Optimal next inspection time for bridges based on corrosion deterioration

As the traffic demands grow constantly, and some vehicle bridges deteriorate due to corrosion, bridge agencies require non expensive procedures to schedule cost-effective maintenance programs. In this paper a reliability-based formulation is proposed for prediction of the next inspection time including the epistemic uncertainty on the corrosion initiation time. For the identification of the bridge integrity state where little or no follow up has been previously made, the prediction of damage state contains a great deal of epistemic uncertainty. The impact of this epistemic uncertainty on the prediction of corrosion initiation time is appraised for the purpose of weighting, later on, the cost/benefit of further and more detailed studies. The bridge reliability is calculated in terms of a damage index that depends on the bridge corrosion deterioration and the corrosion impact is calculated in terms of the moment capacity reduction and the evolution of the bridge failure probability. As the acceptable failure probability is used as the safety threshold, this failure probability is calculated from the minimization of the annual expected life-cycle cost including replacement.