Design of I-Shaped Beams with Diaphragm Bracing

Cold-formed steel panels are used as wall sheathing, roof decking, or floor decking in steel framed buildings. Diaphragms formed by interconnecting these panels have considerable in-plane shear resistance, and can be utilized as bracing against buckling for individual members of a steel frame. The utilization of existing floor or roof diaphragms as bracing for individual beams can eliminate the need for other types of bracing, and reduce required member sizes, or both, thus contributing to economical design. A procedure is presented for the design of I-section beams with diaphragm bracing on either the tension or compression flanges. The procedure is based on the ultimate load capacity of fully braced members, utilizing a conservative estimate of the shear strength and shear rigidity of the diaphragm. A design example is included.