Skip to main content
SpringerLink
Log in

Strength grading of Norway spruce structural timber: revisiting property relationships used in EN 338 classification system

  • Original
  • Published:
Wood Science and Technology Aims and scope Submit manuscript

Abstract

Solid timber for structural applications has to be strength graded prior to its use. In order to remain economic the grading process usually focuses on the most important physical and mechanical properties: density, modulus of elasticity (MOE) and bending strength. Based on respective limits given in standards, the timber is assigned to strength classes. Additional mechanical properties such as tensile and compression strength parallel to the grain are derived from the basic property values by empirical relationships. The objective of this study was to review some of these property relationships based on recently compiled large data sets as a contribution for a future revision of the grading standards. Based on mechanical tests of Norway spruce structural timber with different cross-sections, the following characteristic values and property relationships were evaluated: (a) strength and MOE in bending, (b) in-grade characteristic values of bending strength, bending MOE and density, (c) relationship of characteristic values of tension and compression strength parallel to the grain with respect to the corresponding characteristic value of bending strength, (d) ratio of fifth percentiles and mean values of density and MOE, as well as (e) the ratio of MOE in bending, tension and compression. Mechanical tests were accompanied by measurements of density and ultrasonic wave speed. Resulting dynamic MOE was partly used as an indicator of timber quality.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11

Similar content being viewed by others

References

  • Arnold M, Steiger R (2007) The influence of wind-induced compression failures on the mechanical properties of spruce structural timber. Mater Struct 40(1):57–68

    Article  CAS  Google Scholar 

  • Burger N, Glos P (1995) Relationship of moduli of elasticity in tension and in bending of solid timber. Paper 28-5-2. In: Proceedings of CIB-W18 Meeting 28, April 1995, Copenhagen, Denmark

  • Burger N, Glos P (1997) Strength relationships in structural timber subjected to bending and tension. Paper 30-6-1. In: Proceedings of CIB-W18 Meeting 30, August 1997, Vancouver, Canada

  • Conners TE, Medvecz PJ (1992) Wood as a bimodular material. Wood Fiber Sci 24(4):413–423

    Google Scholar 

  • Curry WT, Fewell AR (1977) The relations between the ultimate tension and ultimate compression strength of timber and its modulus of elasticity. Research Report CP22/77, Princes Risborough Laboratory, Building Research Establishment BRE, Buckinghamshire

  • Ehlbeck J, Werner H (1992) Coniferous and deciduous embedding strength for dowel-type fasteners. Paper 25-7-2. in: Proceedings of CIB-W18 Meeting 25, August 1992, Åhus, Sweden

  • EN 338 (2003) Structural timber–strength classes. Comité Européen de Normalisation CEN

  • EN 408 (2003) Timber structures—structural timber and glued laminated timber—determination of some physical and mechanical properties. Comité Européen de Normalisation CEN

  • EN 384 (2004) Structural timber : determination of characteristic values of mechanical properties and density. Comité Européen de Normalisation CEN

  • Fewell AR (1982) Machine Stress Grading of Timber in the United-Kingdom. Holz Roh Werkst 40(12):455–459

    Article  Google Scholar 

  • Garfinkel G (1973) Wood engineering. Southern Forest Products Association, New Orleans

    Google Scholar 

  • Gehri E (1997) Timber as a natural composite: Explanation of some peculiarities in the mechanical behaviour. Paper 30-6-3. in: Proceedings of CIB-W18 Meeting 30, August 1997, Vancouver, Canada

  • Gindl W, Teischinger A (2002) Axial compression strength of Norway spruce related to structural variability and lignin content. Composites Part a. Appl Sci Manufact 33(12):1623–1628

    Article  Google Scholar 

  • Glos P (1995) Step A6: Festigkeitssortierung. In: Holzbauwerke nach Eurocode 5, Step 1: Bemessung und Baustoffe, Informationsdienst Holz. Arbeitsgemeinschaft Holz e. V, Düsseldorf, Germany

  • Goens E (1931) The determination of the elasticity module of rods with the help of bending fluctuations. Annalen der Physik 11(6):649–678

    Article  Google Scholar 

  • Green DW, Kretschmann DE (1989) A discussion of lumber property relationships in Eurocode 5. Paper 22-6-3. In: Proceedings of CIB-W18 Meeting 22, September 1989, Berlin, German Democratic Republic

