EFFECT OF SHEAR WALL AREA ON SEISMIC BEHAVIOR OF MULTI STORIED BUILDINGS WITH SOFT STORY AT GROUND FLOOR

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International Journal of Research and Innovation (IJRI)
EFFECT OF SHEAR WALL AREA ON SEISMIC BEHAVIOR OF
MULTI STORIED BUILDINGS WITH SOFT STORY AT GROUND
FLOOR
Mohammed Asra Jabeen 1
, Mrs. K. Mythili2
, Mr. Hashim Mohiuddin3
1 Research Scholar, Department Of Civil Engineering, Aurora's Scientific Technological & Research Academy, Hyderabad, India
2 Associate professor , Department Of Civil Engineering, Aurora's Scientific Technological & Research Academy, Hyderabad, India
3 professor , Department Of Civil Engineering, Aurora's Scientific Technological & Research Academy, Hyderabad, India
*Corresponding Author:
Mohammed Asra Jabeen,
Research Scholar, Department Of Civil Engineering,
Aurora's Scientific Technological & Research Academy,
Hyderabad, India
Published: October 25, 2014
Review Type: peer reviewed
Volume: I, Issue : II
Citation: Mohammed Asra Jabeen, Research Scholar (2014)
EFFECT OF SHEAR WALL AREA ON SEISMIC BEHAVIOR
OF MULTI STORIED BUILDINGS WITH SOFT STORY AT
GROUND FLOOR
INTRODUCTION
General
In the last few decades, structural walls have been
used extensively in countries especially where high
seismic risk is observed. The major factors for in-
clusion of structural walls are ability to minimize
lateral drifts, simplicity of design and excellent per-
formance in past earthquakes. Recent earthquakes
were beneficial in better understanding the behavior
and observing the seismic performance of structur-
al walls. As a matter of fact, the term “Shear wall” is
incomplete to define the structural attributes of the
walls since they resist not only the Shear force dur-
ing a Seismic action. Therefore, the term “Structural
wall” is used interchangeably with the term “Shear
wall” throughout the study.
Structural walls are designed to resist gravity loads
and overturning moments as well as shear forces.
They have very large in-plane stiffness that limit the
amount of lateral drift of the building under lateral
loadings. Structural walls are intended to behave
elastically during wind loading and low to moder-
Abstract
The advances in three-dimensional structural analysis and computing resources have allowed the efficient
and safe design of increasingly taller structures. These structures are the consequence of increasing urban
densification and economic viability. The trend towards progressively taller structures has demanded a shift
from the traditional strength based design approach of buildings to a focus on constraining the overall mo-
tion of the structure. Structural engineers have responded to this challenge of lateral control with a myriad
of systems that achieve motion control while adhering to the overall architectural vision.
Reinforced Concrete (RC) wall-frame buildings are widely recommended for urban construction in areas
with high seismic hazard. Presence of structural walls imparts a large stiffness to the lateral-force resisting
system of the building. Proper detailing of walls can also lead to ductile behavior of such structures during
strong earthquake shaking. One of the major parameters influencing the seismic behavior of wall-frame
buildings is the wall-area ratio. Thus shear wall area ratio is set as a key parameter which needs to be in-
vestigated in this analytical study.
An analytical study is performed to evaluate the effect of shear wall area ratio to floor area ratio on the
seismic behavior of multistoried RC structures with soft story at ground floor. For this purpose, 12 build-
ing models that have Five, Eight and Twelve stories and shear wall area ratios ranging between 0.70 and
1.31% in both directions are generated. Then, the behavior of these building models under earthquake load-
ing is examined by carrying out Response Spectrum Analysis and Linear Time History Analysis, by using
structural analysis software called E-TABS. Response Spectrum Analysis is done according to seismic code
IS 1893:2002.Time History Analysis is carried out by considering the three ground motion records namely
Bhuj, Chamba and Uttarkasi. The Main parameters considered in this study is the relationship between
SW area and Base shear , Relationship between SW Area and. Roof drift , Story drift and Inter story drift.
The analytical result indicates that at least 0.91% shear wall ratio should be provided in the design of mul-
tistoried buildings to control the drift. In addition, when the shear wall ratio increases beyond 1.11%, it is
observed that the improvement of the seismic performance is not as significant.
