Investigation on damage evaluation index with ductility factor based on simulation analysis for loading test of piping support structure

Abstract

The importance of seismic probabilistic risk assessment has drawn considerable attention for improving the seismic safety of nuclear facilities against earthquakes that exceed the design input ground motion. The realistic seismic response of the equipment or piping in nuclear power plants for fragility assessment in seismic probabilistic risk assessment must be evaluated. In particular, because piping systems have plant-specific complex configurations, the arrangement and stiffness of piping support structures considerably affect the seismic response characteristics of the entire piping system. However, the current seismic design procedure adopts an evaluation method assuming an elastic response. Therefore, this study develops an elasto-plastic response analysis method to estimate the realistic response of piping systems, including piping support structures. The authors have performed loading tests on piping support structures and optimization studies of elasto-plastic property models to develop an elasto-plastic response analysis method for piping systems, including piping support structures. Herein, the applicability of this method is confirmed through a simulation analysis of the previously reported elasto-plastic response of piping support structure loading test. Consequently, a good correlation is found between the test and simulation analysis results for the ductility factor and the damage status. Therefore, the ductility factor is verified to be effective as a damage evaluation index for piping support structures.

Keywords

• piping support structure
• loading test
• finite element analysis
• elasto-plastic behavior
• ductility factor