Numerical study of the behavior of friction-grip bolted shear connectors in composite beams with cold-formed steel sections

The concurrent use of concrete slab, and cold-formed steel section as a composite beam improves strength and stiffness, thus preventing local and lateral buckling of the beam. The composite action could be fulfilled by suitable shear connectors, though the codes do not prescribe any equation to determine the shear capacity, and design rule of these connectors. The friction-grip bolted shear connectors were introduced and their mechanical performance was studied via the experimental tests and finite element modeling. At first, ANSYS software was used for the 3D finite element modeling of these connections. The obtained results were verified by experimental results. It can be shown that the proposed model can estimate the behavior of friction-grip bolted shear connectors in composite beams with cold-formed steel section. Then, extensive parametric studies with 72 specimens were carried out and the effect of diameter and strength of the bolts, thickness and strength of cold-formed steel sections, clearance between the bolt and concrete hole and pretension force on the behavior of these connectors were evaluated. The effect of each parameter on the shear capacity of the connection was evaluated. Some equations were proposed for figuring out the shear capacity and load-slip curve of these connections based on the experimental and 3D finite element results.