Abstract:
Pakistan lies in one of the seismically active regions of the world. To resist the lateral forces induced by earthquake, usually shear walls are used in medium to high rise buildings in Islamabad. Due to increase in weight, the base shear consequently increases. The cost of project increases correspondingly. The struts and ties developed in shear walls can be modeled by concrete bracings. The use of these concrete bracings can minimize the overall cost of the project. Types, sizes and locations are governing factors for bracing systems used in concrete multistory buildings. The buildings which have been designed and constructed using shear walls are replaced with concrete bracings to find out the use of bracing instead of shear walls, which is relatively safer and cost effective. These buildings include Islamabad Stock Exchange Tower and State Life Tower. These were modeled in ETABs and Response Spectrum Analysis was performed on different cases to extract the results including displacements, time periods and base shear. These cases include different locations, types and cross sectional dimensions of bracings. BCP 2007 was referred for the building configuration, zone factor, importance factor and seismic co-efficient factors. It was found that the displacement value will be decreased by decreasing the eccentricity in a building. Increasing the cross-sectional dimensions will enhance the stiffness, which consequently decrease the displacement. The cross bracing provide optimum results.
