TORSION OF BUILT-UP BOXED COLD-FORMED CHANNEL SECTIONS
Zehua Wang 1* and John Papangelis 2
School of Civil Engineering, The University of Sydney, Sydney, Australia
Built-up boxed cold-formed channel section beams, which consist of two single-channel sections fastened on the top and bottom flanges, are used as flooring and roofing members in buildings. By combining the two channels to form a closed box section, this can increase the flexural-torsional buckling capacity of the beam beyond the capacity of two single channels. The flexural-torsional buckling strength very much depends on the torsion and warping constants of the beam. Although these section properties can be easily determined for a single channel section, the calculation of these quantities for a boxed section with intermediate fasteners is not so well understood due to the discontinuity of the cross-section. In this paper, a finite element analysis is used to analyze a built-up boxed beam under uniform and non-uniform torsion. The results are used to calculate the torsion constant and warping constant for built-up boxed cold-formed channel sections with different geometries and fastener spacings. The results are compared with two single-channel sections and with closed boxed sections.
Torsion; Built-up Channel; Boxed section; Torsion constant; Warping constant; Finite element analysis