Fiber-Reinforced Plastic-Confined Wood Profiles Under Axial Compression

The objective of this research was to provide engineered wood products based on formed wood profiles for structural applications. The formed profiles can be optionally reinforced with technical fibers and/or textiles laminated onto the outer wood surface. The purpose of such composite confinement is to strengthen the wood profile in circumferential direction and to protect wood against environmentally induced damage. The presented research work deals with the analysis and testing of wooden tubes reinforced with fiber-reinforced plastic (FRP) composites. Axial compression tests were conducted to analyze the load-carrying behavior of timber columns with circular hollow cross sections. Static tests showed that the tubes were capable of sustaining high buckling loads as long as brittle failure modes could be prevented. Brittle failure was observed for unreinforced columns, whose longitudinal splitting was due to the expansion of the tubes in circumferential direction, resulting in tension perpendicular to the grain failure. The tests of reinforced tubes demonstrated that load-carrying capacity and ductility can be significantly enhanced by the composite confinement. Standard design equations were applied to estimate the load-carrying capacity of the composite tubes. The results obtained from experiments were used to verify the analysis.