Axial compression strength of gypsum plasterboard and steel sheathed web-stiffened stud walls

Cold-formed steel-framed walls lined with appropriate sheathing materials are increasingly being used as vertical load bearing systems due to their many benefits. Despite this widespread use, attempts at improving their structural efficiency using either optimised studs or novel sheathing elements have been scarce. Arguably, the sustained use of lipped channel studs and conventional sheathing materials have long forestalled such improvements. Firstly, this study provides experimental evidence on the superior characteristics of the web-stiffened studs, developed specifically for load bearing steel-framed wall applications, and their ability to utilise sheathing restraints to achieve higher axial compression strengths. Secondly, it shows that the use of steel sheathing, either in isolation or together with gypsum plasterboards, significantly increases the strength of the web-stiffened stud. Thirdly, single plasterboard web-stiffened stud walls are found to be highly efficient due to the monolithic nature of the sheathing that leads to greater degrees of composite action between the studs and the sheathing. Finally, it presents a spring based analytical model capable of estimating the failure loads of sheathed web-stiffened studs conveniently. The model particularly focuses on the out-of-plane restraints provided by the sheathing, the contribution of which to the overall strength of the wall has traditionally been considered trivial, but is shown to be substantial in the case of web-stiffened studs. Using the improvements proposed, high capacity steel-framed load bearing walls can be developed with significant material and cost savings.