AbstractAn innovative load rating method for skewed highway bridges with steel girders is proposed in this paper. In the proposed method, a field test coupled with a grillage analysis is used to determine the actual safe load-carrying capacity of a bridge and the key factors that contribute to the capacity. Because the actual behavior of the bridge is incorporated via the field test, the method provides a justifiable evaluation of system behavior. The effect of additional system stiffness due to bridge skew is determined using a grillage analysis. The proposed method allows the factors that contribute to the load rating, such as critical span adjustment, longitudinal and lateral load distribution, unintended composite action, slab flexure, and additional system stiffness, to be quantified and qualified. The proposed method is illustrated using a case study of a symmetric steel girder bridge with a 43° skew angle. The case study demonstrates that the proposed method provides an accurate determination of the skew effect, compared to approximate methods of analysis, because the location of the girder and moment under consideration, the cross frames and parapets, and the location of the applied loading are explicitly incorporated.

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