UPTC_17593

As it has been proved in several researches carried out by different authors, riverine floods and the scour induced by these are one of the main causes of bridge collapse. More specifically, local scour causes a loss in the lateral resistance of bridge foundation, thus potentially increasing the seismic vulnerability of a bridge system. The present study assesses the combination of scour and earthquake effects for a bridge located in a road network crossing valleys in the Pyrenees Mountain range (France). The bridge spans over a river stream of trapezoidal cross-section, which is more able to capture actual physical behaviours than the rectangular section generally used for similar studies. The bridge consists in a continuous RC deck supported by two multi-column piers. Making use of the OpenSees software, a 3D finite-element model of the bridge is built and subjected to a suite of 312 ground motions (i.e., non-linear time history analyses). Fragility curves are developed for this multi-hazard case study, considering specific levels of damage that might be of interest, as well a comparison between fragility characteristics obtained in the absence and presence of scour. In order to fully study the potentially detrimental effects of scour on the dynamic behavior of the considered bridge, it is considered different scour combinations in the non-linear time-history analyses, such as: • Equal scour depth in all columns. • Same scour depth in the columns of the same pier. • Same scour depth in columns of different piers. • Scour depth concentrated in just one column of the bridge This study demonstrates the ability of a given numerical model to account for various hazard loadings and failure mechanisms, thus providing support to decision making regarding bridge management and monitoring.