Proposal of a nonlinear spring model on piping support structures for an elastoplastic response analysis method

Takito, Kiyotaka ; Okuda, Yukihiko  ; Nishida, Akemi  ; Li, Y. 

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 important. 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, including support structures is necessary. In this study, a method is proposed for modeling the elastoplastic hysteresis characteristics of piping support structures to establish a seismic response analysis method for piping systems, including support structures. First, the authors proposed 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 proposal of the model.