Feasibility study on the seismic isolation of pool-type LMFBR

Development of seismic isolation devices is a most important factor for the realization of a seismic isolation system in FBR plants. In this study, the seismic isolation system is composed of laminated rubber bearings and energy absorbers. A friction damper is adopted as an energy absorber. The friction damper is able to be designed to provide large energy absorption capability. However, the radical change in friction force excites the high frequency vibration modes of the building ( Kurihara 1986 ). A modified friction damper with an initial soft stiffness to reduce the radical change in the damping force has thus been designed. To investigate the feasibility of applying rubber bearings and modified friction dampers to a seismic isolation system in FBR plants, loading and shaking table tests were performed using scale models. This paper describes: 1) the fracture characteristics of rubber bearings after aging tests and fatigue tests; 2) the dynamic characteristics and durability of the modified friction damper; and 3) the vibration characteristics of the seismic isolation system.