Abstract
Medium dense hardwoods (HWs) show higher tensile strength (TS) values than softwoods (SWs). These advantages cannot be utilised effectively because HW grading is not well developed. The aim of the present paper was to analyse the utilisation potential of European ash (Fraxinus spp.) and maple (Acer spp.) grown in Central Europe, which were graded by different methods. The visual grading characteristics of 869 HW boards were determined and the dynamic modulus of elasticity (MOEdyn) and X-ray attenuation (XRA) were measured by an industrial scanner. The specimens were subsequently tested in tension according to EN 408:2010 and according to German visual grading rules show strength values of 28 MPa and 30 MPa, respectively. Machine strength grading and for a combination of manually assessed boards and MOEdyn give rise to higher strength data. MOEdyn, in particular, results in lamella data with 62 MPa for ash and 42 MPa for maple. There is good agreement with recently presented HW tensile profiles. Machine grading with a multisensor system allows better strength prediction compared to the MOEdyn or visual strength grading. Best performance is achieved by a combined grading approach.
Funding source: German Federal Ministry of Food and Agriculture (BMEL)
Award Identifier / Grant number: FKZ 22011913
Funding statement: This research was supported by the German Federal Ministry of Food and Agriculture (BMEL); Funder Id: 10.13039/501100005908, grant no.: FKZ 22011913.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Employment or leadership: None declared.
Honorarium: None declared.
References
Aicher, S., Reinhardt, H.-W. (2007) Delaminierungseigenschaften und Scherfestigkeiten von verklebten rotkernigen Buchenholzlamellen [Delamination properties and shear strength of glued beech wood laminations with red heartwood]. Eur. J. Wood Prod. 65:125–136.10.1007/s00107-006-0135-7Search in Google Scholar
Aicher, S., Stapf, G. (2014) Glulam from European white oak: finger joint influence on bending size effect. In: Materials and Joints in Timber Structures. Recent Developments of Technology; RILEM Book series, Vol. 9. Eds. Aicher, S., Reinhardt, H.-W., Garrecht, H. Springer, Dordrecht, The Netherlands. pp. 641–656.10.1007/978-94-007-7811-5_58Search in Google Scholar
Aicher, S., Christian, Z., Dill-Langer, G. (2014) Hardwood Glulams – Emerging Timber Products of Superior Mechanical Properties. In: Proceeding of WCTE 2014, Quebec City, Canada. August 10–14.Search in Google Scholar
Ammann, S., Schlegel, S., Beyer, M., Aehlig, K., Lehmann, M., Jung, H., Niemz, P. (2016) Quality assessment of glued ash wood for construction engineering. Eur. J. Wood Prod. 74:67–74.10.1007/s00107-015-0981-2Search in Google Scholar
Bacher, M. (2008) Comparison of different machine strength grading principles. In: Proceedings of Conference COST E53, 29–30 October, Delft, The Netherlands.Search in Google Scholar
Bundesministerium für Ernährung und Landwirtschaft (BMEL). (2015) Der Wald in Deutschland – Ausgewählte Ergebnisse der dritten Bundeswaldinventur [The Forests in Germany – Selected Results of the Third National Forest Inventory]. BMEL, Bonn, Germany.Search in Google Scholar
Deb, K., Pratap, A., Agarwal, S., Meyarivan, T. (2002) A fast and elitist multiobjective genetic algorithm: NSGA-II. IEEE Trans. Evolut. Computat. 6:182–197.10.1109/4235.996017Search in Google Scholar
Denzler, J., Diebold, R., Glos, P. (2015) Machine strength grading – commercially used grading machines – current developments. In: Proceedings of the 14th International Symposium on Nondestructive Testing of Wood, Hannover, Germany. pp. 9–16.Search in Google Scholar
DIN 4074-5. (2008) Strength grading of wood – Part 5: Sawn hardwood. DIN, Berlin.Search in Google Scholar
Ehrhart, T., Fink, G., Steiger, R., Frangi, A. (2016a) Experimental investigation of tensile strength and stiffness indicators regarding European beech timber. In: Proceeding of WCTE 2016, Vienna, Austria. August 23–25. TU Verlag, Vienna.Search in Google Scholar
Ehrhart, T., Fink, G., Steiger, R., Frangi, A. (2016b) Strength grading of European beech lamellas for the production of GLT and CLT. In: Proceedings of 49th INTER and CIB Meeting, Graz, Austria.Search in Google Scholar
EN 13183-1. (2002) Moisture contentof a piece of sawn timber – Part 1: Determination by oven dry method. CEN European Committee for Standardization, Brussels.Search in Google Scholar
EN 408. (2010) Timber structures – structural timber and glued laminated timber – determination of some physical and mechanical properties. CEN European Committee for Standardization, Brussels.Search in Google Scholar
