Probability‐Based Bridge Inspection Strategy

Current inspection requirements for several countries are reviewed. Observations and modeling of general corrosion of steel‐girder bridges are described. A highway steel‐girder bridge is assumed to be subjected to dead load and heavy‐truck traffic load. Three failure modes of the steel girders are considered, i.e., bending, shear, and failure of the stiffened web at the supports. The safety margins for each failure mode and an event margin for repair are described, and the reliability index is defined. The three failure modes are modeled as a series system, and expressions for the failure probability after inspections have taken place are shown. The optimization problem is formulated, with an objective function and constraints, to select an optimal inspection strategy. For example, a typical highway steel‐girder bridge is investigated. The reliability indices are calculated for each girder as a function of time. Based on this an inspection strategy is proposed.