積層ゴム免震要素の終局特性を考慮した地震リスク評価に関する予備研究

抄録

Seismic isolation system is expected to enhance the safety of critical infrastructures, such as nuclear power plants. The system has been becoming widely spread and has applied for various structures. However, in recent year, unexpected ground motion occurs frequently around the world. Ensuring and enhancing the seismic safety against the large events are essential for promoting the implementation into a system. The probabilistic risk assessment is known as a useful tool to measure the safety and used for improving the safety of nuclear power plants. To establish the methodology for estimating the seismic risk of isolation system, ultimate characteristics of isolation device, hardening and slip phenomenon, should be considered. In this paper, the effect of hardening and slip phenomenon on seismic response and risk (annual probability of failure) of isolation device and equipment is investigated. Input ground motions are incremented up to the failure of devices and equipment and seismic response simulations are carried out. As the result of simulations, it was found that the hardening effect suppresses the response displacement of isolation device, although increases the risk of equipment and piping system. Thus, we have to utilize the appropriate evaluation model that can be taken into account the hardening and slip phenomenon of isolation device.