Evaluation of Remediation Techniques for Circular Holes in the Webs of Wood I-Joists

Abstract

Remediation methods and strength predictions were evaluated for wood I-joists with single, circular holes in the webs, leaving utilities in place. A full-scale bending test using four equally spaced point loads was applied to three depths of joists with varying flange widths and span lengths of 4.88 and 2.44 m. Failure modes for long-span joists without holes were in the flanges in tension, compression, or lateral buckling, but once a hole was introduced, the majority failed in shear. The curved beam approach and manufacturers software were used to predict strength. Seven remediation techniques were investigated initially, and remediation effectiveness was evaluated on the basis of strength, stiffness, and ease of installation/cost. The oriented strand board (OSB) collar remediation worked very well and returned 8 of 12 series of joists to a strength statistically equivalent to the “no hole” condition. The OSB collar was not quite as effective in returning stiffness to the joists but was easier to install and less expensive than a laminated strand lumber patch.