New Formula for Influence of Spiral Grain on Bending Stiffness of Wooden Beams
Publication: Journal of Structural Engineering
Volume 121, Issue 11
Abstract
Spiral grain, defined as the situation where wood fibers are inclined in the longitudinal-tangential plane of the tree stem, is known to negatively affect the performance and dimensional stability of structural timber in service. The objective of this study is to evaluate the influence of spiral grain on the bending stiffness of wooden beams through both a theoretical model and an experimental test protocol. The theoretical model is based on a new formula derived from the theory related to the transformation of the second-order tensor of elastic compliances. The experimental protocol is dedicated to the creation of artificial spiral grain and the validation of the new formula. Theoretical results show that the new formula is a better predictor of the bending stiffness than the well-known Hankinson formula. A preliminary validation of the new formula is attempted through experiments on small Douglas-fir beams containing uniform spiral grain. The new formula is shown to be in very good agreement with experimental results.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
American Institute of Timber Construction. (1985). Timber construction manual . John Wiley & Sons, Inc., New York, N.Y.
2.
Batoz, J. L., and Dhatt, G. (1990). Modélisation des structures par la méthode des éléments finis. Volume 1: Les solides élastiques, Les presses de l'Université Laval, Ste-Foy, Qué., Canada.
3.
Biblis, E. J.(1965). “Shear deflection of wooden beams.”Forest Products J., 15(11), 492–498.
4.
Bindzi, I., and Samson, M.(1995). “A new method of grading lumber for spiral grain.”Forest Products J., 45(2), 63–66.
5.
Bodig, J., and Jayne, B. A. (1982). Mechanics of wood and wood composites . Van Nostrand Reinhold, New York, N.Y.
6.
Canadian Standards Association. (1989). “Engineering design in wood (limit states design).”CAN/CSA-O86.1-M89, Rexdale, Ont., Canada.
7.
Forest Products Laboratory. (1987). “Wood handbook. Wood as an engineering material.”Forest Service agricultural handbook 72, Forest Products Lab., U.S. Dep. of Agr., Madison, Wis.
8.
Goodman, J. R., and Bodig, J.(1970). “Orthotropic elastic properties of wood.”J. Struct. Div., ASCE, 96(11), 2301–2319.
9.
Goodman, J. R., and Bodig, J.(1971). “Orthotropic strength of wood in compression.”Wood Sci., 4(2), 83–94.
10.
Harris, J. M. (1989). Spiral grain and wave phenomena in wood formation . Springer Series in Wood Sciences, Springer Verlag, Berlin, Germany.
11.
Kim, K. Y.(1986). “A note on Hankinson formula.”Wood and Fiber Sci., 18(2), 345–348.
12.
Levinson, M.(1981). “A new rectangular beam theory.”J. Sound and Vibration, 74(1), 81–87.
13.
Radcliffe, B. M.(1965). “A theoretical evaluation of Hankinson's formula for modulus of elasticity of wood at an angle to the grain.”Quarterly Bull., Michigan Agric. Experimental Station, 48(2), 286–295.
14.
Teh, K. K., and Huang, C. C. (1979). “Shear deformation coefficient for generally orthotropic beams.”Fiber Sci. and Technol., Vol. 12, 73–80.
15.
Weddell, E. (1961). “Influence of interlocked grain on the bending strength of timber, with particular reference to utile and greenheart.”J. Timber Develop. Assoc., Vol. 7, 56–72.
16.
Wilson, T. R. (1921). “The effect of spiral grain on the strength of wood.”J. Forestry, Vol. 19, 740–747.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 121 • Issue 11 • November 1995
Pages: 1541 - 1546
Copyright
Copyright © 1995 American Society of Civil Engineers.
History
Published online: Nov 1, 1995
Published in print: Nov 1995
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.