Site response analysis of an urban area. A multi-dimensional and non-linear approach

This paper critically examines the numerical predictions of the seismic site response of both ideal and real cases as obtained by means of mono- and multi-dimensional Finite Element (FE) approaches. Ideal case-studies are first considered, aiming at validating the adopted numerical approach against existing analytical or simple numerical solutions. Then a three dimensional model of the Bovino urban area, located in southern Italy, was generated taking into account the real site conditions. Numerical analyses were thus carried out adopting a nonlinear elasto-plastic soil constitutive model implemented in a commercial FE code. The following issues were investigated in detail: geometrical schemes, horizontal direction of the input motion, calibration of the constitutive model and non-linear soil response. Most of the obtained numerical results, presented in terms of amplification factors, indicate that larger amplifications occur when the more realistic multi-dimensional schemes are adopted as compared to the mono-dimensional ones.