Parametric Study and Design Recommendations for In-Span Hinges in Reinforced Concrete Box-Girder Bridges

In-span hinges (ISHs) are located at the bridge deck of reinforced concrete box-girder bridges and are used to transmit vertical loads between two adjacent parts of the deck. ISHs are disturbed regions because of the complex three-dimensional stress state caused by concentrated bearing loads and utility openings. The common modeling practice for ISHs is simplified two-dimensional idealization as short cantilevers following standard procedures. Such simplified analytical and design procedures lead to inefficient detailing because they do not take into account the realistic failure modes of ISHs; punching shear is one of these critical modes. In this study, the influence of reinforcement and geometrical detailing on the behavior and strength of ISHs is assessed using a computational approach. The computational model is calibrated based on previous experimental results and adopts nonlinear three-dimensional finite-element analysis (FEA), accounting for cracking of concrete and elastic–plastic behavior of reinforcement. The concrete material is modeled using the total strain rotating crack method, and the effect of compression softening is incorporated into the constitutive model. The reinforcing steel is modeled using embedded reinforcement formulation assuming a perfect bond between the concrete and the reinforcement. From the computational study, design guidelines are presented for better constructability of these disturbed regions. Findings from this study revealed that the strength of ISHs is mostly improved by increasing the amount of diagonal reinforcement in the seat and by increasing the bearing plate size.