Sandwich construction is increasingly used as wall and roof cladding for building structures. Typically, a cladding panel may consist of two plane or profiled metal faces with a foamed plastic core. The core may be polyurethane, polyisocyanurate, polystyrene or phenolic resin. When such a panel is subject to static loading due, for instance, to wind, snow or temperature gradient, one face is compressed and becomes liable to local buckling.
ABSTRACT: Theoretical, numerical and experimental heat transfer study of components of construction exposed to fire. Within the computational aspects of the work, one and two-dimensional finite difference and finite element methods have been developed to determine the transient temperature distributions in the cross-section of elements of construction subject to furnace fire tests. Either Cartesian or cylindrical polar coordinates can be used in order to conform to the shape of the element to be analyzed.
The convective and radiative heat transfer boundary conditions at the exposed and unexposed sides of components can be simulated. Structures may comprise several materials each having thermal properties varying with temperature. They could be made of traditional construction materials, for example steel, concrete, plasterboard, or novel fire-resistant composite materials, for instance Glass- Reinforced Plastics (GRP) or intumescent coatings. The critical role of the thermal properties of materials with respect to the heat transfer rate was reviewed and the factors which significantly affect the heat transmission, such as the moisture content in hygroscopic materials and the decomposition of plastic matrices, have been investigated in considerable detail. A large number of experimental furnace tests have been conducted in order to reveal the fire-resistant performance of various materials and to verify the numerical modelling. Both the standard cellulosic and hydrocarbon time/temperature regimes have been used to simulate cellulosic and hydrocarbon fires.
The comparison between the computational simulation and experimental measurements is generally excellent. In addition, a number of user-friendly, interactive computer programmes have been developed which may be used to predict the behaviour of building elements exposed to a specified fire environment. The general issues and relevant problems associated with the experimental and computational approaches to fire safety design are discussed. Some recommendations for the further improvement of the existing fire resistance standards are proposed and further required research in the subject areas are identified.
ARTICLE in JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 20(1):75-83 · DECEMBER 1991
Department of Civil Engineering, University of Salford, Salford M5 4WT, UK
Mohammed Rahif Hakmi
Sandwich construction is increasingly used as wall and roof cladding for building structures. Typically, a cladding panel may consist of two plane or profiled metal faces with a foamed plastic core. The core may be polyurethane, polyisocyanurate, polystyrene or phenolic resin. When such a panel is subject to static loading due, for instance, to wind, snow or temperature gradient, one face is compressed and becomes liable to local buckling. If this face has a trapezoidal or similar profile the failure mode is similar to that for profiled steel sheeting, though the failure stress is enhanced by the presence of the core.
The compressed face element first forms a series of buckling waves which increase in amplitude in the postbuckling phase. Failure takes place when one buckle in the region of maximum bending moment cripples.In light gauge steel applications, the conventional design treatment for this phenomenon utilises the concept of effective width. In order to investigate the extension of the effective width concept to plate elements supported by plastic foam material, a series of tests were undertaken on foam-filled steel beams. This paper describes these tests and their interpretation in terms of an enhanced effective width formula.