Experimental study on interface performance of UHPC panel with FRP pipe connectors partially filled with concrete

To enhance the interface performance of composite wall panels utilizing ultra-high-performance concrete (UHPC) as the outer layer, a novel connector composed of a thin-walled fiber-reinforced polymer (FRP) pipe and intersecting anchor bars was proposed. Interface shear tests were conducted to investigate the mechanical properties of the connector employed in sandwich external wall panels under four connector arrangements. The load–displacement response comprised elastic, plateau, and strengthening stages. Compared with the single-connector specimen, the multi-connector specimens increased the initial stiffness by 72–110% and the terminal displacement by 37–74%. The average ultimate load per connector ranged from 13.64 to 21.55 kN, demonstrating the beneficial spatial interaction and load-sharing effects among multiple connectors.