The effect of span-to-depth ratio on the impact bending strength of poplar LVL

In this study, it was studied the effect of span-to-depth ratio on the impact bending strength of laminated veneer lumber (LVL). For the study, LVL boards were produced from rotary-cut poplar veneer using phenol formaldehyde (PF) adhesive. Test samples were prepared from the boards to determine impact bending strength, density, moisture content, and tensile-shear strength. In addition, the compression ratio and densification ratios of LVL for each panel was determined. The impact bending strengths were tested in flatwise and edgewise directions for different span-to-depth ratios, i.e., 7.5, 10, 12.5, 15, 17.5, and 20. The highest impact bending strength was measured when the span-to-depth ratio was 20. The lowest impact bending strength was measured when the span-to-depth ratio was 10. There was a parabolic relationship between impact bending strength and the span-to-depth ratio. In addition, the test results showed that the impact bending strength of all of the samples tested in the flatwise direction were significantly higher than those tested in the edgewise direction.