Optimization of bridge maintenance strategies based on multiple limit states and monitoring

Visual inspections, diagnostic instrumentation and monitoring of bridges are essential for determination of intervention planning. Nowadays, a great challenge is to use bridge monitoring to determine optimal maintenance strategies. Indeed, monitoring data allow updating the knowledge on the structural performance and can significantly affect the intervention strategy. A methodology for structural reliability analysis of superstructures of steel girder bridges incorporating monitoring results is presented. Component reliability indices are computed for the slab and the girders and a time-variant performance analysis is conducted by considering corrosion. This allows dealing with structural capacity and serviceability with respect to permanent deformation under overload. Continuous and simultaneous measurements at discrete points of the bridge superstructure, provided by monitoring, allow to update some parameters of the serviceability limit state function and to perform a fatigue reliability analysis for several bridge components. The consideration of multiple limit states can lead to different optimal maintenance solutions, if taken individually or simultaneously. The aim of this paper is to show the impact of considering a global approach rather than an individual one when determining optimal maintenance strategies associated with several bridge limit states. The approach is illustrated on an existing highway bridge.