Methodology to determine the embedment depth of bridge piers considering the duration of rainfall events

Nowadays, there are many bridges that show damage or collapse due to scour, which produces serious consequences in direct and indirect costs. Although there are several studies that analyze scour in bridges, many of them consider that rainfall events are of unlimited duration, without evolution over time, which produces a conservative estimate. This work shows a methodology to develop fragility curves in bridges due to scour, evaluating the scour depth from its construction to the service life of the structure. The methodology used characterizes hydrological hazard, by evaluating the parameters: number of events, arrival time, and intensity and duration, as random series of Poisson processes. Additionally, the depth and average velocity of the flow are determined at the bridge site. With this information, scour depth values are obtained. Considering the overturning of the pier, the loss of support of the deck and the resistance of the pier as damage states, for each one the probability of failure during the useful life of the bridge is obtained. At the end of the work, some recommendations are included for defining the depth at which the pile should be placed to avoid scour.