Fragility analysis of a school building before and after seismic retrofit

Due to frequent occurrences of earthquakes recently, a concern has been raised that South Korea is no longer a safe region from earthquakes and the importance of the seismic retrofit of existing buildings has been emphasized to respond to earthquake damages. School buildings require high performance levels because earthquakes can result in many casualties and they are used as shelters. Seismic retrofits are needed urgently for most school buildings because seismic design is not applied on them. It is necessary to conduct seismic performance assessment of existing buildings to establish an appropriate seismic retrofit plan. The current seismic performance assessment of existing buildings is deterministic method that assesses the safety of earthquakes by examining the responses of structures for design earthquake. However, since there are uncertainties in earthquake, it is necessary to evaluate the safety of earthquakes stochastically in the seismic performance assessment. The RC Jacketing is a method of increasing the size of the cross section by newly placing the reinforcing bars on the outside of the existing members and casting the concrete. In this study assessed the seismic performance of a school building without seismic details in South Korea using fragility analysis. Besides, chose RC jacketing among the seismic retrofit method and evaluated the retrofit effect by comparing the seismic performance before and after the retrofit. As a result, the RC jacketing method is effective not only in reducing the damage probability in the structural system but also in reducing the damage probability of the weak floor.