Effect of density on the properties of oriented strandboard web stock used in wood I-joists.

摘要

Numerical simulation of structural member behavior requires knowledge of mechanical properties. This study proposes a methodology to obtain reliable mechanical properties of the oriented Strandboard (OSB) web of I-joists, including variability. OSB panel samples were scanned by X-ray densitometry to measure in-plane density variation. Specimens were cut from predefined homogeneous density areas in three different orientations (parallel, perpendicular, and diagonal to the strong axis) to measure three basic elastic properties required for an elastic model of the OSB web of I-joists: modulus of elasticity (MOE) parallel and perpendicular to the panel's strong axis and shear modulus (G). Given the required small specimen size, shear modulus was determined using a combination of in-plane tensile MOEs, including MOE at 45 degrees . Results showed a strong relationship between OSB density and small-scale mechanical properties: coefficients of determination (R2) varied between 0.57 and 0.79. This provided information on I-joist OSB web mechanical properties as a function of density for input into a numerical model. Properties showed considerable variability in the 600 to 900 kg/m3 density range, with a 207 percent increase in tensile modulus of elasticity in the parallel direction, 187 percent in the perpendicular direction, and 172 percent at 45 degrees . The mechanics-based OSB shear modulus equation used proved to be reliable.