Evaluation of the relative and absolute cumulative input energy time history in the near-fault earthquake with visible pulse in acceleration time history, using the relative and absolute energy reflection spectral approach

Several studies have been carried out to evaluate the impact of near-fault earthquake with fling-step motion effects. The obvious feature of such earthquakes is the existence of a pulse with a significant amplitude in the velocity accelerograms. In this article, in order to investigate the effect of pulse-type near-fault earthquakes on the elastic demands of steel moment frames, a 15stories was simulated. After verifying the modelling process, under the influence of 20 near-field and 2 far-field records were analysed. The relationship between effective cyclic energy, ECE, and the displacement, velocity and hysteretic curve of SDOF systems in near- and far-fault earthquakes was evaluated. Then, studying the energy of relative and absolute cumulative input energy with kinetic energy in one section and maximum inter-story drift for 4 different levels of nonlinear behaviours (R = 1.0, 2.0, 4.0, 6.0) in the other section, the effect of higher modes was evaluated. Studying the inter-story drift profile for two near-fault earthquakes, with and without accelerated pulses, indicates the formation of the maximum drift, IDRmax, in upper stories for low nonlinear degrees (R=1.0 and R=2.0) in Records with visible pulses that verify the participation of higher modes. However, in accelerated pulse-free records, in addition to intensifying the IDRmax in the upper stories, a large-scale demand is imposed in the lower stories. In other words, in the lower stories, the first mode is mainly involved in these records.