The use of FRP composites in enhancing the structural behavior of timber beams

This paper describes aspects within an experimental and theoretical programme aimed generally at improving the structural performance of laminated beams fabricated from Irish-grown Sitka spruce. Such timber is characterised by low density and small dimensions, is likely to distort when dried and tends to fail in tension due to the presence of knots. The well-established technique of laminating timber overcomes some of these disadvantages and the improvements are most marked with low quality donor material. It has been found that the addition of modest ratios of FRP composite reinforcement can suppress tension failure in beams. The study of failure modes, particularly in tension-reinforced beams, is the main focus of this paper. It establishes that the ultimate load capacity depends on the behavior of the timber in compression, resulting in much more consistent behavior as well as a considerable increase in flexural stiffness.