Bracing effect of sheathing in point-symmetric cold-formed steel flexural members

This paper presents an experimental investigation on sheathed cold-formed steel wall panels subjected to out-of-plane loading. The objective is to determine the two-sided gypsum sheathing effect on the design and behavior of the point-symmetric CFS studs. The design parameters such as global slenderness of the CFS stud, sheathing thickness and distance between the fasteners are varied, totaling twenty full-scale experiments that were tested under four-point bending. In general, the experimental results indicate that the gypsum sheathing board with a thickness of 15 mm and a fastener spacing of 150 mm hindered the occurrence of the biaxial bending of the point-symmetric CFS stud and led the CFS stud to reach its yield moment. To quantify the bracing effect of sheathing, the design predictions were carried out as per the current AISI report. The design results indicated that the design strength of a majority of the point-symmetric CFS studs can be drastically increased by the sheathing's bracing effect. However, few design results are unconservative compared to the experimental results which was confirmed by the reliability analysis as per AISI. Further investigation reveals that the current AISI design procedure requires significant modification with respect to the loading conditions and geometry of the CFS stud. In addition, the present study also discovered certain procedures to make the current sheathing braced design methods conservative and robust.