Field testing of old concrete slab bridges designed for smaller truck loads shows that these bridges possess much higher strength than that indicated by current rating procedures. Extensive experimental and analytical investigations were carried out to evaluate the behavior of concrete slab bridges. Information gained from conducting the experimental and numerical analysis is used in this paper to develop a state of the art method to rate concrete slab bridges using a probabilistic approach. Monte Carlo simulation technique is used to develop probability density functions (PDF) for both load effect and resistance. The PDFs are then used to develop the probability of failure of the bridge. Results of this investigation indicate that concrete slab bridges, including those originally designed for H15 loads, have large reserve capacities and most of these bridges could carry modern traffic loads. Copyright 2004 ASCE.
