Experimental study on mechanical property of hinge joints in hollow slab reinforced with high-performance grouting material

Damage to the hinge joints of in-service hollow slab bridges impairs the lateral connection capacity between adjacent slabs and disrupts the bridge’s overall force-bearing mechanism. Consequently, conducting in-depth research on the reinforcement of these vulnerable hinge joints is significant and necessary. This experimental investigation employed a full-scale experiment specimen fabricated from three 30 m hollow slabs retrieved from an in-service bridge, where hinge joints were rehabilitated using high-performance grouting material (HPGM). Three distinct loading cases were implemented: central loading, eccentric loading with damaged hinge joint, and post-failure single-slab bending experiments, to study the mechanical behavior and the load transfer mechanism of the joints and the corresponding failure mode was observed. Experimental results demonstrate that under central loading case, hollow slabs initially exhibit collaborative load-bearing behavior and elastic deformation. Damage initiates at the hinge joint when the applied load reached approximately 750kN, the displacement difference between the slabs on both sides of the hinge joint significantly increased. Further application of force revealed that the load transmission capacity of the hinge joint rapidly declined, but it could still rely on frictional force to bear relatively small shear force. Eccentric loading experiment indicated that damaged hinge joint transitioned into plastic deformation phase following minor relative displacement, ultimately progressing to severe structural failure. Finally, the deflection of the single slab increased rapidly as the hinge joint completely lost load transmission capacity completely, leading to the final failure of the hollow slab with the maximum crack width approximately 7 mm on the top surface of the hinge joint. The experimental findings delineate the complete failure progression and mechanical behavior of the hollow hinge joint reinforced with HPGM, which is useful for improving the joint design.