| 1. |
- Alam, Naveed, et al.
(author)
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Large scale travelling fire tests with open ventilation conditions and their effect on the surrounding steel structure– The second fire test
- 2022
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In: Journal of constructional steel research. - : Elsevier Ltd. - 0143-974X .- 1873-5983. ; 188
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Journal article (peer-reviewed)abstract
- In the frame of the European RFCS (Research Fund for Coal and Steel) TRAFIR (Characterization of TRAvelling FIRes in large compartments) project, three natural fire tests in a large compartment were conducted at Ulster University. The aim of this investigation was to understand the conditions in which the travelling fires develop and to study the impact of such fires on the surrounding steel structure. This paper provides details of the second fire test where the size of the openings was reduced to induce different ventilation conditions in comparison to the first fire test. During the test, behaviour of the travelling fire was observed and the gas temperatures at different levels and locations were recorded. The influence of travelling fires on the surrounding structure is studied in terms of the temperatures recorded in the selected steel columns and beams. The influence of change in the ventilation conditions is presented and highlighted through the comparison of results of the second fire test with those recorded earlier during the first fire test. It was found that the travelling fires produce non-uniform temperatures in the compartment irrespective of the ventilation conditions although the magnitude of this non-uniformity is related with the opening sizes. This non-uniformity exists along the length as well as along the height of the test compartment. It was found that for reduced opening sizes, more heat is retained within the compartment which induces higher temperatures in the surrounding steel structure. The transient heating of the surrounding structure caused by travelling fires should be considered while performing the structural fire design of large compartments. The results obtained during the test are state-of-the-art and will help in understating the behaviour of travelling fires and their influence on the surrounding structure which will help to devise fire design methods for future use.
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| 2. |
- Anderson, Johan, et al.
(author)
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FDS SIMULATIONS AND MODELLING EFFORTS OF TRAVELLING FIRES IN A LARGE ELONGATED COMPARTMENT
- 2019
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In: Interflam 2019, proceedings. - : Interscience Communications. ; , s. 2085-
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Conference paper (peer-reviewed)abstract
- The present paper investigates a travelling fire scenario in an elongated structure (Length 18 m x width 6 m x height 3 m) with a controlled fire source of six pans filled with diesel (width 4 m x length 0.5 m). The fire spread is controlled manually by initiating fires subsequently in the pools. Fire Dynamics Simulator (FDS) is used to a-priori investigate variations in geometry, material data and fire load whereas simulations using the final design were performed after the test. The input to the model beside fire source and geometry are thermal material data. The FDS simulation were used to determine the appropriate size of the downstands (2 m from the ceiling in the final design) on the side to create a sufficiently one-dimensional fire spread. The post test simulations indicate that although there are a lot of variations not included in the model similar results were obtained as in the test.
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| 3. |
- Anderson, Johan, et al.
(author)
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FDS simulations and modelling efforts of travelling fires in a large elongated compartment
- 2021
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In: Fire and Materials. - : John Wiley and Sons Ltd. - 0308-0501 .- 1099-1018. ; 45:6, s. 699-
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Journal article (peer-reviewed)abstract
- The present paper investigates a travelling fire scenario in an elongated structure (Length 18 m × width 6 m × height 3 m) with a controlled fire source of six trays filled with diesel (width 4 m × length 0.5 m). The fire spread is controlled manually by initiating fires consecutively in the pools. Fire dynamics simulator (FDS) is used to a-priori investigate variations in geometry, material data and fire load, whereas simulations using the final design and measured heat release rates (HRR) were performed after the test. The input to the model beside fire source and geometry are thermal material data. The FDS simulations were used to determine the appropriate size of the downstands (2 m from the ceiling in the final design) on the side to create a sufficiently one-dimensional fire spread. The post-test simulations indicate that although there are a lot of variations not included in the model similar results were obtained as in the test.
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| 4. |
- Charlier, Marion, et al.
