The performances of seven full-scale, fixed-supported reinforced concrete (RC) beams were investigated with the four-point bending test in this study. One of the RC beams was a reference beam (Ref) and six were strengthened beams. The strengthening of the RC beams was performed with near surface mounted (NSM), external bonded reinforcement (EBR), friction hybrid bonding (FHB), and hybrid techniques. Steel bars, CFRP bars, CFRP sheets, and mechanical fastener systems were used in the strengthening processes, according to the requirements of the applied techniques. The experimental results were evaluated for the effects of strengthening techniques and materials on the load-deflection response, ultimate load-carrying capacity, ductility, dissipated energy, failure modes, strain, and crack pattern. Strengthening applications using the NSM technique, with conventional steel, increased the load-carrying capacity of the RC beams by 22-24.9% while increasing their total energy dissipation by 40.7-68.9%. The load-carrying capacity was increased by 3.7-11.9% in RC beams strengthened by CFRP sheet and CFRP bar. However, except for the FHB technique, CFRP-applied RC beams could not perform the inelastic behavior. The FHB strengthening technique increased the load-carrying capacity and total energy dissipation of the beam by 11.6% and 21.2%, respectively. The results showed that NSM-Steel, NSM-Steel/90, and FHB-CFRP techniques quite improved the performance of the RC beams for both the elastic and plastic regions, while both of EBR-CFRP and Hybrid-CFRP techniques improved the elastic behavior of the RC beams to a great degree.