Key words: Reinforced concrete; Earthquake-resistant structures; Shear walls; Response Spectrum Analy-
sis; linear Time History analysis;
1401-1402

16
ate seismic loading to prevent non-structural dam-
age in the building. However, it is expected that the
walls will be exposed to inelastic deformation during
less frequent, severe earthquakes. Therefore, struc-
tural walls must be designed to withstand forces
that cause inelastic deformations while maintain-
ing their ability to carry load and dissipate energy.
Structural and non-structural damage is expected
during severe earthquakes however, collapse pre-
vention and life safety is the main concern in the
design.
Need For The Present Investigation:
Since stilt type framed structures are widely
adopted in India, there is a need to study the seis-
mic behavior of such structures with shear wall
frame systems. Alternative measures need to be
adopted for this specific situation. The under-lying
principle to this problem is (a) increasing the stiff-
ness of the first storey such that the first storey is at
least 50% stiff as that second storey, and (b) provid-
ing adequate strength in the first storey. The possi-
ble schemes to achieve the above are (i) provision of
stiffer columns in the first storey, and (ii) provision
of a concrete core wall (shear wall) in the building.
Thus the present study attempts for the pos-
sible way to resist the earthquake loads by provid-
ing the shear wall area to floor area ratio on the
seismic behavior of multistoried buildings with soft
story at the ground floor.
Objectives Of The Study:
The main objective of this study is to inves-
tigate the structural behavior of multistoried RC
buildings with soft storey at ground floor level hav-
ing different shear wall area to floor area ratios un-
der earthquake loading and to study the improve-
ment in overall behavior with increasing shear wall
ratios. The results are obtained by considering Re-
sponse Spectrum Analysis and Linear Time History
Analysis, to obtain the effect of shear wall area to
floor area ratio on the seismic performance of mul-
tistoried RC buildings. Basically the Objectives are:
• To study the relationship between Shear wall area
(%) and Base shear.
• To determine the relationship between Shear wall
area (%) and Roof drift.
• To find the out storey drifts and inter story drift.
Scope Of The Study:
Three dimensional space frame analysis will be car-
ried out for different building models ranging from 5,
8 and 12 stories resting on plain ground under the
action of seismic load. Earthquake behavior of these
buildings is evaluated by using Response Spec-
trum Analysis and Linear Time History Analysis.
Response Spectrum Analysis is done according to
seismic code IS 1893: 2002 and Time History Analy-
sis is carried out by using three ground motion re-
cords namely BhujChamba and Uttarkasi ,with the
help of the ETABS Nonlinear version software(CSI
Ltd),with increasing shear wall area ratios by con-
sidering the ground floor as soft storey.
Methodology
Introduction
Earthquake and its occurrence and meas-
urements, its vibration effect and structural re-
sponse have been continuously studied for many
years in earthquake history and thoroughly docu-
mented in literature. Since then the structural en-
gineers have tried hard to examine the procedure,
with an aim to counter the complex dynamic effect
of seismically induced forces in structures, for de-
signing of earthquake resistant structures in a re-
fined and easy manner. This re-examination and
continuous effort has resulted in several revisions
of Indian Standard: 1893: (1962, 1966, 1970, 1975,
1984, and 2002) code of practice on the “Criteria
for Earthquake Resistant Design of Structures” by
the Bureau of Indian Standards (BIS), New Delhi.
In order to properly interpret the codes and their
revisions, it has become necessary; that the struc-
tural engineers must understand the basic design
criteria and procedures for determining the later-
al forces. Various approaches to seismic analysis
have been developed to determine the lateral forces,
ranging from purely linear elastic to non-linear in-
elastic analysis. Many of the analysis techniques
are being used in design and incorporated in codes
of practices of many countries. However, this chap-
ter is restricted to the method of analysis described
or employed in IS 1893 (Part I): 2002 of “Criteria for
Earthquake Resistant Design of Structures” essen-
tially to buildings although in some cases that may
be applied to other types of structures as well.
General Terms
Natural Period (T): Natural period of a structure is
its time period of undamped free vibration.
