Improvements in Frequency Domain Soil-Structure-Fluid Interaction Analysis of Nuclear Power Plants

The next generation of nuclear power plants includes structures with coupled soil, structure and fluid interaction behaviors. An efficient analysis methodology that is capable of performing Soil Structure Interaction (SSI) while incorporating structure-fluid interaction along with operating load analyses is presented. A key part of this methodology is the development of pre-calculated soil impedance substructures and the associated seismic load vectors, which are stored in a Soil Library. The methodology uses a commercial finite element code, with modern structural elements, modern fluid elements and equipment substructures to economically perform frequency domain analyses of the coupled soil-structure-fluid-equipment system. The frequency domain analysis performed with the commercial finite element code is functionally equivalent to SASSI. This paper presents the methodology along with an example problem that compares the commercial finite element solution to a SASSI solution.