Profiled sandwich panels with deep foam cores in flexure

摘要

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.