Numerical simulation and investigation of the base isolated NPPC building under three-directional seismic loading

Reinforced concrete containment (RCC) is the most significant component of the nuclear power plant (NPP). Therefore, the safety and integrity must be ensured during the plant life in any conditions, in particular, in the event of a severe earthquake. Seismic or base isolation is a proven technology for reducing the effects of earthquake shaking on the building and avoiding failure of structure under earthquake. The aim of this paper is to numerically analyze the dynamic response of the RCC with or without high damping rubber bearing (HDRB) isolators, in the event of three Safe Shutdown Earthquakes (SSEs), accomplished by means of the finite element approach and setting up, as accurately as possible, a representative three-dimensional model of mentioned nuclear power plant containment (NPPC) structure. The obtained seismic analyses results in terms of accelerations, propagated from the ground to the building, base shear and displacements are compared for isolated and non-isolated NPPC to validate the reliability of the isolation technology in mitigating structural response. Furthermore, a new decreasing amplitude ratio (DAR) of structure response for the NPP structure is also proposed to estimate the effectiveness of the isolation system. In addition, the study shows that the patterns for non-isolated structure are mainly oscillating motion, whereas in case of seismic isolation they are associated to pure lateral translation. Therefore, it needs to consider the optimum of compatibility for connecting pipelines between the isolated and non-isolated buildings in the design.