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Improved Calculation Method for Insulation-based Fire Resistance of Composite Slabs



Jian Jiang, Adam L. Pintar, Jonathan M. Weigand, Joseph A. Main, Fahim Sadek


A calculation method for estimating the fire resistance of composite slabs with profiled steel decking according to the thermal insulation criterion is provided in Annex D of Eurocode 4 (EC4). In this study, comparisons between validated high-fidelity thermal analysis of composite slabs exposed to a standard fire curve and the calculation method in EC4 indicated that the EC4 method may provide overconservative (by up to 46 %) and unconservative (by up to 35 %) predictions of fire resistance. The reasons for these discrepancies are: (1) the EC4 calculation method is based on a range of slab geometries of commonly used steel deckings in the 1990s which differs from the range used in current applications, (2) the EC4 method does not consider the effect of moisture content of the concrete slab on the fire resistance, and (3) limitations of the statistical approach used in the development of the EC4 method. A new, improved calculation method is proposed in this study based on a sequence of designed computer experiments to determine the insulation-based fire resistance of composite slabs, explicitly accounting for an extended range of slab geometries and moisture content. The accuracy of the proposed method is verified for multiple slab geometries, and is also validated against experimental data. Results show that the proposed method predicts the fire resistance of composite slabs with profiled steel decking, according to the thermal insulation criterion, within 15 min.
Fire and Materials


composite slab, fire resistance, insulation criterion, calculation method, EC4, slab geometry, moisture content.
Created March 2, 2019, Updated May 2, 2019