Bridge material decision for deteriorating structures based on whole-life optimum design considering life-cycle cost

A lifetime cost optimization methodology for planning the maintenance of structures that deteriorate over time is introduced and illustrated through numerical examples. The cost optimization is based on minimizing the expected total life-cycle cost while maintaining an allowable lifetime reliability for the structure. This method incorporates: a) predictive maintenance strategy; b): the effects of aging, deterioration, and subsequent repair on structural performance; c) the time value of money; d) Calculation formulation of life cycle cost. The overall cost to be minimized includes the initial cost and costs of preventive maintenance, inspection, repair and failure. The methodology is illustrated using the reinforced concrete bridge from highway bridges. An optimum maintenance strategy is developed for the bridge that deteriorates due to corrosion in an aggressive environment. The effect of critical parameters such as discount rate, and expected cost are all investigated, along with the effects of both uniform and nonuniform maintenance time intervals. Ultimately, the reliability-based lifetime design method to developing an optimum maintenance strategy demonstrates the potential for cost saving and improved efficiency.