Determination of optimally bundled intervention strategies for bridge elements: A joint replenishment model

A bridge is an engineering system that consists of multiple elements. Interventions are carried out on bridge elements to ensure bridge will continue to provide adequate level of service over its entire lifecycle. In determining an optimal intervention strategy, the existing advanced bridge management systems first determine the type and schedule of the interventions to be performed on each element based on the minimization of long-term steady state costs. Once these intervention types and schedules on each element are determined, they are grouped together, or bundled, using agency rules (e.g. priority rule) to develop an intervention strategy for the bridge. However, no evaluation is made to determine if the bundling of the interventions is optimal. This paper presents a novel joint replenishment model, which can be used to optimally bundle the interventions in bridge management systems. The model was developed based on the concepts of inventory theory and cyclic scheduling of a continuous process in the field of operation research. The methodology was used to determine the optimally bundled intervention strategies for a steel-concrete composite roadway bridge. A comparison of the optimal intervention strategies with and without bundling was made. The results showed that the developed methodology can be successfully used to determine the optimally bundled interventions strategies, thus reducing the negative impacts compared to unbundled intervention strategies.