Strengthening of timber beams with unbonded FRP composites

Wooden bridges date back to the Roman age and had a remarkable expansion during the course of history. Therefore, reinforcing and upgrading of existing timber beams is often necessary. In the last twenty years, Fibre Reinforced Polymer materials (FRP) have been used intensively for reinforcement of timber beams. This paper presents the results of an experimental program on small timber beams (square cross-section of 96x96 mm and length of 2000 mm) strengthened with two different reinforcement techniques. According to the first technique, Carbon Fibre Reinforced Polymer (CFRP) pultruded plates were applied to the beam’s tension surface without the use of polymeric adhesive. The second reinforcement technique consists in the insertion of Basalt Fibre Reinforced Polymer (BFRP) bars into the timber beams to restore the continuity of cracked sections. The experimental campaign is dealing with the evaluation of bending strength and deformation properties of a significant number of un-reinforced and reinforced beams. Increases of beam capacity, bending strength and of modulus of elasticity and analysis of failure modes were measured and discussed