Materiales de Construcción, Vol 69, No 336 (2019)

Comparison between wet and dry timber visual strength grading according to the Spanish (UNE 56544) and German (DIN 4074-1) standards


https://doi.org/10.3989/mc.2019.03319

D. F. Llana
Timber Construction Research Group, Universidad Politécnica de Madrid - Timber Engineering Research Group, National University of Ireland Galway, Spain
orcid http://orcid.org/0000-0001-7758-9456

F. Arriaga
Timber Construction Research Group, Universidad Politécnica de Madrid - Department of Forest and Environmental Engineering and Management, MONTES (School of Forest Engineering and Natural Resources), Universidad Politécnica de Madrid, Spain
orcid http://orcid.org/0000-0001-5535-0786

M. Esteban
Timber Construction Research Group, Universidad Politécnica de Madrid - Department of Forest and Environmental Engineering and Management, MONTES (School of Forest Engineering and Natural Resources), Universidad Politécnica de Madrid, Spain
orcid http://orcid.org/0000-0003-3364-9044

G. Íñiguez-González
Timber Construction Research Group, Universidad Politécnica de Madrid - Department of Forest and Environmental Engineering and Management, MONTES (School of Forest Engineering and Natural Resources), Universidad Politécnica de Madrid, Spain
orcid http://orcid.org/0000-0003-2917-842X

Abstract


Visual strength grading is widely used to estimate mechanical properties of structural timber. National visual grades are allocated to strength classes according to European standard EN1912. The recent discussion about the proper function of visual strength grading standards and the assignment of strength classes shows the need for further research in this field. Spanish-sourced radiata, Scots, Salzmann and maritime pine timber samples were visually graded in wet and dry condition according to the Spanish UNE56544 (2011) and German DIN4074-1 (2012) standards. Rejection was far higher dry due to distortion (warping) parameters. However, this rejection could be significantly mitigated by adopting a higher twist limit (2 mm / 25 mm width). UNE 56544 is more suitable for visually grading these species because it was specifically designed for them and a Spanish source. However, both standards underestimated the Scots pine rejection pieces which mechanical properties fulfill the MEG and S10 grades.

Keywords


Wood; Detection of cracks; Mechanical properties; Modulus of elasticity; Dry grading

Full Text:


HTML PDF XML

References


EN 1912:2012. Structural timber. Strength classes. Assignment of visual grades and species. European Committee of Standardization (CEN), Brussels, Belgium. Released 2012-06-06 as UNE-EN 1912:2012.

EN 338:2016. Structural timber. Strength classes. European Committee of Standardization (CEN), Brussels, Belgium. Released 2016-11-08 as UNE-EN 338:2016.

EN 384:2016+A1:2018. Structural timber. Determination of characteristic values of mechanical properties and density. European Committee of Standardization (CEN), Brussels, Belgium. Released 2019-03-13 as UNE-EN384:2016+A1:2019.

UNE 56544:1999-2011. Clasificación visual de la madera aserrada para uso estructural. Madera de coníferas [Visual grading for structural sawn timber. Coniferous timber]. AEN/CTN 56 Madera y Corcho, Madrid, Spain. Released 2011-11-08.

Stapel, P.; van-de-Kuilen, J.W.G. (2014) Efficiency of visual strength grading of timber with respect to origin, species, cross section, and grading rules: a critical evaluation of the common standards. Holzforschung 68(2):203-2016. https://doi.org/10.1515/hf-2013-0042

Stapel, P.; van-de-Kuilen, J.W.G. (2014) Influence of crosssection and knot assessment on the strength of visually graded Norway spruce. Eur. J. Wood Prod. 72:213-227. https://doi.org/10.1007/s00107-013-0771-7

Hermoso, E.; Mateo, R.; Íñiguez-González, G.; Montón, J.; Arriaga, F. (2016) Visual grading and structural properties assessment of large cross-section Pinus radiata D. Don timber. BioResources 11[2]:5312-5321. https://doi.org/10.15376/biores.11.2.5312-5321

Moya, L.; Domenech, L.; Cardoso, A.; O'Neill, H.; Baño, V. (2017) Proposal of visual strength grading rules for Uruguayan pine timber. Eur. J. Wood Prod. 75:1017-1019. https://doi.org/10.1007/s00107-017-1208-5

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 nondestructive variables and visual grading parameters. Eur. J. Wood Prod. 70[6]:839-844. https://doi.org/10.1007/s00107-012-0626-7

DIN 4074-1:2012 Sortierung von Holz nach der Tragfähigkeit - Teil 1: Nadelschnittholz [Strength grading of wood - Part 1: Coniferous sawn timber]. Normenausschuss Holzwirtschaft und Möbel (NHM), Berlin, Germany. 2012-06.

