A multi-scale approach for predicting the fire response of building barriers

Abstract: Building barriers are compartmentation elements in buildings that limit the passage of fire and smoke to adjacent spaces. They are key elements in the overall response of a building in a fire. The adequate fire response of building barriers is usually assessed by the fulfilment of standardized resistance to fire tests. However, building fire barriers might be exposed to very different fire scenarios than traditional standardized fire tests. The work presented in the thesis consists on an experimental and numerical methodology to use the material thermal properties obtained through reduced scale testing to model the fire response of building barriers in larger scales. The methodology is applied to gypsum-stone wool and steel stone-wool layered composites. The characterization of stone wool properties at micro-scale is conducted with thermogravimetric analysis, micro combustion calorimetry and bomb calorimetry. The thermal conductivity of stone wool is obtained with modified slug calorimetry. At a composite scale samples are exposed to different heating exposures using radiant panels (H-TRIS), reduced scale furnace and full-scale furnace. The different heat exposures allow for identifying thermal degradation phenomena. Heat transfer models are developed increasing in complexity to account for the different phenomena. Those include: heat transfer, heat and mass transfer, kinetic reactions to account for the combustion of the organic content of the stone wool, kinetic reaction to account for the calcination reactions in the gypsum and the paper lining burning. An analysis of the uncertainties linked to assumptions in the input parameters for thermal modelling in standard fire tests is also presented. Finally, the degradation of the mechanical properties of gypsum plasterboard in fire are studied by performing three-point bending tests to pre-heated samples.

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