Beech sawn timber for structural use: A case study for mechanical characterization and optimization of the Italian visual strength grading rule
D. Cibecchini, A. Cavalli, G. Goli, M. Tognihttps://doi.org/10.17221/93/2016-JFSCitation:Cibecchini D., Cavalli A., Goli G., Togni M. (2016): Beech sawn timber for structural use: A case study for mechanical characterization and optimization of the Italian visual strength grading rule. J. For. Sci., 62: 521-528.
The potential use of beech (Fagus sylvatica Linnaeus) sawn timber for structures has been investigated. Beech stands in transition from coppice to high forest after thinning interventions have been sampled from different Italian sources. A sample of 160 beams of two different cross sections was extracted and tested, according to the normalized procedures for the characterization of wood for structures. The specimens were visually graded considering the strength relevant defects, according to the Italian standard. To determine the mechanical properties of the timber (namely strength and stiffness), four-point bending tests were performed and the main characteristic values were derived. The results of the study reveal that knot ratio was the principal defect that influenced both resistance and yields. The potential strength class D30 was achieved with the resulting characteristic values, although, due to the small number of samples tested, the reached class could not be formally assigned. To improve the effectiveness of the grading rule in the Italian standard, some modifications and a new grade were proposed for the beech sawn timber. Finally the D40 strength class could be theoretically reached, but with reduced yields.Keywords:
Fagus sylvatica; grade; modulus of elasticity; modulus of rupture; strength class; strength determining defectReferences:
Aicher Simon, Ohnesorge Denny (2011): Shear strength of glued laminated timber made from European beech timber. European Journal of Wood and Wood Products, 69, 143-154 https://doi.org/10.1007/s00107-009-0399-9Aicher S., Christian Z., Dill-Langer G. (2013): Hardwood glulams – emerging timber products of superior mechanical properties. In: Salenikovich A. (ed.): Proceedings of World Conference on Timber Engineering, Quebec City, Aug 10–14, 2014: 1–10.Bonamini G., Togni M. (1999): Classificazione secondo la resistenza e determinazione dei valori caratteristici. In: Il legno di Castagno e di Douglasia della Toscana. Florence, ARSIA: 41–62.Bouriaud O., Br�da N., Le Mogu�dec G., Nepveu G. (2004): Modelling variability of wood density in beech as affected by ring age, radial growth and climate. Trees - Structure and Function, 18, 264-276 https://doi.org/10.1007/s00468-003-0303-xBrunetti Michele, Nocetti Michela, Burato Paolo (2013): Strength Properties of Chestnut Structural Timber with Wane. Advanced Materials Research, 778, 377-384 https://doi.org/10.4028/www.scientific.net/AMR.778.377Frese M., Blass H.J. (2005): Beech glulam strength classes. In: Proceeding of 38th Meeting of the International Council for Research and Innovation in Building and Construction. Working Commission W18 – Timber Structures, Karlsruhe, Aug 28–31, 2005: 1–10.Frühwald A., Ressel J., Bernasconi A., Becker P., Pitzner B., Wonneman R., Mantau U., Sörgel C., Thoroe C., Dieter M., Englert H. (2003): Hochwertiges Brettschichtholz aus Buchenholz. Hamburg, Bundesforschungsanstalt für Forst- und Holzwirtschaft: 198.Frühwald K. (2008): Procedure for determination of characteristic values of hardwood. Available at http://www.coste53.net/downloads/Oslo/Oslo-WG3/COSTE53-MeetingOslo-WG3-Fruehwald.pdf (accessed July 14, 2016).Frühwald K., Schickhofer G. (2004): Strength grading of hardwoods. In: Ranta-Maunus A., Toratti T. (eds): Proceedings of the 8th World Conference on Timber Engineering, Lahti, June 14–17, 2004: 675–679.Giordano G. (1981): Tecnologia del legno. Vol. 1. Torino, Unione Tipografico-Editrice Torinese: 853.Knorz M., van de Kuilen J.W. (2012): Development of a high-capacity engineered wood product – LVL made of European beech (Fagus sylvatica L.). In: Quenneville P. (ed.): Proceeding of the 12th World Conference on Timber Engineering, Auckland, July 15–19, 2012: 487–495.Lagaňa R., Babiak M. (2012): Quality of beech standing trees related to properties of structural timber. In: Yan I., Liu H. (eds): Proceedings of the 55th International Convention of Society of Wood Science and Technology, Beijing, Aug 27–31, 2012: 1–6.Lagaňa R., Rohanová A. (2011): Characteristics values of beech timber for potential construction applications. Annals of Warsaw University of Life Sciences – SGGW. Forestry and Wood Technology, 75: 26–29.Lo Monaco A, Calienno L, Pelosi C, Balletti F, Agresti G, Picchio R (): Technical properties of beech wood from aged coppices in central Italy. iForest - Biogeosciences and Forestry, , e1-e7 https://doi.org/10.3832/ifor1136-007Ohnesorge Denny, Richter Klaus, Becker Gero (2010): Influence of wood properties and bonding parameters on bond durability of European Beech (Fagus sylvatica L.) glulams. Annals of Forest Science, 67, 601-601 https://doi.org/10.1051/forest/2010002Ranta-Maunus A. (1999): Round Small-diameter Timber for Construction. Espoo, VTT Technical Research Centre of Finland, Ltd.: 210.Togni Marco, Cavalli Alberto, Mannozzi Davide (2013): Chestnut: from coppice to structural timber. The case study of "Uso Fiume" beams sampled in Liguria. Journal of Agricultural Engineering, 44, - https://doi.org/10.4081/jae.2013.241Widmann Robert, Fernandez-Cabo José L., Steiger René (2012): Mechanical properties of thermally modified beech timber for structural purposes. European Journal of Wood and Wood Products, 70, 775-784 https://doi.org/10.1007/s00107-012-0615-x