STRUCTURAL INFLUENCE OF BRACINGS ON BEHAVIOUR OF MULTISTORIED FRAMES

Abstract

Major factors considered in the design of multistoried buildings are strength, rigidity and stability. The strength requirement is the only dominant factor in the design of low-rise buildings. However as the height increases, the horizontal loads acting on the structure becomes predominant. Thus the rigidity and stability requirements become more important and dominant factors in the design of high-rise buildings. The rigidity and the lateral stiffness of the multistoried buildings can be improved by many methods, such as providing shear walls, infills and bracings between floors. The shear wall may develop diagonal cracks which are very difficult to repair. Thus the structural systems with bracings are frequently used in construction of tall buildings to take care of horizontal loads. This dissertation deals with the analytical investigation on the use of steel bracings in concrete-framed structures. The investigation is carried out on a number of model frames. The objective of this study is to compare the effects of different types of bracing systems, various cross sections of bracings and positioning of bracings on the total deflection and inter-storey drift of the multistoried building frames. Dynamic response of frames are obtained taking both earthquake and wind loads as horizontal loads using STAAD-Pro 2001. Results obtained are presented in tabular as.well as in graphical form.