| Wall stud assemblies is used to resist the vertical loads of the Residential Cold-Formed Steel Framing. It usually consists of C-section steel wall studs and gypsum wallboard. Wallboard are intended primarily for architecture purposes, but they may also provide effective restraining action for wall stud. In this paper, the influence of the bracing effect from wallboard to the behavior of wall stud is studied. This paper includes following main contents:(1) Theoretical calculation method for the behavior of wall stud considering bracing effect from wallboard is presented. (2) Under the base of Combined Torsional and Flexural Buckling Model given by Timoshenko and Gere(1961), a mechanical model of wall stud in this paper considering bracing effect from wallboard is presented. (3) Overall buckling loads of wall stud under some typical end conditions are derived from Energy Method. The mode shape equation for the case with bottom fixed and top simply supported can not be presented in simply periodic forms. Therefore, a program MSEWZ with MATLAB6.1 is presented by author to determine and select the rational mode shape equations. (4) Introducing how to evaluate load capacity Pn of wall stud considering post buckling strength of plate element. Local buckling effects are determined according to the Effective Width Method used in Specifications GB500182002 and AISI96. (5) An analytic program WSWZ with MATLAB6.1 is woked out and a typical section is analyzed. The results of calculation and analysis indicate: the bracing effect from wallboard increases the load capacity of wall stud by 1.6-1.8 times; the reasonable distance between fasteners of wall stud is L/8, L is the length of wall stud ; there is no necessity to considering bracing effect from wallboard in the direction of perpendicular to wallboard.
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