Fundamental Natural Period (T1): It is the first (
longest ) modal time period of vibration.
Diaphragm: It is a horizontal or nearly horizontal
system, which transmits lateral forces to the verti-
cal resisting elements, for example, reinforced con-
crete floors and horizontal bracing systems.
Seismic Mass: It is the seismic weight divided by ac-
celeration due to gravity.
Seismic Weight (W): It is the total dead load plus ap-
propriate amounts of specified imposed load.
Centre of Mass: The point through which the result-
ant of the masses of a system acts. This point corre-
sponds to the centre of gravity of masses of system.
Storey Shear: It is the sum of design lateral forces
at all levels above the storey under consideration.
Zone Factor (Z): It is a factor to obtain the design
spectrum depending on the perceived maximum
seismic risk characterized by Maximum Considered
Earthquake ( MCE ) in the zone in which the struc-
ture is located. The basic zone factors included in
this standard are reasonable estimate of effective

17
peak ground acceleration.
Response Spectrum Analysis: It is the representa-
tion of the maximum response of idealized single
degree freedom system shaving certain period and
damping, during earthquake ground motion. The
maximum response is plotted against the undamped
natural period and for various damping values, and
can be expressed in terms of maximum absolute ac-
celeration, maximum relative velocity, or maximum
relative displacement.
Time History Analysis: It is an analysis of the dy-
namic response of the structure at each increment
of time, when its base is subjected to a specific
ground motion time history.
Soft storey
The essential distinction between a soft story
and a weak story is that while a soft story is classi-
fied based on stiffness or simply the relative resist-
ance to lateral deformation or story drift, the weak
story qualifies on the basics of strength in terms of
force resistance (statics) or energy capacity (dynam-
ics).
It is one in which the lateral stiffness is less than 70
percent of that in the storey above or less than 80
percent of the average lateral stiffness of the three
storeys above.
Soft story failure
Storey drift:
Drift is the extent to which a building bends
or sways. Limits are often imposed on drift so a
building is not designed to be so flexible that the re-
sulting drift or swaying during an earthquake caus-
es excessive damage. Figure shows how a building
can be affected by drift in an earthquake. If the level
of drift is too high, a building may pound into the
one next to it. Or the building may be structurally
safe but non-structural components, such as ceil-
ings and walls, could be damaged as the building
bends and the ceilings and walls are ripped away
from their attachments. Of course, people in the
building could be killed or injured from falling de-
bris.
show the effect of high story drift
Effect of shear wall
Reinforced concrete walls are strength and
portent elements frequently used in constructions
in seismic areas because they have a high lateral
stiffness and resistance to external horizontal loads,
these shear walls may be added solely to resist
horizontal forces or concrete walls enclosing stair-
ways elevated shafts and utility cores may serve as
shear walls. shear walls not only have a very large
in plane stiffness and therefore resist lateral load
and control deflection very efficiently but they also
helps in reductions of structural & non-structural
damage. The building incorporated with shear wall
sufficiently ductile will be much away from seismic
vulnerability and building failure in the earthquake
sensitive zones thus resulting in increased life safe-
ty & low property loss.
Behavior of shear wall:
Shear wall constructed in the high rise build-
ings, generally behave as vertical cantilever beam
with their Strength controlled by flexure as shown
in fig(1) rather than by shear such walls are sub-
jected to bending moments and Shears originating
from lateral loads ,and to axial compression caused
by gravity these may therefore be designed in same
manner as regular flexural element .when acting as
a vertical cantilever beam the behavior of a shear
wall which is properly reinforced for shear, will be
governed by the yielding of the tension reinforce-
ment located at the vertical edge of the wall and,
to some degree, by the vertical reinforcement dis-
tributed along the central portion of wall. It is thus
evident that the shear is critical for the Wall with
relatively low height-to-length ratio, and tall shear
walls are controlled mainly by flexural Require-
ments. Since the ductility of flexural member such
as tall shear wall can be significantly affected by
the maximum usable strain in compression zone of
concrete. Confinement of concrete that the ends of
Shear wall section would improve the performance
of such shear wall. Tall shear walls in multi-storey
buildings the shear walls are slender enough and
are idealized as cantilever fixed at base their seismic
response is dominated by flexure. Because of load
reversals, shear walls sections necessarily contains
substantial quantity of compression reinforcement.

