A new model for determining the shear contribution of FRP in RC beams strengthened with U-shape FRP sheets

Due to their lightweight, high tensile strength, and ease to install on irregular surfaces, the use of FRP systems for the repair and strengthening of reinforced concrete structures has become an accepted practice within civil engineering community and codes. Extensive research has been conducted on structural members to identify the improvement in their flexural and axial capacity due to FRP strengthening. However, the analytical and experimental studies on shear strengthening with FRP systems, especially exact determining FRP contribution, are limited. This study provides a multi-layer artificial neural network and group method of data handling approach for predicting the shear contribution of FRP in RC beams strengthened by externally bonded FRP sheets. To achieve the main purpose; ultimate strain of FRP, thickness of FRP, elastic modulus of FRP, width, spacing and angle of FRP sheet, effective depth of FRP, width and of effective depth of beam, compressive strength of concrete, and shear span to depth ratio were considered as input parameters while the shear contribution of the FRP is calculated as the target one. In order to verify the validity of the proposed models, a comparative assessment was conducted between experimental results and predicted values obtained directly from the models and existing guideline equations such as ACI 440, fib-TG9.3, and JSCE. The results indicate that the proposed models could predict the shear contribution of FRP in RC beams strengthened by FRP sheets with a good degree of precision and can be used as a confident approach for pre-design concrete beams strengthened with externally bonded U-shape FRP plates.