Po-Ta Huang and M. A. Delichatsios
This paper develops a probabilistic approach though event trees for the scenarios and Monte-Carlo simulation for the propagation of uncertainties (e.g. in input parameters…
Abstract
This paper develops a probabilistic approach though event trees for the scenarios and Monte-Carlo simulation for the propagation of uncertainties (e.g. in input parameters, models) concerning the evaluation of time and consequences of the failure of structural elements in fires. The time to failure is the output of specific deterministic two zone models (e.g. Ozone) following current regulatory guidelines for possible fire scenarios and input parameters for the design of restrained and unrestrained beams. As a consequence, probabilistic distributions of times replace fixed times to failure of structural elements. These probability distributions are combined in event trees to determine the risk curve for different scenarios, design parameters and fire safety systems such as detection, sprinklers and insulation of beams. The consequence in the risk curve is represented by the magnitude of the probability to failure whereas the associated likelihood is calculated for all possible scenarios. The results allow the relative risk assessment of different design alternatives and the underpinning of sensitive parameters.
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H. Dagdougui, E. Garbolino, O. Paladino and R. Sacile
The purpose of this paper is the definition and the implementation of a simplified mathematical model to estimate the hazard and the risk related to the use of high‐pressurized…
Abstract
Purpose
The purpose of this paper is the definition and the implementation of a simplified mathematical model to estimate the hazard and the risk related to the use of high‐pressurized hydrogen pipeline.
Design/methodology/approach
This study aims to investigate the effects of different hydrogen operations conditions and to tackle with different release or failure scenarios. Based on the combination of empirical relations and analytical models, this paper sets the basis for suitable models for consequence analysis in terms of estimating fire length and of predicting its thermal radiation. The results are compared either with experimental data available in the literature, thus by setting the same operations and failure conditions, or with other conventional gaseous fuel currently used.
Findings
The findings show that the release rate increasingly varies according to the supply pressure. Regarding the effect of the hole diameter, it hugely affects the amount of hydrogen escaping from the leak, up to a value of approximately 0.3 m, after which the release rate remains fixed at a maximum of 43 Kg/s. For failure consequences related to jet flame, the leak dimension has a strength impact on the flame length.
Originality/value
This paper represents a helpful engineering tool, to establish the safety requirements that are related to define adequate safety buffer zones for the hydrogen pipeline in order to ensure safety to people, as well the environment.
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E. Theuns, J. Vierendeels and P. Vandevelde
This paper describes a one dimensional moving grid model for the pyrolysis of charring materials. In the model, the solid is divided by a pyrolysis front into a char and a virgin…
Abstract
This paper describes a one dimensional moving grid model for the pyrolysis of charring materials. In the model, the solid is divided by a pyrolysis front into a char and a virgin layer. Only when the virgin material reaches a critical temperature it starts to pyrolyse. The progress of the front determines the release of combustible volatiles by the surface. The volatiles, which are produced at the pyrolysis front, flow immediately out of the solid. Heat exchange between those volatiles and the char layer is taken into account. Since the model is used here as a stand‐alone model, the external heat flux that heats up the solid, is assumed to be known. In the future, this model will be coupled with a CFD code in order to simulate fire spread. The char and virgin grid move along with the pyrolysis front. Calculations are done on uniform and on non‐uniform grids for the virgin layer. In the char layer only a uniform grid is used. Calculations done with a non‐uniform grid are about 3 times faster than with a uniform gird. The moving grid model is compared with a faster but approximate integral model for several cases. For sudden changes in the boundary conditions, the approximate integral model gives significant errors.
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Basant Kumar Jha and Babatunde Aina
The purpose of this paper is to further extend the work of Weng and Chen (2009) by considering heat generation/absorption nature of fluid.
Abstract
Purpose
The purpose of this paper is to further extend the work of Weng and Chen (2009) by considering heat generation/absorption nature of fluid.
Design/methodology/approach
Exact solution of momentum equation is derived separately in terms of Bessel’s function of first and second kind for heat-generating fluid and modified Bessel’s function of first and second kind for heat absorbing fluid.
Findings
During the course of numerical computations, it is found that skin friction and rate of heat transfer at outer surface of inner cylinder and inner surface of outer cylinder increases with the increase in heat generation parameter while the reverse trend is found in the case of heat absorption parameter.
