Effectiveness of Externally Bonded and Near Surface–Mounted CFRP Reinforcement in Flexural Strengthening of RC Beams: Numerical Approach

Abstract

Externally bonded (EB) reinforcement and near surface–mounted (NSM) reinforcement were extensively studied to strengthen reinforced concrete beams in the last decades. However, few studies compare their effectiveness. This paper aims to study the effectiveness of EB and NSM strengthening techniques using carbon fiber–reinforced polymer (CFRP) strips in strengthening RC beams. In this study, three different parameters were studied, including the strengthening technique (i.e., NSM, EB), CFRP quantity, and NSM-CFRP distribution. In addition, two different bond behaviors were investigated, including perfect and cohesive models. A total of twelve beams were modeled, including six beams with perfect bond behavior and six beams with cohesive bond behavior. Each six tested beams include one control beam, two strengthened beams with EB-CFRP, and three strengthened beams with NSM-CFRP. All beams have the same cross-section dimensions, material properties, and steel reinforcement. The finite-element (FE) models were analyzed using a nonlinear FE analysis by ABAQUS software, and the results were validated with experimental works obtained from literature. In general, the developed FE models accurately predicted the ultimate strengths, strains, maximum deflections, and failure mode when compared to analytical and experimental results. For the same area of CFRP laminates, beams strengthened with the NSM system achieved higher ultimate strength but relatively lower stiffness when compared to beams strengthened with the EB system.