ASSESSING TIME-VARIANT BRIDGE RELIABILITY DUE TO PIER SCOUR

To prevent bridge failure due to pier scour, engineers are being asked to determine the reliability of new and existing bridges. There is currently little guidance for decision making regarding the control of scour at existing piers and the design of piers for avoiding failure due to pier scour. The purpose of this paper is to present a method to assess the risk of bridge failure due to pier scour during the life of the bridge. The analysis involves simulating pier scour for a period of time and determining the probability that the bridge will fail at various points in time during that period. A linear performance function describes the probability of bridge failure due to scour. The distributions and coefficients of variation of the random variables in the performance function are then determined by simulation, and the probability of failure is computed directly. The risk-based failure analysis will enable the engineer to base bridge pier designs and scour control on an estimated probability of failure, thus providing for the safer design of bridges.