Prestressed FRP flexural strengthening of softwood glue - Laminated timber beams

Brittle failure of glue-laminated (glulam) timber beams usually occurs on their tension faces. Fibrereinforced plastic (FRP) composite laminates, bonded to the beam soffit, have successfully been used to enhance their structural performance and induce ductile/plastic compression behaviour. The bending strength, stiffness and ductility can be further improved by pre-tensioning the FRP before bonding it in the tension zone of the glulam beam. Analytical models to predict the stiffness and flexural strength of prestressed FRP reinforced glulams are outlined in this paper. The elastic-plastic behaviour of FRP reinforced timber and various failure modes are incorporated. The theoretical results indicate that the performance of low-strength timber can be significantly enhanced by prestressing with FRP composites.