Investigation of the Fire Performance of Water Film-protected Glass Facades

Description

For aesthetic and economic reasons, glass facades are used extensively in modern buildings(e.g. shopping malls, exhibition centers, and office buildings). However, they are vulnerable tofire exposure and can fail in a brittle manner and fall out. Loss of facade integrity may providea channel for fresh air to enter the compartment and an outlet for the fire to spread horizontallyand vertically, leading to devastating fires with tragic consequences. For example, the BeijingCCTV office building fire in 2009 caused 1 death and the loss of RMB200 million. Atechnology to improve the fire performance of glass facades would make use of the sprinklersthat are already part of the building’s fire protection system. Water films could moderate thetemperature on the exposed glass surface and prevent thermal shock. However, detailedresearch is still needed to understand glass facades protected by water films at different heatingrates.Conventional finite element methods are inefficient in simulating fluid flow, crackpropagation and damage. Hence, the aim of the proposed study is to develop a meshfreecomputational framework that takes into account the fluid-structure interaction (FSI) betweenwater films and glass facades, as well as the thermal-mechanical fracture properties of glassfacades at elevated temperatures during fires. When water film fluid flows down a glass facadesurface, the FSI effect may influence the film’s integrity, which is determined by the water filmthickness as well as velocity and the properties of the glass facade structure. In addition, theinhomogeneous temperature distribution caused by the water spray exerts negative effects onthe stress and strain states. Multiphysics coupling between the laws that describe the fluiddynamics of water film and fracture mechanics of glass facades will be developed.A series of tests will be conducted to investigate the thermal-mechanical behavior of glassfacades with down-flowing water films using controlled sprinklers. Meshfree simulation resultswill be compared and verified with data from the test series. A number of parameters, includingthe water film and glass thicknesses, sprinkler reaction time, maximum temperature towithstand water spray, and crack initiation and propagation, will be investigated to reach acomprehensive understanding of sprinkler systems’ effects on glass facades under fireconditions. Furthermore, an optimization process will be utilized to develop equations for theoptimal design of water-film protected glass facades.