Dynamic behavior of high damping rubber bearings and lead rubber bearings under near-fault earthquakes

Abstract

Civil engineering structures are susceptible to natural calamities such as earthquakes, floods, and strong winds. Base isolation is a proven method for protecting structures during earthquakes. It involves inserting a flexible layer between the foundation and superstructure to isolate the structure from earthquakes, thereby changing the system's dynamic characteristics. The present study compares the dynamic performance of passive base isolators, specifically High Damping Rubber Bearings (HDRBs) and Lead Rubber Bearings (LRBs), under near-fault ground motion conditions to assess their effectiveness in reducing seismic impact on structures. The isolator is first analyzed using a static general approach and validated against existing literature before undergoing dynamic analysis. In this research, the LRB isolation system is analyzed using a dynamic explicit approach in ABAQUS, while the HDRB is analyzed using a dynamic implicit approach. The behavior of these isolators is studied under seismic events such as those from the Imperial Valley, Managua, Loma Prieta, Northridge, and Kocaeli ground motions. The results indicate that LRBs significantly reduce acceleration at the top of the bearing compared to HDRBs. The maximum reductions in response are 68.42% for the Kocaeli earthquake in case of LRBs and 61.80% for the Northridge earthquake in case of HDRBs. The LRB shows a minimum acceleration response reduction of 57.24%, while for HDRB, it is 24.47% for the Imperial Valley records in both cases.