The Fracture Behavior Of Hollow Glass Under Fire Condition

Ordinary single glass applied in the building plays a role in the lighting, ventilation and expanding horizons, but has a poor insulation properties. The appearance of double glazing solve the problem of thermal insulation effectively while it is easy to absorb water vapor etc. in the air to condense and block our vision. Hollow glass consist of two glass plates separated by aluminum gutter and sealed with sealant, not only can make up the poor insulation and fast heat dissipation of the single-layer glass, but also can take the advantages of thermal insulation of the double glazing, with good insulation and anti-condensation properties. But hollow glass also has a risk of breaking and fallout under fire environment which can accelerate the spread of fire and block the escape of people. Therefore, the study on rupture, fallout behavior and fire resistance of hollow glass under fire condition is one of the important tasks of building fire safety.Domestic and foreign scholars have conducted some work about the fracture behavior of hollow glass, and have drawn some qualitative and quantitative conclusions of hollow glass in specific experimental conditions. However, these studies have not yet involved in the influence of the installation of hollow glass.The thermal response of hollow glass under different installation methods and with different air thickness in fire scenarios are studied experimentally, and the selection of installation methods and hollow glass thickness in engineering fields are explored.A total of32sets of experiments are designed to achieve the study purpose. The heat flux at the center of the exposed glass, heat release rate, hollow glass surface temperature distribution, breaking time of exposed glass and back glass, the position of the first crack, crack shape and glass fallout percent are analyzed in detail. If the length of square glass is L, and central point of the glass is0, then the side region of glass can be represented within the scope of [-0.5L,0.5L]. The experiment results show that25kW/m2is the minimum heat flux to crack and fallout for three kinds of hollow glass. The crack initiation point are located in the shaded edge, and within the scope of [-0.25L,0.25L]. Though the breaking time of exposed side under full shaded condition is less than the other two installation methods, fallout percent of exposed side and back side of hollow glass under full shaded situation is much lower, which maintains a better integrity of the glass, reduces fresh air to access and slows down the development of the fire. Falling from the glass frame under vertical shaded situation is more easier than that are shaded horizontally. Cracking and fallout of the exposed glass also has a significant impact on the cracking of the back glass.Further, the thermal response of hollow glass with three different air thickness under some specific shadowing method in the fire scene are studied. A detailed comparative analysis about initial cracking time and fallout percent in the exposed side and back side of three different air thickness hollow glass is given in the paper. The results show that hollow glass with12mm,6mm and12mm air thickness has a longer refractory period and smaller fallout proportion separately under full shaded, horizontal shaded and vertical shaded conditions.