Abstract:
Increasing efforts are being made to promote the use of sustainable construction materials such as timber. The bonding of glass fibre reinforced polymer (GFRP) plate to low-grade timber possesses considerable potential for enhancement of its flexural properties and can be easily and effectively integrated into the glulam manufacturing procedure. The research reported in this thesis comprises both experimental studies and numerical modelling to investigate the development of a cost-effective GFRP reinforced glulam beam using Irish grown Sitka spruce. Hygrothermal compliance was examined of adhesively bonded wood-wood and FRP-wood bond connections, which comprised large proportions of juvenile wood. Strong durable bonds of high quality were obtained when bonding specific GFRP reinforcements with certain conventional wood laminating adhesives, and also when using thin bond lines (0.5mm) with specific epoxy adhesives. Flexural testing of unreinforced glulam and glulam, which was reinforced with practical percentages of GFRP plate in the tension zone, demonstrated that the addition of the reinforcement resulted in moderate enhancements in the stiffness while more significant improvements in the ultimate moment capacity were obtained. Pseudoductile behaviour was associated with the GFRP reinforced beams in comparison with the linear elastic behaviour of the unreinforced beams. A nonlinear finite element plane stress model, which employs anisotropic plasticity theory for the timber, was developed. The finite difference technique was employed to determine global moduli of elasticity for each lamination and material test studies were undertaken to characterize the behaviour of the timber for the model. The failure model used was the maximum stress criterion. The simulated behaviour showed strong agreement with the experimental behaviour.