Improved methodology for endurance time analysis: From time to seismic hazard return period

In the endurance time (et) method, structures are subjected to a calibrated intensifyingaccelerogram and their performance is assessed based on their response at various equivalent intensitylevels. application of the et method in performance-based design of structures has been studied byintroducing a continuous performance target curve, which expresses the limit of the proper seismicperformance of a structure along various times of the et accelerogram. the correlation between timein the et method and the return period for different structural periods is investigated. the procedure isbased on the coincidence of response spectra obtained from the et accelerogram at different times andresponse spectra defined by asce41 at different hazard levels. the results show that substitution of thereturn period for time in et analysis and performance curves increases the usefulness of these curves andcan simplify application of the et method in performance-based design.