Evaluation of bending performance for cross laminated timber (CLT) made out of poplar (Populus alba)

Document Type : Research Paper


1 PhD student, Department of Wood and Paper Science and Technology, College of Natural Resources, University of Tehran, Karaj, Iran

2 Assistant Prof., Department of Wood and Paper Science and Technology, College of Natural Resources, University of Tehran, Karaj, Iran

3 Professor, Department of Wood and Paper Science and Technology, College of Natural Resources, University of Tehran, Karaj, Iran


Bending strength is a critical property of cross laminated timber (CLT) in structural applications, especially in floor of multi-story buildings. Therefore, this study was targeted to evaluate bending strength of CLT made out of poplar (populous alba). Polyurethane adhesive was used for constructing of CLT (300 g/m2). The thickness of planks was used in this study was 16 mm. The results have indicated that modulus of rupture (MOR) and modulus of elasticity (MOE) of CLT with 45o alternating transverse layer were increased 14 and 15%, respectively in comparison with 90o layers. Also, modulus of rupture (MOR) and modulus of elasticity (MOE) of CLT consist of layers with 4cm in width were increased 14 and 5%, respectively in comparison with layers 9cm in width. The results concluded that by layers with lower width, and also 45o alternating layer configuration could be constructed CLT from fast growing trees such as poplar with a considerable bending strength.


[1] Mohammad, M., Gagnon, S., Douglas, B.and Podesto, L., 2012. Introduction to cross laminated timber. Wood Design Focus, 22(2): 3-12.
[2] Gagnon, S., Pirvu, C., 2011. CLT handbook: cross-laminated timber. FPInnovations Québec.
[3] Association, A.T.E.W., 2012. Standard for performance-rated cross laminated timber. ANSI/APA PRG, 320.
[4] Robertson, A.B., 2011. A comparative life cycle assessment of mid-rise office building construction alternatives: laminated timber or reinforced concrete, MSc thesis, University of British Columbia.
[5] Harrison, S.K.and Hindman, D.P., 2007. Test method comparison of shear modulus evaluation of MSR and SCL products. Forest products journal, 57(7/8): 32-38.
[6] Kim, H. K., Oh, J. K., Jeong, G. Y., Yeo, H. M.and Lee, J. J., 2013. Shear performance of PUR adhesive in cross laminating of red pine. Journal of the Korean Wood Science and Technology, 41(2): 158-163.
[7] Park, H. M., Fushitani, M., Sato, K., Kubo, T.and Byeon, H. S., 2003. Static bending strength performances of cross-laminated woods made with five species. Journal of wood science, 49(5): 411-417.
[8] Buck, D., Wang, X.A., Hagman, O.and Gustafsson, A., 2016. Bending Properties of Cross Laminated Timber (CLT) with a 45° Alternating Layer Configuration. BioResources, 11(2): 4633-4644.
[9] Mohamadzadeh, M.and Hindman, D., 2015. Mechanical Performance of Yellow-Poplar Cross Laminated Timber, Virginia Polytechnic Institute And State University, Department of Civil and Environmental Engineering, Blacksburg, Report No. CE/VPI-ST-15-13.
[10] Kramer, A., Barbosa, A.R., Sinha, A., 2013. Viability of hybrid poplar in ANSI approved cross-laminated timber applications. Journal of Materials in Civil Engineering, 26(7): 1-5.
[11] Dinwoodie, J. M., 2002. Timber: its nature and behaviour. CRC Press.
[12] American Society for Testing and Materials., 1999a. “D 143-94: Standard Methods of Testing Small Clear Specimens of Timber,” in 1999 Annual Book of ASTM Standards, Section 4, Vol. 04.10: Wood.
[13] Hochreiner, G., Füssl, J., Eberhardsteiner, J.and Aicher, S., 2014. CLT plates under concentrated loading–Experimental identification of crack modes and corresponding failure mechanisms, Materials and Joints in Timber Structures. Springer, RILEM Bookseries 9: 703-712.
[14] Zhou, Q., 2013. Development of evaluation methodology for rolling shear properties in Cross Laminated Timber (CLT), MSc thesis. University of New Brunswick, Fredericton, NB.
[15] Zhou, Q., Gong, M., Chui, Y.H.and Mohammad, M., 2014. Measurement of rolling shear modulus and strength of cross-laminated timber fabricated with black spruce. Construction and Building Materials, 64: 379-386.
[16] Li, M., Lam, F.and Li, Y., 2014. Evaluating rolling shear strength properties of cross laminated timber by torsional shear tests and bending tests. World Conference In Timber Engineering, 10(18.5): 280.
[17] Ebrahimi, Gh., 2013. Mechanics of wood and wood composites, 4th Ed., University of Tehran, 657 p.
(In Persian).