Moment capacity of back-to-back cold-formed steel channels with edge-stiffened holes, un-stiffened holes, and plain webs

The use of cold-formed steel (CFS) back-to-back channels as floor joists is increasing steadily, and such beams often include un-stiffened holes for installation services, which reduces their flexural strength due to the reduced web area. A new generation CFS with edge-stiffened has been widely used. However, no research undertaken understand effects composite actions on moment capacity built-up beams. In this paper, fourteen experiments are reported various hole spacing, were tested under four-point loading. Finite-element models also established validated experiments. Upon validation, a parametric study involving 63 FEMs was conducted investigate beam length, diameter hole, stiffener length fillet radius. test results show that five holes, increased by 15.4%, compared plain channel. For comparison, same section had 15.1% reduction in capacity. Test distortional buckling predominant failure mode all cases. FE against design capacities predicted American Iron Steel Institute (AISI) Australian New Zealand Standards (AS/NZS) channels. procedure proposed Moen Schafer. It revealed these equations conservative around 23% 49% respectively.