Behavior of Gypsum‐Sheathed Cold‐Formed Steel Wall Studs

Abstract

Designers of load-bearing, cold-formed steel wall studs may use wall sheathing materials to provide bracing against flexural and torsional-flexural buckling. The American Iron and Steel Institute 1986 specification provides a design methodology including the strengthening effects of gypsum wallboard, commonly found on interior wall surfaces. Sheathing is assumed to act as a shear diaphragm with deformations distributed throughout the wall panel. Increased horizontal stud spacing results in increased axial load capacity for each individual stud, as the width of the shear diaphragm and thus its stiffness is increased. Testing of gypsum wallboard and steel-stud panels finds that deformations are localized at the connections. Furthermore, wall-assembly tests show the axial load capacity of gypsum-sheathed wall studs is independent of stud spacing. Thus, although the current American Iron and Steel Institute shear-diaphragm model provides conservative strength predictions for gypsum-sheathed walls, it does not accurately describe system behavior.