EXPERIMENTAL STUDIES OF THE STRENGTH OF WOODEN GLUED BEAMS WITH WOOD DEFECTS
DOI:
https://doi.org/10.31649/2311-1429-2025-2-27-36Keywords:
конструкційні балки, клеєна деревина, вади деревини, шипове з’єднання, модуль пружності, міцність при згиніAbstract
The article investigates the influence of natural wood defects and imperfections in finger joints on the strength and modulus of elasticity of glued laminated timber beams of the strength class C24 (KVH). The relevance of the topic is due to the widespread use of such beams in modern construction as environmentally friendly, energy-efficient and durable load-bearing structures. The aim of the work was to determine the actual strength characteristics of KVH beams made of spruce wood at the production facilities of Milwood LLC, to evaluate the effectiveness of the current technological process, and to develop practical recommendations for its improvement.
The results of experimental tests of ten glued laminated timber beams samples for bending and determining the modulus of elasticity showed that, despite the generally high average strength values, there is significant variability in the results obtained. The coefficient of variation of the elastic modulus exceeded 10%, and the coefficient of variation of bending strength reached about 12%.
It has been established that the most critical defects leading to premature destruction of beams are the presence of knots (especially in the tension zone), the emergence of the core on the surface of the lumber, as well as insufficient gluing quality at the dowel joints. These factors often cause delamination or detachment along the glue joint, which significantly reduces the load-bearing capacity of the structure. In most cases, the onset of destruction of the glued laminated timber beams was observed precisely in areas with a concentration of defects or violations of the technological parameters of gluing.
The obtained results confirm the need to strengthen the quality control system for raw wood and production processes. In particular, it is recommended to improve the procedures for visual sorting of sawn timber, optimize cross-cutting to reduce the number of knots in critical areas, and improve the technology of glue application and the formation of adhesive joints between elements. The implementation of these measures will contribute to improving the uniformity of mechanical properties, reliability and durability of glued wooden structures.
References
A. Ya. Barashykov and V. M. Kolyakova, Budivelni konstruktsii: pidruchnyk. Kyiv: Slovo, 2011, 255 p.
D. Mykhailovskyi, M. Komar, T. Skliarova, and B. Bondarchuk, “Zastosuvannia kleienoi ta poperechno-kleienoi derevyny pry rekonstruktsii ta novomu budivnytstvi,” Budivelni konstruktsii. Teoriia i praktyka, no. 15, pp. 54–65, 2024.
C. O’Ceallaigh, K. Sikora, and A. M. Harte, “An experimental and numerical study of moisture transport and moisture-induced strain development in glued-laminated timber beams,” Maderas. Ciencia y tecnología, vol. 21, no. 4, pp. 555–570, 2019. DOI: https://doi.org/10.4067/S0718-221X2019005000411.
M. Fontana and A. Frangi, “Fire performance of timber structures under natural fire conditions,” Fire Safety Science, vol. 8, pp. 279–290, 2005. DOI: https://doi.org/10.3801/IAFSS.FSS.8-279.
R. Mirski, D. Dukarska, M. Wieruszewski, D. Dziurka, A. Trociński, and J. Kawalerczyk, “The effect of storage conditions on the strength of glulam beams,” Forests, vol. 14, no. 2, article 281, 2023. DOI: https://doi.org/10.3390/f14020281.
A. H. Buchanan, Structural Design for Fire Safety, 2nd ed. Chichester: Wiley, 2017, 437 p. DOI: https://doi.org/10.1002/9781118735844.
M. Tazarv, Z. Carnahan, and N. Wehbe, “Glulam timber bridges for local roads,” Engineering Structures, vol. 188, pp. 11–23, 2019. DOI: https://doi.org/10.1016/j.engstruct.2019.03.049.
M. A. Ritter, Timber Bridges: Design, Construction, Inspection, and Maintenance. Washington, D.C.: USDA Forest Service, 1990, 944 p.
H. Gu, Z. Luo, R. Bergman, M. Puettmann, and I. Ganguly, “Carbon impacts of engineered wood products in construction,” Forest Products Laboratory Research Paper FPL-RP-706, Madison, WI: USDA Forest Service, 2021, 24 p. DOI: https://doi.org/10.2737/FPL-RP-706.
