Comparison of performance of lateral load resisting systems in multi storey flat slab building

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 05 Issue: 03 | Mar-2016, Available @ http://www.ijret.org 15
COMPARISON OF PERFORMANCE OF LATERAL LOAD RESISTING
SYSTEMS IN MULTI STOREY FLAT SLAB BUILDING
Muralidhar G.B1
, Swathi Rani K.S2
1
Lecturer, Civil Engineering Department, University of Gondar, Ethiopia
2
Assistant Professor, Civil Engineering Department, East West Institute of Technology, Karnataka, India
Abstract
This paper introduces the comparison between lateral load resisting systems in multi storey building. Multi storey building
composed of very special class of structure and therefore require special treatment. Hence to overcome the effects of seismic
forces, Flat slab system in which slab rests on drop or capital which is connected to column is induced with different load
resisting systems. The combined systems which is used to withstand seismic forces in this study are 1. Flat slab without lateral
load resisting system, 2. Flat slab with shear wall, 3. Flat slab with infill wall, 4. Flat slab with bracings, 5. Flat slab with shear
wall and bracings. ETABS software version is used to accomplish dynamic analysis and also building is investigated for non-
linear static analysis in order to identify seismic demands. From the obtained results conclusions are drawn.
Keywords: Capital, Bracings, Dynamic, and Treatment etc…
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1. INTRODUCTION
The desolating social and economic impacts of recent
earthquakes in urban areas have resulted towards the
awareness of the potential seismic hazard and the answering
susceptibility of the environment. As being one of the
particular reinforced concrete structural forms, Flat slab
systems require further attention. These flat slab building
structures are significantly more flexible than traditional
beam slab under earthquake excitation. The flat slab system
in high earthquake region shows significant risk, brittle
punching failure arises from the transfer of shearing force
and unbalanced moment between slab and column which
leads to progressive collapse of structure. To prevent this
failure from earthquake forces lateral load resisting systems
play a important role. Also, the undesirable behavior has
originated from the insufficient lateral resistance due to the
absence of lateral load resisting systems such as shear wall,
infilled Frame, braced frame, Outrigger braced, Suspended,
Space structures, and Core system. etc. But our study is
restricted to first three types respectively.
1.1 Overview of Lateral Load Resisting System
Many structural systems to provide the different
architectural needs are available in steel as well as concrete.
For well-formed design of structure, an understanding of the
behavior of the structural system is necessary. The following
section gives an overview of the behavior of various lateral
load resisting systems.
Infill Wall: Reinforced concrete frames with masonry infills
are a popular form of construction of multi- storey building
around the world. Usually, the frame is filled with bricks as
non- structural wall for partition of rooms. The buildings are
generally designed as frame structure without regard to
structural action of masonry infill walls. In the present
practice of structural design in India masonry infill panels
are treated as non- structural element and their strength and
stiffness contributions are neglected.
Shear wall: Shear wall is a slender vertical cantilever,
resisting the lateral load with or without frames. It will resist
the lateral load in flexure with very little shear deformation.
Depending on the size of openings the behavior of shear
wall varies. To control ill-effects of twist in structures, Shear
walls are to be placed symmetrically in plan also along one
or both directions in plan and more effective when placed
along exterior perimeter of the structure.
Braced Frame: To resist earthquake load in multi storied
building steel braced structural frame is extensively used.
Concentrically Braced Frames (CBFs) are a class of
structures resisting lateral loads through a vertical
concentric truss system, the axes of the members aligning
concentrically at the joints. CBFs tend to be efficient in
resisting lateral forces because they can provide high
strength and stiffness. CBFs are a common structural
steel or composite system in areas of any seismicity. The
steel braced systems are used to abate drift demand.
2. MODELLING AND ANALYSIS OF THE
BUILDING
In the present study, analysis is done by ETABS software.
For the analysis, material properties like Grade of concrete,
size of structural elements, various loads are given in below
in Table-1. Plan and elevation of all the analytical model
with a different lateral load resisting system are shown in
Fig 1 to Fig 6

