Author(s)

L. M. R. Mesquita, P. A. G. Piloto & M. A. P. Vaz

Abstract

Heat transfer analysis plays an important role in the temperature prediction of insulated steel members exposed to fire conditions. Based on the results of a previous experimental work, made in intumescent-coated protected elements, the intumescent effective thermal conductivity temperature variation was estimated. An analytical approach, based on the one-dimensional heat transfer parabolic partial differential equation through the insulation, considering a non-homogeneous (time-varying) boundary condition at fire interface and a lumped capacitance at the insulation-steel interface, is presented. Solutions are established with temperature independent thermal properties and then extended to temperature dependent thermal properties. These solutions are compared with numerical results performed by finite element method using Matlab for different values of insulations thicknesses and steel section factors. Keywords: fire resistance, fire protection, intumescent coatings, heat transfer, Duhamel’s theorem, Green’s function. 1 Introduction Fire protection costs may represent an important part of global construction costs, being more significant in the case of steel construction, requiring frequently the application of an insulation material (Longton et al [1]). The use of passive protection materials is one of the measures normally adopted to prescribe structural fire resistance. Intumescent coating represents around one third of steel fire protection and is growing mainly due to their use in off-site applications. The fire resistance of an insulated steel member is determined by assessing the loadbearing capacity of the component during fire exposure. Heat transfer

Keywords

fire resistance, fire protection, intumescent coatings, heat transfer, Duhamel’s theorem, Green’s function.