Abstract Summary
The paper explores the role of nonlinear interfaces in the response of a typical reactor building in a nuclear power plant (NPP). A detailed finite element model of the reactor building-soil system is created using the Real-ESSI Simulator―a finite element software capable of modelling realistically the dynamic response of nonlinear soils, structures, and their interaction in time domain, accounting for the sliding or uplifting that might take place at the soil-structure interface. A relevant artificial accelerogram is chosen as the seismic excitation and implemented so as to generate vertically propagating horizontal shear waves using the Domain Reduction Method (DRM). Firstly, the input parameters of the stress-based nonlinear interface model are investigated in order to evaluate their contribution in the NPP reactor building’s response. A comparison of the nonlinear interface with the tied interface one, where sliding and uplifting at the soil-structure interface are prevented, follows. It is shown that when nonlinear interfaces are considered and the rocking motion prevails, the potential opening and closing of the gap at the soil-structure interface may amplify the response of the NPP reactor building in the higher frequency range (above 20Hz) and, thus, increase the seismic risk of critical components inside the NPP that vibrate close to this frequency range. This outcome indicates that neglecting the effect of nonlinear interfaces may not necessarily be on the safe side, as is usually assumed.
