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School of Architecture
Faculty of Technology, Design and Environment
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.
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 per-formance 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 flex-ural stiffness, when compared to joists designed individually. The experimental results are then compared to predictions from relevant existing analytical models.
Detailed studies have been performed with the aim of determining optimum low carbon solutions for buildings and investigating the complex issues involved in their delivery. The evidence presented herein suggests that building envelope specification has reached the point where the embodied carbon of any additional insulation balances, and may even outweigh, the corresponding saving in operational carbon. However, the extra material in the envelope has an inherent strength and stiffness that could be utilized to reduce the embodied carbon in the structure if appropriately designed. An extensive series of analyses has been undertaken to (a) quantify the aggregated operational and embodied carbon related to modern envelope systems and (b) evaluate the opportunities for embodied carbon reduction of the frame through the exploitation of the envelope’s structural capability. Particular attention was given to the use of longspan composite panels to reduce the number of supporting structural members. It was found that a considerable saving in embodied carbon is possible when compared against traditional construction solutions. The study also suggested the absolute significance of combining operational and embodied carbon analyses in demonstrating the effectiveness of carbon reduction strategies and requirements to shift away from ‘operational carbon only’ methods. The focus of the initial phase of the work has been single-storey industrial buildings, but the conclusions are applicable more broadly.
This paper discusses a series of studies undertaken to quantify potential steelwork savings in single storey industrial buildings by exploiting the increased insulation depth and the corresponding structural capability of modern sandwich panel envelope systems. The primary areas of focus were: (a) use of long span composite panels (to reduce the number of supporting structural members and remove secondary steelwork) with portal frames and other forms of construction (b) use of envelope diaphragm action to stiffen the structural frame (c) frameless and semi-frameless buildings. For all cases, structural forms that offered the greatest potential to exploit the envelope’s capabilities were identified and an extensive series of structural analyses were undertaken. The study found that the greatest potential benefit (38%-60% steelwork saving) arises from the use of long span envelope systems, particularly for trussed roof frames with north light construction. There were only limited opportunities for the use of diaphragm action and frameless buildings. While the study was focused on UK practice, the conclusions are applicable internationally.