SEISMIC PERFORMANCE OF SIMPLY SUPPORTED BRIDGES CONSIDERING UNCERTAINTY IN SCOUR CONDITION

Bridges are crucial components in countries to overcome natural barriers such as rivers and achieve connectivity between different regions. In the context of Chile's hydro-geomorphological characteristics, bridges are necessary to overcome high-gradient rivers that run from the Andes Mountains to the Pacific Ocean. This scenario leads to local scouring processes in the bridge's pile foundation systems, which, under the well-known Chilean seismic scenario, requires quantifying the vulnerability of bridges under the conjunction of seismic demand and variable conditions of local scour. Estimating the depth of scouring is a complex task involving multiple uncertainty factors. Analytical procedures that define scouring consider data from complex hydraulic scenarios with variable soil conditions, channel instability, bed gradation, channel migration, and uncertain flood scenarios. This study evaluates the seismic performance of an actual simply-supported 5-span bridge considering uncertainty informed by characteristic bed parameters of the soil in the location of the bridge, and uncertainty estimated through Bayesian inference to handle the storm scenario to which the bridge is subjected. The study analyzes seismic vulnerability of the bridge through a nonlinear finite element model subjected to ground motion obtained from a probabilistic seismic hazard analysis, including different uncertain scenarios of scour depth, which are defined based on uncertain hydraulic and hydrological conditions at the bridge's site. The main results show how uncertain scour conditions for different scour and return periods and seismic hazards can affect the seismic performance of different structural components of the bridge.