Fire Safety Science Digital Archive

Window glass breakage plays an important role in compartment fire dynamics as the window acts as a wall before breaking and as a vent after breaking. The objective of this work is to investigate the breakage behavior of toughened glass in enclosure fires. A series of full-scale experiments is carried out in the ISO 9705 test fire room to analyze the critical condition of the first breaking of toughened glass using oil pan fires with different heat release rates. The heat release rates, enclosure and local gas temperatures, exposed glass surface temperatures, shaded glass surface temperatures, time to first crack and crack patterns are measured. The dependence of glass breakage on critical parameters like the temperature differences between the exposed and shaded glass surface is analyzed. The results show that the crack of the toughened glass generally occurs initially near the edges of the windows. It is also indicated that the toughened glass breaks under the condition of larger temperature differences than those for float glass, however, almost the whole toughened glass falls out completely soon after the first breakage occurs. These experimental results can be used for the estimation of the occurrence of cracking and failure of toughened glazing assembly in performance-based fire prevention design.