Experimental and analytical study on tensile performance of perfobond connector in bridge engineering application

In addition to general shear loading, perfobond shear connectors (PBLs) also undertake tensile uplift forces at the interfaces between steel parts and concrete components. The tensile behavior of PBLs is as significant as the shear behavior to the safety of composite bridge structures. For further evaluating the combined shear-tensile response of PBLs, it is necessary to first investigate the tensile mechanism of PBLs. Accordingly, uplift tests with three specimens under static and cyclic loading were performed to investigate the tensile behavior of PBLs. The test results showed that the breakouts of concrete blocks dominated the failure of PBLs in tension. The residual separation was negligible when the tension force was below 30 percent of the capacity. Subsequently, a detailed finite element (FE) model for the uplift test was established and validated based on the test results. The strain path inside concrete blocks was presented as a cup shape, whose dimension was relevant to the embedded depth of holes and the boundary conditions. Further, 360 FE models with varying hole diameters, perforated rebar diameters, embedded depths, and concrete strength were conducted to explain the tensile mechanism and provide databases for the theoretical analyses. The results showed that the diameter of perforated rebars was irrelevant to the tensile capacity and stiffness of PBLs, while both the tensile capacity and stiffness increased with the embedded depth and concrete strength. Besides, the tensile stiffness was also related to the hole diameter. Consequently, according to the forms of existing tensile capacity expressions for headed studs and Mindlin's solution, the equations for the tensile capacity and stiffness of PBLs were derived.