Development of Seismic Response Analysis Method of Piping System: Proposal of the Nonlinear Spring Model for Piping Support Structures

Abstract

Abstract In probabilistic risk assessment against earthquakes for nuclear power plants, developing a realistic response analysis method for the fragility assessment of piping systems considering input seismic motions exceeding the design assumptions is critical. Piping systems typically exhibit complex three-dimensional shapes, and the arrangement and stiffness of the piping support structures significantly affect the response characteristics of the entire piping system. Therefore, developing a realistic response analysis method for piping systems and support structures is necessary. This study proposes a method for modeling the elastoplastic hysteresis characteristics of piping support structures to establish a seismic response analysis method for piping systems and support structures. First, the authors propose an elastoplastic spring model that can express the elastoplastic hysteresis characteristics of a piping support structure. Subsequently, using this model, the authors perform a simulation analysis for the loading test of a piping support structure. The analysis and test results correlated well, confirming the effectiveness of the proportion of the model. The main contents, including the proportion of the elastoplastic spring model, the simulation analysis of the loading test, and the comparison between the analysis solutions and the test results, are reported in this paper.