Simulation of near-field pulse-like ground motions using a correlated bimodal fractional stochastic model

Abstract

This paper introduces a two-part stochastic method to simulate completely nonstationary pulse-like records and capture several peaks in the power spectrum. Based on the evolutionary power spectral density compatibility of the acceleration ground motion in different stages, the model is fitted to the target records. The proposed model is flexible enough to consider the decay rate variability of the high-and low-frequency content of the ground motions. Also, using the circular shift and IFFT techniques, the discretization of the model is performed such that the simulation cost is significantly reduced. The horizontal components of 178 near-filed pulse-like ground motions with a rupture distance of less than 10 km, with strike-slip and dip-slip mechanisms, are simulated using the proposed method. The model's efficiency is investigated using different criteria such as the elastic response spectra, Arias intensity, zero-crossing, Fourier spectrum, and the 2DOF system response. Moreover, the simulated records' pulse-like characteristics are investigated, and the model's capability to generate an ensemble of desirable ground motions is studied. Comparing the results with the previous models reveals that the model can generate more compatible records with the seed ones according to various aspects.