Fragility analysis of nuclear power plant structure under real and spectrum-compatible seismic waves considering soil-structure interaction effect

Abstract

Both the real and spectrum-compatible seismic waves are widely used as input loads in the seismic assessment of critical structures in engineering applications, which are also allowed by international codes. However, the effect of the real seismic waves and spectrum-compatible seismic waves generated by different methods on the dynamic responses of structures has not been thoroughly emphasized. This study focused on quantitatively comparing the dynamic responses and fragility of the AP1000 nuclear power plant under real and spectrum-compatible seismic waves. Real and spectrum-compatible seismic waves generated by the modification and synthetic methods were used to perform the time history analysis. The effects of three input motion types on a high-accuracy soil–structure interaction system model were investigated based on various dynamic response indexes. The fragility assessment and maximum tension strain contours of the AP1000 nuclear power plant subjected to the three types of seismic waves were also presented to evaluate the influence of the input motions. The results revealed that spectrum-compatible seismic waves can cause larger dynamic responses than real seismic waves at the same peak ground acceleration level. Additionally, although some response indexes, such as strain energy, are sensitive to the input motions when the nuclear power plant is in a nonlinear state, the generation methods of spectrum-compatible seismic waves have insignificant effects on most dynamic response indexes, fragility assessment, and damaged zone locations.