Influence of shear connector type and degree on semi-rigid joints of composite cold-formed steel beam-to-column connections

This paper presents findings from an experimental study focused on a composite connection between a composite concrete slab and two cold-formed steel C-sections. These sections are positioned in a back-to-back arrangement, serving as both a beam and a column.The study involved testing five specimens of cruciform subassemblies of cold-formed steel (CFS) beam-to-column joints with different shear connection types and degrees of the bolted shear connector. The results obtained from testing the specimens were presented, including their moment capacity, rotational capacity, the slip of the concrete slab, and modes of failure. All the specimens showed high ductile properties with a rotation capacity exceeding 30 mrad, indicating that they are semi-rigid joints that are suitable for plastic analysis and seismic design, according to Eurocode 4 (EC4). The novel approach used in the CFS angle plate shear connector significantly improved the moment and initial stiffness of the joint. The partially bolted shear connector used in the study produced satisfactory results and was within the recommended limits for semi-rigid joints according to the European Code. As a result, the study suggests that the current restrictions on providing full shear connection design within semi-continuous structure-hogging moment regions could be relaxed.