Managing bridge networks using reliability and multiple cost criteria

A methodology for bridge network maintenance planning is presented. This methodology integrates time-dependent structural reliability analysis, highway bridge network assessment, life-cycle cost calculation, and evolutionary computation. At project-level, the safety of individual bridges is assured by enforcing a lower-bound reliability index level. At network-level, life-cycle costs due to maintenance, bridge failure, and the ensuing loss of network service are evaluated probabilistically and subject to balanced minimization. This reliability-based bridge maintenance planning is formulated as a constrained combinatorial multiobjective optimization problem and is solved by genetic algorithm. An application example is provided to maintain the satisfactory performance of deteriorating reinforced concrete deck slabs of an existing bridge network. Numerical results show that this procedure is very effective in enhancing the overall long-term bridge network performance by striving for a balanced reduction of multiple and competing life-cycle costs of different origins while ensuring adequate safety of individual bridges in the network.