Experimental and Numerical Investigation of Headed Bar Joints between Precast Concrete Bridge Slabs Loaded in Tension

A new connection joint between precast concrete bridge slabs, headed bar joints in high-performance fiber-reinforced mortar (HPFRM), is proposed to reduce the lap length and simplify the construction process of the traditional slab joint configurations. To investigate the tensile behavior of the proposed headed bar joints in HPFRM between precast concrete bridge slabs, four groups of 12-headed bar joint specimens were tested in different loading rules. Contributing factors to the joint tensile strength, including anchor plate configurations and loading rules, were investigated. A three-dimensional refined rib-scale finite-element (FE) modeling method was further proposed and verified against the experimental results. The working mechanism of mechanical anchorage and indirect lap splice was analyzed based on the FE analysis. This research shows that with the reinforcing bar spacing and lap length used in this paper, the joint specimens having 60 mm or less anchor plate length encountered conical shear failure before the rebars reached the characteristic tensile strength. At the peak load, with the degradation of the bond between reinforcement and mortar, the coworking mechanism of the mechanical anchorage and bond was switched to mechanical anchorage alone carrying most of the applied load. Increasing the anchor plate thickness can effectively improve the tensile stiffness and strength of the joint and hence avoid conical shear failure, while the influence of loading rules is very limited. The proposed refined rib-scale model can accurately predict the failure mode and tensile strength of the headed bar joints without artificially assuming the bond-slip constitutive relationship.