Push-Out Behavior of Short Headed Stud Connectors in Steel-Ultra High Performance Concrete Composite Deck

A steel-ultra high performance concrete (UHPC) composite deck has good fatigue performance while the thin UHPC slab leaves a very limited space for the connector configuration. This is actually crucial to achieve the composite action. Current literatures concerning the short stud behavior are still limited for a general mechanism understanding. Therefore, a series of push-tests containing 15 specimens were conducted for investigating the mechanical behavior of short studs with various diameters and lengths in UHPC composite deck. And a parametric FEM analysis with nonlinear material constitutions was conducted as well for the bearing performance understanding. The push-out tests showed the shear fracture near stud roots is the leading dominant failure mode, and a longer stud length might introduce a higher percentage of stud shank bending deformation. It explained longer stud length could be helpful to improve the shear strength of stud in UHPC. Meanwhile, the shear stiffness of the push-out specimens were all increased with a larger stud diameter or length. On the other side, the analysis results showed that a pull-out failure could happen when the stud length was less than 25 mm in UHPC and the failure mode of stud could also be affected by the concrete strength. In addition to the tests and analysis, the safety redundancies of strength evaluations of short stud in UHPC based on several civil codes were discussed in terms of the comparison works.