Flexural behavior of UHPC wet joints for precast bridge deck panels

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Over the past decade or so, ultra-high performance concrete (UHPC) has been increasingly used for wet joints of bridge deck panels (BDPs) in bridge superstructures. To evaluate the flexural performance of UHPC wet joints for precast bridge deck panels, a total of seven BDPs were designed, including one monolithic cast-in-place bridge deck panel (MCIPBDP), one precast bridge deck panel (PBDP) with NC wet joints, and five precast bridge deck panels (PBDPs) with UHPC wet joints. The design parameters included reinforcement types (straight bars and U-bars), U-bar lap details (contact lap splice and non-contact lap splice), filling materials (UHPC and NC), and joint widths (150 mm, 200 mm, 250 mm, and 500 mm). Three-point bending tests were performed to evaluate the flexural performance based on the failure mode, load-deflection curve, cracking width in the wet joint region, and stiffness degradation. The experimental results showed that it is feasible to replace 500-mm-width NC wet joints with 200-mm-width UHPC wet joints for PBDPs with U-bars. UHPC wet joints, with a width of 250 mm, effectively prevented straight bars from slipping. As the width of UHPC wet joints decreased, the failure mode shifted from shear failure to bending failure. In addition, the cohesion-friction hybrid model was proposed to simulate the behavior of joint interfaces. The FE analysis results demonstrated that the FE model and modeling method have high accuracy and general applicability. Finally, the flexural capacity calculation formula was developed according to the strut-and-tie model. The theoretical calculation results were in good agreement with test results.