Grouped rubber-sleeved studs-UHPC pocket connections in prefabricated steel-UHPC composite beams: Shear performance under monotonic and cyclic loadings

Prefabricated steel-ultra-high-performance concrete (UHPC) composite beams (PSUCBs) with grouped stud-UHPC pocket connections (GSUPCs) are a successful attempt of UHPC in bridge engineering, which offers significant advantages in accelerating on-site construction, enhancing structural performance, and improving environmental benefits. However, the uneven steel-concrete interfacial shear stresses distribution caused by the insufficient deformability of ordinary studs (OSs) in UHPC may result in the premature stud failure in large interfacial slippage regions. To address this issue, rubber-sleeved studs (RSSs) that wrapped rubber-sleeves around the stud roots were introduced to improve ductility and reduce the stiffness of connectors. However, the shear performance of grouped RSSs embedded in UHPC remains unclear, which hinders their application in practices. Against this background, systematic experimental and numerical studies were conducted to investigate the monotonic and cyclic shear performance of grouped RSSs-UHPC pocket connections. The results indicated that wrapping rubber-sleeve could increase the ultimate slip capacity and remained sufficient shear resistance, demonstrating great potentials of grouped RSSs-UHPC pocket connections in PSUCBs. Increasing the rubbersleeve thicknesses and height effectively improved the ultimate slip capacity and deformation recovery, but led to the significant plastic deformation accumulation and cyclic stiffness degradation. Finally, design recommendation on rubber-sleeve configuration rationalization, ultimate shear resistance and load-slip relationship predictive models were provided.