Predicting Strength of Wood I-Joist with a Circular Web Hole
Publication: Journal of Structural Engineering
Volume 134, Issue 7
Abstract
Web holes are often made in wood I-joists to allow passage of services. Design properties of wood I-joists with a web hole are commonly developed through testing which leads to empirical design information. This paper describes a mechanics-based method to predict the strengths of wood I-joists with a circular web hole that is suitable for implementation as a design tool. Curved beam theory is used to compute stresses around a hole. Peak tensile stresses obtained from curved beam analysis agree well with those predicted using the finite-element method. Failure load is attained by the application of fracture mechanics based finite area method. The method developed is used to predict failure loads of wood I-joists of different depths with different web hole sizes. Simplification of the method leads to the development of a simple expression that can be used for engineering design. It is found that the predicted strengths are in a good agreement with the corresponding test results. The calculation method developed can potentially replace the testing approach generally adopted by the wood I-joist industry.
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Acknowledgments
The writers wish to acknowledge the financial support of the Value to Wood Program, Natural Resources Canada for this research work. Thanks are also due to Boise Cascade AllJoist, Norbord Inc. (I-joists), and Jager Building Systems for their material contributions and technical advice.
References
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 134 • Issue 7 • July 2008
Pages: 1229 - 1234
Copyright
© 2008 ASCE.
History
Received: Feb 18, 2006
Accepted: Nov 28, 2007
Published online: Jul 1, 2008
Published in print: Jul 2008
Notes
Note. Associate Editor: Rakesh Gupta
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