Determination of target time for endurance time method at different seismic hazard levels

Various durations of Endurance Time Acceleration Functions (ETAFs) associated with different seismic hazard levels are presented to enable Endurance Time (ET) method for use in probabilistic seismic demand assessment studies. Various Intensity Measures (IMs) were, first, considered for establishing multiple \IM-duration relationships. A set of 30 RC moment resisting frames were, then, subjected to IDA analysis using 44 ground motion records and the median IM values corresponding to different structural response levels were extracted. These values were compared with the ET-derived IMs by computing the errors corresponding to various demand levels and summating these errors over a complete range of response levels to derive an overall error index. The error indices were then averaged over all structural models and were compared for different IMs, revealing that maximum compatibility with the ETAF generation method dominated selection of the best IM.