A new model to incorporate pulse-like motions effect into the FAS prediction models

A new empirical model is developed in this study for including the amplification effects due to pulse-like ground motions. Differing from previous studies that suggested amplification models for spectral acceleration, the proposed model is employed on Fourier amplitude spectra (FAS). By extracting the large pulse from the original signal by wavelet transform, residual ground motion is achieved. Then, the ratio of FAS obtained from original motions to the FAS of residual motions is used to model the amplification effect of pulse. The new model is a narrow band five segment model against \({T}_{P}^{*}\) -normalized period where \({T}_{P}^{*}\) is a new characteristic period named threshold pulse period. According to the results, higher level of amplification belongs to the range of \(0.3\hspace{0.17em}\le \hspace{0.17em}T/{T}_{P}^{*}\le 0.5\) that is about 2.71. Results also showed that non-directivity-included ground motion prediction equation which was calibrated by multiplying the proposed model could improve estimates the FAS of original pulse-like motions.