Sandwich panels comprising steel faces and insulation core are extensively used within the construction industry for cladding applications. Until recently, foam core depths up to 60 mm were considered sufficient to meet thermal and energy requirements of the Building Regulations. Demand for lower U-values for the building envelope in the UK and Europe has created the need for cladding elements with increased foam insulation depths up to 120 mm. Current approximate analytical methods for the design of profiled insulated panels do not cater for the full range of core depths presently available. Specifically, the stress distribution graphs used for design of double- and multi-spanning panels must be extended in scope to allow analysis of panels with cores at least 120 mm deep. This paper reviews results of 12 single-span and 11 double-span bending tests performed on profiled composite panels with polyisocyanurate cores sandwiched between light-gauge steel faces. Response of the panels is examined with regard to their stiffness, progressive failure under increasing load, failure mechanism at each stage and reserve of strength. A numerical model is developed for the deeper composite panels and verified against existing theory. The model is used to perform a series of parametric studies and to analyse the full range of current and forthcoming composite panel depths (80 mm to 120 mm). The paper reviews the modelling strategy and presents extended stress distribution graphs; these are validated against double-span test results, where good agreement and safety are shown.

In light steel framing, the compression resistance of the walls may be improved by the stabilising effect of plasterboard attached to one or both sides of the wall. This paper presents the results of 28 load tests on 2·4 m high walls using 75, 100 and 150 mm deep C-sections in 1·2 to 1·6 mm thick steel with various types of board. The results were compared to the methodology in the standards BS EN 1993-1-3 and BS 5950-5, taking account of restraint to minor axis buckling. The test results showed that the lateral restraint provided by 12 or 15 mm thick fire-resistant or moisture-resistant plasterboard fixed to one flange is equivalent to an effective length reduction factor of 0·7 in the minor axis direction for a 100 mm × 1·6 mm C-section in a 2·4 m high wall. A theory is developed based on distortional buckling of the C-sections, which allows the test results to be extended to other wall heights and section sizes. The failure loads were predicted by finite-element modelling by considering initial imperfections in the C-sections and the torsional restraint due to the boards.

This article investigates, experimentally, the structural performance of lightweight cold‐formed steel (CFS) ‐ timber board composite flooring systems. Fifteen full‐scale bending tests and twelve companion pushout connection tests were performed. The effect of connection detail (comprising self‐drilling screws with or without a structural adhesive) on structural performance is examined. The results of this research demonstrate that the use of a polyurethane adhesive, in conjunction with screws, leads to a significant increase in connection slip modulus and a higher degree of composite action in the floors, resulting in up to 40% increase in flexural stiffness, when compared to joists designed individually. The experimental results are then compared to predictions from relevant existing analytical models.

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