Shear behavior of low-profile perfobond strip connectors for steel–thin UHPC composite deck structures

This paper aims to investigate the shear performance of a low-profile perfobond strip (LPBL) connector embedded in a thin ultra-high-performance concrete (UHPC) layer of orthotropic steel–UHPC composite decks (OSUCDs). Push-out tests were performed on 20 specimens to determine the effects of overall dimensions of the strip, strip-end bearing, opening shapes, and perforating rebars. The corresponding shear transfer mechanism was examined through precise finite element (FE) analysis, and prediction methods for load–slip process and shear capacity were proposed through theoretical analysis. The results showed that LPBLs demonstrated satisfactory ductility with an ultimate slip exceeding 6 mm. The strip-end bearing and overall dimensions of the strip, particularly strip length and strip thickness, had significant effects on the shear capacity of LPBLs. As strip length and thickness increased, the weak link in shear capacity of LPBLs transitioned from the fracture of strip to the damage of UHPC dowel and strip-end compressive UHPC, and the contribution of perforating rebars progressively increased as the UHPC dowel's damage intensified. When opening areas were identical and ultimate capacity was controlled by UHPC dowels, circular hole LPBLs and those using wide holes had comparable shear performance, and the notch on the hole also had little effect. The configuration of notched wide holes was more conducive to the construction of LPBLs embedded in a thin UHPC layer. The proposed theoretical model based on LPBL's load transfer path predicted the load–slip curves well, and the accuracy of the proposed simplified equation for the shear capacity of LPBLs was also preliminarily validated by the test results.