Effects of local site conditions on inelastic dynamic response of R/C bridges

Abstract

The purpose of this work is to study the effects of site conditions on the inelastic dynamic analysis of a reinforced concrete (R/C) bridge by simultaneously considering an analysis of the surrounding soil profile via the Boundary Element Method (BEM). The first step is to model seismic waves propagating through complex geological profiles and accounting for canyon topography, layering and material gradient effect by the BEM. Site-dependent acceleration time histories are then recovered along the valley in which the bridge is situated. Next, we focus on the dynamic behaviour of a R/C, seismically isolated non-curved bridge, which is modelled and subsequently analysed by the Finite Element Method (FEM). A series of non-linear dynamic time-history analyses are conducted for site dependent ground motions by considering non-uniform support motion of the bridge piers. All numerical simulations reveal the sensitivity of the ground motions and the ensuing response of the bridge to the presence of local soil conditions. It cannot establish a priori that these site effects have either a beneficial or a detrimental influence on the seismic response of the R/C bridge.