DYNAMIC RESPONSE OF HIGH RISE
STRUCTURES UNDER THE
INFLUENCE OF DISCRETE
STAGGERED SHEAR WALLS
Dr. B. KAMESHWARI *
Professor and Head, Department of Civil Engineering,
R.V.S. College of Engineering and Technology, Dindigul. Dr. G. ELANGOVAN
Associate Professor, Controller of Examinations, Anna University of Technology Madurai, Madurai
P. SIVABALA,
Assistant Professor, Department of Civil Engineering, Sree Buddha College of Engineering, Pattoor, Kerala
G.VAISAKH
Assistant Professor, Department of Civil Engineering, Sree Buddha College of Engineering, Pattoor, Kerala
Abstract-It is well-established fact that shear walls are quite effective in lateral load resistance of low-rise to
medium-rise reinforced concrete buildings. Restriction in the architectural design by the presence of the shear walls may contribute to discourage the engineers from adopting the shear walls. Due to this a new concept of providing storey deep and bay wide discrete staggered shear wall panels have been introduced.
In this study, the effect of various configurations of shear walls on high-rise structure is analysed. The drift and inter-storey drift of the structure in the following configurations of shear wall panels is studied and is compared with that of bare frame: (1) Conventional shear walls. (2) Alternate arrangement of shear walls. (3) Diagonal arrangement of shear walls. (4) Zigzag arrangement of shear walls. (5) Influence of lift core walls. Of the configurations studied, the zigzag shear wall configuration is found to be better than the other systems studied in controlling the response to earthquake loading. The diagonal configuration is found to be having significant role in controlling the response of structures to earthquake.
Keywords: High Rise Structures, Shear Wall Panels, Configuration of Shear Wall, Drift, Dynamic Response, Software Analysis.
1. Introduction 1.1 General
The Republic Day earthquake of January 26, 2001 in Gujarat clearly demonstrated the earthquake vulnerability profile of our country. It created a considerable interest amongst the professionals associated with construction activities in any form, as well as the non-professionals regarding the earthquake safety issues. The subject of earthquake engineering has its own sophistication and a lot of new research is being conducted in this subject.
The analysis of a structure can be done using any one of the methods namely linear static analysis, nonlinear static analysis, linear dynamic analysis and nonlinear dynamic analysis. Bureau of Indian standards (BIS) has published the IS 1893 – 2000 “Criteria for Earthquake Resistant Design of Structures”.
In this code, the equivalent static analysis and response spectrum methods are dealt with. It also says the dynamic analysis can be done using the time history analysis [4]. In this work, the analysis is conducted.
1.2 Objectives of the study
The objectives of the study are (1) To study the effect of various configurations of shear wall panels. (2) To study the variation in storey drift due to the presence of shear walls. (3) To study the variations in inter-storey drift due to the presence of shear walls. (4) To obtain the best configuration of shear walls from those under consideration.
2. Study on The Behavior of High Rise Buildings
2.1 General
The following configurations of shear wall panels are studied and are compared with that of bare frame. (1)Conventional shear walls. (2)Alternate arrangement of shear walls. (3)Diagonal arrangement of shear walls. (4)Zigzag arrangement of shear walls. (5)Influence of lift core walls.
Each of these configurations is analysed providing shear walls of thickness 0.10m along the longer plan direction and shorter plan direction of the building. The primary objective is to achieve a configuration where the drift and inter-storey drift is the minimum.
2.2 Nomenclature
The models prepared were designated as follows. Shear wall panels oriented along the longer plan dimension and shorter plan dimension are represented by ALD and ASD respectively. Models with and without shear wall panels in ground storey are represented by WSW and WOSW respectively.
2.3 Bare Frame (BF)
For the analysis, a typical frame of plan dimensions 30m × 20m and of height 91m is considered (Fig. 1). The longer plan dimension is taken as the X direction, the shorter one as Z direction and Y direction is taken in the vertical direction. The aspect ratio is taken as 1.5 so as to study the effect due to the orientation of shear walls along the both plan dimensions. Along the longer dimension in the plan, six frames are considered. Along the shorter direction, four bays are considered. The ground storey height is taken as 4m and the rest of the storeys are taken to be 3m high. The plan of the structure considered is given in Fig. 1.
