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Tunnel Linings under Fire-Induced Heat Exposure: Thermal Demand Evaluation and Structural Risk Assessment.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Tunnel Linings under Fire-Induced Heat Exposure: Thermal Demand Evaluation and Structural Risk Assessment./
作者:	Guo, Qi.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
面頁冊數:	188 p.
附註:	Source: Dissertations Abstracts International, Volume: 82-12, Section: B.
Contained By:	Dissertations Abstracts International82-12B.
標題:	Civil engineering. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28495844
ISBN:	9798515201364

Tunnel Linings under Fire-Induced Heat Exposure: Thermal Demand Evaluation and Structural Risk Assessment.
Guo, Qi.

Tunnel Linings under Fire-Induced Heat Exposure: Thermal Demand Evaluation and Structural Risk Assessment. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 188 p.

Source: Dissertations Abstracts International, Volume: 82-12, Section: B.

Thesis (Ph.D.)--Lehigh University, 2021.

This item must not be sold to any third party vendors.

This study investigates the interaction between the tunnel structure and vehicle fires. Novel approaches are developed to evaluate the thermal demand and structural risk and demonstrated in this dissertation.Computational modeling is first conducted to predict the thermal demand on the tunnel linings in the numerical environment. The modeling is done in Fire Dynamics Simulator (FDS) and validated against two full-scale tunnel fire test programs. The modeling approach is then applied in a parametric study including three tunnel cross sections, four fire sizes and three measurement locations to develop benchmark results when experimental results are limited.A semi-empirical fire model called the Confined Discretized Solid Flame (CDSF) model is proposed to calculate fire-induced thermal demand on tunnel linings. The CDSF model requires minimum computational cost and expertise in combustion or fluid dynamics, which serves as an alternative to the common fire safety design tools such as standard fire curves and high-fidelity computational fluid dynamics software. The CDSF model calculates thermal demand of both radiation from the flame and convection from the smoke and hot gases around the flame. Given the dimension of the tunnel and the fire size, the CDSF model discretizes the tunnel surface into smaller surfaces and calculates the thermal exposure received by each discretized surface. The accuracy and robustness of the CDSF model is validated against results from the computational modeling in FDS.Fire hazard is usually rare in tunnels, but it has potential to cause substantial damage to the tunnel structure which leads to downtime inconvenience and economic loss. Probability is introduced in this study to address the uncertainties in tunnel fire safety and better quantify the fire hazard in tunnels.The uncertainties in fire frequency and fire size are first evaluated to provide insight for design fire demand in tunnel fire protection. The likelihood of a vehicular fire and the associated fire size distribution are used to generate probabilistic distributions of total fire exposure to the reinforced concrete tunnel liner. Two critical thermal demand value from the probabilistic study are selected and compared to thermal demand from standard fire curves in terms of material degradation to frame the probabilistic study of thermal demand in the context of current practice. A case study of the Fort Pitt Tunnel in Pittsburgh, PA is included for demonstration.The probabilistic study of thermal demand is then expanded to a Quantitative Risk Assessment (QRA) approach which considers not only the thermal demand but also the resulting loss in both structural and economic metrics. Traffic statistics such as Weight-in-Motion data and fire statistics from previous survey are utilized to achieve a more realistic representation of the fire frequency and the probability distribution of fire sizes. An empirical relationship between the combustible vehicle weight and the fire size is proposed to convert the available distribution of vehicle weight data to the unavailable distribution of fire size data. The CDSF model developed in this study is utilized to model the heat transfer from the vehicle fire to the tunnel lining. Fire-induced damage to the tunnel lining is categorized into three levels of progressive strength reduction and cracking potential. Economic impacts are calculated in terms of estimated repair costs for a given level of lining damage.The tools and approaches demonstrated in this study are designed to facilitate thermal demand determination and enable informed decision making for the design or renovation of tunnel fire protection by quantifying the probability and loss potential for severe fire hazards in a given tunnel.

ISBN: 9798515201364Subjects--Topical Terms:

860360
Civil engineering.
Subjects--Index Terms:

Numerical modeling

Tunnel Linings under Fire-Induced Heat Exposure: Thermal Demand Evaluation and Structural Risk Assessment.
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502 $a Thesis (Ph.D.)--Lehigh University, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a This study investigates the interaction between the tunnel structure and vehicle fires. Novel approaches are developed to evaluate the thermal demand and structural risk and demonstrated in this dissertation.Computational modeling is first conducted to predict the thermal demand on the tunnel linings in the numerical environment. The modeling is done in Fire Dynamics Simulator (FDS) and validated against two full-scale tunnel fire test programs. The modeling approach is then applied in a parametric study including three tunnel cross sections, four fire sizes and three measurement locations to develop benchmark results when experimental results are limited.A semi-empirical fire model called the Confined Discretized Solid Flame (CDSF) model is proposed to calculate fire-induced thermal demand on tunnel linings. The CDSF model requires minimum computational cost and expertise in combustion or fluid dynamics, which serves as an alternative to the common fire safety design tools such as standard fire curves and high-fidelity computational fluid dynamics software. The CDSF model calculates thermal demand of both radiation from the flame and convection from the smoke and hot gases around the flame. Given the dimension of the tunnel and the fire size, the CDSF model discretizes the tunnel surface into smaller surfaces and calculates the thermal exposure received by each discretized surface. The accuracy and robustness of the CDSF model is validated against results from the computational modeling in FDS.Fire hazard is usually rare in tunnels, but it has potential to cause substantial damage to the tunnel structure which leads to downtime inconvenience and economic loss. Probability is introduced in this study to address the uncertainties in tunnel fire safety and better quantify the fire hazard in tunnels.The uncertainties in fire frequency and fire size are first evaluated to provide insight for design fire demand in tunnel fire protection. The likelihood of a vehicular fire and the associated fire size distribution are used to generate probabilistic distributions of total fire exposure to the reinforced concrete tunnel liner. Two critical thermal demand value from the probabilistic study are selected and compared to thermal demand from standard fire curves in terms of material degradation to frame the probabilistic study of thermal demand in the context of current practice. A case study of the Fort Pitt Tunnel in Pittsburgh, PA is included for demonstration.The probabilistic study of thermal demand is then expanded to a Quantitative Risk Assessment (QRA) approach which considers not only the thermal demand but also the resulting loss in both structural and economic metrics. Traffic statistics such as Weight-in-Motion data and fire statistics from previous survey are utilized to achieve a more realistic representation of the fire frequency and the probability distribution of fire sizes. An empirical relationship between the combustible vehicle weight and the fire size is proposed to convert the available distribution of vehicle weight data to the unavailable distribution of fire size data. The CDSF model developed in this study is utilized to model the heat transfer from the vehicle fire to the tunnel lining. Fire-induced damage to the tunnel lining is categorized into three levels of progressive strength reduction and cracking potential. Economic impacts are calculated in terms of estimated repair costs for a given level of lining damage.The tools and approaches demonstrated in this study are designed to facilitate thermal demand determination and enable informed decision making for the design or renovation of tunnel fire protection by quantifying the probability and loss potential for severe fire hazards in a given tunnel.
590 $a School code: 0105.
650 4 $a Civil engineering. $3 860360
653 $a Numerical modeling
653 $a Risk assessment
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