Three-sided heating of I-beams in composite construction exposed to fire

A new and simplified model to analyse the thermal response of steel I-beams in composite construction exposed to the standard fire is presented. The model includes a convection and radiation heat transfer module, a resistance-capacitance formulation for heat conduction in the steel beam and a correlation for estimating heat conduction from the upper flange to the concrete slab. The radiation component accounts for the emission and absorption of radiation by the main combustion products of the standard fire. Heat transfer to the concrete is estimated using computer modelling of a number of case studies. The two dimensional I-beam section is represented by three lumped masses concentrated at nodes located at the centres of the lower flange, web and upper flange and connected by conduction paths. Comparison between measured and computed temperature profiles shows good correlation for most of the case studies investigated.