Axial load capacity of cold-formed steel wall stud with sheathing

A cold-formed steel wall panel consists of a cold-formed steel frame and sheathing on one or two sides, the latter attached to the frame by self-driving screws. It is observed during tests that the axial behaviour of a wall stud in the panel is significantly different from that of an individual stud. This paper presents an analytical model for predicting the axial failure load of the wall stud with sheathing. The sheathing is simplified as continuous elastic support to the stud. The spring stiffness of the elastic support is calculated by analytical and finite element methods. The predicted results are compared with measurements from full-scale tests. For the range of parameters considered, it is found that: (a) the Poisson ratio of the sheathing material as well as screw spacing have negligibly small influence on panel failure load; (b) the elastic modulus of the sheathing material has a significant influence on the failure load, only if it is smaller than 1000 N/mm2; (c) although in general the thickness of sheathing affects the stud failure load, thinner sheathing may be used without changing the stud load capacity considerably; (d) stud spacing has moderate influence on stud failure load. The results presented in this paper can be used to guide practical wall panel designs.