The majority of timber bridges in the Province of Manitoba require flexural and/or shear strengthening to increase their load-carrying capacity in response to an increase in the allowable gross vehicle weight. The use of glass fibre-reinforced polymer (GFRP) has been investigated as an innovative approach for strengthening these bridges. This paper includes the results of an experimental program using half-scale and full-scale 200 by 600-mm, 10.4-m long beams. The half-scale beam specimens were tested to failure using different reinforcement ratios, including unstrengthened beams as control specimens. The cross section of these beams was 100 by 300 mm, and they were tested under four-point bending monotonic loading. The span of the beams was 4.0 m, with a shear span of 1.7 m. Twenty-two beam specimens, including seven plain timber and 15 timber beams reinforced with GFRP bars were tested. The GFRP bars were installed in grooves cut in the tension zone of the test beams. The grooves, 15 mm wide and 25 mm deep, were cut into the sides of the beams, with GFRP bars bonded to the timber using an epoxy resin. The three reinforcement ratios used were: 0.27, 0.41 and 0.82 percent. Test results using the proposed technique indicate a possible increase in the flexural strength in the range of 25 to 50 percent. Ductility of the beams was also increased. The preliminary results indicate that GFRP is a feasible material for the strengthening of timber bridges. This paper describes the experimental program and the test results.
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