Transfer of shear force in circular reinforced composite dowel: A review

The performance of steel-concrete composite structures is dependent on the effective transmission of shear force at the material interface. Traditional shear connectors, i.e., headed studs, have limitations in shear resistance and fatigue behavior. To overcome these issues, Circular Reinforced Composite Dowel (CRCD) connectors have been developed. CRCDs are created by perforating a steel element, passing a reinforcement bar through the opening, and filling it with concrete. This paper provides a comprehensive review of the mechanical behavior of CRCD connectors, comprising three resistance mechanisms: interfacial bond, concrete dowel action, and traversing rebar resistance. Equations predicting their resistance are analyzed based on 55 experimental datasets. Key findings reveal that doubling the diameter of the traversing rebar can double the resistance of the connector. A 20% increase in connector strength accompanies a doubling of concrete strength. Optimizing bond resistance depends on steel surface treatment and sufficient transverse confinement. In a group of connectors, placing CRCDs in the first layer maximizes stiffness. Furthermore, this review highlights the lack of research on CRCD connectors positioned on H-shaped steel profiles, which could improve stiffness and shear resistance in the load introduction zone of steel-concrete composite columns or foundation piles.