Seismic behavior of a containment internal structure consisting of composite SC walls

This paper presents the lateral load behavior of a 1/10th scale model of a pressurized water reactor (PWR) containment internal structure (CIS). The entire CIS including the steam generator compartments, pressurizer, reactor cavity walls, etc. are made of steel–concrete composite (SC) walls. The lateral load behavior of the 1/10th scale model of the CIS was investigated experimentally by researchers in Japan, and presented at the 10th Structural Mechanics in Reactor Technology (SMiRT) Conference in 1989. Recent advancements in finite element modeling techniques, and computer-based analysis approaches have enabled the numerical simulation of the lateral load behavior of the 1/10th scale CIS tested earlier. This paper presents: (i) the development of 3D nonlinear inelastic finite element (NIFE) models of the 1/10th scale CIS, (ii) the comparison and benchmarking of numerical results with experimental results and observations, and (iii) the overall lateral load-deformation behavior of the CIS including the formation of ductile energy dissipating mechanisms in the SC walls. The results and findings are used to provide recommendations for modeling CIS structures consisting of SC walls while conducting nonlinear analysis to evaluate their seismic performance for design and beyond design basis events.