Influence of scour of foundations on the seismic performance of bridges

Infrastructure deterioration and ageing are growing challenges, also because of budgetary constraints on bridge maintenance and retrofitting. Specifically, scour of foundations is a significant issue for many bridges, particularly in a situation where global climate change is causing an increase in extreme alluvial events. In fact, it not only is the primary cause collapse of existing bridges but also lowers the ability to withstand following catastrophic occurrences, such as earthquakes. For the limited financial resources available for retrofitting, it is crucial to analyze the residual static and seismic capacity of bridges with accurate models. In this regard, soil-structure interaction plays a crucial role both in the assessment of current conditions and in the appraisal of expected performances. In fact, a lot of emphases has been paid in recent years to the use of dynamic testing on bridges to evaluate their current condition, specifically with regard to foundation scour. The fact that the dynamic response of the bridge is altered also when the scour hole is filled with sediment in the aftermaths of big events gives vibration-based monitoring approaches their principal benefit over conventional ones. On the other hand, scour of the foundation has a substantial impact on bridge dynamic response and ability to withstand future earthquakes. Modelling of these phenomena is often over-simplified by assuming homogeneous riverbed erosion as a reference condition, whereas the actual configuration of the scour hole can significantly affect the response of the pier. For proper use of resources, not only from an economic perspective but also for environmental sustainability, a more realistic appraisal is required. To do this, physical models can supply information for the calibration of numerical models, which can subsequently be applied to a realistic evaluation of the static and seismic performances