18
The fig below shows the diagonal tension cracks in
tall shear wall and the formation of plastic hinges in
the axial compression.
Behavior of shear wall under flexure & formation of
plastic hinges
Shear walls are the main vertical structural ele-
ments with a dual role of resisting both the gravity
and lateral loads. Wall thickness varies from 150
mm to 500 mm, depending on the number of stories,
building age, and thermal insulation requirements.
In general, these walls are continuous throughout
the building height a shear wall may be tall shear
wall or low shear wall also known as squat walls
characterized by relatively small height-to-length
ratio.
Methods of Seismic Analysis
Once the structural model has been selected, it is
possible to perform analysis to determine the seis-
mically induced forces in the structures. There are
different methods of analysis which provide dif-
ferent degrees of accuracy. The analysis process
can be categorized on the basis of three factors: the
type of the externally applied loads, the behavior of
structure/or structural materials and the type of
structural model selected. Based on the type of ex-
ternal action and behavior of structure, the analysis
can be further classified as linear static analysis,
linear dynamic analysis, non linear static analysis,
or non-linear dynamic analysis (Beskos and Anag-
nostoulos, 1997).
Method of Analysis Process (Syrmakezis, 1996)
Analytical Modeling
Introduction
Most building codes prescribe the method of
analysis based on whether the building is regular
or irregular. Almost all the codes suggest the use
of static analysis for symmetric and selected class
of regular buildings. For buildings with irregular
configurations, the codes suggest the use of dynam-
ic analysis procedures such as response spectrum
method or time history analysis.
Seismic codes give different methods to carry out
lateral load analysis, while carrying out this analy-
sis infill walls present in the structure are normally
considered as non structural elements and their
presence is usually ignored while analysis and de-
sign. However even though they are considered as
non-structural elements, they tend to interact with
the frame when the structures are subjected to lat-
eral loads.
In the present study lateral load analysis is
performed on twelve buildings models that have five
eight and twelve stories with the same plans but
different shear wall area ratios are generated for
the application of Response Spectrum and Linear
Time history analysis. Response Spectrum Analysis
is carried out by using seismic code IS 1893:2002
and Time History Analysis is done by using three
ground motion records such as Bhuj, Chamba and
Uttaraksi.The Shear wall area ratio is determined
by dividing the total shear wall area in one principal
direction to the plan area of the ground floor (∑Aw/
Ap).In this analytical study, shear wall area ratio of
about 0.70, 0.91, 1.11 and 1.31% are selected to
investigate the seismic behavior of multistoried RC
buildings with ground floor as soft story.
Model Id
Number of
Stories
Shear wall ratio %
x-direction Y-direction
1 5 0.70 0.70
2 5 0.91 0.91
3 5 1.11 1.11
4 5 1.31 1.31
5 8 0.70 0.70
6 8 0.91 0.91
7 8 1.11 1.11
8 8 1.31 1.31
9 12 0.70 0.70
10 12 0.91 0.91
11 12 1.11 1.11
12 12 1.31 1.31
Description of Building Models

19
Plan Layout of Building Models
Front Elevation of Building Models
Design Data:
Material Properties:
Young’s modulus of (M20) concrete,
E=22.360x106kN/m²
Density of Reinforced Concrete= 25kN/m³
Modulus of elasticity of brick masonry=3500x10³kN/
m²
Density of brick masonry= 19.2kN/m³
Assumed Dead load intensities
Floor finishes = 1.5kN/m²
Live load = 4 KN/ m²
Member properties
Thickness of Slab = 0.125m
Column size = (0.4mx0.4m)
Beam size = (0.25m x 0.400m)
Thickness of wall = 0.230m
Thickness of shear wall = 0.250m
Earthquake Live Load on Slab as per clause 7.3.1
and 7.3.2 of IS 1893 (Part-I)- 2002 is calculated as:
Roof (clause 7.3.2) = 0
Floor (clause 7.3.1) = 0.5x4 = 2 kN/m2
Analytical Results
Introduction
In this chapter, the results of the 5, 8 and 12
story building models are presented and discussed
in detail. The result includes of all building models
which are computed using the Response Spectrum
Analysis and Time History Analysis. The analysis of
the different building models is performed by using
ETABS analysis package.
