Cold-formed steel members are widely used in the construction industry due to their versatility,
high strength-to-weight ratio and ease of assembly. Stud columns set in tracks, form the
main members in cold-formed steel wall systems, which are typically sheathed with plasterboard
or oriented strand board (OSB). The interaction between the cold-formed steel
members and the sheathing, which can have a significant effect on the ultimate strength
and flexural stiffness due to composite action and bracing, is currently not systematically
taken into consideration in design.
More than 100 material and connection component tests have been performed to study
the behaviour of plasterboard and OSB and their interconnection with cold-formed steel
through screws acting in shear and tension. The obtained test results, along with a collected
dataset totalling more than 400 physical tests, were used to develop analytical models to
describe their load-deformation behaviour; these are suitable for use in numerical simulations
and advanced design methods. A total of 17 full-scale sheathed wall stud tests were also
performed, with varying connector spacing between either plasterboard or OSB sheathing
panels and the steel members. Tests were performed under pure compression, pure bending
and combined loading. Reducing the spacing of the connectors from 600 mm to 75 mm
resulted in up to 30% increase in capacity while also preventing pull-through connector
failure for specimens sheathed with plasterboard.
Sophisticated finite element models of wall studs were also developed, which, following
successful validation against test results, allowed parametric studies to be undertaken, where
the influence of the sheathing, connector spacing and section depth was investigated. Finally,
a preliminary design guidance has been developed, where the beneficial effects of bracing,
composite action and enhanced boundary conditions at the member ends are recognised,
thus enabling more efficient design of sheathed cold-formed steel wall systems.