Ultimate compressive strength of cold-formed steel angle struts loaded through a single bolt

In cold-formed steel trusses and space frames, angles are commonly used for the members, the load being transferred to the members at both ends through a connection to a gusset plate. Such connections are typically formed through bolts or screws. Since this connection is made through one of the angle legs, the load is therefore eccentric to the centroid of the section. On the other hand, owing to contact with the gusset plate and the bolt-head, the ends of the connection possess partial torsional restraint. When designing cold-formed steel angle sections, an engineer would typically take into account the eccentricity of the connection but ignore the beneficial effect of the partial torsional restraint. This paper describes a non-linear elasto-plastic finite element model of angle sections connected to a gusset plate through a single bolt at each end subjected to axial compressive load. The results of the finite element model are validated against previously published full-scale laboratory test results. A parametric study of both equal and unequal angle sections is presented. From the results of the parametric study, simple design recommendations are proposed.