Debonding characteristics of masonry structures retrofitted with FRP

In recent years engineers proposed to use Fibre Reinforced Polymer (FRP) as a strengthening material to retrofit masonry structures. In order to accurately and conservatively predict the overall capabilities of FRP-strengthened masonry wall, the basic characteristic of shear debonding must be first studied and understood. For shear failures controlled by FRP debonding, stresses in the FRP at failure are controlled by the ultimate bond strength between the FRP and masonry. However, the research in this area is extremely limited for masonry. Hence in this paper, the existing models for estimating FRP strengthened concrete bond capacity due to pure shear are assessed based on a test database of masonry collected from the available literature. The results indicate that the test-to-predicted ratios for all models are generally less conservative although they were performing well when the testing data for concrete was used. A new effective length model was then proposed from this study to improve the accuracy of the model.