Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 9 — Ultimate Properties of Full-Scale Lead Rubber Bearings Based on Breaking Test

Abstract

This paper presents a part of “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”. Ultimate behavior and failure modes of full-scale Lead Rubber Bearings (LRBs) of 1600mm diameter were described herein based on a series of the break tests which conducted on 11 LRBs to obtain a break surface. The shear break tests were monotonically conducted on 3 full-scale LRBs under various axial stresses. Then the monotonic tensile break tests were performed on 5 full-scale LRBs with or without constant offset shear strain. In addition, 3 half-scale LRBs of 800mm diameter were also tested to study the size effect and the ultimate shear behavior in significantly high compression. In the evaluation on the test results, the ultimate strain and stress were firstly summarized to define a break surface for the real-scale LRBs. Then the LRBs broken in the testing were carefully observed to evaluate their failure modes. It was found that the full-scale LRBs exhibited good seismic performance in horizontal ductility capacity and vertical load carrying capacity. It seems that the ultimate properties and the failure modes were basically less affected by the scale of the models.