Heat transfer analysis of components of construction exposed to fire
This thesis describes a 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.