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European Journal of Wood and Wood Products

, Volume 70, Issue 5, pp 603–613 | Cite as

The effect of climate variations on glulam—an experimental study

  • Vanessa AngstEmail author
  • Kjell Arne Malo
Originals Originalarbeiten

Abstract

Climate variations affect timber structures by causing moisture induced stresses which may lead to cracks in timber members. The paper presents experimentally determined moisture induced stresses that arise perpendicular to the grain of glulam specimens during exposure to 1-dimensional drying and wetting. Although to a certain extent reduced by creep effects, the determined tensile stresses can significantly exceed the characteristic tensile strength of glulam. Additional measurements of moduli of elasticity (E) and hygroexpansion coefficients (α) revealed that these parameters are strongly affected by the geometrical configuration (pith locations) of the specimens. By means of all the parameters determined here, it can be avoided that parameters have to be selected from different literature sources, which introduces large uncertainties into the numerical simulations.

Keywords

Moisture Content Moisture Gradient Shrinkage Strain Creep Effect Climate Exposure 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Der Einfluss von Klimavariationen auf Brettschichtholz – eine experimentelle Studie

Zusammenfassung

Klimavariationen beeinträchtigen Holzkonstruktionen indem sie feuchtigkeitsinduzierte Spannungen verursachen, welche zu Rissen in Holzbauteilen führen können. Die Arbeit präsentiert experimentell ermittelte feuchtigkeitsinduzierte Spannungen, welche in Brettschichtholz-Prüfkörpern bei 1-dimensionaler Befeuchtung bzw. Trocknung quer zur Faserrichtung auftreten. Es wurde festgestellt, dass die auftretenden Zugspannungen – obwohl zu einem gewissen Grad durch Kriechen abgebaut – die charakteristische Zugfestigkeit von Brettschichtholz deutlich überschreiten. Zusätzlich zeigten Messungen von Elastizitätsmodulen (E) und differentiellen Quell- und Schwindmassen (α), dass diese Parameter stark von der geometrischen Beschaffenheit (Lage der Markröhre) der Probekörper beeinflusst werden. Mit all den hier ermittelten Parametern kann verhindert werden, dass Parameter aus verschiedenen Literaturquellen ausgewählt werden müssen, was eine beträchtliche Unsicherheit in die numerischen Berechnungen bringt.

References

  1. Burger N, Glos P (1995) Verhältnis zwischen Zug- und Biege-Elastizitätsmoduln von Vollholz. Holz Roh- Werkst 53:73–74 CrossRefGoogle Scholar
  2. COMSOL Multiphysics (2007) User manuals Google Scholar
  3. Dinwoodie JM (2004) Timber—its nature and behaviour. Taylor & Francis, London Google Scholar
  4. Fortino S, Mirianon F, Toratti T (2009) A 3D moisture-stress FEM analysis for time dependent problems in timber structures. Mech Time-Depend Mater 13:333–356 CrossRefGoogle Scholar
  5. Frese M, Blass HJ (2007) Failure analysis on timber structures in Germany—a contribution to COST action E55. Paper presented at the first workshop May 2007, Graz University of Technology, Austria Google Scholar
  6. Frühwald E, Serrano E, Toratti T, Emilsson A, Thelandersson S (2007) Design of safe timber structures—How can we learn from structural failures in concrete, steel and timber? Division of Structural Engineering, Lund Institute of Technology, Report TVBK-3053 edn, Lund, Sweden Google Scholar
  7. Häglund M (2008) Varying moisture content and eigen-stresses in timber elements. Wood Mater Sci Eng 1–2:38–45 CrossRefGoogle Scholar
  8. Jönsson J (2004) Internal stresses in the cross-grain direction in glulam induced by climate variations. Holzforschung 58:154–159 CrossRefGoogle Scholar
  9. Jönsson J (2005) Moisture induced stresses in timber structures. Dissertation, Lund Institute of Technology, Sweden Google Scholar
  10. Jönsson J, Svensson S (2004) A contact free measurement method to determine internal stress states in glulam. Holzforschung 58:148–153 CrossRefGoogle Scholar
  11. Ranta-Maunus A (2003) Effects of climate and climate variations on strength. In: Thelandersson S, Larsen HJ (eds) Timber engineering. Wiley, Chichester, pp 153–167 Google Scholar
  12. Svensson S, Toratti T (2002) Mechanical response of wood perpendicular to grain when subjected to changes of humidity. Wood Sci Technol 36:145–156 CrossRefGoogle Scholar
  13. prEN 14080 (2011) Timber structures—Glued laminated timber and glued solid timber, Brussels Google Scholar

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Department of Structural EngineeringNTNU Norwegian University of Science and Technology, TrondheimTrondheimNorway

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