IJSTE - International Journal of Science Technology & Engineering | Volume 3 | Issue 12 | June 2017 ISSN (online): 2349-784X
Analysis of Outrigger Structural System for Tall Building Subjected to Lateral Loads Preeti. M. Nagargoje PG Student Department of Civil Engineering Saraswati College of Engineering, Kharghar Navi Mumbai, India
Shilpa. Kewate Associate Professor Department of Civil Engineering Saraswati College of Engineering, Kharghar Navi Mumbai, India
Abstract The aim of this paper is to analyze the outrigger structural system for tall building subjected to lateral loads. Due to the urbanization and industrialization metro cities facing the problem of land so that tall buildings are generally preferred in metro cities. When the building increases the height, stiffness is very important criteria which can be reduced sufficiently by providing the outrigger beam between shear wall and outer columns. 40 storey RCC models has been developed and analyzed which is subjected to lateral loads by using ETABS software. The parameters of earthquake and wind load has been defined as per IS 1893 (Part-1): 2002 and IS 875 (Part-3): 1987 respectively. Dynamic analysis has been carried on RCC model without outrigger by using response spectrum method. The Results shows large values for lateral displacement, storey drift, velocity, acceleration, time period and base shear. To minimize the above parameters, four RCC models with single outrigger provided on 10th, 20th, 30th and 40th storey and one without outrigger model has developed and analyzed. The Comparative result show small reductions in above parameters. Therefore new four models has developed with Multioutrigger system (two outriggers) on different storey and analyzed. The comparative results of without outriggers model and Multioutriggers models shows considerable changes in parameters. This paper also have objective to find optimimum positions of Multioutrigger in Rcc model. From the result it is concluded that the provision of Outrigger system is very effective in Minimizing the lateral displacement, storey drift, base shear, acceleration, velocity. Keywords: Outriggers, ETABS, storey drift, lateral displacement ________________________________________________________________________________________________________ I.
INTRODUCTION
Due to increases in urbanization and less availability of land in Metro cities, the height of the building increases and become narrower therefore the stiffness of the building reduces. The stiffness of the structure becomes more important. For building taller than certain height, moment resisting frame structure, shear wall structure, braced frame structure, tubular structure may not provide adequate stiffness to resist lateral load therefore introduction of outrigger beams between the shear walls and exterior columns is more commonly used to give sufficient lateral stiffness to the structure. Outriggers are Stiff beam that connects the shear wall to the exterior columns to enhance building overturning stiffness and strength. When Tall building subjected to the lateral forces developed by the wind or earthquake, that forces are resisted by the system of Outriggers. Column resists the rotation of shear wall. This would result in significant reduction in lateral displacement at the top and base movement.
Fig. 1: Shows Elevation of Outrigger
II. MODELLING AND ANALYSIS Dynamic analysis of outrigger structural system for G+40 RC building. The model considered for this study is 120 m high rise reinforced concrete building frame. The Plan area of the Structure is 35m x 21 m with columns spaced at 3.5 m from center to
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