Reliability-based system-level optimization of bridge maintenance and replacement decisions

This paper addresses the problem of optimizing bridge maintenance and replacement (M&R) decisions for a heterogeneous system of facilities. The objective is to determine optimal M&R policies for each facility over a finite planning horizon based on the knowledge of the current facilities conditions and on the prediction of future conditions. The system-level problem is based on the results of an M&Roptimization problem for each facility. The results of the facility-level optimization are incorporated in a reliability-based, bottom-up, system-level formulation that provides recommendations for each individual facility. We derive sufficient conditions for optimality and prove the result for the continuous case. A parametric study shows that the results obtained in the discretecase implementation of the solution are valid approximations of the continuous case results. The computational efficiency of the system-level solution makes the formulation suitable for systems of realistic sizes.