Parametric Analysis of the Seismic Response of Irregular Topographic Features

Since the 2D modeling of topographic features, through numerical analysis, has been done up to now, all by symmetrical geometries, there is a problem that, whether the seismic response of asymmetrical models are so different or not. As the natural features are not symmetric, it is so important for engineers to know whether they can analyze them based on symmetrical models and how much is their risk. Therefore, in this paper we have evaluated the 2D site response based on parametric study of several asymmetric geometry models of hill (asymmetric semi-sine, triangular and trapezoidal shapes) and have compared them with the response of their corresponded symmetrical models. The studies have been done in time domain and soil material is considered linear elastic. Also, the assumed input motion was a Ricker type wavelet which was considered as SV and P plane wave and applied vertically. All calculations are executed in time-domain using the direct boundary element method. Clear perspectives of the amplification patterns of the hill are presented by investigation of the frequency-domain responses. In general the results shown that the increase of asymmetry rate between two side of features model haven't has a considerable effect on their seismic response and the response are mainly affected by geometric properties of the part of models which includes larger surface of model plane. Also the opposite component of incident motion wave response at the crest has been more amplified due to asymmetry affects.