Fig. 1. Plan of the structure
The isometric view of the structure is shown in Fig.2(a). Up to the 20th storey, the column cross section is taken as 1.20m × 0.50m. For the rest 10 storeys, the column cross section is taken as 1.10m × 0.50m. Up to the 3rd storey, the beam cross section is taken as 0.30m × 0.60m. From 3rd storey to the 20th storey, the beam cross section is taken as 0.30m × 0.50m. For the remaining top ten storeys the cross section of beams are taken as 0.30m × 0.40m. The floor slabs are modelled as plates of 0.15m thickness.
All the supports are modelled as fixed supports. Non-linear analysis is conducted on each of these models. The loads considered for the analysis are given below.
2.4 Dead Load
The dead load of the structure is obtained from Table 1, Page 8, of IS 875 – Part 1 – 1987. The permissible value for unit weight of reinforced concrete varies from 24.80kN/m3 to 26.50kN/m3. From the table, the unit
2.5 Imposed Load
The imposed load on the floor is obtained from Table 1 of IS 875 (Part 2) – 1987. The uniformly distributed load on the floor of the building is assumed to be 4kN/m2 (for assembly areas, corridors, passages, restaurants,
business and office buildings, retail shops etc).
2.6 Earth Quake Load
The structure is assumed to be in Kerala (Zone 3 as per IS 1893 – 2002). So the zone factor is taken as 0.16 as per Table 2 of IS 1893 – 2002. The damping is assumed to be 5%, for concrete as per Table 3 of IS 1893 – 2002. Importance factor is taken as 1.5 as per Table 6 of IS 1893 – 2002.
2.7 Wind Load
Basic wind speed is taken as 39 m/s. Form appendix A, a risk factor, k1 is taken as 1.0 as per Table 1 and k2 is taken as 1.20 as per Table 2 of IS 875 – Part 3.
3 Bare Frame with Conventional Shear Walls (CSW)
3.1 Bare Frame with Alternate Arrangement of Conventional Shear Wall System (AASW)
In the conventional shear wall system, all the shear wall in a frame are provided one above the other. The shear walls in the alternate storeys are placed at the two extreme ends of the frame, as shown in Fig. 2(c). In this case models with shear walls provided along the longer plan dimension and shorter plan dimension are prepared. Separate models were prepared with shear walls in ground storey to study the effect of soft ground storey on the overall response of the structure. Non linear analysis is conducted in all these models.
3.2 Bare Frame with Lift Core Walls (LCW)
The high rise structures will be having lifts. The core walls (shear walls) around the lift core will add up to the stiffness of the structure, thereby reducing the deflection. This set of models is intended to study the effect of lift core walls on the response of the structure. The model used is shown in the Fig. 2(d). Three sides of the lift chamber are having shear wall panels and the fourth side is left open to provide access to the lift chamber. Different sets of models similar to the previous cases are prepared and nonlinear analysis is conducted on each of the models.
3.3 Diagonal Arrangement of Shear Walls in the Bare Frame (DSW)
In this set of models, the shear walls in each frame are arranged in such a way that they form a diagonal pattern. For example, if we start with a shear wall panel in the 1st bay in the 1st storey, the shear wall panel in the 2nd storey will be in the 2nd bay and so on. On reaching the extreme right bay, the shear wall panel in the next storey is located again in the 1st bay. The arrangement is given in Fig. 2(e). As in the previous cases, the models with shear wall panels along the longer plan dimension as well as shorter plan dimension are modelled. Also the model with and without shear wall panels in ground storey are considered and linear as well as non-linear analysis are conducted on the models.
3.4 Zigzag Arrangement of Shear Walls in the Bare Frame (ZZSW)
The zigzag arrangement of shear wall panels is similar to the diagonal arrangement of shear wall panels except the following aspect. On reaching the extreme right end, instead of going to the left end for next storey, the shear wall panel in the next storey will be placed on the bay to the left of that of the shear wall in the lower storey. On reaching the extreme left end, the shear wall panel in the next storey is placed in the bay to the right of the bay where the shear wall panel is placed in the lower storey. The model is shown in Fig. 2(f).
4 Summary
The models are created and are analysed using STAAD Pro 2004. Non linear analysis was conducted on each of the models. The quantities of interest were storey drift and inter-storey drift.
