Development of Average Power Spectrum-Consistent Seismic Scenario-Specific Endurance Time Excitation and Its Application in Base-Isolated RC Buildings

Endurance Time (ET) analysis is a computationally efficient alternative to nonlinear time-history analysis, but its accuracy depends on how well the excitation represents target seismic characteristics. This study proposes a frequency-dependent methodology for generating scenario-specific ET excitations that are consistent with frequency band-wise average power spectra of target ground motions. The method derives target spectra, develops average power spectrum-based trial excitations, and refines them through spectrum matching. Validation using nonlinear analyses of base-isolated RC buildings shows improved agreement with target SA, PSA, and SD responses, reduced dispersion in seismic risk estimates, and reliable identification of optimal isolator properties for seismic performance assessment.