Díez, M.R.; Conde, M.; Fernández-Gofín, J.I.; Rosskopf, S. (2000) Clasificación visual de madera estructural de pino laricio (Pinus nigra Arn.): Comparación de resultados usando las normas UNE 56544 y DIN 4074 [Visual grading of structural timber of Salzmann pine (Pinus nigra Arn.): Comparison of results using standards UNE 56544 and DIN 4074]. Inv. Agrar-Sist. Rec. F. 9[2]:375-380.

Conde, M. (2003) Caracterización de la madera estructural de Pinus nigra Subsp. Salzmannii. [Characterization of structural timber from Pinus nigra Ssp. Salzmannii]. Doctoral thesis. ETS de Ingenieros de Montes Universidad Politécnica de Madrid. 209 p.

Adell, F.J.; Hermoso, E.; Arriaga, F.; Richter, C. (2008) Comparison of the Spanish visual strength grading standard for structural sawn timber (UNE 56544) with the German one (DIN 4074) for Scots pine (Pinus sylvestris L.) from Germany. Holz. Roh. Werkst. 66:253-258. https://doi.org/10.1007/s00107-008-0241-9

Baño, V.; Arriaga, F.; Soilán, A.; Guaita, M. (2011) Prediction of bending load capacity of timber beams using a finite element method simulation of knots and grain deviation. Biosyst. Eng. 109:241-249. https://doi.org/10.1016/j.biosystemseng.2011.05.008

van-de-Kuilen, J.W.G.; Blass, H.J. (2005) Mechanical properties of azobé (Lophira alata). Holz. Roh. Werkst. 63:1-10. https://doi.org/10.1007/s00107-004-0533-7

Baño, V.; Arriaga, F.; Guaita, M. (2013) Determination of the influence of size and position of knots on load capacity and stress distribution in timber beams of Pinus sylvestris using finite element model. Biosyst. Eng. 114:214-222. https://doi.org/10.1016/j.biosystemseng.2012.12.010

Ridley-Ellis, D.; Stapel, P.; Baño, V. (2016) Strength grading of sawn timber in Europe: an explanation for engineers and researchers. Eur. J. Wood Prod. 74[3]:291-306. https://doi.org/10.1007/s00107-016-1034-1

Ravenshorst, G.J.P. (2015) Species independent strength grading of structural timber. Doctoral thesis. Technische Universiteit Delft. 277 p.

UNE 56525:1972. Clasificación de la madera aserrada de construcción [Visual grading for construction sawn timber]. IRANOR/CTN 56 Madera y Corcho, Madrid, Spain. 1972-12.

CP 112-2:1971. The structural use of timber. Metric units. British Standards Institution. London, UK. ISBN 0 580 06911 7. Released 1971-06-15.

Argüelles, R.; Arriaga, F. (1986) Norma de cálculo de estructuras de madera. [Timber structures design standard]. Ed. AITIM. Madrid, Spain. 80-89.

EN 13556:2003. Round and sawn timber - Nomenclature of timbers used in Europe. European Committee of Standardization (CEN), Brussels, Belgium. Released 2004-01-23 as UNE-EN 13556:2004.

Fernández-Golfín, J.I.; Díez, M.R.; Gutiérrez-Oliva, A. (1998) Caracterización mecánica de la madera aserrada de uso estructural, clasificada visualmente de acuerdo con la norma UNE56544 [Mechanical characterization of sawn timber for structural use, graded visually in accordance with Spanish standard UNE56544]. Mater. Construcc. 48[252]:45-59. https://doi.org/10.3989/mc.1998.v48.i252.463

Fernández-Golfín, J.I.; Díez, M.R.; Baonza, M.V.; Gutiérrez-Oliva, A.; Hermoso, E.; Conde, M.; van den Eynde, V. (2001) Caracterización de la calidad y las propiedades de la madera de Pino laricio (Pinus nigra Arn. salzmannii) [Quality and properties characterization of timber from Salzmann pine (Pinus nigra Arn. salzmannii)]. Inv. Agrar-Sist. Rec. F. 10[2]:311-331.

Íñiguez-González, G.; Arriaga, F.; Barrett, J.D.; Esteban, M. (2007) Visual grading of large structural coniferous sawn timber according to Spanish standard UNE 56544. Forest Prod. J. 57[10]:45-50.

UNE 56546:2013. Clasificación visual de la madera aserrada para uso estructural. Madera de frondosas [Visual grading for structural sawn timber. Hardwood timber]. AEN/CTN 56 Madera y Corcho, Madrid, Spain. Released 2013-11-20.

