Time-Dependent Bridge Network Reliability: Novel Approach

A novel reliability-based approach to evaluating the overall performance of a bridge network and to assessing the reliability importance of individual bridges to the bridge network is presented. The new concepts of the time-dependent bridge network reliability and bridge reliability importance factor (RIF) are introduced. A bridge network is regarded as an assembly of nodes, points, and links. The bridge network reliability is formulated in terms of connectivity between the origin and destination locations. However, this formulation can be extended to include traffic capacity and impacts of bridge maintenance activities on economy, environment, and society. Reliability importance factor is defined as the sensitivity of the bridge network reliability to changes in individual bridge system reliability. This clearly represents the reliability importance of individual bridges in the network. Based on a bridge network topology, a series-parallel path model is created to compute the bridge network reliability using network theories and techniques. This novel approach is illustrated on a group of fourteen existing bridges of different material and structural types located in Colorado. This study provides the basis of a network-level bridge management system where lifetime reliability and life-cycle costs are the key considerations for optimal bridge maintenance strategies.