Scaling and modeling the creep of Eucalyptus globulus

  • Duarte Barroso Lopes
  • João Emílio Matos
Keywords: Blue gum, creep limit, eucalypts, mechano-sorption, model, test

Abstract

Eucalyptus, with the commercial name of Blue gum, is a viscoelastic material strongly influenced when under constant load (Creep), being this phenomenon - in the context of displacements - exacerbated with transient relative humidity (variations of the water content in the wood material).

The evaluation of bending creep was done in indoor / constant and transient humidity conditions. In the latter, mechano-sorptive effect, the creep bending tests were done for a period of 60 days with cycles of wetting-and-drying. Each cycle has 7 days of duration. Defect free specimens with dimensions of 20*20*400 mm3 (approximately to the scale 1:10) of Eucalyptus globulu. wood species were used.

To fit the creep behaviour and extrapolate results for different periods (1, 10 and 50 years) a survey of different numerical models was done. Rational, parabolic and polynomial functions were chosen.

In bending, Blue gum wood species presented a behaviour without a creep limit, therefore labile. Through the models used for extrapolations a significant variability was found for different periods. Values of the main standard of wood design (Eurocode 5) were exceeded. The most consistent mathematical model was the rational model because it is the one that has led to closer and stable results.

Downloads

Download data is not yet available.

References

Baker, G.A.; Graves-Morris, P.R. 1996. Padé Approximants. Encyclopedia of Mathematics and its Applications. Cambridge University Press. ISBN 9780521450072, Vol 59

Bengtsson, C.; Kliger, R. 2003. Bending creep of High-temperature dried spruce timber. Holzforschung 57:95-100.

Bodig, J.; Jayne, B.A. 1982. Mechanics of wood and wood composites. Krieger Pub Co, p.712. ISBN 0-442-00822-8.

Calvo, C.F.; Cotrina, A.D.; Cuffré, A. G.; Piter, J. C.; Stefani, P. M.; Torrán, E. A. 2002. Creep in small clear specimens of Argentinean Eucalyptus grandis. Maderas-Cienc Tecnol 4(2):124-132.

Carvalho, A. 1997. Madeiras Portuguesas, vol. II. Estrutura anatómica, propriedades, utilizações., Ed. Direcção Geral das Florestas: Lisbon. ISBN 9789728097264, p.415.

Carvalho, S.V.S. 2015. Creep materials (Fluência de materiais). Master Thesis (n.º 1323). School of Engineering of Oporto. p.112. Available(access:13/ 11/ 2018)

Deutsches Institut für Normung. DIN. 1978. Testing of wood; Bending test. DIN 52186. 1978.

Direcção geral de recursos florestais. DGRF. 2010. 5º Inventário florestal Nacional, < 5º Inventário florestal Nacional, http://www.afn.min-agricultura.pt/portal/ifn/relatorio-final-ifn5-florestat-1 > (access: 13/11/2018).

European Committee for Standardization. ENV. 1999. Wood-based panels. Determination of duration of load and creep factors. ENV-1156. 1999. CEN European Committee for Standardization: Bruxelles. ISBN 0 580 32137 1

European Committee for Standardization. EN-NP. 2003. Timber structures - Structural timber and glued laminated timber - Determination of some physical and mechanical properties. EN-NP-408. 2003. CEN European Committee for Standardization: Bruxelles.

European Committee for Standardization. EN. 2003. EC 0, Eurocode 0 - Eurocode - Basis of structural design. EN-1990. 2003. CEN European Committee for Standardization: Bruxelles.

European Committee for Standardization. EN. 2003. EC 5, Eurocode 5 - Design of timber structures - Part 1-1: General - Common rules and rules for buildings. EN-1995:1-1. 2003. CEN European Committee for Standardization: Bruxelles .

European Committee for Standardization. EN. 2009. EC 0, Eurocode 0 - Basis of structural design. EN-1990. 2009. CEN European Committee for Standardization: Bruxelles .

Esteves, B.M.M.L. 2006. Melhoramento tecnológico por modificação térmica de madeiras Portuguesas. PhD Thesis, Universidade Técnica de Lisboa, I.S. Agronomia, Lisboa, Portugal

Epmeier, H. 2006. Moisture-related properties of modified timber - an experimental study. PhD Thesis, Chalmers Tekniska Högskola, Institutionen för tillämpad mekanik, Goeteborg, Sweden.

