Seismic performance of an idealized steel-plate composite (SC) modular structure subjected to accident thermal loading

摘要

This paper presents a numerical study to estimate the lateral load performance of an idealized steel-plate composite (SC) modular structure subjected to accident thermal loading. Finite element analysis (FEA) method was employed to perform the structural pushover analysis of the idealized SC modular structure that resembled a generic containment internal structure including the steam generator, pressurizer compartments, and reactor cavity walls. The paper will elaborate on the findings from the study including the nonlinear behavior of the SC modular structures subjected to seismic and accident thermal loading, while incorporating four different modeling techniques (including three nonlinear and one linear models) with different complexity levels. Nonlinear analysis techniques employed in the study provided similar responses for the lateral load response and behavior of the idealized SC modular structure. Nonlinear analysis results indicated that the temperature gradient due to heating caused thermal cracking in the concrete infill and reduced the lateral stiffness of the structure. The severity of the lateral stiffness reduction depended on the applied surface temperature amplitude. A marginal reduction (about 10%) in the lateral strength of the structure was observed for the elevated temperature cases. The peak structure strength for the accident thermal cases were reached at larger drift ratios in comparison to the ambient case. The results from the nonlinear analysis have been used to verify a linear elastic analysis (LEFE) approach to accurately establish the lateral stiffness of the SC structures subjected to seismic and thermal (operating or accident thermal) conditions. The LEFE approach was implemented as a tool for practicing engineers in industry to obtain accurate design demands. The study also investigated the influence of stress and deformations in the steel faceplates and tie bars induced by concrete casting pressures on the lateral performance of the SC modular structure.