Effect of Lamina Thickness on Parallel-to-Grain Strength in Small Douglas-Fir Samples

Timber has a rich history of use in bridge construction. Its small environmental footprint, pleasing aesthetics, long-term durability, and cost effectiveness assure its continued use for generations to come. That said, continued improvements in design, analysis, and construction with timber are highly sought. The inclusion of high-strength tensile-face laminations, such as fiber reinforced polymers, is increasingly common. This research investigated the impact of timber lamina thickness on axial compression strength parallel to the grain. Results showed that strength variability decreased with decreasing lamina thickness. This finding suggests that stronger and stiffer timber beams and stringers can be achieved by applying thinner wood lamina to the extreme compression faces. As such, the information contained herein can be used by glue-laminated-timber and fiber reinforced polymer/timber bridge designers to more effectively utilize wood as a structural material in bridges.