Experimental Study on an Innovative Shear Connector in Steel-UHPC Composite Structure

In order to improve the stiffness and shear bearing capacity of steel-UHPC composite bridge, an innovative shear connector named arc-shaped reinforcement shear connector was proposed and compared with the stud and perforated bar steel plate shear connector using the static push-out test. Considering shear connector diameter, a total of ten push-out specimens for five groups were designed. The results indicated that the failure modes and failure mechanism of the arc-shaped reinforcement shear connectors were significantly different from stud shear connector and perforated bar steel plate. Obvious failure characteristics such as crack and reinforcement were not observed for the arc-shaped reinforcement specimens except for fine cracks on the top of one specimen, but these were observed for the others two types of shear connector. The relative slip value of arc-shaped reinforcement shear connector at the maximum load was the smallest and less than 1 mm in three types of shear connectors. The stiffness and shear bearing capacity of arc-shaped reinforcement were higher than those of stud and perforated bar steel plate under the same diameter. Increasing arc-shaped reinforcement diameter could improve significantly static behavior of shear connector. When the diameter of arc-shape reinforcement was increased from 8 mm to 12 mm, the ductility factor, stiffness, and shear bearing capacity of arc-shaped reinforcement shear connector were improved by 174.32%, 214.76%, and 54.2%, respectively. A calculation method of shear bearing capacity was proposed by the least square method and multiple regression analysis and agreed well with the test result.