Stressed Skin Action of Modern Steel Roof Systems

‘Stressed skin ’design has generally been applied primarily to roofs or walls with a single skin of sheeting directly fixed to the purlins, side-rails or beams by, for example, self-drilling, self-tapping screws or fired pins. However, many modern roof systems involve two metal skins with insulation positioned between them, and this affects their in-plane resistance. This paper reviews the potential for the stressed skin design of these modern roofs on the basis of eight full-scale diaphragm tests of diflerent, but ‘generic’, roof systems. The tests showed that built-up roofs comprising a liner tray, Z spacers, and roof sheeting , performed well and that significant ‘composite’ action between the roof sheeting and the liner tray took place. The performance of all liner trays could be enhanced significantly if their local shear buckling resistance is improved, leading to enhanced potential for use in ‘stressed skin’ design.

Professor J.M. Davies and R.M. Lawson