Structural Evaluation of Ledges in Shiplap Hinge Joints

Ledges in shiplap hinge joints are pivotal elements of the overall structural system because they support other spans with in-span hinges to form a multi-frame bridge system. While this design allows for sufficient longitudinal expansion and contraction caused by various loads, relatively high tensile and shear stresses are concentrated in this shallower region that can lead to bridge collapse if not properly designed and constructed. This study focuses on evaluating the ultimate strength capacity of a bridge ledge designed in 1969 and comparing the results to design estimates using the empirical method. The ultimate capacity is determined from a physics-based finite element model created in ABAQUS. The finite element model is used to estimate the existing capacity and predict the failure mechanism for a bridge located in the Midwest (USA). Results also reveal different failure mechanisms determined from the two methods: (1) punching shear when using the empirical method and (2) shear friction as the governing failure mechanism determined by the finite element model. Moreover, the estimation results show that the shear friction capacity and the nominal interface shear computed using the empirical method were overestimated by approximately one and a half times more than the capacity determined from the finite element model.