Repair optimization of highway bridges using system reliability approach

As reliability based methods gain increased acceptance, there is greater op portunity to use scarce resources more efficiently while maintaining a pres cribed level of reliability of a structure throughout its service life. The goal is to provide management decisions that will balance lifetime system reliability and expected lifecycle cost in an optimal manner. This study pr oposes a system reliability approach for optimizing the lifetime repair str ategy for highway bridges. The approach is demonstrated using an existing C olorado State highway bridge. The bridge is modeled as a series-parallel co mbination of failure modes, and the reliability of the overall bridge syste m is computed using time-dependent deterioration models and live load model s. Based on an established repair criterion, available repair options, repa ir costs, and updating, the optimum lifetime repair strategy is developed. The sensitivity of the optimum strategy to changes in various problem param eters including the prescribed service life, system failure criterion, and net discount rate is studied. Finally, the conclusions reveal that the prop osed approach demonstrates real potential for practical applications, needs frequent updates through inspection, and requires considerable research ef fort to develop accurate input data.