Experimental and theoretical investigation of cold-formed single lipped sigma columns

Experimental and theoretical studies are carried out to investigate the behavior and strength of cold-formed single lipped sigma columns. The local, distortional and overall geometric imperfections of sixteen specimens are measured in the laboratory. In addition, the residual stress pattern of the sections is concluded. Only eight specimens of cold-formed sigma columns with different variables are chosen. The tested specimens are subjected to an axial compressive load. A finite element model is developed using a software program (ANSYS). The developed model includes both geometric and material nonlinearities. Numerous models of slender sigma column sections with different variables such as flange width-thickness ratios, web return ratios, and overall slenderness ratios are chosen. The behavior of sigma columns along with different failure modes illustrated local, distortional, and global buckling is investigated. Complete ultimate strength curves are drawn as well as different failure modes are discussed for different cross-sections and member lengths. Finite element axial capacities are compared with the predicted capacities using AISI and DSM methods. Both AISI and DSM results are comparable with the finite element results. Eventually, A reliability analysis is carried out.