Coupled approach for the assessment of basin effects on the seismic demand of nonlinear structures

Abstract

Sedimentary materials enclosed in basins modify the ground motion by energy trapping, resonance and surface wave generation at the basin edge. In general, the effects of basin presence are approximated by aggravation factors (AGF), but the particular surface wave part of the ground motion is never explicitly measured. The current study assesses the impact of basin effects on the seismic damage of a nonlinear structure, representing a bridge column, using a complete time-analysis from the earthquake source to the structure. The numerical wave propagation simulation is performed with a coupled 3D SEM-FEM approach using the Domain Reduction Method (DRM), including non-linearities in the structure. Therefore, with this model, the coupled basin effects on the seismic hazard and on the structural demand are quantified and contrasted. The findings indicate that basins' effect on structural damage may be estimated in a simplified form using a combination of a structural behaviour predictor and AFs derived from the free-field ground motions. However, these factors should be correctly predicted, including both basin and source variability.