Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Building Environment and Energy Engineering | en_US |
| dc.contributor.advisor | Jiang, Liming (BEEE) | en_US |
| dc.contributor.advisor | Usmani, Asif (BEEE) | en_US |
| dc.creator | Chu, Tianwei | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/13729 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Fire behavior in modern buildings considering window glass fallout and active ventilation | en_US |
| dcterms.abstract | Modern architectural designs increasingly preferred larger open-plan layouts to enhance spatial flexibility and larger glass windows for more natural lighting as well as better inhabiting experiences. However, such designs fundamentally change fire safety design practices, as the fire behavior in these compartments exhibiting time-variant localized burning is different from the traditional paradigm that focuses on ventilation-controlled fires in small compartments. In this thesis, the first main objective is to better understand fire behavior in modern designed compartments, and the interaction between window glass failure and fire development has been identified as a crucial factor. This inspires the second objective of this thesis, which is to develop an innovative solution of 'active opening' windows to mitigate fire development in modern large open plan compartments. | en_US |
| dcterms.abstract | In this thesis, Chapter 1 presents a comprehensive review of the literature on glass behavior and compartment fire research, which illustrates the complexities of considering glass fire behavior in compartment fires. Particularly, the localized burning in large compartments would impose complex fire action on glass panels and complete failure of glass to ensure the commonly assumed initial window openings cannot be achieved within a few minutes. Hence, it is of vital importance to re-assess the role of window glass in providing crucial ventilation to speed up or to slow down the fire development. To address these needs, Chapter 2 establishes a 'criterion-controlled' approach to bring glass fallout effect to the CFD fire simulation. This modelling approach subdivides the glass panel into multiple glass sub-modules, and the removals of these sub-modules are controlled by the fallout criteria derived from Shields Tests. After validation against fire test data, this approach is applied to the simulation of modern large open-plan compartment fires, which surprisingly shows that the fire development path has been fundamentally altered. The fire spread becomes much faster due to the later window glass fallout, whereas the presumed sufficient ventilation conditions become invalid. In view of the uncertainties of glass fallout in fire, Chapter 3 introduces a Weibull probability distribution model into the Shields fallout criteria governed by the glass surface temperatures. Implementing this probabilistic approach with 200 large-scale fire simulation cases, diverse fire development patterns are found as influenced by the stochastic nature of glass fallout and varying thermal conditions. These results clearly demonstrate the complexity introduced by glass fallout to fire behaviors in open-plan compartments and the necessity of considering glass-fire interaction. | en_US |
| dcterms.abstract | Inspired by the slower fire development observed in Chapter 3 with virtually very early glass removal, Chapter 4 introduces an innovative 'active opening' strategy. In contrast with the common intuition of enhancing glass fire resistance, this thesis proposes to actively open windows at an early stage of a fire to mitigate fast fire development in modern compartments. This concept has been verified with CFD simulations, in which fast fire spread is avoided, benefiting from a thin smoke layer after active window opening. Through various modelling attempts, the factors including the upper edge of windows and the activation temperatures are found to be important in achieving effective mitigation of fire spread. Subsequently, Chapter 5 validates the 'active opening' strategy for the first time using real fire tests and demonstrates the fast fire spread in the same scaled compartment with window glass. The mechanisms of 'active opening' have been analyzed with the test data and the corresponding simulation. The benefit of reduced smoke radiation is found dominant compared to the introduction of fresh air, which prevents fast pre-heating of floor fuel and avoids rapid progression of flame front. Chapter 6 further examines the effectiveness of using 'active opening' in more realistic applications, which numerically investigates a tall building model of non-uniform fuel load and opening configurations. It is shown that the implementation of 'active opening' effectively reduces smoke and mitigates flame spread, as well as reducing the heating impact on building façades, avoiding the risk of vertical fire spread. The effects of window opening setups, the number of windows opened, and detector designs are investigated. In Chapter 7, the overall conclusions of this thesis are drawn, followed by the discussion of future tasks of implementing active opening towards real applications in modern buildings. | en_US |
| dcterms.extent | viii, 138 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2025 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.LCSH | Fires | en_US |
| dcterms.LCSH | Windows | en_US |
| dcterms.LCSH | Fire prevention | en_US |
| dcterms.LCSH | Hong Kong Polytechnic University -- Dissertations | en_US |
| dcterms.accessRights | open access | en_US |
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