Two heterogeneous algorithms for partitioned analysis of nuclear power plants considering soil-structure interaction

In order to efficiently perform the dynamic analysis of nuclear power plants considering soil-structure interaction, two partitioned algorithms in parallel manner were proposed, in which the factors such as structural damping, soil nonlinearity, and foundation flexibility can be reasonably considered. For both algorithms, soil node motions were calculated by the explicit time integration method, while there are differences in the computational models and methods for structural dynamic analysis. One is to use 'strong' coupling, which was realized by overlapping elements between soil and structure partitions, and the structural dynamic analysis was performed using the implicit time integration method with Rayleigh damping. The other involves using a 'weak' coupling, where the soil and structure partitions were modeled separately, and the structure analysis was carried out using the mode-superposition method with modal damping. The accuracy of the proposed methods was be verified through a simple model. The seismic response analysis of the CAP1400 nuclear power plant on a nonrock site was conducted. Comparing the structural dynamic responses with Rayleigh damping and modal constant damping, it can be concluded that the damping model has an obvious influence on the structural response, and the structural damping model should be reasonably selected in practical engineering.