Steel-concrete-steel sandwich composite beams with thin perfobond connectors and C-ties: Shear behaviour

Abstract

A novel connector comprising the thin perfobond connector and C-tie (PBL-CT) was proposed and integrated into steel-concrete-steel (SCS) sandwich composite beams. While retaining the excellent shear resistance of traditional perfobond connectors (PBLs), the PBL-CT enhances the structural shear performance by incorporating C-ties into the perforated rib. Static tests were conducted on eight SCS sandwich composite beams, focusing primarily on the effect of connection arrangement, steel plate thickness, and shear-span ratio on the shear performance of beams. Test results indicated that the configuration of PBL-CTs influenced the cracking process and failure mode of SCS sandwich beams. When densely arranged, PBL-CTs elevated the degree of shear connection at the steel-concrete interface, leading to shear-compression failure of beams; otherwise, diagonal-tension failure occurred. Moreover, the load-deflection behaviour of SCS sandwich composite beams can be classified into four distinct stages: initial, elastic, yielding, and recession stages. The bottom steel plate and perforated rib experienced tension-shear failure in the recession state, and the C-ties were straightened. In addition, the analysis showed that C-ties and bottom steel plate significantly augmented the shear performance of SCS sandwich beams, encompassing shear carrying capacity, ductility, and initial stiffness. On the contrary, the influence of the top steel plate on the shear performance could be negligible. Finally, a reasonable predictive analysis model for the shear carrying capacity of SCS sandwich composite beams was proposed, in which the shear carrying capacity was divided into three components: concrete core, C-ties, and bottom steel plate.