Epmeier, H.; Westin, M.; Rapp, A. 2004. Differently modified wood: Comparison of some selected properties. Scandinavian Journal of Forest Research 19(5): 31-37.

Epmeier, H.; Johansson, M.; Kliger, R.; Westin, M. 2007. Bending creep performance of modified timber. Holz Roh Werkst 65: 343-351.

Fridley, K.J.; Tang, R.C.; Soltis, L.A. 1992. Creep behavior model for structural lumber. Journal of Structural Engineering 118:2261-2276.

Hoffmeyer, P. 1990. Failure of wood as influenced by moisture and duration of load. PhD Thesis, State University of New York, Syracuse, New York.

Hauska, M.; Bucar, B. 1996. Mechano-sorptive creep in adult, juvenile and reaction wood. In: Proceedings of the International COST 508 Wood Mechanics Conference, Stuttgart, Germany.

Lagana, R.; Babiak, M.; Krakovsky, A. 2008. Creep parameters of spruce wood in high temperature environment. Madera-Cienc Tecnol 10(1): 19-24.

Lopes, D.B. 2013. Technological improvement of Portuguese pinewood by chemical modification. PhD Thesis, Georg-August-Universität Göttingen, Gӧttingen, Germany, 146p. Available (access: 13/11/2018)

Lorenzo, D.; Troya, M.T.; Prieto, M.J.; Baso, C.; Touza, M. 2007. Study of the natural durability of Spanish Eucalyptus globulus Wood. In Proceedings IRG 38 th Annual Meeting IRG/WP 07-10617 The International Research Group on Wood Protection: Jackson Lake Lodge, Wyoming, USA. 20-24 May.

Mårtensson, A. 2003. Short- and long-term deformations of timber structures. Edited by Thelandersson, S; Larsen, HJ. John Wiley & Sons Ltd: West Sussex, England. ISBN 0-470-84469-81.

Navi, P.; Pittet, V.; Plummer, C.J.G. 2002. Transient moisture effect on wood creep. Wood Science and Technology 36(6): 447-462.

Norimoto, M.; Gril, J.; Rowell, R.M. 1992. Rheological properties of chemically modified wood: Relationship between dimensional stability and creep stability. Wood Fiber Science 24(1):25-35.

Okimoto, F.S. 2001. Análise da perda de protensão em pontes protendidas de madeira. PhD Thesis, Escola de Engenharia de São Carlos, Universidade de São Paulo. São Carlos, Brasil. Available (access: 13/11/2018)

Piter, J.C.; Calvo, C.F.; Cuffré, A.G.; Rougier, V.C.; Sosa Zitto, M.A.; Torrán, E.A. 2007. Creep in structural-sized beams of Argentinean Eucalyptus grandis. Maderas-Cienc Tecnol 9(2):117-126.

Piter, J.C.; Zerbino, R.L.; BLAß, H.J. 2006. Deflections in beams of Argentinean Eucalyptus grandis under long-term loading. Holz als Roh- und Werkstoff 64(5):351-355.

PROTIMETER 2005. Instruction manual protimeter moisture measurement system MMS, INS5800A. Available (access: 5/10/2011)

Santos, J.A. 2000. Mechanical behaviour of Eucalyptus wood modified by heat. Wood Science and Technology 34(1):39-43.

Santos, J.A. 2009. Estudo de modelos e caracterização do comportamento mecânico da madeira. PhD Thesis, Universidade do Minho, Guimarães, Portugal. Available

Villegas, M.S.; Rivera, S.M. 2002. Revisión xilológica de las principales especies del género Eucalyptus L’Herit. cultivadas en Argentina. Revista de la Facultad de Agronomía 105(1):9-28.
Published
2018-08-29
How to Cite
Barroso Lopes, D., & Emílio Matos, J. (2018). Scaling and modeling the creep of Eucalyptus globulus. Maderas. Ciencia Y Tecnología, 21(2). Retrieved from http://revistas.ubiobio.cl/index.php/MCT/article/view/3435
Section
Article