Assessment of design procedures for the use of externally bonded FRP composites in shear strengthening of reinforced concrete beams

Shear strengthening of reinforced concrete (RC) elements with fibre reinforced polymer (FRP) composites is actually a research topic far to be completely solved. Existing shear strength models lead sometimes to overly non-conservative results and need to be validated with a sufficient number of experimental tests. The aim of this work is to assess some common design models for the prediction of the shear capacity of RC beams strengthened with externally bonded FRP composites. The research is based on a wide database collected from recent literature and is mainly focused on the combination of the basic codes for RC structures (without strengthening) with current models for FRP shear strengthened structures. The research significance of this work is due to the lack of information on the performance of the above models when combined with basic codes. Particular attention was dedicated on the consistency of the models for FRP strengthened structures with Eurocode 2, since it assumes a method based on the truss model with variable inclination of the compressed strut. Lastly, some improvements of the model proposed by Pellegrino and Modena, which takes into account the interaction between steel and FRP contributions to the shear capacity, are proposed