Numerical and theoretical investigation on interfacial shear performance of prefabricated steel-UHPC composite beams with grouped stud-UHPC pocket connections

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. These innovative composite structures exhibit many advantages in terms of reducing on-site construction time, enhancing the structural performance, and improving environmental benefits, which makes them competitive alternatives for accelerated bridge constructions. However, the interfacial shear performance of PSUCBs still remains unclear, which hinders their application in practice. To this end, systematic numerical analyses on large-scale composite beams were carried out to further investigate the interfacial shear mechanism of PSUCBs. Based on the experimentally verified finite element model (FEM), the structural failure mechanism, interfacial shear force distribution, and the internal shear/axial stress transfer mechanisms were revealed. The extensive parametric analysis results further confirmed that increasing both the stud diameter and stud tensile strength effectively enhanced the load bearing capacity and limited the interfacial slippage of the composite beams. Employing different concrete strengths for prefabricated slabs and shear pockets led to minor differences in the structural performance of PSUCBs failed in flexural. Various failure modes were observed for specimens under different shear-tospan ratios, resulting in significant deviations in the structural performance of the PSUCBs. Based on the rigid plastic analysis, theoretical models considering the interfacial shear performance were developed for predicting the ultimate bending capacities of PSUCBs with GSUPCs.