Experimental Investigation of Fire Resistance of GLT Beams

Experimental Investigation of Fire Resistance of GLT Beams

L. Kucíková T. Janda M. Šejnoha J. Sýkora

Department of Mechanics, Czech Technical University in Prague, Czech Republic

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| Citation



Mechanical and fire loading play together with geometric and material properties of glued laminated timber beams a decisive role in theoretical investigation into the time-dependent fire resistance of these elements. This is a multidisciplinary problem including heat conduction, water evaporation, internal gas pressure evolution, pyrolysis, volume change, etc. If properly calibrated, such complex models should allow us to forecast the evolution and shape of the charred or zero strength layer. It is doubtless that the calibration and validation steps require experiments. In particular, the results of large-scale fire experiment are discussed in this contribution focusing on the influence of fire intensity and duration on the temperature and the charred layer evolution. The influence of fire on stiffness and strength will also be addressed through the results of Pilodyn measurements of wood elastic modulus and three-point bending tests of original and fire-exposed beams.


charred layer, fire curve, GLT beam, residual-bearing capacity


[1] Esteves, B.M. & Pereira, H.M., Wood modification by heat treatment: A review.BioResources,4(1), pp. 370–404, 2009.

[2] Kačíková, D., Kačík, F., Čabalová, I. & Ďurkovič, J., Effects of thermal treatment onchemical, mechanical and colour traits in Norway spruce wood. Bioresource Technology,144, pp. 669–674, 2013. https://doi.org/10.1016/j.biortech.2013.06.110

[3] Winandy, J.E. & Rowell, R.M., Chemistry of wood strength. Handbook of WoodChemistryand Wood Composites, ed. R.M. Rowell, CRC press: Boca Raton, Florida,pp. 303–347, 2005.

[4] Buchanan, A.H. & Abu, A.K., Structural Design for Fire Safety, 2nd ed. John Wiley &Sons Inc.: United Kingdom, 2017.

[5] Yildiz, S., Gezer, E.D. & Yildiz, U.C., Mechanical and chemical behavior of sprucewood modified by heat. Building and Environment, 41(12), pp. 1762–1766, 2006.https://doi.org/10.1016/j.buildenv.2005.07.017

[6] Dietenberger, M. & Hasburgh, L., Wood products thermal degradation and fire.ReferenceModule in Materials Science and Materials Engineering, pp. 1–8, 2016.

[7] Lineham, S.A., Thomson, D., Bartlett, A.I., Bisby, L.A. & Hadden, R.M., Structuralresponse of fire-exposed cross-laminated timber beams under sustained loads. FireSafety Journal, 85, pp. 23–34, 2016. https://doi.org/10.1016/j.firesaf.2016.08.002

[8] Friquin, K.L., Material properties and external factors influencing the charring rate ofsolid wood and glue-laminated timber. Fire and Materials, 35(5), pp. 303–327, 2011.https://doi.org/10.1002/fam.1055

[9] Pozzobon, V., Salvador, S., Bézian, J.J., El-Hafi, M., Le Maoult, Y. & Flamant, G.,Radiative pyrolysis of wet wood under intermediate heat flux: Experiments and modelling.Fuel Processing Technology, 128, pp. 319–330, 2014. https://doi.org/10.1016/j.fuproc.2014.07.007

[10] Lange, D., Boström, L., Schmid, J. & Albrektsson, J., The Influence of ParametricFire Scenarios on Structural Timber Performance and Reliability. Technical report, SPTechnical Research Institute of Sweden, 2014.

[11] European Committee for Standardization, E.C., Eurocode 5: Design of Timber Structures- Part 1-2: General -Structural Fire Design, 2004.

[12] Thi, V.D., Khelifa, M., Oudjene, M., El Ganaoui, M. & Rogaume, Y., Finite elementanalysis of heat transfer through timber elements exposed to fire. Engineering Structures,143, pp. 11–21, 2017. https://doi.org/10.1016/j.engstruct.2017.04.014

[13] Štemberk, T., Application of Wood in Modern Architecture. Diploma thesis, Universityof West Bohemia, p. 129 (in Czech), 2018.

[14] Šejnoha, M., Janda, T., Melzerová, L., Nežerka, V. & Šejnoha, J., Modeling glulams inlinear range with parameters updated using Bayesian inference. Engineering Structures,138, pp. 293–307, 2017. https://doi.org/10.1016/j.engstruct.2017.02.021

[15] Lautenberger, C. & Fernandez-Pello, C., Generalized pyrolysis model for combustiblesolids. Fire Safety Journal, 44(6), pp. 819–839, 2009. https://doi.org/10.1016/j.firesaf.2009.03.011

[16] Moghtaderi, B., The state-of-the-art in pyrolysis modelling of lignocellulosic solidfuels. Fire and Materials, 30(1), pp. 1–34, 2006. https://doi.org/10.1002/fam.891

[17] Shi, L. & Chew, M.Y.L., A review of fire processes modeling of combustible materialsunder external heat flux. Fuel, 106, pp. 30–50, 2013. https://doi.org/10.1016/j.fuel.2012.12.057

[18] Kung, H.C., A mathematical model of wood pyrolysis. Combustion and Flame, 18(2),pp. 185–195, 1972. https://doi.org/10.1016/s0010-2180(72)80134-2