GENERATION OF ARTIFICIAL ACCELEROGRAMS CONSISTENT WITH EARTHQUAKE-INDUCED GROUND MOTIONS

摘要

Seismic response history analysis is the most significant approach for seismic analysis of structural and geotechnical systems, especially when nonlinearities are present. The main purpose of this analysis is the determination of the system response when it is subjected to a ground motion acceleration. Several approaches have been proposed to select the most appropriate seismic acceleration. The various approaches use, respectively: a) real accelerograms;;b) synthetic accelerograms and c) artificial accelerograms. The artificial accelerograms for their versality are the most adopted. However, the main drawback of generated artificial accelerogram is the impossibility to take into account of both the time and frequency contents of real accelerograms when the spectrum compatibility is satisfied. In this paper an alternative method is proposed. The proposed method requires the following steps: i) to select a target accelerogram;;ii) to find a fully non-stationary model of earthquake ground acceleration such that the target accelerogram may be considered as one of its samples;;iii) to evaluate the mean elastic spectrum of a set of generate fully non-stationary accelerogram samples;;iv) to satisfy the compatibility of so determined elastic spectrum to elastic target response spectrum by means of an iterative procedure. In order to quantify the influence of accelerogram models on the seismic response a non-liner geotechnical system is analysed. In particular, selected a target accelerogram recorded in a stiff soil, the response of a real soil deposit is evaluated assuming for the soil a non-linear one-dimensional (1D) model.