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Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
117
COMPARATIVE STUDY ON SOLID AND COUPLED
SHEAR WALL
Reshma Chandran1, Unni Kartha G
2, Preetha Prabhakaran
3
1PG Student, Civil Engineering Department, SNGCE, Kolenchery,Kerala, India 2Head of the Department, Civil Engineering, FISAT, Angamaly, Kerala, India
3Associate Professor, Civil Engineering Department, SNGCE, Kolenchery, Kerala, India
ABSTRACT
Coupled shear walls are one of the systems commonly used in medium and high rise structures to resist lateral
forces. Yet these systems should not collapse or be induced severe damage during earthquake actions. For this reason,
coupled shear walls must have high strength, high ductility, high energy absorption capacity and high shear stiffness to
limit lateral deformations. So we generally preferred solid shear wall.
In the first part of the project, compare the building with solid shear wall and same building with coupled shear
wall. For that coupled shear wall with varying depth of coupling beam were used and then compared with the solid shear
wall. And studied behavior of those buildings. The performance of the building against lateral loads is different in both
the conditions. Finally, found out the critical slenderness ratio of the coupling beam which gives approximately same
results of building with solid shear wall. In the second part, studied the behavior of coupling beam in coupled shear wall
system. And also assessed the effect of variation of building height on the structural response of the shear wall. This
analysis is done by using ETABS. The analysis show that the performance of building with coupling shear wall is varies
with the depth of coupling beam. For each building, there must be a critical slenderness ratio for the coupling beam of
coupled shear wall.
Keywords: Base Moment, Coupling Degree, Drift, Slenderness Ratio, Diagonal Reinforcement.
1. INTRODUCTION
A coupled shear wall is part of a shear wall system, made of coupling beams and wall piers. It provides more
openings, which increase the functional flexibility in architecture. Furthermore, by coupling individual flexural walls, the
lateral loads resisting behavior changes to one where overturning moments are resisted partially by an axial
compression–tension couple across the wall system rather than by the individual flexural action of the walls.
The key parameter in coupled shear walls, stiffness ratio of coupling beams to wall piers, is a representative of
the degree of coupling between wall piers. Over coupling should be avoided, which causes the system to act as a single
pierced wall with little frame action. Similarly, light coupling should also be avoided as it causes the system to behave
like two isolated walls. Since the coupling action between wall piers is developed through shear force in the coupling
beams, correct modeling of coupling beams may substantially affect the overall response of coupled shear walls.
Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
125
From the results it is observed that, lateral displacement is maximum for MODEL I as compared to the other
models and minimum for Model V, i.e. Building with solid shear wall. In static and response spectrum analysis solid
shear wall shows lesser lateral displacement both in X and Y directions. When coupling aspect ratio increases lateral
deflection also increases. Response spectrum analysis gives higher value than the Equivalent static analysis.
8.2 Time Period of the Building
From the table it is observed that, MODEL I had more time period than other models. As the coupling beam
aspect ratio increases time period also increases.
TABLE 2: Time Period of the Building
MODEL
NO:
10 FLOORS 20 FLOORS 40 FLOORS
MODEL I 0.755 1.6265 4.066
MODEL II 0.6601 1.4723 3.82
MODEL III 0.5903 1.3776 3.698
MODEL IV 0.5318 1.3134 3.62
MODEL V 0.5067 1.2752 3.547
8.3 Maximum Deflection at the Roof
Maximum deflection at roof level for different models of 10, 20 and 40 storey buildings are shown in the table.
Deflection at the roof level is more for building with coupled shear wall of 300mm depth coupling beam. And building
with solid shear wall shows lesser roof deflection. Maximum deflection at roof level is increases with increase the (H/B)
ratio.
TABLE 3: Maximum Deflection At Roof Level
MODEL NO: 10 FLOORS 20 FLOORS 40 FLOORS
MODEL I 15.000
60.877 247.4
MODEL II 13.633 56.627 234.7
MODEL III 12.330 53.864 229.7
MODEL IV 10.821 52.374 227.3
MODEL V 9.901 51.208 223.7
8.4 Base Shear of Building
As the coupling beam aspect ratio increases base shear decreases. Solid shear wall have higher base shear than
the other models.
