Assessment of the bond behaviour of NSM FRP materials by pullout tests

Pullout tests are often used to determine the optimal bond length (Le) between Fibre Reinforced Polymers (FRP) and Reinforced Concrete (RC). Using the results of these tests, the Le and the local bond stress-slip relationship have also been obtained by performing inverse analysis with FEM-based numerical tools and analytical models. The Le parameter and the local bond stress-slip relationship participate in some design guidelines in the context of structural strengthening with FRP systems, and, therefore, their rigorous assessment is a target of high relevance. In this context, in the present work three types of bond tests are analysed to highlight their positive and negative aspects, and to recommend the most appropriate test setup for the bond characterization in terms of NSM flexural and shear strengthening