Investigation of Fire Resistance of Film-protected Glass Facades

Glass facades are used extensively in modern high-rise buildings to satisfy aestheticrequirements and provide transparency and illumination. However, during fires, glass failurecan allow air circulation, facilitating the spread of flames horizontally, vertically, and possiblyto adjacent buildings, thereby escalating fatalities and losses; for example, the Beijing CCTVoffice building fire (2009) caused RMB200M in damages.Glass is brittle and can crack and break easily at elevated temperatures, mainly due todifferential thermal stresses resulting from its low thermal conductivity. Controllingtemperature gradients may result in better behavior. The properties of glass in fire areconventionally obtained from fire tests and numerical studies using finite element method(FEM) approaches. However, FEM is not efficient in simulating crack propagation, and thehypothesis of this proposal is that the meshless method could provide more efficient andaccurate solutions.To reduce thermal gradients, the proposed project will develop a new transparent thermallyconductive film that can be attached directly to the fire-exposed surface. This will deflect theheat sideways, reducing thermal loading on the glass. A second silicon oxide (SiO2) aerogelfilm can be added behind this layer to further reduce heat transfer to the glass. Finally, a thirdconductive film is needed to enable the more uniform distribution of thermal loading on theglass. These films create anisotropic thermal conductivity, leading to high thermal conductivityin parallel with, and low thermal conductivity perpendicular to, the glass surface. Thefilm-protected glass facade will enhance energy conservation, noise insulation, fire resistance,anti-crack properties and mechanical strength.To facilitate the design and better understand the overall properties of the film-protectedglass, two series of experimental investigations will be conducted: (1) for thethermal-mechanical properties and (2) simulated fire scenario testing on glass facades. Theseexperiments will be of crucial to derivation of the glass properties. Based on the experimentalresults, a meshfree framework will be developed to simulate the heat conduction and failurebehavior of film-protected glass facades. This framework will be compared and verified withdata from the second test series and used for parametric studies. The stress distribution, crackinitiation, propagation and breakage time will be investigated to identify the degree ofenhancement by the proposed thin films. Different parameters, including the thicknesses andarrangement of layers, will be considered. Furthermore, an optimization process will beimplemented to find the optimal layer design.