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UBC Theses and Dissertations

Bond analysis of fibre reinforced polymer (FRP) rods and timber beams Walline, Devin Rodney


The use of timber in structures has been common for thousands of years, however, in the last century timber has been losing a significant market share to other construction materials such as concrete and steel due to their superior load carrying capabilities. In order for timber to be widely utilized as a structural material, a solution needs to be found which will provide increased structural capacity and could potentially act as a strengthening or repair method in the event of building code changes or damage. One potentially attractive solution is to incorporate high strength fibre reinforced polymer (FRP) rods as a reinforcement similar to that of steel in reinforced concrete. This can be completed through the application of near surface mounted (NSM) FRP rods along the soffit of the beam to act as a flexural reinforcement. For this strengthening method to be feasible, the behaviour of the bond between the FRP rod and timber material must be understood to prevent bond failure which is sudden and brittle. This study was conducted to determine the impacts of different variables on the bond behaviour between FRP rods and timber beams. The studied variables included loading type, FRP material, rod diameter, notch size, and bonded length. In total 93 specimens (75 flexural and 18 double shear) were prepared and tested with important performance measures being recorded, including load at failure, failure mode, load-slip relationship, and strain distribution. Results showed that FRP material, rod diameter, and bonded length were all statistically significant variables when considering the bond stress. From these results, linear regressions were conducted to quantify the relationships and determine a required development length in order to reach the ultimate load in the FRP rod given a specific loading condition. In addition, it was found that loading the FRP rods in an axial manner resulted in a relative increase in bond of between 5.4 and 13.3 depending on rod diameter and bonded length.

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