Strengthening reinforced concrete beams: A comparative study of NSM and EB FRP systems using Cast3m software and theoretical analysis

Externally Bonded (EB) and Near-Surface Mounted (NSM) are the two well-known systems for strengthening Reinforced Concrete (RC) beams in flexure using Fiber-Reinforced Polymer (FRP) materials in the shapes of sheets, plates, bars, etc. Previous experimental research proved the effectiveness of the NSM FRP system compared to the EB FRP system. In this field, the current research presents a comparison between these systems using Cast3m software and theory. The beams were modeled in a 2D model, and the FRP materials were perfectly embedded in the concrete surface in order to ensure failure by FRP rupture. Firstly, the ability of the numerical model in predicting the flexural behavior of strengthened RC beams was tested against earlier experimental results. In this context, a good agreement between the predicted and the experimental results was obtained, where a significant convergence between P-o curves and similarity in failure way were observed. After that, the comparison was carried out. Hence, the comparison confirmed the effectiveness of the NSM FRP system in terms of strength, ductility, and economy. Moreover, it comes out that the use of NSM FRP system decreased the tension area and the stresses in concrete.