TABLE 4: Design Seismic Base Shear of 10 Storey Building
MODEL NO: VB(kN)
MODEL I 2853.19
MODEL II 3138.93
MODEL III 3330.14
MODEL IV 3432.63
MODEL V 3549.55
8.5 Interstorey Drift
Story drift is the displacement of one level relative to the other level above or below. From the results observed
that drift increases as height of the building increases and reduced at the top floors.
For 10 and 20 storied building, the storey drift is maximum for MODEL I i.e. coupled shear wall with 300mm
beam depth, as compared with other models. But top most floors MODEL I shows lesser drift than the other models. And
drift increases with increase the aspect ratio between shear wall heights to the coupled shear wall width (H/B) ratio for
each storey level.
Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
126
Fig. 18: Inter Storey Drift in X Direction Fig. 19: Inter Storey Drift in X Direction
for 10 storey building for 20 storey building
Fig. 20: Inter Storey Drift in Y Direction Fig. 21: Inter Storey Drift in Y Direction
for 10 storey building for 20 storey building
Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
127
Fig. 22: Inter Storey Drift in X Direction Fig. 23: Inter Storey Drift in Y Direction
for 40 storey building for 40 storey building
8.6 Storey Shear
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
0 2 4 6 8 10 12 14 16 18 20
ST
OR
EY
SH
EA
R (
kN
)
STOREY NO.
MODEL I
MODEL II
MODEL III
MODEL IV
MODEL V
Fig. 24: Storey shear for 10 storey Building Fig. 25: Storey shear for 20 storey Building
Storey shear for 10 and 20 storey building are shown in the figure. From the graph, solid shearwall have more
storey shear than coupled shearwall. Coupled shearwall wall with 300mm depth have less storey shear.
Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
128
8.7 Axial Force in Column
Axial force in column C12 of 10, 20 and 40 storey buildings are shown in the tables.
TABLE 5: Axial force in column C12 for 10 storey building
FOR 10 STOREY BUILDING
MODEL
NO.
COLUMN
NO.
STATIC ANALYSIS DYNAMIC ANALYSIS
LOAD
COMBINATION
AXIAL
FORCE
kN
LOAD
COMBINATION
AXIAL
FORCE
kN
I 12 EQX 614.38 REX 644.68
II 12 EQX 677.42 REX 712.10
III 12 EQX 715.66 REX 726.57
IV 12 EQX 686.68 REX 655.26
V 12 EQX 592.82 REX 557.46
TABLE 6: Axial force in column C12 for 20 storey building
FOR 20 STOREY BUILDING
MODEL
NO.
COLUMN
NO.
STATIC ANALYSIS DYNAMIC ANALYSIS
LOAD
COMBINATION
AXIAL
FORCE
kN
LOAD
COMBINATION
AXIAL
FORCE
kN
I 12 EQX 1255.01 REX 1255.84
II 12 EQX 1320.58 REX 1320.97
III 12 EQX 1360.98 REX 1324.87
IV 12 EQX 1345.38 REX 1259.87
V 12 EQX 1237.18 REX 1135.81
TABLE 7: Axial force in column C12 for 40 storey building
FOR 40 STOREY BUILDING
MODEL
NO.
COLUMN
NO.
STATIC ANALYSIS DYNAMIC ANALYSIS
LOAD
COMBINATION
AXIAL
FORCE
kN
LOAD
COMBINATION
AXIAL
FORCE
kN
I 12 EQX 2447.69 REX 2381.88
II 12 EQX 2509.78 REX 2463.88
III 12 EQX 2533.65 REX 2476.43
IV 12 EQX 2498.28 REX 2461.10
V 12 EQX 2284.48 REX 2179.19
From the table it is clear that column C12 in MODEL V have less axial force than other models. And axial force
is less in the case of coupled shear wall with 1800mm depth coupling beam compared with other models with coupled
shear wall. So the amount of reinforcement in column can be reduced in MODEL IV and MODEL V.
In the second part, in order to assess the behavior of the coupled shear wall and the influence of the size of the
coupling beam on the system, the following parameters are selected to be studied and discussed in this section:
� Coupling Degree (CD)
� Induced shear force in the coupling beam
� Induced Bending moment in the individual shear wall
8.8 Coupling Degree
Figs.29 represents the coupling degree (CD) in percentage versus to beam (span/depth), (Lb/h) ratio for different
buildings stories numbers 10, 20, and 40, respectively. The seismic analysis for these cases was done using static analysis
and response spectrum analysis.
Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
129
Fig.30 represents the same relation between the CD versus to different building stories number of different
coupling beam (span/depth) ratio in trial to expect the optimum value of beam (span/depth) with high coupling degree
percentage.
From the above figures, the Coupling degree is inversely proportional to the Lb/h ratio. And from the second
figure efficiency of the coupled shear wall systems increases with increase in the slenderness ratio (H/B) of the building
system until a certain value (in this study until slenderness of 13.33. i.e. 20 stories building) after this value the system
showed much lower efficiency. To conclude there is an optimum slenderness ratio for coupling beam system depends on
the dimensioning of the system and door openings size and location.
Fig. 26: Coupling degree (CD) versus beam (span/depth) ratio under response spectrum analysis
Fig. 27: Coupling Degree (CD) versus number of building stories
8.9 Induced Shear Force In The Coupling Beam
In this study the induced shear for in the coupling beam (Vb) is proportioned to the applied base shear of the
building (V). As shown in Fig. coupling beam exhibits the maximum shear at the second floor. For the current case study
the maximum (Vb/V) is 70%. It is worth to note that the maximum ratio of (Vb/V) do not affected by the slenderness of
the building system, in other words maximum (Vb/V) is constant for a particular coupling beam system for all building
heights. In the current case study the opening width to the total length of coupling system ratio (Wopen/B) has a constant
percent for all cases.
Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
130
Fig. 28: Coupling shear ratio (Vb/V) building height for 10 storey versus building
Fig.29: Coupling shear ratio (Vb/V) versus building height
Fig. 30: Coupling shear ratio (Vb/V) versus building height
Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
131
8.10 Induced Bending Moment in the Individual Shear Wall In order to generalize the concept, induced bending moment in the individual wall (Mw) is proportioned to the
applied base moment of the building (M). As shown in Fig. the induced bending moment is ranging from 8% to 18% the
base moment.
The induced bending moment in the individual wall is inversely proportional to the beam size. As the efficiency
of the coupled shear wall systems increases by the increase of the slenderness ratio (H/B) of the system until a certain
value, the induced bending moment in the individual wall to base moment ratio also decreased until it reaches a
minimum value at a critical slenderness ratio after that this ratio of the induced bending moment to base moment started
to increase again. The minimum value of induced bending moment in the individual wall and the critical slenderness
ratio for coupling beam system varies from system to another depending on the dimensioning of the system and door
openings size and location.
Fig. 31: Wall bending moment to base moment ratio versus beam span-to-depth ratio
9. CONCLUSION
The seismic response of high rise buildings with solid and coupled shearwall with different height, 10, 20, and
40 stories building are investigated for the static and response spectrum analysis to evaluate structural behavior , the
effect of the geometry parameters (Span/depth) ratios (1, 2.5, 4 and 6), and the aspect ratio of the shear wall height to
coupled shear wall width (H/B) effects on the monolithic reinforcement concrete coupling beams of symmetrical coupled
shear wall system.
1. Building with solid shear wall is more stable than building with coupled shear wall, because displacement and
drift in X and Y directions are more in the case of building with coupled shear wall.
2. Coupled shear wall with 1800mm depth shows approximately same results of solid shearwall. So the critical
slenderness ratio of the coupling beam is equal to one.
3. MODEL IV and MODEL V have less axial force in columns. So these models are more beneficial.
4. CSW will react to lateral loadings on the basis of its degree of coupling (DC). The Coupling degree is inversely
proportional to the Lb/h ratio.
5. Coupled shearwall is more efficient in case of 20 storey building.
6. Coupling beam exhibits the maximum shear at the second floor. And for 10, 20 and 40 storey building shear
force is high from second to sixth floor level, so transverse reinforcement should be confirmed.
7. The coupling shear wall as a lateral resistance system of seismic load will be not sufficient to improve the
performance of building system and may be it will be necessary to adding additional resistance lateral load for
building system depend on the building slenderness ratio (H/B).
Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
132
10. ACKNOWLEDGMENT
First and foremost I thank to lord almighty for the grace, strength, and hope to carry out the Master’s Thesis report.
I wish to record my sincere thanks to Dr. V.S. Pradeepan, Head of Civil Engineering Department, SNGCE, for
his valuable suggestion.
