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Reinforced concrete (RC) infrastructure is an essential part of modern civilization. However, the serviceability of RC infrastructure in extreme weather has become challenging due to the susceptibility of the initiation of cracks. Hence, the demand for strengthening and retrofitting RC infrastructure is rapidly increasing. The RC specimens strengthened with existing externally bonded reinforcement (EBR) and near-surface mounted (NSM) techniques; however, they suffered a prematurely brittle or debonding failure. Hence, the merging of side near surface mounting (SNSM) and side externally bonded reinforcement (S-EBR) methods ended up resulting in the development of an innovative side hybrid (SH) strengthening approach that is designed to overcome these drawbacks. In this investigation, six rectangular RC beam specimens were flexurally strengthened utilizing carbon fiber-reinforced polymer (CFRP) with the SH technique, and then four-point bending experiments were performed to failure. The beam specimens were categorized into two types: (I) control specimens and (II) specimens strengthened with the SH technique applying CFRP varying bonded length from 1600 mm to 1900 mm. The initial cracking, yield, and ultimate load-bearing capabilities, deflection, failure modes, cracking characteristics, stiffness, energy absorption capacity, and strain on the utmost fiber of concrete, the tensile strain of major steel rebars, SNSM bars, and S-EB plates were assessed from the experimental investigation. The SH technique substantially improved the flexural performance of the beam specimens. The initial cracking load, yield, and ultimate load-bearing capabilities were enhanced remarkably by 387%, 108%, and 163%, respectively, over the reference specimen. The flexural stiffness and energy absorption capacity substantially improved by 120% and 103%, respectively, compared with the reference specimen. [ABSTRACT FROM AUTHOR]

Existing structural components require strengthening after a certain period of time due to increases in service loads, errors in design, mechanical damage, and the need to extend the service period. Externally-bonded reinforcement (EBR) and near-surface mounted (NSM) reinforcement are two preferred strengthening approach. This paper presents a NSM technique incorporating NSM composites, namely steel and carbon fiber-reinforced polymer (CFRP) bars, as reinforcement. Experimental and analytical studies carried out to explore the performance of reinforced concrete (RC) members strengthened with the NSM composites. Analytical models were developed in predicting the maximum crack spacing and width, concrete cover separation failure loads, and deflection. A four-point bending test was applied on beams strengthened with different types and ratios of NSM reinforcement. The failure characteristics, yield, and ultimate capacities, deflection, strain, and cracking behavior of the beams were evaluated based on the experimental output. The test results indicate an increase in the cracking load of 69% and an increase in the ultimate load of 92% compared with the control beam. The predicted result from the analytical model shows good agreement with the experimental result, which ensures the competent implementation of the present NSM-steel and CFRP technique. [ABSTRACT FROM AUTHOR]