Tests of composite beams with cold-formed sections

Use of cold-formed sections as composite beams in slab systems offers high flexibility in design and several advantages. Among these advantages are the enabling of shallow overall slab depth, easy adaptation to irregular geometries, freedom in design of cross-sections and ready availability of materials and sections. The main problem in implementation of the designs is ensuring adequate shear transfer between the concrete slab and the cold-formed beam section, whose thickness is often too small for welding of conventional shear studs. The paper presents designs and test results for several technologies involving cold-formed sections in composite construction, including self-drilling screwed cold-formed shear connectors, and built-up sections bolted to precast concrete planks. The tests include extensive push-out tests of numerous types of connectors, as well as full-scale composite element tests. Results indicate that design of shear connectors can in most cases be conservatively based on codes of practice for the design of cold-formed connections. Full-scale tests indicate high ductility and capacity which exceeds design assumptions.