International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 03 | Mar -2017
p-ISSN: 2395-0072
www.irjet.net
Wind Analysis of Tall Building with Floor Diaphragm Abhishek Soni 1, Aruna Rawat2 , Suresh Singh Kushwah3 Department of Civil Engineering University Institute of Technology (RGPV) Bhopal, India Co Guide & Asst. Prof. Department of Civil Engineering University Institute of Technology (UIT) RGPV, Bhopal 3 Guide & HOD Department of Civil Engineering University Institute of Technology (UIT) RGPV, Bhopal 1
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Abstract - In this study, wind analyses of three-dimensional (3-D) G+20 tall buildings with and without rigid floor diaphragm is considered. The effect of diaphragm on three different geometrical plans hexagonal, pentagonal and square is also studied. The buildings are considered with different elevation floors that are 5 floors, 10 floors, 15 floors and 20 floors for all the geometrical plan buildings. The buildings are analyzed as per IS 875-1987 part 3 for wind zone II. In this way total 24 buildings are analyzed with 27 load combinations. The responses in terms of bending moment, shear force in beams and floor displacements are analysed and these responses are compared with building without rigid floor diaphragm. Key Words: Displacement, Floor diaphragm, Bending moment, Wind loading.
1.INTRODUCTION Recent years, many tall buildings and structures are constructed and more are being planned in the world. Wind loads and responses are the key factors for their structural designs. The need for tall buildings is increasing in our country day by day as land is becoming scarce which is encouraging the commercial utilization and the construction of the tall buildings. Behaviour of tall buildings to wind loading has to be critically examined considering various geometrical and wind parameters. For strengthening buildings against lateral force horizontal structural systems such as diaphragm and trussing system are used. Diaphragm is a building component that transmits lateral force to vertical force resisting components. Some of the prominent literatures on the topic are as follows Phillips et al. (1993) constructed full-scale single-storey wood house and tested under lateral loads at various stages of loading to evaluate the load-sharing characteristics and structural response. Different sheathings, fastener arrangements, and openings are incorporated to create shear walls with varying stiffness. The results showed that roof diaphragm affected the distribution of lateral load to the shear walls of the building. Lee et al. (2007) described an easy and accurate method to estimate peak interstorey drifts for low rise shear wall structures having rigid or flexible floor diaphragm. The Š 2017, IRJET
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method was based on principal modes acquired from a principal components analysis (PCA) of computed dynamic response data and is applicable for both elastic and inelastic response. Ambadkar and Bawner (2012) considered wind loads as specified in IS: 875 (Part 3) - 1987. G+11 storey building was analyzed by using STAAD PRO. The analysis was done for variations in obstructions height. Bhuiyan and Leon (2013) investigated the impact of diaphragm flexibility on structural response of tall buildings. A model of floor was constructed which consist of all primary structural members and an equivalent shell element floor model was constructed. The result showed that accelerations and displacements in flexible diaphragm structural model was more than rigid diaphragm structural model. And also the fundamental periods of vibration was more in case of flexible diaphragm structural model. Rehan and Mahure (2014) discussed the design and analysis of G+15 stories R.C.C., steel and composite building under effect of earthquake and wind using STAAD Pro. The result showed that steel-concrete composite building was better alternative for earthquake and wind forces. Patil et al. (2015) analyzed and designed a high rise building under wind load. G+19 storey building was studied for its behaviour in wind loading. The results of the study were in terms of diaphragm displacement due to wind force, change in reinforcement in column, change in behaviour of beam, storey drift, storey shear, displacement of the structure, and torsion due to wind force. Due to high wind pressure in tall structures displacement of the diaphragm is more and this creates additional stresses in building components. Wakchaure and Gawali (2015) considered different shapes of building of height 150 m having equal stiffness of column and equal plan area for wind load analysis. Wind loads are determined based on gust effectiveness factor method. Building models of different shapes were prepared by ETAB’s software and were compared for different aspects such as storey shear, storey drifts, storey displacement. The results showed that with the change in shape of building from square to elliptical the wind intensity, storey drifts, the lateral displacements, storey shear of the building decreases. Finally, it was concluded that wind load can be reduced by maximum percentage with an elliptical plan.
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