EN 14358. (2016) Timber structures – calculation of characteristic 5-percentile and mean values for the purpose of initial type testing and factory production control. CEN European Committee for Standardization, Brussels.Search in Google Scholar
EN 338. (2016) Structural timber – Strength classes. CEN European Committee for Standardization, Brussels.Search in Google Scholar
EN 384. (2016) Structural timber – Determination of characteristic values of mechanical properties and density. CEN European Committee for Standardization, Brussels.Search in Google Scholar
FprEN 14081-2. (2017) Timber structures – Strength graded structural timber with rectangular cross section – Part 2: Machine grading; additional requirements for initial type testing. CEN European Committee for Standardization, Brussels.Search in Google Scholar
Frese, M., Blaß, H.J. (2007) Characteristic bending strength of beech glulam. Mater. Struct. 40:3–13.10.1617/s11527-006-9117-9Search in Google Scholar
Frühwald, K., Schickhofer, G. (2005) Strength grading of hardwoods. 14th International Symposium on Nondestructive Testing of Wood, Hannover. pp. 198–210.Search in Google Scholar
Giudiceandrea, F. (2005) Stress grading lumber by a combination of vibration stress waves and X-ray scanning. In: 11th International Conference on Scanning Technology and Process Optimization in the Wood Industry (ScanTech 2005), Las Vegas, NV, USA. pp. 99–108.Search in Google Scholar
Glos, P., Lederer, B. (2000) Sortierung von Buchen- und Eichenschnittholz nach der Tragfähigkeit und Bestimmung der zugehörigen Festigkeits- und Steifigkeitskennwerte [Strength grading of beech and oak timber and derivation of strength and stiffness property values]. Report Nr. 98508. TU München, München, 125 pp.Search in Google Scholar
Glos, P., Torno, S. (2008) Allocation of domestic maple, ash and poplar species into the European Standard EN 1912 Structural timber – strength classes – assignment of visual grades and species. (in German.) 06517_B. TU München, München.Search in Google Scholar
Green, D.W., McDonald, K.A. (1993) Mechanical properties of red maple structural lumber. Wood Fibre Sci. 25:365–374.Search in Google Scholar
Hübner, U. (2013) Mechanische Kenngrößen von Buchen-, Eschen- und Robinienholz für lastabtragende Bauteile: Dissertation. Technische Universität Graz, 424 pp.Search in Google Scholar
Janowiak, J.J., Manbeck, H.B., Hernandez, R.H., Moody, R.C. (1997) Red maple lumber resources for glue-laminated timber beams. Forest Prod. J. 47:55–64.Search in Google Scholar
Jeitler, G., Augustin, M., Schickhofer, G. (2016) BIRCH | GLT&CLT: mechanical properties of glued laminated timber and cross laminated timber produced with the wood species birch. In: Proceeding of WCTE 2016, Vienna, Austria. August 23–25. TU Verlag, Vienna.Search in Google Scholar
Knorz, M., Schmidt, M., Torno, S., van de Kuilen, J.-W. (2014) Structural bonding of ash (Fraxinus excelsior L.): resistance to delamination and performance in shearing tests. Eur. J. Wood Prod. 72:297–309.10.1007/s00107-014-0778-8Search in Google Scholar
Kolling, C. (2007) Klimmahüllen für 27 Waldbaumarten [Climate shells for 27 forest tree specimens]. AFZ-DerWald: 1242–1245.Search in Google Scholar
Kollmann, F.F.P., Côté, W.A. Principles of Wood Science and Technology: I. Solid wood. Springer-Verlag, Berlin, 1968.10.1007/978-3-642-87928-9Search in Google Scholar
Konak, A., David, W.C., Alice, E.S. (2006) Multi-objective optimization using genetic algorithms: A tutorial. Reliab. Eng. Sys. Safe. 91:992–1007.10.1016/j.ress.2005.11.018Search in Google Scholar
Konnerth, J., Kluge, M., Schweizer, G., Miljković, M., Gindl-Altmutter, W. (2016) Survey of selected adhesive bonding properties of nine European softwood and hardwood species. Eur. J. Wood Prod. 74:809–819.10.1007/s00107-016-1087-1Search in Google Scholar
Kovryga, A., Stapel, P., van de Kuilen, J.W.G. (2016a) Optimizing characteristic properties of visually graded soft- and hardwoods lamellas for the glulam production. In: Proceeding of WCTE 2016, Vienna, Austria. August 23–25. TU Verlag, Vienna.Search in Google Scholar
Kovryga, A., Stapel, P., van de Kuilen, J.W.G. (2016b) Tensile strength classes for hardwoods. In: Proceedings of 49th INTER and CIB Meeting, Graz, Austria.Search in Google Scholar
Kretschmann, D.E., Green, D.W. (1999) Mechanical grading of oak timbers. J. Mater. Civ. Eng. 11:91–97.10.1061/(ASCE)0899-1561(1999)11:2(91)Search in Google Scholar
Luedtke, J., Amen, C., van Ofen, A., Lehringer, C. (2015) 1C-PUR-bonded hardwoods for engineered wood products: influence of selected processing parameters. Eur. J. Wood Prod. 73:167–178.10.1007/s00107-014-0875-8Search in Google Scholar
