Wood I-Joists with Excessive Web Openings: An Experimental and Analytical Investigation
Publication: Journal of Structural Engineering
Volume 135, Issue 6
Abstract
Two series of tests with different depth wood I-joists were conducted to study the effects of circular and square web openings and the placement of steel angle retrofits at openings. Finite-element analysis of all test configurations was used to improve understanding of how web openings and retrofits affect the stiffness, stress distributions around openings, and ultimate failure mechanisms. Test results show failure loads well above prescribed design loads; however, the presence of web openings affected the type of failure modes. Control joists failed at the tension flange, whereas joists with web openings failed in shear through web openings or by means directly attributable to the presence of an opening. Ultimate capacity and stiffness was generally reduced by the presence of a web opening, with openings located closer to high shear areas producing worse results. Square web openings lowered the ultimate capacity approximately 10% more than circular openings when located at the same location. Steel angle retrofits improved capacity if an adequate retrofit length was used to redistribute stress concentrations. Finite-element models accurately predicted decreases in stiffness due to web openings; however, the models predict an improvement in stiffness due to the presence of steel retrofits that was not ascertained in experimental results.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 135 • Issue 6 • June 2009
Pages: 655 - 665
Copyright
© 2009 ASCE.
History
Received: Jul 2, 2008
Accepted: Dec 16, 2008
Published online: Feb 19, 2009
Published in print: Jun 2009
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