Steel and ultra-high performance concrete ( UHPC ) composite decks are effective at reducing fatigue cracking and asphalt pavement damage. The shear behavior of innovative open steel tube ( OST) connectors in steel-UHPC composite decks was investigated by conducting push-out tests. The test parameter is the presence of reinforcement in the deck. The load-slip curves and shear behavior of the push-out specimens were obtained and discussed. The test results indicate that as compared with plain concrete specimens , the limit slip of reinforced specimens decreased by 32％ and the shear stiffness increased by 10％, but the ultimate shear capacity was almost the same. The use of UHPC influenced the failure process as it was observed that the OST connector was sheared off at its lower semi-tube, followed by the pull-out failure of the upper semi-tube. A finite element model was verified by tests and was then used to analyze the deformation and failure behaviors of the composite deck with open tubes. The model demonstrates that there is a stress concentration zone at the connector root, and the lower semi-tube is the main component that is subject to loads.