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Table -1: Modelling Properties of the Multi storied building
Grade Of Concrete M-25,M-35,M-40
Beam Size 300x600mm, M25
Column Size 600x600mm, M35
600x600mm, M40
Drop thickness 200mm
Slab thickness 175mm
Imposed Load : 3.0KN/m2
Floor Finish & Partitions 2.0 KN/m2
Specific Weight of RCC 25 KN/m3
Type of Soil III
Response Spectra As per IS 1893 (Part- 1) 2002
Damping 5%
Importance Factor 1.5
Response reduction Factor 5.0
Seismic Zone V
Number of storeys Basement + Ground floor+ 8
Fig -1: Plan of the building model
Fig -2: Bare Frame structure (Model-I)
Fig -3: Structure with shear wall (Model-II)
Fig -4: Structure with infill wall (Model-III)

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Fig -5: Structure with Bracings (Model-IV) Fig -6: Structure with Shear wall & Bracings (Model-V)
3. RESULTS AND DISCUSSIONS
Table -2: Dynamic Properties of the Multi storied building
ModelNo.
Storytype
Base Shear in KN
Scale up Factor Time period in seconds
Max.story
displacement of
10th floor in mm
Max.story drift
of Ground
floor in mm
Equivalent Static
Method
Response
Spectrum Method
X Y X Y X Y Mode-1 Mode-2 Mode-3 X Y X Y
1 upto8 6543.55 6543.55 3285.13 3491.91 2.93 2.75 2.174 2.029 1.783 198.069 171.074 4.551 4.137
2 upto8 7148.75 7148.75 6143.07 6753.17 1.71 1.55 1.147 1.007 0.663 67.277 52.054 0.8886 0.672
3 upto8 7027.71 7027.71 5836.57 6454.48 1.77 1.60 1.244 1.088 0.742 78.09 60.0114 1.032 0.776
4 upto8 6637.31 6637.31 4868.39 5443.08 2.00 1.79 1.463 1.264 0.888 102.515 76.947 1.738 1.297
5 upto8 7046.46 7046.46 6067.13 6554.21 1.70 1.58 1.18 1.071 0.705 71.24 58.277 0.879 0.747
*NOTE: Upto8 means Basement + Ground floor + 8
Table -3: Performance point and Hinge status in longitudinal and transverse direction for all flat slab building models
Storey Models Displace
ment in mm
Base Force in
kN
Performance levels
Total HingesA-B B-IO
IO-
LS
LS-
CP
CP-
C
C-
D
D-
E >E
B+G+8
Model – I-X-
direction 190.942 6543.552
2076 222 46 0 0 0 0 0 2344
Model – I-Y-
direction 171.549 6543.552
2006 300 38 0 0 0 0 0 2344
B+G+8
Model –II-X-
direction 53.5298 7148.746
2248 96 0 0 0 0 0 0 2344
Model –II-Y-
direction 40.104 7148.746
2254 90 0 0 0 0 0 0 2344
B+G+8
Model – III-X-
direction 59.601 7027.708
2242 102 0 0 0 0 0 0 2344
Model – III-Y-
direction 44.025 7027.708
2244 100 0 0 0 0 0 0 2344
B+G+8
Model – IV-X-
direction 81.682 6637.299
2220 124 0 0 0 0 0 0 2344
Model – IV-Y-
direction 57.396 6637.299
2210 134 0 0 0 0 0 0 2344
B+G+8
Model – V-X-
direction 53.347 7046.457
2248 96 0 0 0 0 0 0 2344
Model – V-Y-
direction 42.421 7046.457
2254 90 167 0 0 0 0 0 2344

