Application of the Modified Endurance Time Method for Predicting Seismic Response of Base-Isolated Structures Under Pounding

The pushover method is often used instead of the nonlinear time history (NTH) method for analyzing base-isolated structures due to its simplicity. However, pushover analysis cannot account for reversible earthquake effects on structural damage. An alternative fast method is the endurance time (ET) method, which has fewer limitations in considering the dynamic effects of earthquakes on structures. However, the accuracy of this method is questionable due to the inability to distinguish non-converged results of individual records. To clarify this question, this study investigates the application of the modified endurance time (MET) method, which is an enhanced version of the ET method under pounding. For this study, three base isolated special moment frames (SMFs) designed based on the design earthquake hazard level were analyzed under the earthquake hazard level with 2475-year return periods (EHL2475). The results of the MET and pushover methods were compared to each other with respect to the NTH analysis, which was considered the reference method. The results have indicated that the MET had less error than the pushover in predicting structural damage based on the maximum interstory drift ratio (IDR). In contrast to the pushover, the MET can predict nonstructural acceleration-sensitive element damage with errors of 12.3–20.8%.