Abstract Summary
Sedimentary materials enclosed in basins complexify the ground motion by energy trapping, resonance and surface wave generation at the basin edge. In general, effects of basin presence are estimated by aggravation or adjustment factors (AGF). The present study evaluates the influence of basin effects on the seismic damage of a nonlinear structure, representing a bridge column, with a complete analysis from the earthquake source to the structure. The numerical simulation of wave propagation is performed with a coupled 3D SEM-FEM approach using the Domain Reduction Method, including non-linearities in the structure with a multifiber beam. To evaluate different seismic scenarios affecting the structure, a parametric study is performed with simplified basin geometries and homogeneous material properties. Two types of seismic sources are simulated: plane waves with vertical incidence and deep and shallow double-couple point sources. Besides, the spatial variability inside the basin is analyzed by inserting the bridge column in different positions, altering the ground motion wavefield arriving at the base of the structure consequently. The structural damage is estimated by the plastic energy dissipation index. The results show that basins' effect on structural damage can be estimated in a simplified form using a combination of a structural behaviour predictor and AGFs computed from the free-field ground motions. However, these factors should be correctly predicted, including both basin and source variability.
