In this article we introduce a new version of Incremental Dynamic Analysis (IDA) by which the effect of earthquake duration on the nonlinear dynamic response of the structure seems to be more obvious. We believe that the input energy of earthquakes is a better Intensity Measure (IM) than the spectral acceleration in first mode of the structure vibration (Sa(T1,5%)) for the study of duration effects. We used artificial acceleration time-histories simulated by the specific barrier model modified slightly for this study as well as real records apropriately selcted. Results confirm our proposed aproach.
