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Lateral buckling of wood composite I-joists as a mechanism causing falls from elevation.

Hindman DP; Bamberg CR; Timko PD
Research and Practice for Fall Injury Control in the Workplace: Proceedings of International Conference on Fall Prevention and Protection. Morgantown, WV: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2012-103, 2011 Nov; :146-149
Wood composite I-joists are common materials used for floor and roof joists in residential construction. The shape of I-joists reduces the amount of wood fiber required to carry vertically applied loads. However, these joists have low stiffness in the lateral and torsional directions, requiring bracing by sheathing and additional bridging elements. During construction, workers may walk on these I-joists and induce lateral buckling,which could lead to worker falls. Walking loads contain both vertical and horizontal loading components which could induce lateral buckling. The purpose of this paper was to explore the loading and deflection of workers walking on unbraced I-joists to see if lateral buckling was initiated. A safety platform allowed workers to walk on unbraced I-joists safely. Measurements of the horizontal load and deflection of the top flange at mid span showed increasing load and deflection due to increased worker static weight, respectively. Differences in the load and deflection were observed between I-joists of different lengths and manufacturers. The phenomenon of lateral buckling may be more serious for overweight workers since the addition of horizontal load decreases the vertical load needed for buckling,and increased deflection may increase the tendency of workers to fall from unbraced joists.
Wood; Construction; Construction-industry; Construction-materials; Construction-workers; Fall-protection; Workers; Risk-factors; Exposure-levels; Accidents; Accident-potential; Injuries; Traumatic-injuries; Humans; Men; Women; Safety-measures; Weight-factors
Daniel P. Hindman, Department of Wood Science and Forest Products, Virginia Tech, 1650 Ramble Road, Blacksburg, VA 24061
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Research and Practice for Fall Injury Control in the Workplace: Proceedings of International Conference on Fall Prevention and Protection
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Virginia Polytechnic Institute and State University
Page last reviewed: April 1, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division