Push-out test of large perfobond connectors in steel-concrete joints of hybrid bridges

The size of perfobond connectors in steel-concrete joints of hybrid bridges is typically less than 75 mm. Given the limited capacity of connectors, it is essential to tightly arrange the connectors for transmitting large internal forces. Large-sized perfobond connectors with increased capacity act as an excellent alternative to reduce the number of connections, thereby simplifying the structure in steel-concrete joints. Additionally, an increased diameter can contribute to the flow of concrete coarse aggregate. To verify the mechanical properties of large perfobond connectors, 13 groups of 39 push-out specimens are introduced. The effects of hole size, hole shape, perforating rebar, concrete strength, and lateral confinement are investigated on the failure modes and load-slip curves of large perfobond connectors. The test results indicated that, under a high level of confinement of a concrete dowel, increases the geometrical size of the hole significantly improve its bearing capacity without weakening its ductility. Finally, an empirical formula is proposed for the shear capacity considering various influencing factors.