The results of Fundamental natural period of vibra-
tion, relationship between shear wall area and Base
shear, relationship between shear wall area and
roof drift, story drift and Inter story drift for the dif-
ferent building models for each of the above analy-
sis are presented and compared. An effort has been
made to study the effect of shear wall area to floor
area ratio by considering ground floor as soft story
in the analysis.
Fundamental Natural Period
Natural Period of Vibration for five eight and twelve
story building models along longitudinal and trans-
verse directions are shown below.
Fundamental Natural Period T (sec)
Model
No.
Number
of story Codal Analytical
1 5 0.329 0.393
2 5 0.329 0.378
3 5 0.329 0.367
4 5 0.329 0.358
5 8 0.526 0.69
6 8 0.526 0.671
7 8 0.526 0.657
8 8 0.526 0.647
9 12 0.789 1.12
10 12 0.789 1.09
11 12 0.789 1.07
12 12 0.789 1.03
Codal and Analytical Fundamental natural periods
for different building models along longitudinal – di-
rection
Fundamental Natural Period T (sec)
Model
No.
Number
of story
Codal Analytical
1 5 0.371 0.393
2 5 0.371 0.378
3 5 0.371 0.367
4 5 0.371 0.358
5 8 0.593 0.69
6 8 0.593 0.671

20
7 8 0.593 0.657
8 8 0.593 0.647
9 12 0.89 1.12
10 12 0.89 1.09
11 12 0.89 1.07
12 12 0.89 1.03
Codal and Analytical Fundamental natural periods
for different building models along transverse direc-
tion.
It can be observed from the above tables that natu-
ral period of five story building for model 1 is more
than the codal provision when comparing it with
analytical results. Were as in model 2 by increasing
the shear wall area ratio, natural period is almost
similar to codal provision. Thus by increasing the
shear wall area ratio there is a considerable reduc-
tion in time period.
It can be clearly understood from the above tables
that by increasing shear wall area ratio in both x
and y direction reduction in the time period takes
place.
SHEAR WALL AREA (%) VERSUS BASE SHEAR
(kN)
Base Shear:It is the sum of design lateral forces at
all levels above the storey under consideration.
Response Spectrum Analysis
The below graphs and the Tabular Columns rep-
resents the relationship between SW area vs. Base
shear for different types of building Models (0.70%,
0.91%, 1.11% and 1.31%), performed by using Re-
sponse Spectrum Analysis.
Model
No.
Number
of
Story
SW
Area
(%)
Base
Shear
(kN)
1 5 0.70 2148.26
2 5 0.91 2181.18
3 5 1.11 2219.08
4 5 1.31 2260.14
5 8 0.70 3378.31
6 8 0.91 3515.89
7 8 1.11 3634.66
8 8 1.31 3710.4
9 12 0.70 4226.59
10 12 0.91 4435.29
11 12 1.11 4615.09
12 12 1.31 4789.73
shear wall area (%) and Base Shear (kN) along lon-
gitudinal direction
(Response Spectrum Analysis)
Model
No.
Number
of
Story
SW
Area
(%)
Base
Shear
(kN)
1 5 0.70 2092.09
2 5 0.91 2128.22
3 5 1.11 2166.25
4 5 1.31 2207.6
5 8 0.70 2822.26
6 8 0.91 2959.68
7 8 1.11 3080.21
8 8 1.31 3190.7
9 12 0.70 3926.52
10 12 0.91 4178.12
11 12 1.11 4498.1
12 12 1.31 4565.45
shear wall area (%) and Base Shear (kN) along
Transverse direction
Shear wall area (%) versus Base shear of five, eight
and twelve story along longitudinal direction
and twelve story along Transverse direction

21
(Time History Analysis)
(Time History Analysis)
% of Shear wall area vs. Roof drift along longitudinal
direction. (Response Spectrum Analysis)
% of Shear wall area vs. Roof drift along Transverse
direction. (Response Spectrum Analysis)
In this case the relationship between SW area vs.
