Impact Assessment of SC Walls Using Idealized SDOF and TDOF Models

Steel-plate composite (SC) walls have been used recently in overseas and domestic nuclear power plant (NPP) projects. For safety-related NPP facilities, these walls may be required to resist the effects of impact. Analysis of the structural global response of conventional reinforced concrete (RC) walls to impact loadings, such as those from tornado borne missiles or turbine-generated missiles and secondary wall impacts due to heavy load drops, is reasonably approximated using simplified dynamic analysis methods. For cases in which global bending dominates the response, an inelastic single-degree-of-freedom (SDOF) model is effective. For some impact loadings, the response includes considerable localized deformation. Analysis for these cases requires a cascaded two-degree-of-freedom (TDOF) model with one mass and resistance representing the global flexural response and a second mass, resistance and damping representing the local deformation response. In this paper, the methodology to complete dynamic analysis of impact loadings on SC walls (both SDOF and TDOF models) is provided, and SDOF and TDOF model results are compared to SC wall dynamic response from nonlinear finite element models.