Originality/value
In view of the amount of works done on natural convection with internal heat generation/absorption, it becomes interesting to investigate the effect of this important activity on natural convection flow in a vertical annular micro-channel. The purpose of this paper is to further extend the work of Weng and Chen (2009) by considering heat generation/absorption nature of fluid.
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Ranjit Kumar Chaudhary, Tathagata Roy and Vasant Matsagar
Despite recognizing the significance of risk-based frameworks in fire safety engineering, the usual approach in structural fire design is largely member/component level, wherein…
Abstract
Purpose
Despite recognizing the significance of risk-based frameworks in fire safety engineering, the usual approach in structural fire design is largely member/component level, wherein effect of uncertainties influencing the fire resistance of structures are not explicitly considered. In this context, a probabilistic framework is presented to investigate the vulnerability of a reinforced concrete (RC) members and structure under fire loading scenario.
Design/methodology/approach
The RC structures exposed to fire are modeled in a finite element (FE) platform incorporating material and geometric nonlinearity, in which the transient thermo-mechanical analysis is carried out by suitably incorporating the temperature variation of thermal and mechanical properties of both concrete and steel rebar. The stochasticity in the system is considered in structural resistance, thermal and fire model parameters, and the subsequent fragility curves are developed considering threshold limit state of deflection.
Findings
The fire resistance of RC structure is reported to be significantly lower in comparison to the RC members, thereby illustrating the current prescriptive design approaches based on studies of structural member behavior to be crucial from a safety and reliability point of view.
Practical implications
The framework developed for the vulnerability assessment of RC structures under fire hazard through FE analysis can be effectively used to estimate the structural fire resistance for other similar structure to enhance safety and reliability of structures under such extreme threats.
Originality/value
The paper proposes a novel methodology for vulnerability assessment of three-dimensional RC structures under fire hazard through FE analysis and provides comparison of the structural fragility with fragility developed for structural members. Moreover, the research emphasizes to assume 3D behavior of the structure rather than the approximate 2D behavior.
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Md Delwar Hossain, Md Kamrul Hassan, Anthony Chun Yin Yuen, Yaping He, Swapan Saha and Waseem Hittini
The purpose of this study is to review and summarise the existing available literature on lightweight cladding systems to provide detailed information on fire behaviour…
Abstract
Purpose
The purpose of this study is to review and summarise the existing available literature on lightweight cladding systems to provide detailed information on fire behaviour (ignitibility, heat release rate and smoke toxicity) and various test method protocols. Additionally, the paper discusses the challenges and provides updated knowledge and recommendation on selective-fire mechanisms such as rapid-fire spread, air cavity and fire re-entry behaviours due to dripping and melting of lightweight composite claddings.
Design/methodology/approach
A comprehensive literature review on fire behaviour, fire hazard and testing methods of lightweight composite claddings has been conducted in this research. In summarising all possible fire hazards, particular attention is given to the potential impact of toxicity of lightweight cladding fires. In addition, various criteria for fire performance evaluation of lightweight composite claddings are also highlighted. These evaluations are generally categorised as small-, intermediate- and large-scale test methods.
Findings
The major challenges of lightweight claddings are rapid fire spread, smoke production and toxicity and inconsistency in fire testing.
Originality/value
The review highlights the current challenges in cladding fire, smoke toxicity, testing system and regulation to provide some research recommendations to address the identified challenges.
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Xuehui Wang, Tiannian Zhou, Qinpei Chen and Jian Wang
This study aims to investigate the controlling mechanisms of ambient oxygen and pressure on piloted ignition of solid combustibles under external…
Abstract
Purpose
This study aims to investigate the controlling mechanisms of ambient oxygen and pressure on piloted ignition of solid combustibles under external radiant heating.
Design/methodology/approach
The numerical simulation method was used to model the influence of ambient oxygen concentration on the piloted ignition of a thermally irradiated solid sample in reduced pressure atmospheres. The solid phase decomposition and gas phase kinetics were solved simultaneously.
