Timber as a primary structural material has been forced to continually evolve to keep abreast with the changing demands of the construction industry. This paper presents further research undertaken by Queen’s University Belfast to evaluate the advantages provided by the post-tensioning of timber members using novel basalt fibre reinforced polymer (BFRP) rods. Using the high strength, low density, highly durable BFRP tendons experimental investigations utilising the four-point bending method were conducted and monitored. From the experimentation it was found that there was an increase in load carrying capacity, a more favourable ductile failure mode and a further benefit of less net deflection due to the precamber induced by the post-tensioning prior to load application.
This paper describes a series of four-point bending tests that were conducted, under service loads and to failure, on unreinforced, reinforced and post-tensioned glulam timber beams, where the reinforcing tendon used was 12mm diameter toughened steel bar. The research was designed to evaluate the benefits offered by including an active reinforcement in contrast to the passive reinforcement typically used within timber strengthening works, in addition to establishing the effect that bonding the reinforcing tendon has on the materials performance.
The laboratory investigations established that the flexural strength and stiffness increased for both the reinforced and post-tensioned timbers compared to the unreinforced beams. The flexural strength of the reinforced timber increased by 29.4%, while the stiffness increased by 28.1%. Timber that was post-tensioned with an unbonded steel tendon showed a flexural strength increase of 17.6% and an increase in stiffness of 8.1%. Post-tensioned beams with a bonded steel tendon showed increases in flexural strength and stiffness of 40.1% and 30% respectively.