Experimental study on the flexural performance of concrete hollow composite slabs with tightly connected panel sides

The performance of joint connections in composite slabs is crucial for ensuring their bidirectional load-bearing capacity and overall structural integrity. To effectively address the challenge of protruding rebar in precast components, a new structural form of a tightly connected hollow concrete composite slab without protruding rebar on the slab side is proposed. To investigate the mechanical performance and failure modes of this slab-side tight-joint connected hollow concrete composite slab, bending performance tests under monotonic load were conducted on three tightly connected hollow composite slabs and one seamless hollow composite slab. The analysis focused on the failure modes, crack distribution, bending capacity, and bending stiffness of additional steel bars at the joints of the slabs. The results indicate that, under normal operating conditions, the flexural performance development of concrete hollow composite slabs with tightly connected slab sides is generally consistent with that of the non-spliced cast hollow composite slab. Under ultimate conditions, tearing or brittle fracture failure at the joint interface is likely to occur in the composite slabs, leading to a reduction in flexural bearing capacity. With an increase in joints, the bending capacity of the hollow composite slab decreases by 17.1%, Conversely, when joints are positioned away from the most stressed section, the flexural stiffness of the section increases by 13.5%. A comparison of experimental data and theoretical calculations indicates that the additional rebar at the joints effectively contributes to the lateral load transfer in the hollow composite slab, achieving bidirectional load-bearing capacity. This further validates that the design of the single-joint, tight-joint connected hollow concrete composite slab without protruding rebar meets the requirements for bidirectional load-bearing performance.