I wish to express my deep sense of gratitude to our Project coordinator Mrs.S.Usha, Professor, Department of
Civil Engineering for the sustained guidance and useful suggestions in completing the Master’s Thesis.
I wish to record my sincere gratitude to Mr. Harinarayanan. S, Professor, Civil Engineering, our Project
coordinator for the sustained guidance and useful suggestions in completing the Master’s Thesis work.
I wish to express my deep sense of gratitude to Mr. Unnikartha G, Head of the Civil Engineering Department,
FISAT Engineering College, Angamaly for his valuable time, sustained guidance and useful suggestions, which helped
me in the Thesis.
I wish to express my deep sense of gratitude to my guide Mrs. Preetha Prabhakaran, Associated Professor,
Department of Civil Engineering, for her valuable time, sustained guidance and useful suggestions, which helped me in
completing the Thesis work, in time.
Last, but not the least, I would like to express my heartfelt thanks to my beloved parents for their blessings, my
friends/classmates for their help and wishes for the successful completion of this Master’s Thesis.
REFERENCE
[1] P. P. Chandurkar ,Dr. P. S. Pajgade(2013), Seismic Analysis of RCC Building with and Without Shear Wall,
International Journal of Modern Engineering Research (IJMER), Vol.3, Issue.3, pp-1805-1810
[2] Dawn E. Lehman, M.ASCE; Jacob A. Turgeon; Anna C. Birely, M.ASCE; Christopher R. Hart, M.ASCE;
Kenneth P. Marley; Daniel A. Kuchma; and Laura N. Lowes(2013), Seismic Behavior of a Modern Concrete
Coupled Wall, American Society of Civil Engineers, pp-1-11
[3] Nam Shiu, M. ASCE, T. Takayanagi, and W. Gene Corley, F. ASCE(1984), Seismic Behavior Of Coupled Wall
Systems, American Society of Civil Engineers ,pp-1-16
[4] Dipendu Bhunia, Vipul Prakash, and Ashok D. Pandey(2013). A Conceptual Design Approach of Coupled
Shear Walls, ISRN Civil Engineering, pp-1-29.
[5] Mazen A. Musmar(2013), Analysis of Shear Wall with Openings Using Solid65 Element, Jordan Journal of
Civil Engineering, Volume 7, No. 2, 164 - 173
[6] P. S. Kumbhare, A. C. Saoji(2012),Effectiveness of Changing Reinforced Concrete Shear Wall Location on
Multi-storeyed Building, International Journal of Engineering Research and Applications, Vol. 2, Issue 5,
pp.1072-1076
[7] Romy Mohan and C Prabha(2011), Dynamic Analysis of RCC Buildings with Shear Wall, International Journal
of Earth Sciences and Engineering, Volume 04, pp 659-662
[8] Himalee Rahangdale and S.R.Satone(2013), Design And Analysis of Multistoreied Building With Effect of
Shear Wall, International Journal of Engineering Research and Applications (IJERA), Vol. 3, Issue 3, May-Jun
2013, pp.223-232
[9] M.D. Kevadkar, P.B. Kodag(2013), Lateral Load Analysis of R.C.C. Building International Journal of
Modern Engineering Research (IJMER),Vol.3, Issue.3, pp-1428-1434
[10] Varsha R. Harne(2014), Comparative Study of Strength of RC Shear Wall at Different Location on Multi-
storied Residential Building, International Journal of Civil Engineering Research. Volume 5, pp. 391-400
[11] Shahzad Jamil Sardar and Umesh. N. Karadi(2013), Effect Of Change In Shear Wall
[12] Location on Storey Drift of Multistorey Building Subjected to Lateral Loads, International Journal of
Innovative Research in Science, Engineering and Technology, Vol. 2, Issue 9, pp-1-9
[13] P. S. Kumbhare and A. C. Saoji(2012), Effectiveness of Changing Reinforced Concrete Shear Wall Location on
Multi-storeyed Building, International Journal of Engineering Research and Applications, Vol. 2, Issue 5,
pp.1072-1076
[14] Ashish S.Agrawal and S.D.Charkha(2012), Effect of Change In Shear Wall Location on Storey Drift of
Multistorey Building Subjected To Lateral Loads, International Journal of Engineering Research and