Experiments on sheathed cold-formed steel studs in compression

The stability and strength of cold-formed steel lipped C-section columns (studs) with sheathing attached to the flanges is the subject of this paper. Stud configurations both with and without sheathing, either oriented strand board or gypsum board, are tested for failure in compression. A total of twenty-six tests covering short, intermediate and long specimens, varied sheathing configurations, and varied end boundary conditions are completed. Dimensions and geometric imperfections of the specimens are measured in detail. The measured geometric imperfections are reduced to scalar magnitudes consistent with local, distortional, and global buckling modes. During the testing, mid-height cross-section deformations are recorded using five position transducers. The deformations indicate the impact of the different combinations of sheathing, and of the end boundary conditions, on the strength and stability of the studs. Composite action between the stud and sheathing, and isolating direct loading of the sheathing, are shown to be significant in determining the strength and controlling limit state of the stud. Tested strengths are compared with existing North American (American Iron and Steel Institute) specification methods and potential improvements are explored.

Research highlights
► Tests on sheathed cold-formed steel studs.
► Influence of sheathing type (e.g., gypsum) and stud length explored.
► Sheathing insures local buckling limit states.
► Dissimilar sheathing (different on the two sides) is effective in the observed tests.
► Observed capacities are greatly in excess of current prediction methods.