  • Green DW, Kretschmann DE (1990) Stress class systems: an idea whose time has come? Research Paper FPL-RP-500. Forest Products Laboratory, Madison

    Google Scholar 

  • Hearmon RFS (1966) Vibration testing of wood. Forest Prod J 16(8):29–40

    Google Scholar 

  • ISO 3131 (1975) Wood; Determination of density for physical and mechanical tests. International organization for standardization

  • Kollmann F, Krech H (1960) Dynamische Messung der elastischen Holzeigenschaften und der Dämpfung. Holz Roh-Werkst 18(2):41–54

    Article  Google Scholar 

  • Kollmann FFP, Côté WA Jr (1968) Principles of wood science and technology, vol 1: solid wood. Springer, Berlin

    Google Scholar 

  • Mischler-Schrepfer V (2000) Der Einfluss der Waldlagerung von Fichten-Rundholz auf die Längs-Zugeigenschaften des Schnittholzes, Ph.D. thesis, ETH Zürich, Switzerland

  • Ruli A (2004) Determination of the compression strength of glulam - longitudinal and perpendicular to the grain. Diploma thesis, Institute of Timber Engineering and Wood Technology, Graz University of Technology, Austria

  • Sandoz J-L (1990) Triage et fiabilité des bois de construction validité de la méthode ultrason, Lausanne, Ph.D. thesis, EPF Lausanne, Switzerland

  • Schneider MH, Phillips JG (1991) Elasticity of wood and wood polymer composites in tension, compression and bending. Wood Sci Technol 25(5):361–364

    Article  CAS  Google Scholar 

  • Steiger R (1995a) Biege-, Zug- und Druckversuche an Schweizer Fichtenholz, Institut für Baustatik und Konstruktion, ETH Zürich, Research Report Nr. 207, Birkhäuser Verlag, Basel, Switzerland

  • Steiger R (1995b) Versuche an Fichten-Kanthölzern: Biegemoment-Normalkraft-Interaktion, Institut für Baustatik und Konstruktion, ETH Zürich, Research Report Nr. 209, Birkhäuser Verlag, Basel, Switzerland

  • Steiger R (1996) Mechanische Eigenschaften von Schweizer Fichten-Bauholz bei Biege-, Zug-, Druck- und kombinierter M/N-Beanspruchung, Research Report Nr. 221, Birkhäuser Verlag, Basel, Switzerland

    Google Scholar 

  • Steiger R, Arm H, Gehri E (1994) Einspannvorrichtung für Zugversuche an Holzproben grösseren Querschnitts, Institut für Baustatik und Konstruktion, ETH Zürich, Research Report Nr. 204, Birkhäuser Verlag, Basel, Switzerland

    Google Scholar 

  • Steiger R, Fontana M (2005) Bending moment and axial force interacting on solid timber beams. Mater Struct 38(279):507–513

    Article  Google Scholar 

  • Thelandersson S (1995) Step 3/11: Deformations in timber structures. In: Holzbauwerke nach Eurocode 5, Step 3: Grundlagen, Entwicklungen, Ergänzungen, Informationsdienst Holz. Arbeitsgemeinschaft Holz e. V, Düsseldorf

    Google Scholar 

  • Thunell B (1941) Über die Elastizität schwedischen Kiefernholzes. Holz Roh- Werkst 4(1):15–18

    Article  Google Scholar 

  • Ylinen A (1942) Über den Einfluss des Spätholzanteiles und der Rohwichte auf die Festigkeits- und elastischen Eigenschaften des Nadelholzes. Acta forest. Fenn. 5:1. Cited In: Kollmann FFP, Côté Jr. WA (Ed.): Principles of Wood Science and Technology, vol 1: Solid Wood, Springer, Berlin, 1968, pp 346

Download references

Author information

Authors and Affiliations

  1. Empa, Swiss Federal Laboratories for Materials Testing and Research, Wood Laboratory, Überlandstrasse 129, 8600, Dübendorf, Switzerland

    René Steiger & Martin Arnold

Authors
  1. René Steiger
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Martin Arnold
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to René Steiger.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Steiger, R., Arnold, M. Strength grading of Norway spruce structural timber: revisiting property relationships used in EN 338 classification system. Wood Sci Technol 43, 259–278 (2009). https://doi.org/10.1007/s00226-008-0221-6

Download citation

  • Received:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00226-008-0221-6

Keywords

Search

Navigation