Experimental assessment of bolt-based connections for cold-formed steel and cross-laminated timber composite floor systems

Connections play an important role in the overall performance of steel-timber composite (STC) floor systems. Innovative STC connections were developed for cold-formed steel (CFS) and cross-laminated timber (CLT) floor systems based on bolt solutions. Such systems were designed for improved mechanical performance, low cost, and reversibility. Although different connection systems for STC have been proposed in the literature, the aspect of demountability in STC is still limited, particularly for CFS-CLT floor systems. Four different connection systems were considered, combining different elements, such as washers, nuts, threaded inserts, and T-nuts. Push-out tests were performed to obtain the ultimate shear load capacity, slip modulus, ductility, and failure modes of the tested solutions. The bolted systems, using special nut types, achieved the highest load-bearing capacity and slip modulus. The overall performance of the developed connections was assessed, considering the mechanical performance, ease of construction process, feasibility, and reversibility of the system. From the analysis, the solution with a threaded insert was considered to have the best potential for practical application. • Bolted connections were developed for CFS-CLT composite structures. • Mechanical performance was improved in relate to reference bolted connections. • Thickness of the CFS and the diameter of the connector influenced the formation of plastic hinges. • The constructive process and feasibility of the connections were evaluated together with the mechanical performance.