EFFECT OF DIFFERENT POSITION OF SHEAR WALL ON DEFLECTION IN HIGH RISE BUILDING

Transcription

1 EFFECT OF DIFFERENT POSITION OF SHEAR WALL ON DEFLECTION IN HIGH RISE BUILDING Rajesh Jayarambhai Prajapati 1 &Vinubhai. R. Patel 2 1 M.Tech. Research Scholar & 2 Assistant Professor, Applied Mechanics & Structural Engg.Department, Faculty of technology & Engineering. M. S. University of Baroda, Vadodara , Gujarat, India. ABSTRACT This paper discusses importance of the lateral stiffness of a building on its wind and seismic design. To reduce damage in the event of wind and an earthquake, it is desirable to have large lateral stiffness. Shear walls contribute significant lateral stiffness, strength, and overall ductility and energy dissipation capacity. Therefore we have introduced shear walls at different location on plan of building like side centre shear wall, corner shear wall, shear wall at near to centre of building plan. The effect of shear wall on deflection is studied in A1, B1, C1& D1 models of 30 storied building. KEYWORDS: Deflection, position of shear wall. I. INTRODUCTION Tallness, however, is a relative matter, and tall building cannot be defined in specific terms related just to height or to the number of floors. From the structural engineer s point of view, however, a tall building may be define as one that, because of its height, is affected by lateral forces due to wind or earthquake actions to an extent that they play an important role in the structural design.the influence of these action must therefore be considered from the very beginning of design process. Tall towers and building have fascinated mankind from the beginning of civilization, their construction being initially for defence and subsequently for ecclesiastical purposes. The growth in modern tall building construction, however, which began in the 1880s, has been largely for commercial residential purpose. Tall commercial buildings are primarily a response to the demand by business activities to be as close to each other, and to the city centre, as possible, thereby putting intense pressure on the available land space. Loading on tall building differs from loading on low-rise building in its accumulation into much larger structural forces, in the increased significance of wind loading, and in the greater importance of dynamic effects. The collection of gravity loading over a large number of stories in a tall building can produce column loads of an order higher than those in low-rise building surface, but also with greater intensity at the greater heights and with a larger moment arm about the base than on a low-rise building. Although wind loading on a low-rise building usually has an insignificant influence on the design of the structure, wind on high-rise building can have a dominant influence on its structural arrangement and design in the wind may have to be considered in assessing the loading applied by the wind. In earthquake regions, any inertial loads from the shaking of the ground may well exceed the loading due to wind and, therefore, be dominant in influencing the building s structural form, design, and cost. As an inertial problem, the building s dynamic response plays a large part in influencing, and in estimating, the effective loading on structure Vol. 6, Issue 4, pp

2 II. GENERAL DESIGN CONSIDERATIONS 2.1 Types of Models The mathematical models developed in ETABS V9.5 for the purpose of this study are having the following: Way to read models (A1, B1, C1 and D1) A=Without Shear Wall Model B=Side Center Shear Wall Model C=Corner Shear Wall Model D=Shear Wall At Center Of Building Plan Model 1=Cross Section Of Column Change General Geometry Data of 30 Story Building for Model (A1, B1, C1, D1) Plan dimension : m m Total height of building from ground level : m Structural plan of building as shown in figure 1 (A) PLAN OF BUILDING (B) FRONT VIEW (C) SIDE VIEW (D) 3 D VIEW Figure 1 (A) Plan, (B) Front View, (C) Side view, (D) 3 D View of 30 Story Building Type of soil : Medium Total Story : Basement +Ground +29 Basement story height : 3.9 m Ground floor height and first floor height : 3.9 m Typical floor height : m Grade of steel use in building : Fe500 only Grade of concrete use in building : M45 only Autoclave aerated block (AAC BLOCK) used instead of brick masonry work in building 1849 Vol. 6, Issue 4, pp

3 DRY DENSITY (Kg/m 3) TABLE 1 Property of Autoclave Aerated Block PROPERTY OF AAC BLOCK COMPRESSIVE STRENGTH N/mm 2 STATIC MODULUS OF ELASTICITY (KN/mm For Models (A1, B1, C1, D1) Column size (In mm) STORY 27 TO 31 : mm STORY 23 TO 26 : mm STORY 18 TO 22 : mm STORY 11 TO 17 : mm STORY 6 TO 10 : mm STORY 1 TO 5 : mm Slab Thickness : 150 mm Beam size (Basement story and ground floor story) : mm (1 st story to 5 th story) : mm (6 th story to 30 th story) : mm Thickness of service shear wall (lift purpose) SW1 : 150 mm SW2 : 200 mm Thickness of other shear wall SW : 300 mm Along shorter direction of a building plan length of SW : 4.0 m Along longer direction of a building plan length of SW : 3.0 m Periphery wall (used autoclave aerated block) : 230 mm Different Location of Shear Wall in Plan A1 MODEL B1 MODEL C1 MODEL D1 MODEL FIGURE 2 B+G+29 Storey Building Plan W/O Sw Model(A1), Side Centre Sw Model(B1), Corner Sw Model(C1), Sw At Centre Of Building Plan Model(D1) With Changing C/S Of Column III. LOAD CONSIDERED 1) Floor finish load 1850 Vol. 6, Issue 4, pp

