A dependency test of shear strain and compressive stress of full scale lead rubber bearings for nuclear power plant

Given the critical importance of nuclear power plants, seismic isolators must have been tested for reliability before applying to nuclear facilities. Rubber bearings are a good example of seismic isolators recommended for nuclear power plants. Among the different types of rubber bearings, lead rubber bearings (LRB) deform according to shear strain during an earthquake, and absorb energy due to the plastic behavior of lead core. When an earthquake occurs, the flexibility of LRB is used to lengthen the period of a seismically isolated structure, thus reducing seismic force exerted on the superstructure. For energy dissipation, a cylindrical lead is inserted into the rubber bearing, contributing to the attenuation performance of the seismically isolated structure based on the plastic behavior of lead. This prevents excessive change in the seismically isolated device and reduces seismic force exerted on the superstructure. In this study, we applied seismic isolation to APR1400 to derive characteristic values from a preliminary design of the seismic isolation system, and created actual test specimens to analyze the dynamic behavior of LRB