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Chart -1: Shows the performance of model v/s base shear
for EQ method
Chart -2: Shows the performance of model v/s base shear
for RS method
Chart -3: Shows the Modal Time period
Chart -4: Shows the performance of Story Displacement in
X &Y direction at 10th
level
Chart -5: Shows the performance of Story Drift in X &Y
direction at GF level
3. CONCLUSIONS
This study concentrates on accomplishment of RC flat slab
multistory building comprehending of various lateral load
resisting systems like shear wall, infill wall and bracings.
These models are analyzed for seismic zone V of IS 1893-
2002 Part-I. Comparisons are done with various dynamic
properties we can assess the seismic vulnerability of the
building. The apprehension of plastic hinges are examined
by performing nonlinear static analysis. The adoption of
push over analysis focus on the effect of correct lateral load
pattern, this will maintain the prejudicial persuasion of
seismic performance of flat slab building. From the obtained
above results we can conclude:
1. The performance level of all the Flat slab building
models in longitudinal and transverse direction are found
within B-IO (between operational and immediate
occupancy) except in model 1. Hence incorporation of
lateral load resisting system will perform well.
2. From obtained results, due to non-linear analysis the
total number of plastic hinges of all the models are same.
But, performance base shear found to be more in Flat
slab building with shear wall with decrease in
performance displacement.
3. Time period in Flat slab building with shear wall (Model
2) is comparatively less than other models. Even,
building with shear wall and bracings (Model 5) shows
less time period. But, stiffness and strength of Model 2 is
more than Model 5.
4. There is an increase in base shear for Flat slab building
with shear wall (Model 2) due to more mass and stiffness
compared to other models.
5. Use of Flat slab with drop increases the drift value. But
providing lateral load resisting system limits the drift in
the structure. Building with shear wall (Model 2)
experience less drift compared to other models.
6. Incorporating lateral load resisting system in Flat slab
building will rapidly reduce the lateral displacement. So,
as observed in all the models adoption of shear wall
shows less displacement thereby assures the safety to the
structure.

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REFERENCES
[1].Andreas J Kappos , Georgios Panagopoulos (2004),
“Performance-based seismic design of 3D R/C buildings
using inelastic static and dynamic analysis procedures”,
ISET journal of earthquake technology, paper no. 444,
vol. 41, no. 1, pp. 141-158.
[2].Apostolska1 R.P and Necevska-Cvetanovska G. S,
“Seismic performance of flat-slab building structural
systems” The 14th World Conference on Earthquake
Engineering October 12-17, 2008, Beijing, China
[3].Ashraf Habibullag, S.E. and Stephen Pyle S.E. “
Practical Three Dimensional Nonlinear Static Pushover
Analysis” published in Structural Magazine, Winter,
1998.
[4].FEMA 308 (1998), “Evaluation of earthquake damaged
concrete and masonry buildings”, Federal Emergency
Management Agency”, Washington D.C.
[5].I.S. 1893, “Criteria for Earthquake Resistant Design of
Structures (part 1) General Provisions and Buildings
(Fifth Revision)”, Bureau of Indian Standards, 2002.
[6].Mr. Muralidhar G.B and Mrs. Swathi Rani
K.S,”Comparison of Seismic Susceptibility Assessment
of Low to Medium Rise RC Buildings by Considering
the Effect of Shear wall”, International Journal of
Science, Engineering and Technology, Volume 3 Issue 6,
2015
[7].Mr. Muralidhar G.B and Mrs. Swathi Rani K.S,” Study
of Seismic Performance of RC Building with Flat Plate
Influenced by Concrete Wall”, International Research
Journal of Engineering and Technology, Vol.3, Issue No.
1:357-361, 2016.
[8].Sabri Attajkani, Abdellatif Khamlichi,”Modelling the
Effect of Infill Walls on Seismic Performance of
Reinforced Concrete Buildings”, International Journal
of Engineering Research and Applications, Vol. 3, Issue
1, January -February 2013, pp.1178-1183
[9]. Sachin Dhiman, Mohammed Nauman,” Behaviour of
Multistory Steel Structure with Different Types of
Bracing Systems (A Software Approach)”, International
Refereed Journal of Engineering and Science , Volume
4, Issue 1 (January 2015), PP.70-82

Comparison of performance of lateral load resisting systems in multi storey flat slab building

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Comparison of performance of lateral load resisting systems in multi storey flat slab building