Findings
It was determined that the elevated oxygen atmospheres resulted in a higher flame temperature and a thicker temperature profile over the solid surface. Also, increasing oxygen and reducing pressure had a similar effect in the decrease of the ignition delay time. The shorter ignition time in reduced pressure was mainly because of the decreasing of convective heat losses from the heated solid. As oxygen was reduced, however, ignition occurred later and with a greater mass loss rate because more volatiles of solid fuel at transient ignition were required to sustain a complete reaction under an oxygen-poor condition.
Research limitations/implications
The results need to be verified with experiments.
Practical implications
The results could be applied for design and assessment of fire-fighting and fire prevention strategies in reduced pressure atmosphere.
Originality/value
This paper shows the effect mechanism of ambient oxygen and pressure on piloted ignition of solid combustibles.
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Kaihang Shi, Qianru Guo and Ann Jeffers
This paper describes a preliminary study to explore the use of Monte Carlo simulation to assess the reliability of structures in fire given uncertainty in the fire, thermal, and…
Abstract
This paper describes a preliminary study to explore the use of Monte Carlo simulation to assess the reliability of structures in fire given uncertainty in the fire, thermal, and structural model parameters. The methodology requires (1) the probabilistic characterization of the uncertain parameters in the system, (2) a stochastic model for the thermo-structural response, and (3) a limit state function that describes the failure of the system. The study focuses on assessing the failure probability of a protected steel beam under natural fire exposure. The system was modeled stochastically using a series of sequentially coupled thermo-structural finite element analyses that were embedded within a Monte Carlo simulation. Although the example considered here is relatively simplistic in that it focuses on member level performance, it effectively demonstrates the application of the proposed reliability method and provides insight into the practicalities of extending the approach to more complex structural systems.
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Michael Quinn, Ali Nadjai, Faris Ali and Abid Abu-Tair
Breakage and fallout of glazing systems create openings in an enclosure that affect the fire growth and the development of post flashover flames emerging outside of the openings…
Abstract
Breakage and fallout of glazing systems create openings in an enclosure that affect the fire growth and the development of post flashover flames emerging outside of the openings. The behaviour of glazing is the result of its thermally induced stress response to the heat fluxes from the fire in an enclosure. In recent times building façade designs have evolved and now incorporate many different shapes, orientations and materials. The conventional single and double glazing panels have been surpassed by composite type glazing systems including glazing and transparent resins. This paper presents experimental testing of these comp osite glazing panels having different orientations subjected to localized fires, which have the same fire load. The experimental findings of interest include the varying first crack times for both scenarios as well as the variable final crack patterns on the glazing panels. The effect of localized fire on the materials tested as seen in the final char patterns on both glazing systems is also note worthy. The paper also includes details of three-dimensional finite element modeling completed for the prediction of response of the glazing panels at different orientations to the elevated temperatures of the localised fire scenario as tested in the laboratory. This finite element analysis allows for an assessment of glazing thermal stresses at various times throughout each test.
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Soheila Bahrami and Davood Zeinali
This paper explores the quality and flow of facade product information and the capabilities for avoiding the risk of facade fires early in the design process.
Abstract
Purpose
This paper explores the quality and flow of facade product information and the capabilities for avoiding the risk of facade fires early in the design process.
Design/methodology/approach
A qualitative case study using the process tracing method is conducted in two stages. First, a thematic analysis of reports and literature identified two categories for the problems that caused fast fire spread across the Grenfell Tower facade. This enabled classifying the identified problems into four stages of a facade life cycle: product design and manufacturing, procurement, facade design and construction. Second, the capabilities for avoiding the problems were explored by conducting in-depth interviews with 18 experts in nine countries, analyzing design processes and designers' expertise and examining the usability of three digital interfaces in providing required information for designing fire-safe facades.
Findings
The results show fundamental flaws in the quality of facade product information and usability of digital interfaces concerning fire safety. These flaws, fragmented design processes and overreliance on other specialists increase the risk of design defects that cause fast fire spread across facades.
Practical implications
The findings have implications for standardization of building product information, digitalization in industrialized construction and facade design management.
Originality/value
This research adds to the body of knowledge on sustainability in the built environment. It is the first study to highlight the fundamental problem of facade product information, which requires urgent attention in the rapid transition toward digital and industrialized construction.