Site specific analysis using topography conditioned response spectra

Abstract

Abstract We address topographic effects in site response analysis. By splitting a generalized surface topography into simple geometric elements we identify fundamental concepts that control the dynamic response. We show that in the construction of a model for a particular topographic scenario the geometric details that must mandatory be retained into the model depend upon the expected period range of interest in the response spectra. We refer to this limited spectra as a topography conditioned response spectra. To fully test the newly introduced idea, we conducted extensive parametric analysis of the previously identified fundamental elements and generate a proxy to relate a lower bound of the target structural period to the maximum dimensionless frequency required in the model. This dimensionless frequency indicates accurately what elements of the profile can be eliminated as these are irrelevant for the spectral response. The proposed analysis technique is further explained using as case of study the topographic scenario corresponding to the Aburra Valley region in Medellin, Colombia. Our results show that with relatively simple models we can predict accurately the spectral response up to the prescribed target period.