5 Results and Discussion
5.1 Model: WOSW – ASD
Fig.3. Storey Drift: WOSW – ASD
Fig.4. Inter-storey Drift: WOSW – ASD
The inter-storey drift for various storey levels for various configurations of the shear wall panels are plotted in Fig.4. From Fig.4 and Table 1, for various configurations of shear wall panels, as in the above case, it can be seen that the bare frame is having the maximum inter-storey drift. The conventional shear wall system, alternate arrangement of conventional shear wall system and the lift core wall is having almost same values of inter-storey drift. The inter-inter-storey drift for the diagonal shear wall system and the zigzag shear wall system are much lesser than the other four. The maximum values of inter-storey drift and the percentage decrease when compared with the bare frame is given in Table1 and Table 2 respectively. The reduction in inter-storey drift, when compared to bare frame, is the maximum for the zigzag shear wall system which is about 78 percent. The reduction in inter-storey drift for the diagonal shear wall system is about 78 percent. The zigzag shear wall and the diagonal shear wall performed well in reducing the inter-storey drift.
5.2 Model: WSW – ASD
The storey drift for various storey levels for various configurations of the shear wall panels are plotted in Fig.5. From Fig.5 and Table 1, for various configurations of shear wall panels, as in the previous case, we can see that the bare frame is having the maximum storey drift of 146.90mm. The conventional shear wall system, alternate arrangement of conventional shear wall system and the lift core wall is having almost same values of storey drift. The storey drift for the diagonal shear wall system and the zigzag shear wall system are 28.64mm and 25.80mm respectively, which are much lesser than the other four. The maximum values of storey drift and the percentage decrease when compared with the bare frame is given in Table1 and Table 2 respectively. The reduction in storey drift, when compared to bare frame, is the maximum for the zigzag shear wall system which is about 83 percent. The reduction in storey drift for the diagonal shear wall system is about 81 percent. The
0 5 10 15 20 25 30 35
0 25 50 75 100 125 150 175
drift in mm
s
tor
e
y
Bare frame
Conventional SW
Alternate arrangement of SW Diagonal SW
Zig zag SW
Lift CW
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
0 1 2 3 4 5 6 7
drift in mm
st
o
re
y
Bare frame
Conventional SW
Alternate arrangement of SW Diagonal SW
Zig zag
Fig.5. Storey Drift: WSW – ASD
The inter-storey drift for various storey levels for various configurations of the shear wall panels are plotted in Fig.6. From Fig.6 and Table 1, for various configurations of shear wall panels, as in the previous case, we can see that the bare frame is having the maximum inter-storey drift of 6.05mm. The conventional shear wall system, alternate arrangement of conventional shear wall system and the lift core wall is having almost same values of inter-storey drift. The inter-storey drift for the diagonal shear wall system and the zigzag shear wall system are 1.36mm and 1.35mm, which are much lesser than the other four. The maximum values of inter-storey drift and the percentage decrease when compared with the bare frame is given in Table1 and Table 2 respectively. The reduction in inter-storey drift, when compared to bare frame, is the maximum for the zigzag shear wall system which is about 78 percent. The reduction in drift for the diagonal shear wall system is about 78 percent. The zigzag shear wall and the diagonal shear wall performed well in reducing the inter-storey drift in the X direction.
Fig.6. Inter-storey Drift: WSW – ASD
5.3 Model: WOSW – ALD
The resultant drift for various storey levels for various configurations of the shear wall panels are plotted in Fig.7. From Fig.7 and Table 1, for various configurations of shear wall panels, as in the previous case, we can see that the lift core wall is having the minimum storey drift of 117.20mm. All the other five models are having almost same but higher values. There is not much difference in the response of the structure in the presence of shear walls, independent of its configuration. Moreover, the lift core walls which are having two shear walls in the shorter plan dimension performed well. The interpretations like the shear walls are inefficient if provided along the longer plan dimensions holds good here also. The maximum values of inter-storey drift and the percentage decrease when compared with the bare frame is given in Table1 and Table 2 respectively.
