Seismic Performance and Retrofitting of Steel Building

Some special Engineering firms are taken for rehabilitation by Performance based seismic design (PBSD). The existing building that has high value of facilities is important to make functional after immediate post-earthquake. Current codes and provisions cannot cover all structures located in active seismic zone and these structures are not capable of withstanding seismic action. Furthermore, heavy active earthquakes in urban areas have obviously established an urgency to measure performance of the existing building, upgrade and strengthen these seismic undersupplied structures. Many researchers worked in recent years to measure the performance of the building structures and develop various strengthening and rehabilitation techniques to improve the seismic performance of structures. The main objectives of this research are to evaluate the seismic performance of the steel frame building is designed as a multi-storey office building under seismic action located in Timisoara, Romania and using pushover analysis for the Life Safety performance level under an earthquake hazard level with 10% probability of exceedance in 30, 50, 100, 225, 475 and 975 years. The seismic performance of the building is measured by the push-over analysis by FEM software SAP2000. For this push over analysis, the target displacement of the top of the building is measured for life safety performance. The demand curve for the life safety, emergency occupancy, Local damaged, structural damaged, collapse of the building is conducted for different seismic actions. Capacity curve of the building is compared to the demand curve for checking the performance mentioned above. The capacity curve is less than the demand curve for all seismic actions. The building must be retrofitted for increasing the performance during seismic actions. The steel building is retrofitted by providing the steel bracing. The bracing size used is TUB-168.3x4 mm in the direction of tension and the performance of the building is tested by using pushover analysis for the same conditions that are done for unbraced structure. The performance of the building again determined for the same seismic actions. The lateral displacement of the building has significantly improved. The capacity curve coincides the first four accelerations for unbraced structure. The capacity curve is more than the demand curve and coincide all demand curves for all return periods and all accelerations for braced frame. The size of concentric tension brace is bigger; that is why no plastic hinges formed for all peak ground accelerations.