Direct shear behavior of steel fiber-reinforced concrete single-keyed dry joints: Finite element analysis and calculation model

For precast concrete segment bridges, the keyed dry joint is essential to the bridge's overall structural behavior, warranting thorough investigation to better understand its shear performance. This paper investigated the direct shear performance of SFRC single-keyed dry joints (SSKDJs) based on the finite element simulation. The load-slip relationship, shear capacity, and crack pattern of the SSKDJs can be accurately predicted. Parametric studies were carried out to assess the impacts of key influential factors on the shear behavior. The shear transfer mechanism analysis revealed that reducing principal tensile stress in the shear key or enhancing the strength of concrete could effectively improve the shear capacity of the SSKDJs. The shear strength of the SSKDJs increased nearly linearly with horizontal confining stress and concrete strength. As the key depth-to-height ratio increased, the shear strength initially increased and then gradually decreased with a small magnitude. However, the optimal ratio decreased as the horizontal confining stress increased. The shear behavior of the SSKDJs was superior to that of ordinary concrete specimens due to the inclusion of steel fibers. An RBF neural network model was constructed based on FEM results to assess the shear resistance of the SSKDJs with extreme parameters. Finally, the applicability of the AASHTO formula for the shear strength of the SSKDJs was evaluated and a modified calculation model was proposed to predict the shear capacity of the SSKDJs.