Measurement and Computational Modeling of the Mechanical Properties of Parallel Strand Lumber

Wood products tend to have a very large variability resulting in over design of engineered products. A relatively new structural composite wood material, Parallel Strand Lumber (PSL) has been introduced with the expectation to reduce the inherent biological variation wood products tend to have between specimens and species. A probabilistic approach is being taken to model effective properties, strain, and strength of PSL. Biological variation of grain angle, effective properties, biological defects such as voids, strand dimensions, and constitutive species composing each PSL member were taken into account. Methods will be used to verify experimental results for the ultimate stress or maximum stress, modulus of elasticity, lengthwise variability, and stress-strain behavior of Parallel Strand Lumber made from southern yellow pine. Experimental compression data is measured from 64 A specimens with the dimensions 1.10 in x 1.10 in x 3.25 in and 162 B specimens with the dimensions 1.55 in x 1.55 in x 5.00 in. This data yields compression modulus of elasticity values of 1840 ksi with a standard deviation of 300 ksi for the A specimens and 1860 ksi with a standard deviation of 400 ksi for the B specimens. The ultimate stress at failure of the A specimens is 7.71 ksi with a standard deviation of 1.09 ksi and the ultimate stress at failure of the B specimens is 8.97 ksi with a standard deviation of 1.02 ksi. Experimental bending data is measured from 1 A specimen with the dimensions 5.25 in x 5.25 in x 192 in and 9 B specimens with the dimensions 1.55 in x 1.55 in x 96 in. These experiments yield edgewise modulus of elasticity values in bending of 1775 ksi with a standard deviation of 25 ksi for the A specimen and 1648 ksi with a standard deviation of 150 ksi for the B specimens