Investigation on shear behavior of large diameter short stud connectors in steel- thin UHPC bridge deck

Ultra-high performance concrete (UHPC) is a promising alternative for improving the mechanical performance of the steel and reinforced concrete composite bridge deck. Because of the excellent compression and tensile strength as well as the superior durability, the thickness of the UHPC slab can be effectively reduced. Therefore, large diameter short headed stud connector was proposed in this study to match the thin UHPC slab. To investigate the shear behavior of the large diameter headed studs in steel-thin UHPC composite bridges, 6 groups of 12 push-out specimens were designed and tested under the static loading. During the test, the failure mode, load-slip curves, the ductility, shear stiffness and shear strength of the specimens were emphatically focused. Besides, the influences of the aspect ratio of the stud, the thickness of the UHPC slab and the number of the stud in one position on shear behavior of the specimens were evaluated. Furthermore, the ABAQUS software has been used to analyse the large diameter short stud. A proposed modelling strategy used for further parametric analysis was validated with the test results. For the parametric research, different aspect ratio of stud and ultimate strength of stud were evaluated. Test and FEM results showed that the specimens failed in the failure of the root of the stud and the crushing of the concrete. With the increasing of the diameter of the stud, the thickness of the UHPC slab and the ultimate strength of stud, the shear strength and the shear stiffness of the specimens increased. Under the same cross-sectional area of the stud, the shear behavior of a single large diameter short stud connector could be comparable to that of two conventional stud connectors. Finally, after evaluating the results obtained from existing formulas, a predictive equation for the shear bearing capacity of large diameter short studs was proposed, and the accuracy of the calculated results was verified.