Ap/Vp specific inelastic displacement ratio for the seismic response estimation of SDOF structures subjected to sequential near fault pulse type ground motion records

This research study is focused on an improved statistical equation proposed to estimate the inelastic displacement ratio, C1, of structures subjected to sequential (pre-shock, main shock, after shock) pulse type near fault (NF) ground motions. Proposed equation considers the effects of fundamental vibration period of the structure, T, lateral strength ratio, R, and frequency content of the design earthquake on the variation of the response. Frequency content of the design earthquake, represented by the Ap/Vp ratio (i.e. ratio of peak ground acceleration (Ap) to peak ground velocity (Vp)), is a function of the earthquake magnitude, distance to fault, faulting mechanism and site class. In scope of the study statistical analyses were conducted to develop a simple and accurate statistical equation to estimate the C1 of structures subjected to sequential pulse type NF ground motions. From the results of the study it was observed that the C1 values obtained from the proposed equation are, generally, in good agreement with the calculated exact results. Also, the C1 and T relationships were plotted together with those of a former study to clearly show the detrimental effect of the sequential ground motion loading in terms of amplified displacement demands.