P. Alaei and E. Frühwald, “A digital image correlation method for deformation and fracture analysis of structural timber,” Construction and Building Materials, vol. 291, article 123268, 2021. DOI: https://doi.org/10.1016/j.conbuildmat.2021.123268.
H. Yang, X. Zhang, and J. Liu, “Performance of glued joints in engineered timber under cyclic loading,” Engineering Structures, vol. 250, article 113486, 2022. DOI: https://doi.org/10.1016/j.engstruct.2021.113486.
L. Rossi, U. Müller, and M. Heeb, “Long-term durability of adhesive bonds in glulam structures,” Wood Science and Technology, vol. 57, no. 2, pp. 421–438, 2023. DOI: https://doi.org/10.1007/s00226-022-01413-9.
M. Udovytska, V. Mayevskyy, O. Udovytskyi, Z. Kopynets, and A. Manzyuk, “Development of mathematical model for predicting the cupping of lumber”, Bulletin of the Transilvania University of Brasov Series II: Forestry, Wood Industry, Agricultural Food Engineering, vol. 17(66), no. 2, pp. 111–126, 2024. DOI: https://doi.org/10.31926/but.fwiafe.2024.17.66.2.7.
S. V. Gayda, “A investigation of form of stability of variously designed blockboards made of post-consumer wood,” ProLigno, vol. 12, no. 1, pp. 22–31, 2016.
S. V. Gayda, “Research on physical and mechanical characteristics of front blockboards made from post-consumer wood [Дослідження фізико-механічних характеристик фасадних столярних плит із вживаної деревини],” Forestry, Forest, Paper and Woodworking Industry, vol. 42, pp. 33–50, 2016. DOI: https://doi.org/10.36930/42164206.
S. V. Gayda, “Strength of combined blockboard made of post-consumer wood (PCW),” Bulletin of KhNTUA, no. 197, pp. 3–9, 2018 (in Ukrainian).
EN 14080:2013. Timber Structures – Glued Laminated Timber and Glued Solid Timber – Requirements. Brussels: CEN, 2013, 88 p.
EN 14081-1+A1:2011. Timber Structures – Strength Graded Structural Timber with Rectangular Cross Section – Part 1: General Requirements. Brussels: CEN, 2011.
EN 15497:2014. Structural Finger Jointed Solid Timber – Performance Requirements and Minimum Production Requirements. Brussels: CEN, 2014.
EN 16351:2021. Timber Structures – Cross Laminated Timber – Requirements. Brussels: CEN, 2021, 68 p.
DBN V.2.6-161:2017. Derev’iani konstruktsii. Osnovni polozhennia. Kyiv: Ukrarkhbudinform, 2017, 111 p.
DBN V.2.6-161:2010. Konstruktsii budynkiv i sporud. Derev’iani konstruktsii. Osnovni polozhennia. Kyiv: Ukrarkhbudinform, 2011, 102 p.
DSTU EN 338:2016. Konstruktsiina derevyna – klasy mitsnosti. Vyznachennia kharakterystychnykh znachen mekhanichnykh vlastyvostei. Kyiv: DP “UkrNDNTs,” 2016, 15 p.
EN 1995-2: Eurocode 5: Design of timber structures – Part 2: Bridges. EN 1995-2:2004, Nov. 2004.
EN 301:2022. Phenolic and Aminoplastic Adhesives for Load-bearing Timber Structures. Classification and Performance Requirements. Brussels: CEN, 2022.
EN 302-3:2023. Adhesives for Load-bearing Timber Structures – Test Methods – Part 3: Determination of the Effect of Acid Damage to Wood Fibres by Temperature and Humidity Cycling on the Transverse Tensile Strength. Brussels: CEN, 2023.
EN 16254:2023. Adhesives – Emulsion Polymer Isocyanate (EPI) for Load-bearing Timber Structures – Classification and Performance Requirements. Brussels: CEN, 2023.
Downloads
-
pdf (Українська)
Downloads: 33