Roof drift has been studied. The % of shear wall
area ratio’s are taken on x-axis and the base shears
is taken on y-axis, The graphs are plotted for Time
History Analysis for different types of building mod-
els with increasing shear wall area ratio by consid-
ering the ground floor as soft story.
As the observed Roof drift decreases, when this ratio
exceeds 1.11%, the reduction in the values of roof
drift becomes less pronounced compared with the
reduction in drift levels for a change of the shear
wall ratio beyond 0.70%. Examination of 5-story
buildings indicated that at least 0.91% of the shear
wall ratio should be provided during design to con-
trol the drift of a shear wall-frame structure.
Time History Analysis
The below graphs represents the relationship be-
tween SW area vs. Base shear for different types of
building Models (0.70%, 0.91%, 1.11% and 1.31%),
performed by using Time History Analysis.
% of Shear wall area vs. Roof drift along longitudinal
direction. (Time History Analysis)
% of Shear wall area vs. Roof drift along Transverse
direction. (Time History Analysis)
STORY DRIFTS
The story drift is the difference of story later-
al displacement a level above or below to that story.
The story drift is calculated and illustrated in the
below tables and figures.

22
The below graphs and the Tabular Columns
represents the story Drift for different types of build-
ing Models (0.70%, 0.91%, 1.11% and 1.31%), per-
formed by using Response spectrum Analysis.
FIVE STORY
Story No
Ux Uy
5 0.286 0.464
4 0.355 0.533
3 0.413 0.576
2 0.406 0.525
1 0.242 0.248
Story drift (mm) along Longitudinal and transverse
direction for five Story building Model (0.70% SW
Area)
Story No. Response Spectrum
Ux Uy
5 0.286 0.457
4 0.343 0.511
3 0.387 0.535
2 0.367 0.473
1 0.208 0.244
Story drift (mm) along Longitudinal and transverse
direction for five Story building Model (0.91% SW
Area)
Story-wise drift for five story building models along
X-direction (Response Spectrum Method)
Story-wise drift for five story building models along
Y-direction (Response Spectrum Method)
EIGHT STORY
Story No.
Response Spectrum
Ux Uy
8 0.378 0.558
7 0.476 0.659
6 0.594 0.784
5 0.701 0.893
4 0.775 0.956
3 0.793 0.942
2 0.714 0.8
1 0.359 0.41
Story drifts (mm) along Longitudinal and transverse
direction for eight Story building Model (0.70% SW
Area)
Story No.
Response Spectrum
Ux Uy
8 0.391 0.585
7 0.481 0.676
6 0.592 0.789
5 0.691 0.885
4 0.756 0.933
3 0.761 0.903
2 0.666 0.747
1 0.326 0.338
direction for Five Story building Model (0.91% SW
Area)
Story Drift for eight story building models along X-
direction (Response Spectrum Method)

23
Story Drift for eight story building models along Y-
direction (Response Spectrum Method)
TWELVE STORY
Story No.
Response Spectrum
Method
Ux Uy
12 0.361 0.507
11 0.432 0.583
10 0.521 0.683
9 0.609 0.78
8 0.687 0.869
7 0.753 0.944
6 0.806 1.01
5 0.841 1.03
4 0.8536 1.03
3 0.822 0.965
2 0.713 0.719
1 0.395 0.398
direction for Twelve Story building Model (0.70%
SW Area)
Story No. Response Spec
Ux Uy
12 0.361 0.515
11 0.427 0.586
10 0.513 0.679
9 0.599 0.774
8 0.678 0.861
7 0.745 0.934
6 0.798 0.989
5 0.831 1.01
4 0.837 1.04
3 0.797 0.926
2 0.673 0.743
1 0.316 0.3
direction for Twelve Story building Model (0.91%
SW Area)
Story Drift for Twelve story building models along
X-direction (Response Spectrum Method)
Story Drift for Twelve story building models
along Y-direction (Response Spectrum Method)
In this case the variation of story drift is
examined by Response Spectrum Analysis with in-
creasing shear wall area ratios, by taking drift on
x-axis and No. of story’s on y-axis.
