Seismic performance of RC frame retrofitted using steel bracing.

Abstract

High rise buildings which are very common nowadays are subjected to problems due to lateral loads. Due to lateral loads like wind, earthquake etc. the structural stability of the structure is reduced. The lateral loads produce sway moment and induce high stresses in the structure. In order to reduce these effects of lateral loads bracings are efficient and effective. Bracings can be used for seismic retrofitting due to their high stiff-ness. Retrofitting approaches can be used to improve the seismic performance of the ex-isting structures, before that aresubjected to an earthquake. There are two retrofitting approaches, first is to add a new structural element like steel braces or shear wall and second is to provide concrete or steel jacketing. In this work steel bracings are used to retrofit the structure and they are provided in both concentric and eccentric manner. The main aim of the work is to analyze the performance of the building when the bracings are provided in eccentric manner. This study also focuses on performance of building with mega braced frame. Braced frames reduce lateral displacement and the bending moment in columns. Steel bracing is economical, easy to erect, occupies less space and has flexi-bility to design for meeting the required strength and stiffness. Different types of bracing such as V bracing, X bracing and diagonal bracing are provided. Seismic analysis is done using ETABS software.