Analytical Post Earthquake Damage Assesment Of Rc Building And Its Retrofitting: A Case Study

Abstract

Majority of earthquake damaged buildings can be safely used by employing retrofitting measures after systematic post earthquake damage assessment. The study considers evaluation of structural performance under earthquake using empirical and analytical approach. The subject building in this research is Abbas Institute of Medical Sciences (AIMS) Muzzafarabad. It is a three story RC frame structure with masonry infill walls and a lift well which is located at one corner of the building. This institute was in operation at the time of October 08, 2005 earthquake. After earthquake no significant damage was observed in the structural members. However, infill walls suffered minor damages at some locations. Seismic evaluation was carried out in three phases. First phase was the screening phase in which evaulation was performed by an emperical approach. Second phase was the analytical evaluation phase in which modal and linear static analysis (LSA) are performed. Third phase was the detailed evaluation phase in which pushover analysis was carried out on the existing and retrofitted building models to access performance of the building by using capacity spectrum method. The first phase concluded that building can be used after the earthquake with minor repairs but the results of Linear static and nonlinear pushover analysis revealed that the building was weak not only under seismic but also under gravity loading. This was due to the absence of mathematical modeling of infill walls in the computer model made with ETABS. After modeling of retrofitted building, results showed that strength and stiffness was increased along both orthogonal directions. However, ductility was little affected in strong direction but a significant gain occurred in weak direction.