Manbeck, H.B., Janowiak, J.J., Blankenhorn, P.R., Labosky, P., Moody, R.C., Hernandez, R. (1993) Performance of red maple glulam timber beams. Res. Pap. FPL-RP-519. U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, WI, 33 pp.Search in Google Scholar
Nocetti, M., Bacher, M., Brunetti, M., Crivellaro, A., van de Kuilen, J.W.G. (2010) Machine grading of Italian structural timber: preliminary results on different wood species. In: Proceeding of WCTE 2010, Riva del Garda, Trento, Italy. June 20–24.Search in Google Scholar
Nocetti, M., Brunetti, M., Bacher, M. (2016) Efficiency of the machine grading of chestnut structural timber: prediction of strength classes by dry and wet measurements. Mater. Struct. 49:4439–4450.10.1617/s11527-016-0799-3Search in Google Scholar
Nocetti, M., Pröller, M., Brunetti, M., Dowse, G., Wessels, C. (2017) Investigating the potential of strength grading green Eucalyptus grandis lumber using multi-sensor technology.BioResources 12:9273–9286.10.15376/biores.12.4.9273-9286Search in Google Scholar
Oliver-Villanueva, J.-V., Quer, M., Becker, G. (1996) Influence of structural parameters on the nondestructive evaluation of ash timber (Fraxinus excelsior L.) Eur. J. Wood Prod. 54:109–112.10.1007/s001070050148Search in Google Scholar
Ravenshorst, G.J.P. Species independent strength grading of structural timber. Technische Universiteit Delft, Delft, 2015.Search in Google Scholar
Schmidt, M., Glos, P., Wegener, G. (2010) Verklebung von Buchenholz für tragende Holzbauteile. Eur. J. Wood Prod. 68:43–57.10.1007/s00107-009-0382-5Search in Google Scholar
Schmidt, M., Thönnißen, A., Knorz, M., Windeisen, E., Wegener, G. (2012) Relevant wood characteristics for gluing beech and ash with regard to discoloration. Eur. J. Wood Prod. 70:319–325.10.1007/s00107-011-0555-xSearch in Google Scholar
Stapel, P., van de Kuilen, J.-W.G. (2014) Influence of cross-section and knot assessment on the strength of visually graded Norway spruce. Eur. J. Wood Prod. 72:213–227.10.1007/s00107-013-0771-7Search in Google Scholar
Torno, S., Knorz, M., van de Kuilen, J.W.G. (2013) Supply of beech lamellas for the production of glued laminated timber. In: 4th International Scientific Conference on Hardwood Processing (ISCHP), Florence, Italy.Search in Google Scholar
van de Kuilen, J.-W.G., Torno, S. (2014) Material properties of ash for application in glulam. (in German.) TU München, Munich, 82 pp.Search in Google Scholar
Vega, A., Dieste, A., Guaita, M., Majada, J., Baño, V. (2012) Modelling of the mechanical properties of Castanea sativa Mill. structural timber by a combination of non-destructive variables and visual grading parameters. Eur. J. Wood Prod. 70:839–844.10.1007/s00107-012-0626-7Search in Google Scholar
von Wedel, K. (1966) Bohrspanuntersuchungen über das Gewicht des Bergahorn und des Spitzahornholzes [Investigations on the weight of increment cores from sycamore and norway maple]. Eur. J. Wood Prod. 24:329–338.10.1007/BF02619213Search in Google Scholar
Z-9.1-679. (2013) German technical building approval issued by DIBt for “Glulam from beech wood and beech hybrid glulam beams” (in German), approval issued first on 07. Oct. 2009; approval holder: Studiengemeinschaft Holzleimbau e. V., Germany. Issued by Deutsches Institut für Bautechnik (DIBt), Germany.Search in Google Scholar
Supplementary Material
The online version of this article offers supplementary material (https://doi.org/10.1515/hf-2018-0142).
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Articles in the same Issue
- Frontmatter
- Original Articles
- Influence of tree height on the hydrophilic and lipophilic composition of bark extracts from Eucalyptus globulus and Eucalyptus nitens
- Modelling the viscoelastic mechanosorptive behaviour of Norway spruce under long-term compression perpendicular to the grain
- Frequency-dependent viscoelastic properties of Chinese fir (Cunninghamia lanceolata) under hygrothermal conditions. Part 1: moisture adsorption
- Frequency-dependent viscoelastic properties of Chinese fir (Cunninghamia lanceolata) under hygrothermal conditions. Part 2: moisture desorption
- Evolution of extractive composition in thermally modified Scots pine during artificial weathering
- Dynamic mechanical analysis (DMA) at room temperature of archaeological wood treated with various consolidants
- Visual and machine strength grading of European ash and maple for glulam application
- Evaluation of bond strength of cross-laminated LSL specimens under short-span bending