Heating Machanism of building components exposed to a lacalized fire. CFD Prediction of the Heat Flux of a Steel Beam.

Wakamatsu, Takashi; Hasemi, Yuji; Ptchelintsev, Alexander

doi:10.3210/fst.20.1

Cited by 9 publications

(10 citation statements)

References 5 publications

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“…In both cases, the distance from the burner to the lower flange of the ceiling beam was 1. [31]. The emissivity of all solid surfaces was taken as 0.9 [31].…”

Section: The Fire Structure Interfacementioning

confidence: 99%

“…[31]. The emissivity of all solid surfaces was taken as 0.9 [31]. Other properties of the materials were taken from [31] The grid sizes used is one of the most important numerical parameter in CFD dictating its numerical accuracy.…”

Section: The Fire Structure Interfacementioning

confidence: 99%

“…The emissivity of all solid surfaces was taken as 0.9 [31]. Other properties of the materials were taken from [31] The grid sizes used is one of the most important numerical parameter in CFD dictating its numerical accuracy. The necessary spatial resolution for a proper LES simulation is customary defined in terms of the characteristic diameter of a plume, which is defined as [19],…”

Section: The Fire Structure Interfacementioning

confidence: 99%

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Integrated Fire-Structure Simulation of a Localzied Fire Test on a Ceiling Steel Beam

Zhang¹,

Li²

2017

Volume 13 Number 2

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Performance based method is increasingly used for structural fire safety design of modern buildings with large enclosure. The design fire scenarios in large enclosure are localized fires. Integrated fire-structure simulation method is required to accurately predict the response of structures in realistic fires (e.g. localized fires). In recent years, there is an increase in use of FDS (Fire Dynamics Simulator) -FEM (finite element method) approach for performance-based structural fire design. This paper discusses the FDS-FEM approach for predicting the thermal response of structures subjected to localized fires. A fire-structure interface, named adiabatic surface temperature (AST), was applied to transfer data from FDS to ANSYS. By comparing the predicted and measured heat fluxes and steel temperatures of a steel ceiling beam exposed to a localized fire condition, the FDS-FEM method was tested. The FDS predicted heat fluxes matched well with the test data. The difference between the predicted and measured maximum heat fluxes was within 6% for the investigated two cases. The FDS-FEM method gave good prediction of the steel temperatures. The over-prediction of maximum steel temperature was within 11% for the investigated case. The methods described in this study provide a feasible way to study the complex behavior of structures in realistic fires.

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“…In both cases, the distance from the burner to the lower flange of the ceiling beam was 1. [31]. The emissivity of all solid surfaces was taken as 0.9 [31].…”

Section: The Fire Structure Interfacementioning

confidence: 99%

Section: The Fire Structure Interfacementioning

confidence: 99%

Section: The Fire Structure Interfacementioning

confidence: 99%

See 1 more Smart Citation

Integrated Fire-Structure Simulation of a Localzied Fire Test on a Ceiling Steel Beam

Zhang¹,

Li²

2017

Volume 13 Number 2

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“…OPEN vents were used on the exterior mesh boundaries to represent opening conditions in the experiments [7]. Thermal properties of the steel were taken from [21]. The default emissivity of solid surfaces (0.9) was used.…”

Section: Description Of the Experimentsmentioning

confidence: 99%

Fire Dynamic Simulation on Thermal Actions in Localized Fires in Large Enclosure

Zhang

Li²

2012

Volume 8 Number 2

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ABSTRACT:Large enclosures commonly exist in many buildings like atria, open car parks and airport terminals. There is an international trend to prompt performance-based method (PBM) for fire resistance design. By PBM, the temperatures of structures in design fires should be determined. Localized fires are always adopted as design fires in large spaces. Currently, no agreed calculation method is available for the calculation of the heat flux from a localized fire to a vertical column. This paper aims at providing a feasible way of calculating the thermal actions in localized fires. Particularly, gas temperatures in localized fires and heat transfer from localized fires to steel vertical columns have been numerically investigated. The popular CFD code FDS is adopted as the numerical tool. A design fire scenario and four real localized fire tests are simulated in FDS. The effects of input parameters, including grid size and number of solid angles, on the accuracies of the numerical results have been investigated. Numerical results are compared with correlations and test data, which shows good agreement. INTRODUCTIONA compartment fire will generally undergo six stages which include ignition, growth, flashover, full fire development or steady burning, decay and extinguishment. Flashover is the rapid transition between the primary fire which is essentially localized around the item first ignited, and the general conflagration within the compartment when all fuel surfaces are burning [1]. Depending on whether flashover will happen or not, the real fires are usually divided into pre-and post-flashover fires. For small and middle scaled compartments with sufficient fuel and ventilation, the potential fires will develop to flashover and be characterized as post-flashover fires. For large scale enclosures or where sprinklers work effectively, flashover is unlikely to occur and the fires are characterized as pre-flashover fires. Post-flashover fires provide the worst case scenarios which are usually considered in fire resistance design. However, localized heating of key elements of structure in pre-flashover fires must be also considered.For post-flashover fires, the gas properties within the compartment are approximately uniform that temperature-time curves are usually adopted to represent the fire environments. Correspondingly, the temperature of exposed members can be easily determined by interpreting the homogenous gas temperature as the effective black body radiation temperature and as the same gas temperature for convection calculation. At present, various formulae are provided by fire codes in different countries for calculating the temperature of steel members in post-flashover fires [2][3][4]. However, for pre-flashover or localized fires, the distribution of gas temperature is spatially non-uniform.

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“…Subsequently, we have formulated heat flux distribution on every part of the beam as a function of heat release rate and the distance from the fire source to the member. Then we made FEM, FDM and CFD-based numerical calculation models, and the validity of these models was verified by comparing the numerical temperature results with those obtained through the experiment [2,3,4,5,6]. From the results of these studies, we demonstrated the practical feasibility of our FEM and FDM-based mo dels to predict the temperature of members, also proposed a correction method of heat flux data, and developed a heat transfer coefficient for the experimental conditions.…”

Section: Introductionmentioning

confidence: 99%

Heating Mechanism Of Unprotect4ed Steel Beam Installed Beneath Ceiling And Exposed To A Localized Fire: Verification Using The Real-scale Experiment And Effects Of The Smoke Layer

Wakamatsu¹,

Hasemi²,

Kagiya³

et al. 2003

Fire Safety Science - Proceedings of the Seventh International

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Measurements of the heating condition of a steel beam installed beneath a ceiling and exposed to a localized fire source are made on a real-scale experiment. The data of thermal response obtained from the experiments are compared with previous small-scale experiments. The effects of the smoke layer which influences upon the heating condition of the beam are investigated through the smoke experiments setting the smoke protection soffits to the same experimental equipment. FDM-based calculation is demonstrated using the average temperature of the smoke layer for the boundary conditions to predict the thermal response of the beam. Applicability of the approximated temperature of the smoke layer is examined by comparing the numerical results of the temperature with those obtained through the experiment.

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Heating Machanism of building components exposed to a lacalized fire. CFD Prediction of the Heat Flux of a Steel Beam.

Cited by 9 publications

References 5 publications

Integrated Fire-Structure Simulation of a Localzied Fire Test on a Ceiling Steel Beam

Integrated Fire-Structure Simulation of a Localzied Fire Test on a Ceiling Steel Beam

Fire Dynamic Simulation on Thermal Actions in Localized Fires in Large Enclosure

Heating Mechanism Of Unprotect4ed Steel Beam Installed Beneath Ceiling And Exposed To A Localized Fire: Verification Using The Real-scale Experiment And Effects Of The Smoke Layer

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