ROLE OF THE SOIL THICKNESS IN THE SITE RESPONSE ANALYSIS: A PARAMETRIC STUDY

Site Response Analyses (SRA) are generally performed in order to find the surface seismic excitations accounting for the specific soil properties of the site. In this regard, calibration of numerical models is the most critical issue. In particular, the results depend largely on many assumptions, such as soil thickness and mechanical properties. In this work, a refined 3D analytical approach has been performed by applying the credited platform OpenSees. Several parameters, such as mesh geometry and boundary conditions, have been calibrated and validated. In addition, SRA have been performed on various soil profiles. A large scatter in the main parameters (shear velocity and cohesion) has been introduced in order to represent the different soil classes, as proposed by the Eurocode 8 (EC8). Different values of thickness have been considered for each soil type and seismic intensity in order to check its effects on the obtained results. Ensembles of seven ground motions have been selected based on spectrum-compatible to the elastic spectra provided by EC8 for the soil-type A (bedrock). Three levels of seismic hazard have been considered.