(author)
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TRAFIR: Characterization of TRAvelling FIRes in large compartments
- 2020
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Reports (other academic/artistic)abstract
- Inspection of recent fire events in large compartments reveals them to have a great deal of non-uniformity, they generally burn locally and move across floor plates over a period of time. This phenomenon which generates transient heating of the structure is idealized as “travelling fire”.A first series of tests was launched to define a fire load representative of an office building according to Eurocodes. Additional tests where the fire dynamics were controlled were launched to develop an understanding of the fire exposure to steel structures.Then, a second series of large scale tests were performed in real building dimensions. These tests had no artificial control over the dynamics, which allowed a realistic characterization of the fire. The fire load was identical for all tests, only the openings were modified.CFD numerical models were developed to reproduce the experimental campaign and to launch parametrical analyses. This allowed to provide information concerning the conditions which may lead (or not) to a travelling fire scenario.An analytical model for the characterization of a travelling fire was developed and implemented in a simple calculation tool. It allows to evaluate the fire location, the gas temperatures in the flames, the heat fluxes in the different parts of the compartment and the temperature in a steel member. In addition, the methodology is introduced in the FEM software SAFIR and OpenSees.Ultimately, a design guide was prepared including worked examples which are detailed step-by-step and for which the influence of the inputs on the results is analysed.
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| 5. |
- Charlier, Marion, et al.
(author)
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Travelling fire experiments in steel-framed structure : numerical investigations with CFD and FEM
- 2021
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In: Journal of Structural Fire Engineering. - : Emerald Group Holdings Ltd.. - 2040-2317 .- 2040-2325. ; 12:3
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Journal article (peer-reviewed)abstract
- Purpose: The purpose of this paper is to propose a simplified representation of the fire load in computational fluid dynamics (CFD) to represent the effect of large-scale travelling fire and to highlight the relevance of such an approach whilst coupling the CFD results with finite element method (FEM) to evaluate related steel temperatures, comparing the numerical outcomes with experimental measurements. Design/methodology/approach: This paper presents the setup of the CFD simulations (FDS software), its corresponding assumptions and the calibration via two natural fire tests whilst focusing on gas temperatures and on steel temperatures measured on a central column. For the latter, two methods are presented: one based on EN 1993-1-2 and another linking CFD and FEM (SAFIR® software). Findings: This paper suggests that such an approach can allow for an acceptable representation of the travelling fire both in terms of fire spread and steel temperatures. The inevitable limitations inherent to the simplifications made during the CFD simulations are also discussed. Regarding steel temperatures, the two methods lead to quite similar results, but with the ones obtained via CFD–FEM coupling are closer to those measured. Originality/value: This work has revealed that the proposed simplified representation of the fire load appears to be appropriate to evaluate the temperature of steel structural elements within reasonable limits on computational time, making it potentially desirable for practical applications. This paper also presents the first comparisons of FDS–SAFIR® coupling with experimental results, highlighting promising outcomes.
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| 6. |
- Dai, Xu, et al.
(author)
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An engineering CFD model for fire spread on wood cribs for travelling fires
- 2022
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In: Advances in Engineering Software. - : Elsevier Ltd. - 0965-9978 .- 1873-5339. ; 173
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Journal article (peer-reviewed)abstract
- The temperature heterogeneity due to fire in large open-plan office compartments is closely associated with fire spread behaviour and has been historically limited to experimental investigations using timber cribs. This study explores the ability of Computational Fluid Dynamics (CFD) models, specifically the Fire Dynamics Simulator (FDS), to reproduce the results of full-scale tests involving fire spread over timber cribs for continuous fuel-beds. Mesh schemes are studied, with a fine mesh over the crib and 2 × 2 cells in the wood stick cross-section by default, this being relaxed in the surrounding regions to enhance computational efficiency. The simple pyrolysis model considers the charring phase and moisture. In application to the TRAFIR-Liège LB7 test, this calibrated “stick-by-stick” representation shows a good agreement for interrelated parameters of heat release rate, fire spread, gas phase temperature, and burn-away, a set of agreements which has not been demonstrated in previous studies. Fire spread shows relatively high sensitivities to: heat of combustion, ignition temperature, thermal inertia, radiation fraction, heat release rate per unit area, and the fuel load density. An approximately linear regression was found between the different fire modes and the thermal exposures, with “travelling” (and decaying) fires characterised by heat fluxes associated with the fire plume, while the growing fires were associated with proportionally higher heat fluxes on the horizontal surfaces of the sticks, in conditions where these receive more pre-heating. The trends in the overall HRR are more dependent on the fire spread rates than variations in the stick burning rates. © 2022 The Author(s)
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| 7. |
- Nadjai, Ali, et al.