In this graph, it is observed that there is a decrease
in drift in the x-direction of 5-story buildings when
the shear wall ratio is increased from 0.70 to 0.91%.
When this ratio is increased further to 1.11 and
1.31%, the roof drifts are 0.25 and 0.29 respec-
tively. When the y-direction of the 5-story buildings
is considered, the decrease in drift starts to decay
signiﬁcantly after 0.91% shear wall area ratio. The
roof drift values of this case for 1.11 and 1.31% of
the shear wall ratio are 0.47 and 0.45. In addition,
the roof drift value for a 0.70% shear wall ratio in
the y-direction is 0.464, respectively.
The trend in the variation of drifts for 8-story and
12 story buildings differs from that of 5-story build-
ings. At first glance, the normalized values of roof
drifts are relatively close. A decrease in roof drifts is
observed to be more significant for shear wall ratios
up to 0.91% compared with higher wall ratios. How-
ever, after 0.91% wall ratio, the reduction in drift is
nearly constant in the y-direction, which is almost
a 5% decrease for each increase in the shear wall

24
area ratio.
This indicates that shear wall ratio up to 0.91%
could signiﬁcantly improve seismic performance.
However, a shear wall ratio less than 0.91% is not
sufficient to limit the observed drift.
The below graphs and the tabular columns
represents the story drift for different types of build-
ing Models performed by using Bhuj , Chamba and
Uttarkasi as Ground Motion records for Time His-
tory Analysis.
FIVE STORY
Story drift for five story building models along X-
direction (Time History Analysis)
Story drift for five story building models along Y-
EIGHT STORY
Story drift for eight story building models along Y-
TWELVE STORY
Story drift for twelve story building models along X-
Story drift for twelve story building models along Y-
In this case the variation of story drift is ex-
amined by Time History Analysis with increasing
shear wall area ratios, by taking drift on x-axis and
No. of story’s on y-axis.
In this graph, it is observed that there is an abrupt
change in drift in the x-direction of 5-story build-
ings in case of Uttarkasi when compare with that
of Bhuj and Chamba. When the shear wall area ra-
tio is increased further to 1.11 and 1.31%, the roof
drifts are 0.301, 0.791 and 0.9, respectively. When
the y-direction of the 5-story buildings is consid-
ered, similar effect can be seen. The roof drift values
of this case for 1.11 and 1.31% of the shear wall
ratio are 0.37, 0.936 and 2.35 respectively.
The trend in the variation of drifts for 8-story and
12 story buildings is also similar to that of 5-story
buildings.
INTER STORY DRIFT
It is the relative horizontal displacement between
two adjacent floors bounding the story.

25
Response Spectrum Method
The below graphs and the Tabular Columns
represents the story Drift for different types of build-
ing Models (0.70%, 0.91%, 1.11% and 1.31%), per-
formed by using Response spectrum Analysis.
FIVE STORY
Inter Story drift for five story building models along
X-direction (Response Spectrum Analysis)
Y-direction (Response Spectrum Analysis)
The below graphs and the tabular columns
represents the story drift for different types of build-
ing Models performed by using Bhuj , Chamba and
Uttarkasi as Ground Motion records for Time His-
tory Analysis.
FIVE STORY
X-direction (Time History Analysis)
Y-direction (Time History Analysis)
Summary
In this chapter, the results obtained from Response
Spectrum Analysis and Time History Analysis per-
formed by using E-tabs includes relationship be-
tween shear wall area and Base shear, relationship
between shear wall area and Roof drift, Story Drift
and Inter Story Drift has been discussed for differ-
ent building model with increasing Shear wall area
ratio by considering the ground floor as soft story.
CONCLUSION
On the basis of the results of the analytical inves-
tigation of 5, 8 and 12 story building models with
increasing shear wall area ratio by considering the
ground floor as soft story, the following conclusions
are drawn:
• The Fundamental Period of Vibration for five, eight
and twelve story building model with 0.70% shear
wall area ratio is high when compared to that of
other models. This is because as the shear wall area
increases the fundamental time period decreases.
