency of beams or girders and load from slab is directly
transferred to column and then to the foundation. To take
care of heavy shear and bending moment the portion of slab
around the column is thickened. This thickened portion
which is usually square or rectangular in plan is called as
drop or Drop panel. Also for this, columns are generally
provided with enlarge head called as column heads or
capitals. IS 456:2000 gives following two methods of
analysis and design for flat slab system. One is direct design
method and other is equivalent frame method.
The devastating social and economic impacts of
recent earthquakes in the world have resulted in increased
awareness of the potential seismic hazard and the
corresponding vulnerability of the built environment.
Greater effort has been given to reasonable estimates,
predictions and mitigation of the risk associated with these
potential losses. In order to be successful in mitigation
efforts; the expected damage and associated loss in urban
areas caused by severe earthquake should be proper
estimated. It is also appropriate to consider the expected
damage as a measure of seismic vulnerability. The
determination of such vulnerability measures requires the
assessment of the systemic performances of all types of
building structures typically constructed in an urban region
when subjected to a variety of potential earthquakes
Modern concrete construction in high systemic
zones of India has traditionally been done using Special
Moment Resisting Frame (SMRF)-(ref 1893-2002), with or
without shear walls. The columns are designed to be
stronger than the beams. Ductile detailing provisions of
IS13920-1993 insurance this. Generally flat slabs are
designed in lower seismic zone areas for gravity loads and
due to absence of deep beams, flat slab structural system is
significantly more flexible for lateral loads than traditional
slab-beam-column frame system. Also the provision of
ductile detailing of flat slab in IS code is not givenseparately.
This makes the flat slab more vulnerable during seismic
events. For this purpose the study of flat slab building under
seismic load is very important.
2. Scope of the present study
1) To study and compare flat slab building and regular
frame building using equivalent static method.
frame building using Non-linear Pushover analysis.
frame building with different locationsofshearwall
using equivalent static method.
frame building with different locationsofshearwall
using Pushover analysis.
3. Methodology
The methodology adopted for achieving the above-
mentioned objectives is as follows.
1) Six building models are modelled having
approximately similar weight one with regular
frame structure and other with different location
of shear wall for flat slab building.
2) The buildings are analysed with bare frames
without any infill load. The structures are
analysed usingstaticanalysisandusingnon-linear
static pushover analysis.

3) The performance point and hingeformationinthe
structure is studied.
4. Problem data
Type of frame: Ordinary moment
resisting frame.
Seismic zone: III
Story No. 4(G+3) and 10 (G+9)
Size of bay: 5m X 5m
Plan area: 20m X 20m
Storey height: 3.5m
Plinth height: 2.0m
Column: 450mm X 450mm
Plinth beam: 300mm X 450mm
Floor Finish: 1KN/m2
Live load: 3KN/m2
LL on terrace: 1.5 KN/m2
Materials: Concrete M20, Steel
Fe415
Density: 25KN/m3
Type of Soil: Medium
Damping of structure: 5%
Table-1: Problem statement for analysis.
5. DESCRIPTION OF BUILDING
A four storied and ten storied flat slab buildingsituated
in zone III, is taken for the purpose of study. The plan area of
a building is 20mX20m with 2.0m as height of plinth above
top of footing and remaining stories havingheightas3.5m.It
consists of 4 bays of 5m each in X-direction and Y-direction.
The building is considered as an ordinary Moment resisting
frame. Damping of structure is assumed as 5% of critical
damping.
The various models of flat slab building that are
modelled are as follows.
FS-Flat slab building
RFB-1- Regular frame building.
FS-S1- Flat Slab Building with Shear wall at exterior
corner location.
FS-S2- Flat Slab Building with Shear wall at exterior mid
location.
FS-S3- Flat Slab Building with Shear wall at interior corner
location.

