Enhancing the load-slip behaviour of cross-laminated timber-concrete composite using FRP connections: Experimental and numerical investigation

This study investigates the structural behaviour of timber-concrete composite (TCC) connections using innovative shear connectors made from fibre-reinforced polymer (FRP) materials. Push-out tests were conducted on 18 specimens with six different types of connections to examine the load-slip behaviour, load-carrying capacity, stiffness and failure modes of the composite joints. Cross-laminated timber (CLT) was positioned between two concrete bricks to create symmetric TCC joints, utilising both conventional and novel FRP composite connectors. The conventional connectors used in this study include SFS steel screws and perforated steel plate connectors. In contrast, the FRP connectors comprise T-shaped plates made from bidirectional FRP mats and pultruded FRP reinforcing bars with helically wrapped profiles. Both carbon FRP (CFRP) and glass FRP (GFRP) materials were employed. Results from the push-out tests indicate that GFRP rods (GR) exhibit the highest shear strength and serviceability stiffness among all tested specimens. Furthermore, connections made with T-shaped GFRP plates (GP) demonstrated the second highest shear capacity and serviceability stiffness, CFRP rods (CR) and T-shaped CFRP plates (CP) also showed higher load-carrying capacity and stiffness compared to conventional connections. Notably, despite the inherently brittle nature of FRP materials, CFRP connections displayed remarkable ductility at failure. Additionally, Finite Element (FE) models were developed to validate the experimental findings and perform a parametric study. • New FRP connectors for timber-concrete composite connections are proposed. • Load-slip behaviour of timber-concrete composite connections is studied. • FRP connectors show higher stiffness and strength in TCC connections. • FE models were developed, and parametric studies were performed. • Connector configurations and dimensions significantly impact load-slip behaviour.