(author)
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Large scale fire test : The development of a travelling fire in open ventilation conditions and its influence on the surrounding steel structure
- 2022
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In: Fire safety journal. - : Elsevier Ltd. - 0379-7112 .- 1873-7226. ; 130
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Journal article (peer-reviewed)abstract
- In the frame of the European RFCS-TRAFIR project, natural fire tests in large compartment were conducted by Ulster University, involving steel structure and aiming at understanding the conditions in which a travelling fire develops, how it behaves and impacts the surrounding structure. During the experimental programme, the path and geometry of the travelling fire was studied and temperatures, heat fluxes and spread rates were measured. The experimental data is presented in terms of gas temperatures recorded in the test compartment at different positions and levels. The influence of the travelling fire on the surround structure is presented in terms of the temperatures recorded in the selected steel columns and beams. The temperatures in the test compartment were dependent on the positioning of the travelling fire band as well as the height from the floor level. The non-uniform temperatures in the compartment lead to transient heating of the nearby structural steel elements, resulting in a reduction of their resistance which may influence the global structural stability. The results obtained will help to understand the behaviour of travelling fires and their influence on the structural members. This knowledge will help to reduce the travelling fire associated risks in future.
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| 8. |
- Xu, Dai, et al.
(author)
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CHARACTERISING NATURAL FIRES IN LARGE COMPARTMENTS – REVISITING AN EARLY TRAVELLING FIRE TEST (BST/FRS 1993) WITH CFD
- 2019
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In: Interflam 2019, proceedings. - : Interscience Communications. ; , s. 2111-
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Conference paper (peer-reviewed)abstract
- This paper presents a careful assessment of fire conditions in a long enclosure, open only at one end, which contained a regularly spaced timber crib fire load and is dominated by under-ventilated combustion. Though the geometrical arrangement, with fully enclosed side walls, differs from many more recent “travelling fire” tests, the essential fire behaviour shows a very clear progression of the main burning zone, driven by a combination of fire spread, ventilation and fuel burn out. By contrast many other travelling fire tests have been designed to be fuel-controlled, in much more open structures. Moreover, due to the enclosed nature of the test, it was observed to result in very high temperatures in the protected and unprotected steel beam members, especially during the phase when the fire travelled back from the opening to the ignition location at the rear of the compartment. The investigated test in this paper is Test number 2, which is one of nine tests carried out at the BRE Cardington laboratory in the UK, led by British Steel Technical (BST) and hosted by the Fire Research Station (FRS).CFD modelling, with NIST’s Fire Dynamics Simulator (FDS), is invoked to assist in exploration and interpretation of the test results, and to evaluate model capabilities for this complex fire scenario. For simplicity, instead of modelling the complex pyrolysis and combustion of timber on a stick-by-stick basis, the entire wood cribs are represented in the FDS model as single objects. Thus ignition and burning are represented in a simplified manner at the scale of the individual crib faces, with idealised mass loss curves derived from measurements in selected rows. Though tied to empirical mass loss, the model is stretched in representing heavily under-ventilated conditions occurring in certain domains. Despite these simplifications and challenges the model does prove capable of representing the qualitative behaviours to a satisfactory level. In particular, with appropriate parameter choice for reaction-to-fire properties, the FDS models are able to represent the fire spread rates for the two distinct stages of the fire: the fire travelling from rear to the front of the compartment in search of oxygen; and the fire travelling back from the opening to the rear as fuel is consumed. The results suggest the potential value of such simplified representations of cribs in FDS for travelling fire scenarios.In the calibrated model, the magnitude of the thermocouple (TC) temperatures at three locations (ignition location, centre location, and opening location) shows generally good agreement between the FDS model and the test at the stage when the fire travels to the opening. However, significantly higher discrepancy appears at the stage when the fire travels back. In addition to the highly simplified representation of crib burning, another likely reason for the latter may be the malfunction of the mass loss measurement in several wood cribs at this stage, which led to significant uncertainties in prescribed burning rates. Another large source of uncertainty relates to residual heat in compartment boundaries and fuel embers, the latter not being easy to represent in CFD models. These results suggest avenues to explore in future model development.
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