0 5 10 15 20 25 30 35
0 25 50 75 100 125 150 175
drift in mm
st
or
e
y
Bare frame
Conventional SW
Alternate arrangement of SW Diagonal SW
Zig zag SW
Lift CW
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
0 1 2 3 4 5 6 7
drift in mm
s
tor
e
y
Bare frame
Conventional SW
Alternate arrangement of SW
Diagonal SW
Zig zag
Fig.7. Storey Drift: WOSW – ALD
The resultant inter-storey drift for various storey levels for various configurations of the shear wall panels are plotted in Fig.8. From Fig.8 and Table 1, for various configurations of shear wall panels, the interpretations of the results obtained here are exactly same as above. The maximum values of inter-storey drift and the percentage decrease when compared with the bare frame is given in Table1 and Table 2 respectively.
Fig.8. Inter-storey Drift: WOSW – ALD
5.4 Model: WSW – ALD
The resultant drift for various storey levels for various configurations of the shear wall panels are plotted in Fig.9. From Fig.9 and Table 1, for various configurations of shear wall panels, the interpretations of the results obtained here are exactly same as in the case of WOSW – ALD. The maximum values of inter-storey drift and the percentage decrease when compared with the bare frame is given in Table1 and Table 2 respectively. The inter-storey drift for various storey levels for various configurations of the shear wall panels are plotted in Fig.10. From Fig.10 and Table 1, for various configurations of shear wall panels, the interpretations of the results obtained here are exactly same as in the case of WOSW – ALD. The maximum values of inter-storey drift and the percentage decrease when compared with the bare frame is given in Table1 and Table 2 respectively.
0 5 10 15 20 25 30 35
0 25 50 75 100 125 150 175
drift in mm
s
tor
e
y
Bare frame
Conventional SW
Alternate arrangement of SW
Diagonal SW
Zig zag SW
Lift CW
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
0 1 2 3 4 5 6 7
drift in m m
st
o
rey
Bare frame
Conventional SW
Alternate arrangement of SW Diagonal SW
Zig zag
Fig.9. Storey Drift: WSW – ALD
6 Summary of results
The maximum storey drift and inter-storey drift are tabulated in Table1, for the various configurations of shear wall panels. The percentage reduction in the maximum storey drift of the various configurations, when compared with the bare frame is given in Table2. .It can be seen from the Table1 and Table2 that the drift as well as inter-storey drift are lesser when the shear wall panels are aligned along the shorter plan dimension. It can be also seen that the diagonal shear walls and zigzag shear walls are more effective in resisting the lateral loads during the dynamic excitation than those under consideration.
Fig.10. Storey Drift: WSW – ALD
Table1. Maximum storey drift in mm
STOREY DRIFT
BF CSW AASW
DSW ZZSW LCW
WOSW – ASD
D 146.91 110.92
ISD
6.06
4.34
105.52
4.12
29.56 26.76
1.37 1.36 4.54
117.20
WOSW - ALD
D 146.91 145.35
143.49 144.62
144.49
117.20
ISD
6.06
5.97
5.93
5.96 5.95 4.54
WSW – ASD
D 146.91 109.58
104.14
28.64 25.80
121.39
ISD
6.06
4.33
4.10
1.26 1.02 4.79
WSW – ALD
D 146.91 144.97
142.79 144.26
144.10
114.26
ISD
6.06
5.95
5.91
5.96 5.94 4.48
0 5 10 15 20 25 30 35
0 25 50 75 100 125 150 175
drift in mm
st
ore
y
Bare frame
Conventional SW
Alternate arrangement of SW Diagonal SW
Zig zag SW
Lift CW
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
0 1 2 3 4 5 6 7
drift in mm
st
o
rey
Bare fram e
Conventional SW
Alternate arrangem ent of SW Diagonal SW
Zig zag
Table 2. Percentage reduction in storey drift
% REDUCTION IN STOREY DRIFT
CSW AASW DSW ZZSW LCW
WOSW - ASD
D 24.49 28.17 79.88 81.79 20.22
ISD 28.36 31.94 77.44 77.59 25.05
WOSW - ALD
D 1.06 2.33 1.55 1.64 20.22
ISD 1.44 2.00 1.50 1.77 25.05
WSW - ASD
D 25.41 29.11 80.50 82.44 17.37
ISD 28.55 32.24 79.21 83.14 20.88
WSW - ALD
D 1.32 2.80 1.80 1.91 22.22
ISD 1.67 2.33 1.57 1.95 26.04
7 Conclusions
The analytical study on the dynamic response of various shear wall configurations was done and the storey drift and inter-storey drift for various shear wall configurations are obtained. From the study, the following conclusions can be drawn out.
