Performance of shear wall building during seismic excitations

1. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
73
PERFORMANCE OF SHEAR WALL BUILDING DURING
SEISMIC EXCITATIONS
Anila Anna Samson1
, Preetha Prabhakaran2
, Dr. Girija K3
1, 2
(Civil Engineering Department, SNGCE, Kolenchery, Ernakulam, Kerala, India)
3
(Civil Engineering Department, Govt. Engineering College, Barton Hill, Thiruvanathapuram, Kerala, India)
ABSTRACT
Design of civil engineering structures is typically based on prescriptive methods of building codes. Normally,
loads on these structures are low and result in elastic structural behaviour. However, under a strong seismic event, a
structure may actually be subjected to forces beyond its elastic limit. Earthquakes demonstrate vulnerability of various
inadequate structures, every time they occur. The lessons taught from the aftermath of earthquakes and the research
works being carried out in laboratories give better understanding about the performance of the structure and their
components. An introduction of flanged shear wall represents a structurally efficient solution to stiffen a building
structural system because the main function of a flanged shear wall is to increase the rigidity for lateral load resistance.
Shear walls in medium and high rise reinforced concrete buildings for the sake of interaction with the lateral forces, used
by many of engineers, however past studies on the behaviour and situation of shear wall indicated that shear walls with
flange has better behaviour. And this is due to interaction of flange and wall web. The present study was carried out in a
25 story shear wall building, located in seismic zone 3.Two models was considered for the study, first one was the
building with L type shear wall and the second one was with core type shear wall. Three time history analysis were
conducted and from the time history analysis, the maximum displacement obtained for building with for building with L
type shear wall than the building with core type shear wall. i.e storey drift is reduced when shear wall is provided as core
type. To analyse the wall-frame interaction behaviour, lateral forces obtained from the equivalent static analysis were
applied on the nodes of exterior faces. The study shows that as the height of building increases, shear wall absorb more
lateral force than the frame.
Keywords: Equivalent Static Procedure, Lateral Force, Shear Wall, Storey Drift, Time History Analysis.
1. INTRODUCTION
Earthquakes demonstrate vulnerability of various inadequate structures, every time they occur. The lessons
taught from the aftermath of earthquakes and the research works being carried out in laboratories give better
understanding about the performance of the structure and their components. Damage in reinforced concrete structure was
mainly attributed to the inadequate detailing of reinforcement, lack of transverse steel and confinement of concrete in
structural elements. Typical failures were brittle in nature, demonstrating inadequate capacity to dissipate and absorb
inelastic energy. This necessitates a better understanding of the design and detailing of the reinforced concrete structures
under various types of loading. In modern tall buildings, shear walls are commonly used as a vertical structural element
for resisting the lateral loads that may be induced by the effect of wind and earthquakes.
INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND
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2. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
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Shear walls are generally used in various cross sections such as rectangular shapes to more irregular cores such
as channel, I, T, H, L, U, C, Z barbell shape, box etc. An introduction of flanged shear wall represents a structurally
efficient solution to stiffen a building structural system because the main function of a flanged shear wall is to increase
the rigidity for lateral load resistance. Past studies on the behavior and situation of shear wall indicated that shear walls
with flange has better behavior. This is due to interaction of flange and wall web. In shear wall the flange is provided to
increase the ductility, stiffness and resistance to bending of shear wall.
1.1 Flanged Cantilever Shear Walls
Shear walls meeting each other at right angles result in flanged configurations and are referred to as flanged
walls. In such cases, a portion of the intersecting wall can be treated as a flange of the shear wall (e.g., as an I-section or
a T-section). Such walls are normally required to resist earthquake forces in both principal directions of the building. The
flanges will considerably boost the moment capacity of tall cantilever shear wall. Hence the shear resistance of their
webs may become a critical design item. The large demand for web reinforcement can be conveniently met by using steel
with higher yield strength.
1.2 Behaviour of shear wall building
Only seldom will a single cantilever wall be called upon to resist the whole of the lateral load acting upon a
multistorey structure. It is more 1ikely that a number of such walls wi1l share in the total load resistance. In the majority
of multistorey buildings shear wal1s wi1l occur around the service core and rigid jointed frames are likely to carry the
gravity load over the remainder of the floor. The response of rigid jointed frames and cantilever shear walls to lateral
loads can be so markedly different, particularly in the upper storeys, that undesirable interaction may ensure. The two
types of structures may work against each other, and an unusually large ductility demand may possibly result in the
process of developing the ultimate strength of the whole structure. Openings in shear walls can be provided in a regular
and rational pattern to develop extremely efficient structural systems, particularly suited for ductile response with very
good energy-dissipation characteristics. However, the presence of openings reduces the rigidity of shear walls.
Efficiency of shear walls is described in terms of rigidity (or stiffness). Solid shear walls are most efficient so it
is highly desirable. Often openings are required in shear walls for functional necessity (e.g., doors and windows); such
walls are referred to as perforated (i.e., wall with openings). The portion of a shear wall between two adjacent openings
is called a pier, whereas, the segment of shear wall above the adjacent openings is called a spandrel or a beam.
A shear wall with openings can be analysed as a frame composed of short stiff wall segments (also called piers).
In many shear walls, a regular pattern of windows or doors, or both, is required for functional considerations. In such
cases, the walls between the openings may be interconnected by spandrels (or beams), resulting in coupled shear walls.
The connecting elements (i.e., beams) between coupled shear walls typically require horizontal and vertical
reinforcement to transfer shear from one segment of the wall to the other. When the connecting elements are incapable of
transferring shear from one shear wall to the other, the walls are referred to as non-coupled and can be analysed as
cantilevers fixed at the base.
2. LITERATURE REVIEW
Ravikanth Chittiprolu, Ramancharla Pradeep Kumar,(2014), studied about the Significance of Shear Wall in
High rise Irregular Buildings. The usefulness of shear walls in the structural planning of multistory buildings has long
been recognized. When walls are situated in advantageous positions in a building, they can be very efficient in resisting
lateral loads originating from wind or earthquakes. Reinforced concrete framed buildings are adequate for resisting both
vertical and horizontal loads acting on them. Extensive research has been done in the design and analysis of shear wall
high rise buildings. However, significance of shear wall in high rise irregular structures is not much discussed in
literature. A study on an irregular high rise building with shear wall and without shear wall was studied to understand the
lateral loads, story drifts and torsion effects. From the results it is inferred that shear walls are more resistant to lateral
loads in an irregular structure. Dynamic linear analysis using response spectrum method is performed and lateral load
analysis is done for structure without shear wall and structure with shear wall. Results are compared for the frame lateral
forces and storey drifts of both the cases. It is also observed that lateral forces are reducing when the shear walls are
added at the appropriate locations of frames having minimum lateral forces. Therefore, it is inferred that shear walls are
more resistant to lateral loads in an irregular structure. Also they can be used to reduce the effects of torsion.
Ashish S. Agrawal, S.D.Charkha (2012), studied about the Effect of change in shear wall location on storey
drift of multistorey building subjected to lateral loads. In this paper, study of 25 storey building in zone V is presented
with some preliminary investigation which is analysed by changing various position of shear wall with different shapes
for determining parameters like storey drift, axial load and displacement. This analysis is done by using standard package
ETAB.
The preliminary investigation revealed significant effects on deflection in orthogonal direction by shifting the
shear wall location. Placing Shear wall away from centre of gravity resulted in increase in most of the members forces.

3. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
75
The displacement of the building floor at storey 25 has been reduced due to presence of shear wall placed at centre. Drift
is increased as height of building increased and reduced for top floor. The column which placed at the edge of the
building is heavily axially loaded due to seismic forces. Location of shear wall influenced static and dynamic axial load
on the column. The displacement of building is uni-directional and uniform for all the grids in the case of Zero
eccentricity for seismic loading. With the increase in eccentricity, the building showed non-uniform movement of right
and left edges of roof due to torsion and this induced excessive moment and forces in member.
Iftekhar Anam and Zebun N. Shoma (2010), studied about the Nonlinear properties of Reinforced Concrete
structures. The importance of various nonlinearities involved in the static and dynamic analyses of Reinforced Concrete
structures is investigated in this paper. The nonlinearities studied here are geometric (caused by large deformations and
consequent effect on the elastic properties of the structure) as well as material (due to the nonlinear stress-strain
relationship of concrete and steel). In the first part of the paper, the nonlinear moment-curvature relationship of arbitrary
Reinforced Concrete cross-sections is developed numerically using nonlinear stress-strain relationships for concrete and
steel. The relative importance of geometric and material nonlinearity is studied for a simple 2-storeyed frame under static
vertical load. Although the effect of material nonlinearity is more important in most of the cases studied here, the
geometric nonlinearity becomes significant at higher loads. The effect of axial load on the moment-curvature relationship
is studied, and the effect of typical axial loads on the flexural behaviour of column is found to be significant. The shear
strength of the beams and columns proved to be very important here. Using the nonlinear sectional properties thus
obtained, the nonlinear structural dynamic analyses of the building are performed subjecting the structure to seismic
vibrations using nonlinear structural dynamics. Recorded ground motion data from two major earthquakes of the past;
e.g., the El Centro earthquake in USA (1940) and the Kobe earthquake in Japan (1995) are used in the dynamic analyses.
The results showed the difference between the linear and the nonlinear structural response.
3. BUILDING DESCRIPTION
3.1 Structure and analytical model
A twenty five storey RC building with core type shear wall and L type shear wall in zone III on medium soil is
analyzed using the software SAP 2000-14. The analytical model is shown in Figure 1. Seismic analysis is performed using
nonlinear time history analysis.
Description of Structure
No of bays in X direction = 5
No of bays in Y direction = 5
Storey height = 3 m
Column size = 0.7 m x 0.7 m
Beam size = 0.5 m x 0.4 m
Density of concrete = 25 kN/m3
Live load on floors = 2 kN/m2
Floor finish = 1 kN/m2
Density of brick wall = 20kN/m3
3.1.1 Building with core type shear wall
Fig. 1: plan of the building

4. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
76
3.1.2 Building with core type shear
Fig. 2: plan of the building
3.2 Nonlinear hinge assignment
In order to model nonlinear behavior in any structural element, a corresponding nonlinear hinge must be
assigned in the building model. Nonlinear hinges were assigned to the following structural elements expected to undergo
inelastic deformation.
The moment-rotation curve can be idealised as shown in Fig.3, where the point ‘A’ corresponds to the unloaded
condition, the point ‘B’ corresponds to the nominal yield, the point ‘C’ corresponds to the ultimate strength, the point ‘D’
corresponds to the residual strength, if any, in the member. It is usually limited to 20% of the yield strength and the point
‘E’ defines the maximum deformation capacity and is taken as 15θu.
Fig. 3: idealised moment-rotation relation for rc element
Linear static analysis results
4. RESULTS OBTAINED FROM SAP 2000 14
TABLE 1: Storey displacement obtained from linear static analysis of 25 storey building
Storey number
Building with Core type
shearwall
Displacement(mm)
Building with
L type shear wall
Displacement(mm)
0 0 0
1 0.855264 0.371724
2 2.664907 1.225381
3 4.916523 2.466994
4 7.395279 4.031361
5 10.004637 5.862031
6 12.697545 7.910904
7 15.447458 10.135895
8 18.236153 12.499775
9 21.048566 14.969307

5. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
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Storey number
Building with Core type
shearwall
Displacement(mm)
Building with
L type shear wall
Displacement(mm)
10 23.870635 17.514612
11 26.688445 20.108686
12 29.488016 22.727044
13 32.255558 25.347494
14 34.978391 27.94995
15 37.647318 30.516811
16 40.254528 33.036386
17 42.769371 35.484988
18 45.168701 37.848834
19 47.432346 40.11762
20 49.541107 42.284243
21 51.476606 44.34535
22 53.222147 46.302009
23 54.765416 48.160243
24 56.105152 49.934776
25 57.262738 51.604203
Fig. 4: storey height – displacement profile graph
5. TIME HISTORY ANALYSIS
According to Uniform Building Code, 1997, Clause 1631.6.1,Time-history analysis shall be performed with
pairs of appropriate horizontal ground-motion time history components that shall be selected and scaled. The parameter
of interest shall be calculated for each time history analysis.
Fig. 5: hinges formed in the structural Fig. 6: hinges formed in the structural elements
elements(building with L type shear wall) (building with core type shear wall)

6. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
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Considered earthquake:-lacc-nor-1
TABLE 2.Storey displacement obtained from the time history 1 analysis of 25 storey building
Storey number
Building with core
type shearwall
Displacement(mm)
Building with
L type shear wall
Displacement(mm)
0 0 0
1 3.242447 1.546963
2 10.384009 4.804155
3 19.66246 9.190612
4 30.323767 14.31016
5 42.8723 19.837425
6 55.312237 25.476216
7 66.453421 30.969549
8 75.562889 36.124826
9 82.640527 40.784858
10 88.049031 48.639549
11 92.203058 57.826231
12 95.459125 67.406502
13 98.023061 77.210127
14 99.972997 87.070676
15 101.348972 96.86368
16 102.235936 106.490882
17 102.909346 115.800424
18 103.855138 124.71575
19 105.587756 133.226099
20 108.37663 141.338314
21 112.072753 149.056528
22 116.158164 156.396572
23 120.040085 163.401455
24 123.321552 170.139684
25 125.927825 176.4972
Fig. 7: storey height – displacement profile graph

7. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
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Considered Earthquake:Lacc-Nor-2
TABLE 3: Storey displacement obtained from the time history 2 analysis of 25 storey building
Storey number
Building with core type
shearwall
Displacement(mm)
Building with L
type shear wall
Displacement(mm)
0 0 0
1 3.35115 1.678856
2 9.844158 5.110344
3 17.685011 9.670371
4 26.039311 14.94176
5 34.253671 20.558654
6 41.981939 26.266248
7 48.972137 31.883903
8 55.143518 37.293387
9 60.578554 42.40899
10 65.52081 47.132085
11 71.250176 51.403582
12 76.35383 55.163643
13 80.893858 59.477239
14 85.035423 64.281577
15 89.020473 72.245647
16 94.244771 81.229545
17 101.407844 91.488724
18 108.281765 102.37723
19 114.778444 112.796989
20 120.829317 122.645642
21 126.365802 131.864194
22 131.316944 140.45494
23 135.641259 148.479592
24 139.35499 156.112277
25 143.235667 163.350643
Fig. 8: storey height – displacement profile graph

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Considered earthquake: lexint-1
TABLE 4: Storey displacement obtained from the time history 2 analysis of 25 storey building
Storey number
Building with core type
shearwall
Displacement(mm)
Building with L type
shear wall
Displacement(mm)
0 0 0
1 3.475256 1.54811
2 10.694745 4.877076
3 19.435864 9.511771
4 28.681023 14.991219
5 37.896635 20.952334
6 46.764996 27.213676
7 55.035305 33.495789
8 62.48801 39.601473
9 70.019524 47.090486
10 78.006218 54.729379
11 85.241104 62.135694
12 91.522978 69.102726
13 96.682155 75.445708
14 100.621309 81.033749
15 103.35553 85.818909
16 105.819083 89.786726
17 108.513891 94.337458
18 110.144906 99.298575
19 110.788851 103.581573
20 113.699457 107.195925
21 120.139981 110.185672
22 126.86881 112.651622
23 132.867358 116.382905
24 137.960358 122.779296
25 142.157292 128.792773
Fig. 9: storey height – displacement profile graph

9. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
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6. ANALYSIS UNDER EQUIVALENT STATIC EARTHQUAKE LOADING
Only seldom will a single cantilever wall be called upon to resist the whole of the lateral load acting upon a
multistorey structure. It is more 1ikely that a number of such walls wi1l share in the total load resistance. In the majority
of multistorey buildings shear wal1s wi1l occur around the service core and rigid jointed frames are likely to carry the
gravity load over the remainder of the floor. The response of rigid jointed frames and cantilever shear walls to lateral
loads can be so markedly different, particularly in the upper storeys, that undesirable interaction may ensure. The two
types of structures may work against each other, and an unusually large ductility demand may possibly result in the
process of developing the ultimate strength of the whole structure.
Most of the seismic codes recommend an equivalent static procedure for the design of regular buildings where
the design base shear is calculated as a fraction of the seismic weight, based on factors such as seismic zone, importance
of the building, design ductility, fundamental natural period and type of soil.
The design procedure starts with an approximate estimation of fundamental period, which is usually less than
the analytical fundamental period of the structure. As per IS 1893:2002, the design base shear is calculated as,
Vb = W, where Z is the zone factor, I is importance factor, is the spectral acceleration coefficient and W is the
seismic weight of the building.
1. Zone factor = 0.16(zone III)
2. Soil type = medium soil
3. Response reduction factor (R) = 5 (steel frame with eccentric bracing)
4. Importance factor (I) = 1
5. Damping = 5 %
6.1 Twenty-Five Storey Building
TABLE 5: Values of lateral force from equivalent static earthquake analysis
Height ,H (m) Force,Qi (KN)
G 0
3 0.307
6 1.23
9 2.764
12 4.9135
15 7.6773
18 11.0553
21 15.047
24 19.654
27 24.874
30 30.709
33 37.158
36 44.22
39 51.898
42 60.1898
45 69.095
48 78.615
51 88.7493
54 99.498
57 110.8598
60 122.84
63 135.43
66 148.632
69 162.45
72 176.88
75 191.93

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6.2 Ten Storey Building
TABLE 6: Values of lateral force from equivalent static earthquake analysis
Height ,H (m) Force,Qi (KN)
G 0
3 4.407
6 17.63
9 39.665
12 70.515
15 110.179
18 158.66
21 215.95
24 282.06
27 356.98
30 440.72
6.3 Twenty-five storey building with L type shear wall
Earthquake forces are applied to the structure as nodal forces in X direction.
Total applied forces in the nodes in X direction=1697.106 kN
Sum of reactions from the column supports=965.46 kN
Percentage of lateral force taken by the shear wall in Y direction= = 43.11%
6.4 25 storey building with core type shear wall
Earthquake forces are applied to the structure as nodal forces in X direction and reactions are obtained as given below.
Total applied forces in the nodes in X direction =1697.106 kN
Sum of reactions from the column supports =1008.692 kN
Percentage of lateral force taken by the shear wall in Y direction= = 40.564%
6.5 Core type shear wall building 10 storied
Earthquake forces are applied to the structure as nodal forces in X direction and reactions are obtained as given below.
Total applied forces in the nodes in X direction =1697.106 kN
Sum of reactions from the column supports =1114.168 kN
Percentage of lateral force taken by the shear wall in Y direction= = 34.33%
CONCLUSION
The seismic performance of the structure is determined on the basis of its damage state under 3 earthquake
ground motion. The nonlinear response of structures is very sensitive to the structural modelling and ground motion
characteristics. From the 3 time history analysis, the maximum displacement obtained for building with core type shear
wall is 143.2357 mm and for building with L type shear wall is176.4972 mm. i.e, storey displacement is reduced when
shear wall is provided as core type. Shear wall absorb more lateral force as the height of the building increased.
Therefore, more systematic and complete parametric studies, considering different periods and different earthquake
ground motions, will be required to establish definite criteria for efficient design of reinforced concrete special moment
resisting frame system.
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