Seismic Performance Assessment and Reliability Analysis of a Building Equipped with Lead Rubber Bearings Using the Endurance Time Method

In this study, the seismic performance and reliability of a three-story steel moment-resisting frame equipped with lead rubber bearings (LRBS) are comprehensively evaluated using the Endurance Time Method (ETM). Nonlinear dynamic analyses were conducted using ET۲۰in acceleration functions in SAP۲۰۰۰ to assess the structural response under escalating seismic intensities. The inter-story drift was adopted as the primary performance metric, and the influence of the LRB isolation system on mitigating inelastic deformations was systematically investigated. The mechanical properties of the LRBS were optimized using the Chaos Game Optimization-Differential Evolution (CGO-DE) algorithm, which enhanced seismic demand reduction. Reliability analyses, incorporating uncertainties of ۱۵%, ۲۵%, and ۳۵% in the structural and isolator parameters, were performed in OpenSees, integrated with RTx for probabilistic sampling, and quantified using the First-Order Reliability Method (FORM) with a modified Hasofer-Lind-Rackwitz-Fiessler (HL-RF) algorithm. The results demonstrated that LRBS significantly reduced inter-story drifts, improved reliability indices, and enhanced overall seismic performance, even under varying uncertainty conditions. The findings underscore the efficacy of the ETM and CGO-DE in advancing the performance-based seismic design of base-isolated structures.

Keywords:

Seismic Performance , Reliability Analysis , Lead-Rubber Bearings , Endurance Time Method , Chaos Game Optimization-Differential Evolution