Risk assessment of highway bridges under multiple hazards

The aim of this paper is to provide a rational framework for the quantitative risk assessment of highway bridges under multiple hazards. Risk is a crucial indicator to be considered when managing structures of great importance such as highway bridges. It associates the consequences of a structural failure or malfunction with the probability of bridge failure. Time-dependent total risk is computed and the effect of structural redundancy is investigated and implemented. The proposed framework includes the estimation of the effects of multiple common hazards such as abnormal traffic loads, environmental attacks, scour, and earthquakes. The failure probabilities associated with the considered hazards are evaluated separately using different approaches. Time-dependent failure probabilities, hazard functions, and probability density functions of the time-to-failure are also assessed for each hazard. These assessments contribute to the evaluation of risk considering the traffic flow and the local economy at the bridge location. Both epistemic and aleatory uncertainties are considered in this approach. Time-dependent profiles of risk, accounting for direct and indirect consequences, are obtained for an existing highway bridge.