Experimental and numerical investigation on shear and bond-slip behaviors of FSK-reinforced FRP-UHPC composite beams

The shear performance of fiber-reinforced polymer (FRP)-ultra-high-performance concrete (UHPC) composite beams with FRP shear keys (FSK) was investigated through a four-point loading test and refined finite element (FE) analysis. In total, five test specimens having different concrete strength, concrete slab width and height as well as FSK spacings were experimentally tested. The test specimens were simulated using a refined FE model in ABAQUS. The concrete damaged plasticity model (CDPM) and the Puck failure criterion were adopted to simulate the progressive damage of concrete and FRP profiles, respectively. The mechanical behavior of the interface was captured using a bilinear cohesive zone model (CZM). The comparison between the FE analysis and experimental results demonstrated a good agreement. Based on the validated model, a parametric analysis was conducted on the shear performance of FRP-UHPC composite beams with FSK, focusing on parameters such as concrete slab strength, height and width, FRP web shear strength, shear modulus, height and thickness, and FSK spacing. The results indicate that the maximum local slip beam is less than 4 mm, which verifies that FSK has good interfacial shear resistance. Increasing the strength and section size of the concrete slab can improve the flexural stiffness and the shear capacity of composite beams. The use of UHPC for concrete slabs can also effectively inhibit interface slip. Increasing the shear strength and thickness of FRP web can result in improved load-carrying capacity and reduced deformation of composite beams. This can also lead to a shift in the failure mode from shear failure to bending failure. The reduction of FSK spacing can effectively enhance the shear performance of the interface, thereby improving the composite action and increasing the bearing capacity and deformation resistance of composite beams.