Mechanism and Design Method of Load Transfer into Concrete-Filled Steel Tubular Arch Ribs through Perfobond-Rib-Shear Connectors

In terms of load transfer, the design of the joints in concrete-filled steel tubular (CFST) arch bridges is more critical than that in buildings due to the higher likelihood of steel–concrete-interface debonding. To improve the contact at the steel–concrete interface, a novel arch rib was manufactured by longitudinally welding perfobond-rib-shear connectors to the inner surface of a steel tube and then filling the tube with concrete. In this study, extensive numerical and analytical investigations on the mechanism of introducing loads into CFST arch ribs through perfobond-rib-shear connectors were carried out. A deck CFST arch bridge, namely, the Shuangbao Bridge in China, was selected as a typical application location. The design parameters, including the geometric dimensions of the perfobond-rib-shear connector and the arrangement of the perfobond rib along the cross-section and longitudinal section of the arch rib, were evaluated. The design flow for the joint with perfobond-rib-shear connectors between the vertical columns and the CFST arch ribs was proposed. To improve the load-transfer efficiency, the design scheme of the joint in the Shuangbao Bridge was optimized by replacing the weld studs with perfobond ribs. Significant increases of 1.84–4.02 in the shear resistance were found for the perfobond ribs compared to the welded studs. Additionally, the fabrication of the perfobond ribs was more convenient compared to that of the welded studs.