Assessment of seismic fragility using a three-dimensional structural model of a reactor building

Nishida, Akemi  ; Choi, B.  ; Shiomi, Tadahiko; Kawata, Manabu; Li, Y. 

The new regulatory requirements in Japan have strengthened the mitigation of damage caused by natural disasters, such as earthquakes, and the operational guide for safety improvement evaluation recommends the probabilistic risk assessment (PRA) as the evaluation method in Japan. In the PRA of an earthquake, also known as the seismic PRA, the realistic assessment of the structural seismic response and the damage probability (fragility) assessment using the realistic response assessment of the nuclear buildings and equipment is one of the most important issues. Accordingly, the authors have conducted this study on the realistic seismic response analysis methods and seismic fragility assessment methods to ensure the seismic safety of the nuclear buildings and equipment. In this study, a nonlinear seismic response analysis is conducted for input ground motions beyond the ground motions assumed in the design by using a three-dimensional (3D) structural model of a reactor building. In addition, the damage mode of the structural components of the reactor building associated with the equipment is identified, and the seismic fragility is assessed based on the 3D behavior of the reactor building. The local response and detailed damage process of the reactor building that have been obtained through seismic response analysis, are reported in this study, along with the results of the seismic fragility assessment.