Experimental study on fire response of double glazed panels in curtain walls

Double glazing is increasingly employed in glass curtain walls, but very little is known about its thermal response under fire conditions. In this work, a total of twenty seven 600 × 600 mm² double glazing units, with 6 mm, 9 mm and 12 mm air spacings, were tested. Three different installation types were adopted: 1) exposed frames, 2) horizontal-hidden frames and 3) vertical-hidden glass in order to study their potential effects on the glazing breakage behavior. A 500 × 500 mm² n-heptane pool fire was used to heat the glass panes. The breaking time, surface temperature, total heat flux, heat release rate, and crack and fallout morphology were measured and analyzed. The test result suggests that different installation types have a significant effect on the fracture behavior of double glazing, especially for glass panes located at the fire side. Glass in exposed framing is more prone to cracks than those in semi-exposed frame, but fallout may more easily occur in semi framing façades. When no, or very limited fallout occurs at the fire side pane, thicker air space leads to a longer breakage time of ambient glass panes, thus improving the unit's integrity during fire. The experimental results obtained in this study is valuable for the development of practical guidelines for fire safety design.