Application of Endurance Time method in linear seismic analysis

The Endurance Time (ET) method is a time-history based dynamic pushover procedure for seismic analysis and design of structures. In this procedure, structures are subjected to a specially designed intensifying accelerogram and their Endurance Time is measured based on the time interval during which they can resist the imposed dynamic actions. In this paper, application of the ET method in linear seismic analysis of structures has been investigated. The procedure for generating code compliant uniformly intensifying ET accelerograms has been explained. A set of three such accelerograms have been applied to various moment and braced steel frames and the results of analysis are compared to conventional equivalent static and response spectrum seismic analysis procedures. Code compliant ET analysis and base shear scaling in this method is discussed. Story drifts and internal forces are shown to be consistent with response spectrum analysis and static analysis results within acceptable tolerances. In the case of irregular structures, when static analysis results tend to diverge from response spectrum analysis results, the ET method’s results are closer to the response spectrum’s results. In general, it has been concluded that ET method can be considered as an alternative time-history based analysis in the linear range.