4 IV. For all floor levels =1.5 kn/m 2 2) Imposed Load (Live load) For all Floor Levels = 4 kn/m 2 3) Wall Load on Periphery For Terrace Level = 1.68 kn/m For Typical Floor Level = 4.66 kn/m 4) Wind Load: (only in Y-direction) As per IS 875(part 3) 1987 Wind speed Vb (m/s) = 44 Terrain category = 2 Structure class = C Risk coefficient (k1 Factor) = 1 Topography (k3 factor) = 1 For wind co-efficient referred Figure 4A, Page no 39 in IS-875(part-3) ) Earthquake Load: As per IS 1893:2002 Considering, Seismic zone = III Zone Factor = 0.16 Type of Soil = Medium Soil Importance Factor = 1 Response Reduction Factor = 5. PARAMETERS FOR ANALYSIS AND DESIGN The mathematical models developed are subjected to dead load, live load, wind load and earthquake load to analysis and design using ETABS VERSION 9.5 software. In this term we are taking maximum deflection according to DCON 6 wind combination (DCON 6 = 1.5 DL WL). In 30 story building we have compared different models (Models A1, B1, C1, D1) with respect to displacement. V. RESULTS The analysis and design results for different models are shown in tabular and graphical form, their results are compared with each other. Notation D is used for deflection in showing the results in the tabular form: D - Displacement in mm SR NO STORY NAME TABLE 2 Displacement for (Model A1, B1, C1, D1) DISPLACEMENT D IN (mm) A1 B1 C1 D1 1 STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY Vol. 6, Issue 4, pp

5 14 STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY STORY Graph 1 Displacement for (Model A1, B1, C1, D1) VI. DISCUSSION OF RESULTS 6.1. As per IS CL : 20.5 page no 33 maximum top deflection of building due to wind should not exceed H/500, where H is total height of building in mm, Means in our case 93240/500 is equal to mm. For earth quake As per IS CL : page no 27, The story drift in any story due to minimum specified design lateral force, with partial load factor of 1.0 shall not exceed times story height. For deflection 0.4 percentage of height of story it means H/250, where H is height of story. In our case 3048/250 is equal to mm. Because of book of Analysis and Design of tall building by Bryan Stafford Smith and Alex Coull, maximum top deflection of 100m height or 33 story building is 100 mm to 500 mm (6 inch to 20 inch), or, alternatively width of 1852 Vol. 6, Issue 4, pp

6 building m which is too small compare to length of building m in our case, so that wind case more governing/severe than the earth quake case. 6.2 As per, a relative deflection of 3 to 15 mm (0.12 to 0.6 inch) over a story height of 3 m (10 ft). For Model A1, B1, C1, D1. As per table 1 and Graph 1 of Top deflection, top deflection observed for wind combinationdcon6 (1.5 DL WL) for each models A1, B1, C1 and D1. In without shear wall model A1 top deflection is mm which is reduce up to 40% in top deflection due to shear wall at centre of building plan and side centre shear wall but drastically (suddenly) reduction up to 75% in top deflection by using corner shear wall. At this stage we observed an effect of position of shear wall on top deflection of a building. VII. CONCLUSION As per discussion of results we conclude that there is marginal reduction in deflection, by introducing side centre shear wall, shear wall at centre. But the deflection is reduced drastically by introducing shear wall at corner along both directions. Width of building is too small compare to length of building in plan in present work therefore wind case is governing case in our building. VIII. IX. FUTURE SCOPE Study of all the system without infill walls and its effect. Study of coupled shear wall. Study of different parameters like thickness, height and tapered section for shear wall. Study of foundation for various systems CASE STUDY GIFT CITY, A 30 story building, near Gift City circle, Gandhinagar (zone - 4), Gujarat, India. REFERENCES [1] Bryan Stafford Smith and Alex Coull Analysis and Design of tall building, A wiley-interscience publication, NEW YORK. [2] IS 456:2000, Indian Standard plain and reinforced concrete-code of Practice, Bureau of Indian Standards, New Delhi, [3] IS: 875 (Part 1), Indian Standard Code of Practice for design loads for building and structures, Dead Loads Bureau of Indian Standards, New Delhi. [4] IS: 875 (Part 2), Indian Standard Code of Practice for design loads for building and structures, Live Loads Bureau of Indian Standards, New Delhi. [5] IS: 875 (Part 3), Indian Standard Code of Practice for design loads (Other than earthquake) for building and structures, Wind Loads Bureau of Indian Standards, New Delhi. [6] David Scott & David Farnsworth The effects of complex geometry on tall towers new york, usa [7] R. K. L. Su1, A. M. Chandler1, M. N. Sheikh1 and N. T. K. Lam2 Influence of non-structural components on lateral stiffness of tall buildings 1 department of civil engineering, university of Hong Kong, Hong Kong 2 department of civil and environmental engineering, University of Melbourne, Parkville, Victoria, Australia. [8] S. Lee, S. Tovar, A. Kareem Shape and topology sculpting of tall buildings under aerodynamic loads department of civil engineeringand geological sciences,university of Notre dame. [9] MisamAbidi, MangulkarMadhuri. N. Review on shear wall for soft story high-rise buildings International journal of engineering and advanced technology [10] Wenjuan Lou, Mingfenghuang, hujin, guohuishenand C. M. Chan Three-dimensional wind load effects and wind-induced dynamic responses of a tall building with x-shape AUTHORS V. R. Patel is currently assistant professor in applied mechanics department at faculty of technology and engineering, M.S. University of Baroda, Vadodara. He obtained his B.E. civil, M.E. structure and Ph.D. from M.S. University of Baroda, Vadodara, Gujarat Vol. 6, Issue 4, pp

7 R. J. Prajapati is currently M.E. Research Scholar in Applied Mechanics Department at Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara. He obtained his B.E. Civil degree from B.V.M. College, S.P. University, V.V. Nagar, Anand and M.E. Civil (structural Engineering) degree from M.S. University of Baroda, Vadodara, Gujarat Vol. 6, Issue 4, pp