Design Approach of Laminated Rubber Bearings for Seismic Isolation of Plant Equipment

EasyChair Preprint no. 2447

Abstract

The Korean type NPP represented as APR1400 has been designed to withstand 0.3g of SSE with seismic performance about 0.5g. The APR1400 contains a variety of structures and equipment, among which some may be vulnerable to earthquake. If the target seismic performance of APR1400 is raised to more than 0.6g, the range of vulnerable equipment may increase. This study aims to achieve an enhancement of the seismic performance of the NPP through application of passive seismic isolation to the equipment of high safety importance. Seismic isolation of a structure refers to reducing the seismic inertia force transmitted to the super structure by intentionally applying friction support or flexible device at the foundation. The techniques of seismic Isolation of large structures like buildings or bridges using LRBs are already well known and widely used in the world. Unlike the isolators for large structures, there are not many studies and tests for application of small LRB for NPP equipment subject to this study, and the relevant technical codes and standards have not been established yet. By the way, it is still understood tough to fabricate thin rubber layers meeting the target performance of flexibility and vertical stiffness. In the study, design development, manufacturing, and performance test of small LRBs are to be discussed to reach the goal of small equipment seismic isolation as much as possible. As a result, the seismic analysis based on the prototype model of isolator with upper structure of about 1-2 ton weight show that the horizontal natural frequency has been adjusted enough to reduce the seismic load. From the static performance test, it is concluded that the closed curve area in the hysteresis curve appeared as predicted and that the seismic isolator has a certain attenuation effect about 11%. Verification of the performance of the seismic isolator through dynamic analysis and dynamic performance test with various damping will be carried out soon.

Keyphrases: hysteresis curve, Isolator, LRB, natural frequency

@Booklet{EasyChair:2447,
  author = {Jinhyeong Lee and Taemyung Shin and Gyeonghoi Koo},
  title = {Design Approach of Laminated Rubber Bearings for Seismic Isolation of Plant Equipment},
  howpublished = {EasyChair Preprint no. 2447},

  year = {EasyChair, 2020}}