Procedure for determining the strength to shear of reinforced concrete beams strengthened with NSM CFRP

The use of the near-surface mounted (NSM) technique in the strengthening of reinforced-concrete (RC) structures with carbon fiber-reinforced (CFRP) has proven to be effective for improving the shear strength and bending performance of RC beams. However, the analytical models available in the literature have not yet been sufficiently consolidated, and designers require an analytical method capable of designing RC beams strengthened with NSM CFRP laminates. To address this limitation, a review of the analytical models for design and slip models for concrete-adhesive-CFRP bonding using the NSM technique was performed. A critical analysis was conducted to identify the limitations of the models, and then a procedure was proposed according to the assessed studies. Seventy experimental results for RC beams from seven works were used to evaluate the performance of the procedure, and the results were compared with four available analytical proposals. Variables such as the cross section of the laminates and failure modes were analyzed. The proposed procedure exhibited an average V-f(ana)/V-f(exp) ratio of 0.94, and higher accuracy compared to the available models. The laminate section (perimeter and area) affected the results, and the most common failure mode was related to the concrete substrate.