A novel approach to determine charring of wood in natural fire implemented in a coupled heat-mass-pyrolysis model

Pečenko, Robert; Hozjan, Tomaž

doi:10.1515/hf-2020-0081

Cited by 7 publications

(2 citation statements)

References 41 publications

(67 reference statements)

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“…The comparison of the obtained modeling results showed an accuracy of more 90%. The temperature curves from the simulations also faithfully simulated the se with a constant temperature at 100 °C, which Regueira and Guaito [22], Pecenko, Sven and Hozjan [43] simulated only partially. The results of Martínez et al [45] did not s late this range at all.…”

Section: Discussionmentioning

confidence: 57%

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Determining the Charred Layer of Wooden Beams with Finite Element Analysis Based on Enthalpy Approach

et al. 2022

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In the process of computer modeling the formation of a charred layer in wood materials, it is important to implement the correct material data. In thermal analysis, there exist two different approaches of implementation: the temperature-dependent material data properties, heat capacity approach and enthalpy approach, which is not commonly used but which has a few advantages. This approach should be examined in more detail because it can solve the problem associated with inaccurate results at temperatures around 100 °C. This scientific paper deals with the assessment of the computer-aided fire modeling and simulation suitability based on the enthalpy approach for determining the charred layer of structural elements. The structural elements selected for testing were spruce wooden beams with rectangular and circular cross-sections. A finite element model (FEM) was created in ANSYS software. The model was validated by medium-scale fire tests data of the spruce wooden beams loaded with a radiation panel. Boundary conditions were identical to the medium-scale fire test. Due to the enthalpy approach, the temperature curves from the simulations also faithfully simulated the section with a constant temperature around 100 °C. Within the temperature profiles, the accuracy of simulations averaged 91.7%. The accuracy of the simulations describing the total area of the charred layer was 93.0% on average. Presented FEM can be used in the search for new construction solutions for wooden elements and modifications to the design of cross-sections of wooden beams or wooden joints so that they can better withstand fire conditions.

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Section: Discussionmentioning

confidence: 57%

“…Pecenko Svensson and Hozjan [43,44] presented a new numerical model named PyCiF for determining the charring of wood exposed to standard and natural fire. The new model couples an advanced 2D heat-mass model with a pyrolysis model.…”

Section: Introductionmentioning

confidence: 99%

Determining the Charred Layer of Wooden Beams with Finite Element Analysis Based on Enthalpy Approach

et al. 2022

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Thickness of zero-strength layer in timber beam exposed to fuel-controlled parametric fires

2023

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Fire resistance is one of the essential requirements to be fulfilled in the design of timber structures. For this purpose, a reduced cross-section method is given in the European standards, Eurocodes. The method is based on the assumption that an initial, rectangular timber cross-section exposed to fire conditions reduces to an effective cross-section, which has material properties as at a room temperature. The reduced part of the cross-section with no resistance is determined by a sum of two parameters, namely a charring depth and a thickness of zero-strength layer. Eurocodes give a value of the latter only for the standard fire exposure, which is only one of the fire curves proposed in the same standards. Therefore, the present paper examines the thickness of zero-strength layer in case of 46 different fuel-controlled parametric fire exposures applied to a timber beam from three sides. A four-phase numerical analysis is applied for this purpose that includes the use of a hygro-thermal model and a mechanical model to determine temperatures of timber over the cross-section and the mechanical resistance of timber beam in fire conditions, respectively. The results show that the thickness of zero-strength layer takes the values between 7.9 and 18.4 mm for the fuel-controlled parametric fire exposures. Since it is clearly dependent on the parameters describing the parametric fire curve, five equations are proposed that can be used for determination of the thickness of zero-strength layer in case of parametric fire exposures.

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Scale modeling of thermo-structural fire tests of multi-orientation wood laminates

Gangi,

Lattimer,

Case

2024

Wood Sci Technol

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The stacking sequence of laminated wood significantly impacts the composite mechanical behavior of the material, especially when scaling down thermo-mechanical tests on plywood. In previous research, we developed a scaling methodology for thermo-structural tests on samples with similar cross sections, however this paper focused on testing plywood samples with different stacking sequences between the scales. Plywood samples at ½-scale and ¼-scale were subjected to combined bending and thermal loading, with the loading scaled to have the same initial static bending stresses. While the ¼-scale 4-layer [0°/90°]s laminate and the ½-scale 8-layer [0°/90°/90°/0°]s laminate had an equal number of 0° and 90° layers, as the char front progresses, the sections behave differently. Thus, modeling becomes essential to extrapolating the data from the smaller ¼-scale test to predict the behavior of the larger ½-scale test. Reduced cross-sectional area models (RCAM) incorporating classical laminated plate theory were used to predict the mechanical response of the composite samples as the char front increased. Three methods were proposed for calibrating the RCAM models: Fourier number scaling, from detailed kinetics-based pyrolysis GPyro models, and fitting to data from fire exposure thermal response tests. The models calibrated with the experimental char measurements produced the most accurate predictions. The experimental char models validated to predict the behavior of the ¼-scale tests within 2.5%, were then able to predict the ½-scale test behavior within 4.5%.

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A novel approach to determine charring of wood in natural fire implemented in a coupled heat-mass-pyrolysis model

Cited by 7 publications

References 41 publications

Determining the Charred Layer of Wooden Beams with Finite Element Analysis Based on Enthalpy Approach

Determining the Charred Layer of Wooden Beams with Finite Element Analysis Based on Enthalpy Approach

Thickness of zero-strength layer in timber beam exposed to fuel-controlled parametric fires

Scale modeling of thermo-structural fire tests of multi-orientation wood laminates

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