Fernández-Golfín, J.I.; Díez, M.R.; Hermoso, E.; Baso, C.; Casas, J.M.; González, O. (2007) Caracterización de la madera de Eucalyptus globulus para uso estructural [Characteristics of Eucalyptus globulus wood for structural purposes]. CIDEU 4:91-100.

Correal, E.; Vilches, M.; Iglesias, C. (2013) Clasificación visual de la madera estructural de Castanea sativa del Sistema Mediterráneo Catalán [Visual grading for structural sawn timber of Castanea sativa from Catalan Mediterranean source]. Proceedings of 6º Congreso Forestal Español. June 10-14. Vitoria, Spain. 12p.

Vega, A.; Arriaga, F.; Guaita, M.; Baño, V. (2013) Proposal for visual grading criteria of structural timber of sweet chestnut from Spain. Eur. J. Wood Prod. 71[4]:529-532. https://doi.org/10.1007/s00107-013-0705-4

UNE 56547:2018. Clasificación visual de los postes de madera para líneas aéreas [Visual classification for wood overhead poles]. CTN 56 Madera y Corcho, Madrid, Spain. Released 2018-07-02.

Newspaper article (1912) Gebräuche im südwestdeutschen holzhandelsverfehr [Uses in the southwest German timber trade]. Illustrierte schweizerische Handwerker-Zeitung, Zurich, Switzerland. 158-159.

Glos, P.; Richter, C. (2002) Sortierhilfen und Erläuterungen zur Anwendung der DIN 4074 in der Praxis [Recomendations and explanations on the application of DIN 4074 in practice]. Report No. 02502. Holzforschung München. Munich, Germany. 8 p.

DIN 4074-2:1958 Bauholz für Holzbauteile; Gütebedingungen für Baurundholz (Nadelholz) [Building Timber for Wood Building Components; Quality Conditions for Building Logs (Softwood)]. Normenausschuss Holzwirtschaft und Möbel (NHM), Berlin, Germany. Released 1958-12.

DIN 4074-5:2003 Sortierung von Holz nach der Tragfähigkeit - Teil 5: Laubschnittholz [Strength grading of wood - Part 5: Sawn hard wood]. Normenausschuss Holzwirtschaft und Möbel (NHM), Berlin, Germany. Released 2003-06.

EN 14081-1:2016. Timber structures - Strength graded structural timber with rectangular cross section - Part 1: General requirements. European Committee of Standardization (CEN), Brussels, Belgium. Released 2016-05-18 as UNE-EN 14081-1:2016.

Esteban, M. (2003) Determinación de la capacidad resistente de la madera estructural de gran escuadría y su aplicación en estructuras existentes de madera de conífera [Determination of the load carrying capacity of large cross-section structural coniferous timber on existing structures]. Doctoral thesis. ETS de Ingenieros de Montes. UPM. Madrid. 365 p. PDF File: http://oa.upm.es/1404

Arriaga, F.; Esteban, M.; Relea, E. (2005) Evaluación de la capacidad portante de piezas de gruesa escuadría de madera de conífera en estructuras existentes [Evaluation of the load carrying capacity of large cross section coniferous timber in standing structures]. Mater. Construcc. 55[280]:43-52. https://doi.org/10.3989/mc.2005.v55.i280.205

EN 408:2010+A1:2012. Timber structures. Structural timber and glued laminated timber. Determination of some physical and mechanical properties. European Committee of Standardization (CEN), Brussels, Belgium. Released 2012-09-26 as UNE-EN 408:2010+A1:2012.

EN 13183-2:2002. Moisture content of a piece of sawn timber. Part 2: Estimation by electrical resistance method. European Committee of Standardization (CEN), Brussels, Belgium. Released 2002-07-29 as UNE-EN 13183-2:2002.

EN 13183-1:2002. Moisture content of a piece of sawn timber. Part 1: Determination by oven dry method. European Committee of Standardization (CEN), Brussels, Belgium. Released 2002-07-29 as UNE-EN 13183-1:2002.

Montón, J.; Arriaga, F.; Íñiguez-González, G.; Segués, E. (2015) Warp requirements and yield efficiency in the visual grading of sawn radiata pine timber. BioResources 10[1]:1115-1126. https://doi.org/10.15376/biores.10.1.1115-1126




Copyright (c) 2019 Consejo Superior de Investigaciones Científicas (CSIC)

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Contact us materconstrucc@ietcc.csic.es

Technical support soporte.tecnico.revistas@csic.es