1. Bay wide and storey high shear walls can be effectively used in reducing the dynamic response of a structure.
2. Shear walls placed along the shorter plan dimension gives better results than that in longer plan dimension in controlling the dynamic response.
3. There is 83% reduction in drift and 84% reduction in inter-storey drift, as compared to bare frame, when zigzag configuration of shear wall panels is employed.
4. Zigzag shear wall configuration is most effective for the structures in the earthquake prone areas. 5. There is 81% reduction in drift and 79% reduction in inter-storey drift, when compared to bare frame,
where diagonal shear wall configuration of shear wall panels is employed.
6. Diagonal shear wall configuration is also found to be effective for structures in the earthquake prone areas.
7. Presence of zigzag shear walls enhances the strength and stiffness of the structure by reducing the lateral drift and inter-storey drift than other types of shear walls.
8. The results obtained by linear and nonlinear analysis are showing almost the same trends. The values obtained by the linear and nonlinear analysis vary up to 9 percent.
9. The maximum inter-storey drift is observed at a height of 31m, which is approximately equal to the larger plan dimension.
8 References
[1] Arturo, Tena-Colunga, and Miguel, Ángel Pérez-Osornio (2005), “Assessment of Shear Deformations on the Seismic Response of Asymmetric Shear Wall Buildings”, Journal of Structural Engineering, ASCE, pp 1774 – 1779.
[2] Peter K. Dean1 and Harry W. Shenton (2005), “Experimental Investigation of the Effect of Vertical Load on the Capacity of Wood Shear Walls”, Journal of Structural Engineering; ASCE, pp 1104 – 1113.
[3] Kuang J. S. and Shubin Li (2005) “Interaction-Based Design Formulas for Transfer Beams: Box Foundation Analogy”, Practice Periodical on Structural Design and Construction, ASCE, pp 127 – 132.
[4] Bryan Folz1 and Andre Filiatrault, 2001, “Cyclic Analysis Of Wood Shear Walls”, Journal of Structural Engineering, Vol 127, Issue 4, pp 433-441.
[5] Qiuhong Zhao and Abolhassan Astaneh-Asl, 2004, “Cyclic Behavior of Traditional and Innovative Composite Shear Walls”, Journal of Structural Engineering, Vol 130, Issue 2, pp 271-284.
[6] John W. van de Lindt, and Matthew A. Walz, 2003, “Development and Application of Wood Shear Wall Reliability Model”, Journal of Structural Engineering, Vol 129, Issue 3, pp 405-413.
[7] Barham et al.,2005,“Development of the large increment method for elastic perfectly plastic analysis of plane frame structures under monotonic loading” International Journal of Solids and Structures 42 (2005), pp 6586–6609.
[8] Honggun Park and Taesung Eom,2005, “Direct Inelastic Earthquake Design Using Secant Stiffness” Journal of Structural Engineering, Vol 131,Issue 9, pp 1355-1362.
[12] IS: 875 (Part 1) – 1987, “Code of Practice for Design Loads (Other Than Earthquake) for Buildings and Structures – Dead Loads”, Bureau of Indian Standards, New Delhi.
[13] IS: 875 (Part 2) – 1987, “Code of Practice for Design Loads (Other Than Earthquake) for Buildings and Structures – Imposed Loads”, Bureau of Indian Standards, New Delhi.
[14] IS: 875 (Part 3 – 1987, “Code of Practice for Design Loads (Other Than Earthquake) for Buildings and Structures – Wind Loads”, Bureau of Indian Standards, New Delhi.
[15] Tissell, J. R. ~1993!. “Structural panel shear walls.” Res. Rep. 154, American Plywood Association, Technical Services Division, Tacoma, Wash.
[16] Ni, C., Karacabeyli, E., and Ceccotti, A. 1999, “Design of shear walls with openings under Lateral and vertical loads.”Proc. Pacific Timber Engineering Conf., Rotorua, New Zealand, 144-18.
