Inelastic Seismic Test of the Small Bore Piping and Support System: Part 3 — Simulation Analysis for the Piping Seismic Test

Abstract

Seismic safety is one of the major key issues of nuclear power plant safety in Japan. It is demonstrated that nuclear piping possesses large safety margins through the small bore piping and support system test, consisted of three dimensional piping, supports, U-bolts, and concrete anchorages, using the E-defense vibration table of National Research Institute for Earth Science and Disaster Prevention, Hyogo Earthquake Engineering Research Center at Miki city, by the extremely higher seismic excitation level [1, 2]. A simulation analysis for the piping system is described with a focus on the inelastic behavior of the support to the whole piping system response, and the subsequent interaction when both piping and support shows inelastic behavior. The analysis for the inelastic response of the piping seismic test was conducted using the FEM program ABAQUS. It requires a large amount of time to carry out a strain behavior analysis of the localized piping element and also calculate the dynamic inelastic response of the whole piping system, simultaneously. Therefore the following two steps analysis method is proposed. (Step 1) Seismic response analysis of the piping system. (Step 2) Evaluation for local strain of elbows. The simplified piping system model is adopted to solve the non-linear dynamic response both of the supports and elbows of the piping system in (Step 1). On the other hand, the piping system model with partially detailed elbow shell elements is applied to evaluate local strain behavior of the elbow in (Step 2).