Investigation of cold-formed steel top-hat sections under bending

In recent years, with the introduction of higher strength grades, cold-formed steel sections have become increasingly more slender. As a result, top-hat purlin sections have become an alternative to conventional zed purlins, particularly when smaller purlin spans (around 4 m) are required. Such top-hat sections are torsionally stiffer than zed purlins, and have greater resistance against lateral-torsional buckling. Furthermore, they do not require anti-sag rods. However, when determining their strength, they are susceptible to buckling. In this paper, a combination of full-scale laboratory tests and finite element analyses are used to investigate the bending strength of such top-hat sections. Both upward and downward loading conditions are considered. In this paper, twenty-seven full-scale experimental tests on top-hat sections are described. The moment capacities obtained experimentally are compared against those predicted by the Eurocodes and non-linear elasto-plastic finite element analyses.