L.M.R. Mesquita

Temperature analysis on fire resistance experiments of partially encased beams

Twelve fire resistance tests, grouped in four series, were developed using partially encased beams (PEB) without concrete slab, for different load level and shear connection. PEB were built with standard hot rolled IPE100 profile and reinforced concrete between flanges. Fire resistance was determined for standard ISO834 nominal heating curve, using small fire resistance furnace and portal frame. Temperature was measured in three different sections along PEB length, for three different materials (steel, concrete and reinforcement). Average temperature in each section and material was compared to the average over length temperature. Each series presented similar results, with good reproducibility. Special focus was given to critical temperature. The maximum temperature difference between sections S1, S2, S3 and the average element length temperature is smaller than 3.2% for test series 1. For test series 2, 3 and 4 the maximum temperature difference is smaller than 5.1%, 6.3% and 11.2%, respectively. Temperature is not uniform in cross-section. After the initial heating stage, temperature revealed a constant difference of approximately 150oC between temperatures measured inside and outside, defining two main temperature evolutions. Temperatures measured outside revealed always higher temperature level.

Temperature evaluation in steel fire protected elements with intumescent coating

This paper describes how heat transfer analysis plays an important role in the temperature prediction of insulated steel members that are exposed to fire conditions. Based on the results of previous experimental work, which was made in intumescent-coated protected elements, the intumescent effective thermal conductivity temperature variation was estimated. An analytical approach that is based on the one-dimensional heat transfer parabolic partial differential equation through the insulation considers a non-homogeneous (time-varying) boundary condition at fire interface and a lumped capacitance at the insulation-steel interface is presented in the paper. 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.