Static-dynamic coupled analysis of pumping station structure of a nuclear power plant using viscoelastic static-dynamic unified artificial boundary

The pumping station providing essential cooling water circulation are critical components in nuclear power plants (NPPs) throughout China. It is of great significance to investigate the seismic behavior of the pumping station structure considering complex heterogeneity site and load conditions according to the nuclear safety design requirements. In this study, a novel viscous-spring boundary, which is a more efficient and accurate methodology, is proposed and implemented in the ANSYS finite element software to study the seismic safety of the pumping station structure of NPPs. The Viscoelastic Static-Dynamic Unified (VSDU) artificial boundary based on Newmark’s integration scheme is proposed for nonlinear analysis of structures under coupled static-dynamic excitation. The User Programmable Features (UPFs) available in ANSYS were employed to integrate the proposed analysis method. Also, a complete toolkit for general static-dynamic coupled analysis is created using scripting-based ANSYS Parametric Design Language (APDL) and Graphical User Interface (GUI). Three validation examples are presented to demonstrate the accuracy and efficiency of the proposed method. Finally, seismic safety analysis of pumping station structure of NPPs based on the actual complex site conditions in China is also presented to illustrate the analysis procedure, and the results demonstrate that the proposed technique of investigating the seismic responses and stability of pumping station structure can provide more objective indices to evaluate the seismic safety during safety shutdown earthquake.