FS-S4- Flat Slab Building with Shear wall at interior
mid location.
Table-2: Weight of G+ 3 Structures
Model Slab
thickness
(mm)
Drop
wall
thickness
(mm)
Shear
wall
thickness
(mm)
Weight of
building
(KN)
FS-1 200 350 NA 61013.750
RFB-1 150 NA NA 59626.000
FS-S1 200 300 150 60979.200
FS-S2 200 300 150 60984.800
FS-S3 200 300 150 60990.400
FS-S4 200 300 150 60997.150
Model Slab
thickness
(mm)
Drop
wall
thickness
(mm)
Shear
wall
thickness
(mm)
Weight of
building
(KN)
FS-1 200 350 NA 61013.750
RFB-1 150 NA NA 59626.000
FS-S1 200 300 150 60979.200
FS-S2 200 300 150 60984.800
FS-S3 200 300 150 60990.400
FS-S4 200 300 150 60997.150
Table-3: Weight of G+ 9 Structures
6. Analysis and Results:
The models of flat slab buildings and regular frame
buildings are analyzedby equivalentlateral forcesmethodas
per IS 1893 part-1 using ETAB 2016.
The results obtained are for G+ 3 structures. The
comparison of Base Shears and Roof displacement shows
that-
1. Base shear of Flat slab building is more than base
shear of Regular frame building. For example, for
Model FS-1 Vb = 1382.70KN and for Model RFB-1
Vb = 1345.82KN.
2. Roof displacement of Flat slab buildingismorethan
roof displacement of Regular frame building. For
example, for Model FS-1 displ. = 27.76mm and for
Model RFB-1 displ. = 23.45mm. So there is 15.52%
reduction in roof displacement.
3. Flat Slab building with Shear wall at its core (S4
location) gives minimum displacement than Shear
wall at exterior corners (S1 location), Shear wall
along periphery at central (S2 location) and Shear
wall at interior corners (S3 location).
Table-4: Roof displacement of buildings.
Model
No.
Model Base Shear
(KN)
Disp.(mm)
1 FS-1 1382.70 27.76
2 RFB-1 1345.82 23.45
3 FS-S1 1378.00 19.57
4 FS-S2 1379.01 14.63
5 FS-S3 1379.32 14.21
6 FS-S4 1379.47 12.54
Graph-1: Variation of roof displacement by equivalent
static analysis for G+ 3 structures.
The results obtained for flat slab buildings and regular
frame buildings are shown below for G+9 structure.
1. Base shear of Flat slab building is more than base
shear of Regular frame building having same mass
as that of Flat slab building. For example, for Model
FS-1 Vb = 1769.976KN and for Model RFB-1 Vb =
1729.709KN.
2. Roof displacement of Flat slab buildingismorethan
roof displacement of Regular frame building. For
example, for Model FS-1 displ. = 92.403mm and for
Model RFB-1 displ. = 76.250mm. So thereis17.48%
reduction in roof displacement.
3. Flat Slab building with Shear wall at its core (S4
location) gives minimum displacement than Shear

wall at exterior corners (S1 location), Shear wall
along periphery at central (S2 location) and Shear
Model
No.
Model Base Shear
(KN)
Disp.(mm)
1 FS-1 1769.976 92.403
2 RFB-1 1729.709 76.250
3 FS-S1 1768.965 84.768
4 FS-S2 1769.1278 70.263
5 FS-S3 1769.290 59.530
6 FS-S4 1769.486 57.280
Table-5: Data for G+ 9 Structures
Graph-2: Variation of roof displacement by equivalent
static analysis for G+ 9 structures.
The comparison shows that,Performanceofregular
frame building is better than flat slab building i.e.BaseShear
capacity of regular building is more compared to flat slab
building.
The result obtained shows that, Performance of flat
slab building increases with the use of Shear wall. The Shear
wall at core (S4 location) of a flat slab building gives better
performance than shear at exterior corners (S1 location),
Shear wall along periphery at central (S2location)andShear
Table-6: OBSERVATIONS OF FLAT SLAB
BUILDING AND REGULAR FRAME BUILDING WITH
SHEAR WALL (G+3) BY PUSHOVER ANALYSIS
Models Base Shear (KN) Roof displacement
(mm)
FS-1 3554.7809 85.4770
RFB-1 3718.0716 90.5840
FS-S1 5095.0221 95.4150
FS-S2 6680.6427 112.385
FS-S3 14373.2875 115.755
FS-S4 14627.9500 99.5980
Graph-3: Variation of Base shear by Pushover analysis.
Table-7: OBSERVATIONS OF FLAT SLAB
BUILDING AND REGULAR FRAME BUILDING WITH
SHEAR WALL (G+9) BY PUSHOVER ANALYSIS
Models Base Shear (KN) Roof displacement
(mm)
FS-1 3422.7275 169.206
RFB-1 3666.0354 181.293
FS-S1 4733.2659 188.486
FS-S2 5783.5259 196.763
FS-S3 8659.8096 209.502
FS-S4 9010.3524 207.227
Graph-4: Variation of Base Shear by Pushover analysis
3. CONCLUSIONS
Pushover analysis of Flat slab building and
Regular frame building gives,
1) Performance of regular frame building is better
than flat slab building.
2) Performance of flat slab building improves much
more with the use of shear wall.
3) Shear wall at core of a building gives minimum
lateral displacement.
4) It is encountered from non-linear analysis, that the
reserve strength of structure without shear wall
buildings is less in comparison to buildings with
shear wall.

REFERENCES
[1] C.S Garg, Yogendra Singh and Pradeep Bhargava
“Seismic Performance of Flat-Slab Shear Wall
System” Journal of Structural Engineering Vol.37
No.3 August-September 2010 pp.203-207.
[2] Dr. Uttamasha Gupta, Shruti Ratnaparkhe, Padma
Gome – “Seismic Behavior of Buildings having Flat
Slabs with Drops” International Journal ofEmerging
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[3] Ema Coelho, Paulo Candeias, Giorgios Anamateros,
Raul Zaharia, Fabio Taucer, Artur V. Pinto 2004 –
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ANALELE UNIVERSITĂłII “EFTIMIE MURGU”
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Issue: 03 June-2015 www.irjet.net p-ISSN: 2395-
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[6] IS: 1893:2002, Criteria for earthquake resistant
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[8] Thimmayapally dileepkumar,A.Mownika Vardhan
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[10] B.Anjaneyulu, K Jaya Prakash - Analysis And Design
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