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Effect of environmental conditions on the flexural properties of wood I-beams and lumber

Informally Refereed

Abstract

Flexural properties as affected by environmental conditions were evaluated for full-sized wood composite I-beams webbed with oriented strand board (OSB), randomly oriented flakeboard (RF) and 3-ply Structural I plywood (PLY). Solid-sawn southern pine 2 by 10's, ordinarily used in light-frame building construction, were also tested for comparative purposes. Environmental conditions selected were 65 percent relative humidity (RH) (dry), 95 percent RH (humid) at 75°F, and 24-hour water-spraying (wet) at ambient temperature. In the dry condition, the OSB group carried the largest load among the four beam types, but the load capacities of the four beam types were not significantly different in the humid and wet conditions. Deflections at maximum load of the four beam types were significantly different in the three environmental conditions. The value for the lumber group was consistently higher than the I-beam types in each test condition. Loads at I-inch deflection for the four beam types were also significantly different in the three environmental conditions. However, the value for the lumber group was consistently lower than those of the I-beam types. In the dry condition, most failures that occurred in the PLY group were in shear mode, while the majority of the OSB and RF members failed in bending, and the failures occurred in the flanges. In the humid condition, most of the I-beam and lumber specimens failed in shear and bending, respectively. In the wet environment, however, most of the I-beams failed in web buckling, while most of the lumber members failed in bending.

Citation

Chen, Gwo-Huang; Tang, R.C.; Price, E.W. 1989. Effect of environmental conditions on the flexural properties of wood I-beams and lumber. Forest Products Journal 39(2):17-22
https://www.fs.usda.gov/research/treesearch/7982