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Evaluation of the End Effect Impact on the Torsion Test for Determining the Shear Modulus of a Timber Beam through a Photogrammetry Approach

Authors: Niaz Gharavi, Hexin Zhang, Yanjun Xie


The timber beam end effect in the torsion test is evaluated using binocular stereo vision system. It is recommended by BS EN 408:2010+A1:2012 to exclude a distance of two to three times of cross-sectional thickness (b) from ends to avoid the end effect; whereas, this study indicates that this distance is not sufficiently far enough to remove this effect in slender cross-sections. The shear modulus of six timber beams with different aspect ratios is determined at the various angles and cross-sections. The result of this experiment shows that the end affected span of each specimen varies depending on their aspect ratios. It is concluded that by increasing the aspect ratio this span will increase. However, by increasing the distance from the ends to the values greater than 6b, the shear modulus trend becomes constant and end effect will be negligible. Moreover, it is concluded that end affected span is preferred to be depth-dependent rather than thickness-dependant.

Keywords: Timber Engineering, end effect, structural-size torsion test, shear properties, binocular stereo vision

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[1] A. P. Boresi and R. J. Schmidt, Advanced Mechanics of Materials. John Wiley and sons, 2003.
[2] BS EN 408:2010+A1:2012, “British Standard: Timber structures Structural timber and glued laminated timber Determination of some physical and mechanical properties,” BSI Standards Publication, 2012.
[3] L. A. Soltis and D. R. Rammer, “Shear Strength of Unchecked Glued-Laminated Beams,” Forest Product Journal, vol. 44, pp. 51–57, 1994.
[4] R. Gupta, L. R. Heck, and T. H. Miller, “Experimental Evaluation of the Torsion Test for Determining Shear Strength of Structural Lumber,” Journal of Testing and Evaluation, vol. 30, no. 4, p. 283, 2002.
[5] A. M. Khokhar, H. Zhang, D. Ridley-Ellis, and J. Moore, “Determining the Shear Modulus of Sitka Spruce from Torsion Tests.” in Proceedings of the 10th World Conference on Timber Engineering, 2008.
[6] R. Gupta and T. Siller, “Shear strength of structural composite lumber using torsion tests,” vol. 33, no. 2, pp. 110–117, 2005.
[7] R. Gupta, L. R. Heck, and T. H. Miller, “Finite-Element Analysis of the Stress Distribution in a Torsion Test of Full-Size, Structural Lumber,” Journal of Testing and Evaluation, vol. 30, no. 4, p. 291, 2002.
[8] Z. Peng and N. Guo-Qiang, “Simultaneous Perimeter Measurement for 3D Object with a Binocular Stereo Vision Measurement System,” Optics and Lasers in Engineering, vol. 48, no. 4, pp. 505–511, 2010.
[9] Christian Wohler, 3D Computer Vision, Efficient Methods and Applications, 2nd ed. Springer, 2013.
[10] BS EN 13183-1:2002, “British Standard: Moisture content of a piece of sawn timber. Determination by oven dry method,” BSI Standards Publication, no. December, 2007.
[11] Y. Li, P. Chen, M. Zhang, Y. Li, A´ . P. Chen, and M. Zhang, “The Vehicle Distance Measurement System Based on Binocular Stereo Vision,” Lecture Notes in Electrical Engineering, vol. 378, 2016.
[12] ASTM-D198, “Standard Test Methods of Static Tests of Lumber in Structural Sizes,” ASTM International, pp. 1–27, 2014.