Flexural Performance and Design Modelling of Cross-Laminated Timber-Concrete Composite Beams with Fibre-reinforced Polymer Shear Connectors

The increasing adoption of timber-concrete composite (TCC) systems in mid-rise and long-span timber structures has intensified the need for high-performance shear connectors to ensure efficient composite action. In TCC members, shear connectors transfer interface shear and restrict slip between the timber and concrete layers. Fibre-reinforced polymer (FRP) connectors have recently emerged as a lightweight, corrosion-resistant alternative to conventional steel fasteners; however, experimental evidence on their flexural performance within TCC applications remains scarce. This study evaluates the flexural performance of CLT-concrete composite beams incorporating six types of shear connections: SFS Intec screws (SFS), perforated steel plate (PSP), carbon and glass FRP rods (CR and GR), and T-shaped CFRP and GFRP plates (CP and GP). The beams were designed to transfer loads solely through the shear connectors, with a plastic sheet placed between the timber and concrete to eliminate direct interfacial bonding and friction. Four-point bending tests showed that FRP connectors can enhance composite action, bending stiffness, and bending capacity. Among the tested specimens, the GR connection achieved a higher capacity than the SFS connection, whereas the CR connection exhibited a lower value. In addition, both CP and GP connections achieved higher average maximum loads than the PSP connection. Analytical predictions of stiffness and bending capacity, based on partial composite action theory, showed reasonable agreement with the experimental results, supporting the applicability of the γ-method and Timoshenko beam theory to the tested beam configurations. Overall, this study provides an evaluation of FRP connections in TCC members, offering critical evidence to support their broader adoption in structures.