• The percentage of the base shear carried by the
ground floor shear walls increases significantly un-
til the shear wall ratio has reached 0.91%. However,
the rate of increase is considerably higher between
1.11 and 1.31% shear wall ratios than between 0.70
and 0.91%. In buildings having a shear wall ratio of
1.11%, ground floor shear walls carry about 80% of
the base shear. The base shear carried by the walls
is observed to be more than 90% for shear wall ra-
tios of 1.31% however; the reflection of this increase
on the drift performance is significant.
• As the shear wall ratio increases, the roof drift de-
creases; however, when this ratio exceeds 0.91%,
the reduction in the values of roof drift values be-
comes less pronounced compared with the reduc-
tion in drift levels for a change of the shear wall ra-
tio beyond 0.91%. Examination of 5-story buildings
indicated that at least 1.0% of the shear wall ratio
should be provided during design to control the drift
of a shear wall-frame structure.
• In general, when the shear wall area to floor area
ratio increases, the story drift decreases. For 8 and
12 -story buildings, the story drift values for two
orthogonal directions have similar magnitudes;
however, for 5-story buildings, the difference is not
much significant, especially for 0.91% and higher
shear wall ratios. This is believed to be because of
the fact that fundamental periods of the 5-story
buildings are close to the dominant period of the
selected earthquake records.
• It is examined that the Inter story drift are
generally smaller in magnitude compared with max-
imum story drifts; however, their general trend is

26
quite similar except for the ground floors. For both
5- and 8-story buildings, the minimum inter story
drifts are observed between the top two stories when
the shear wall ratio is greater than 0.91%.
Scope For Future Study
Further it would be desirable to study more
cases before reaching definite conclusion about
the behavior of RC frames buildings. Studies can
be conducted on high rise buildings (Multistoried)
by providing more thickness of shear walls, provid-
ing shear wall at various other locations and also
by providing dual system, which consists of shear
wall (or braced frame) and moment resisting frame.
Study for better ductility beam-column junction can
also be made.And further study can be made on an
existing building for seismic evaluation. Where, a
preliminary investigation using FEMA-273 can be
done before evaluation of the existing building us-
ing mathematical modeling with the help of finite
element analysis package.
The study can also be done on Sloping grounds,
various damping mechanisms and its applications
on structures, and also by conducting the struc-
tures having base isolation system.
REFERENCES
1.Canbolat, B. B., Soydas, O., and Yakut, A. (2009). “Inﬂuence of
shear wall index on the seismic performance of reinforced con-
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ropean Council of Civil Engineers - Turkish Chamber of Civil
Engineers (WCCE-ECCE-TCCE) Joint Conf. (CD-ROM), Tubitak,
Ankara, Turkey.
2.Comlekoglu, H. G. (2009).“Effect of shear walls on the behavior
of reinforced concrete buildings under earthquake loading.” M.S.
thesis, Middle East Technical Univ., Ankara, Turkey.
3.Hassan, A. F., and Sozen, M. A. (1997). “Seismic vulnerabil-
ity assessment of low-rise buildings in regions with infrequent
earthquakes.” ACI Struct. J., 94(1), 31–39.
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forced concrete buildings.” M.S. thesis, Middle East Technical
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5.Tekel, H. (2006). “Evaluation of usage of 1% shear wall in re-
inforced concrete structures.” Turkish Eng. News, 444–445
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6.Wallace,J.W.(1994).“Anewmethodologyforseismicdesignofreinf
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7.European Committee for Standardization. (2003). “Design of
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Belgium.
8.Comlekoglu, H. G. (2009). “Effect of shear walls on the behavior
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uhendislikHaberleri, Sayi, 425(3), 13–22
11.Paciﬁc Earthquake Engineering Research Center (PEER).
(2009).“Strong motion database.”http://peer.berkeley.edu/
peer_ground_motion_databaseæ (Jan. 30, 2009).
12.IS -1893, “Criteria for Earthquake Resistant Design of Struc-
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tation and Training Manuals
author
Mohammed Asra Jabeen,
Research Scholar, Department Of Civil Engineering,
Hyderabad, India
K. Mythili,
Associate professor , Department Of Civil Engineering,
Hyderabad, India
Hashim Mohiuddin,
Professor , Department Of Civil Engineering, Aurora's
Scientific Technological & Research Academy,
Hyderabad, India

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