Load-Carrying Capacity of Lengthwise Cracked Wood Beams Retrofitted by Self-Tapping Screws
Publication: Journal of Structural Engineering
Volume 143, Issue 6
Abstract
Longitudinal cracks in wood beams of heavy timber structures are commonly seen and can impair the load-carrying capacity of such beams. This paper presents the experimental and numerical modeling results on 35 pieces of full-scale wood beams with saw kerfs that simulate lengthwise checks. The influences of the checks and self-tapping screws used for retrofitting purposes were identified based on the normalized load-carrying capacity of the tested beams. It was found that a longitudinal check (up to 2/3 of the beam span) may cause a resistance loss up to 46.2% compared to an unchecked beam, and the use of self-tapping screws may increase the resistance to no less than 86% of that of an unchecked beam. A three-dimensional (3D) finite-element method based model was developed and verified to further quantify the stress intensity factor at the check tip. Based on the modeling and test results, a simple formula was established for prediction of the stress intensity factor, considering the geometry of the checks and the contribution of the self-tapping screws. The generated formula was verified with good agreement and therefore can be used for determination of the shear resistance of checked wood beams and the required screw spacing for retrofitting purposes.
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Acknowledgments
This research was financially supported by the National Natural Science Foundation of China (Grant No. 51478336) and the Shanghai Science and Technology Committee (Grant No. 13231201700).
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Information & Authors
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Published In
Journal of Structural Engineering
Volume 143 • Issue 6 • June 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Apr 10, 2016
Accepted: Nov 2, 2016
Published ahead of print: Feb 6, 2017
Published online: Feb 7, 2017
Published in print: Jun 1, 2017
Discussion open until: Jul 7, 2017
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