Thermal breakage and fallout behaviors of non-tempered glass under the effect of water film

Abstract

Delayed activation of the sprinkler or water film system may accelerate the crack and fallout process of the heated glass when encountered in a fire. A series of tests were conducted to investigate the thermal breakage and fallout behavior of a non-tempered glass fac xade with down-flowing water films. The most widely used non-tempered glass, low emissivity coated glass (Low-E), and float glass were studied in this work. An n-heptane pool fire was employed to heat up the glass panes and the water film was acted when the maximum glazing temperature reached the different designed values. The results illustrate that water film has little influence on the fracture behavior of float glass. However, the water film does accelerate the crack and fallout process of Low-E glass significantly when the glazing temperature is over 70°C. This is because large thermal stress is generated inside the glass due to the continuous cooling of the cold water film, which exceeds the ultimate tensile stress of glass. The water film also has a large impact on the crack propagation and fallout ratio of the glass panes.

Crack evolution process of window glass under radiant heating

“…The main and secondary fracture processes are defined in Section 3.1. The first main fracture also named the first crack in the previous studies because there was no crack before the first main fracture. Process of crack evolution under fire conditions had received less attention than the final crack patterns in the previous studies.…”

“…Wang et al investigated the fracture behavior of 4‐pointed fixed and framing coated glass curtain walls under fire conditions. Recently, the combined effect of fire and water film on glass breakage has been studied by Shao et al, and the combined effect of thermal loading and wind loading on glass breakage has been studied by Zhao et al…”

“…Life span of glass in a fire can be divided into 2 stages: one is a fire‐resistant period, and the other is a period of losing integrity. Much attention was focused on time to the first crack, namely, the fire‐resistant period of glass pane in previous studies . In fact, the fall‐out time of glass is always longer than the time to first crack.…”

Modeling glass cooling mechanism with down-flowing water film via the smoothed particle hydrodynamics

“…The most common type of water film experiment consists of standard glass pane size of 600×600×6 mm 3 , while the water source and recovery of water film system consist of nozzles fixed at the top of the glass pane, water tanks to measure the amount of unevaporated water, pipes and hydraulic pump. It was revealed that the release time of the water film is a crucial factor in glass protection because discharging the water film at early stages of fire is more efficient in protecting the glass from falling apart [7,8].…”

“…T, the temperature values at some of these points are used in the verification stage and during the numerical simulation of new scenarios.Fig. 2(b) shows the heat flux variation induced by a fire pool located near the glass pane[7]. Throughout this work, the origin of the coordinate system (x = 0 mm, y = 0 mm) is placed at the lower point of the exposed glass surface as shown inFig.…”