Ultimate Properties of Large-Scale Lead Rubber Bearing Using Full-Scale Break Test

Abstract

Shinji KOSUGI, Tetsuo IMAOKA, Kenji KANAZAWA, Takafumi HIRAKI, Seiji NAGATA, Takashi NAKAYAMA, Kunihiko SATO, Masakazu JIMBO and Yoshito UMEKI Application of a seismic base-isolation system using lead rubber bearings (LRBs) has been developed for the purpose of enhancing the seismic safety of nuclear power plants (NPPs). To grasp the mechanical properties of the seismic isolator over the design limit, the break tests for a 1600-mm diameter LRB have been conducted using full-scale specimens in order to avoid the difficulties considering size effect. As a result, linearity limit state and break limit state of the full-scale LRBs were found to be well-evaluated as expected; i.e., the breaking shear strain under axial compression shall exceed the commercial reference value of 400%. Further, statistical models of linearity limit and break limit of LRBs are evaluated on the basis of the real-sized break tests. By using these statistical models of limit state of the LRBs, a residual risk for seismic base-isolated NPPs against earthquake events beyond design basis can be investigated more accurately.

Evaluating the Seismic Diversity and Robustness of Nuclear Power Plants

“…Subsequently, the pseudo velocity response spectrum determined based on the acceleration response spectrum corresponding to the annual exceedance frequency of 10 −5 (year −1 ) was set as the median capacity of each device. The natural periods of the SDDs and SIDs were assumed to be 0.3 s and 3.0 s, respectively, as a representation of various SSCs based on the performance of an actual NPP [41][42][43].…”