<p>This study experimentally investigates the effects of different repair and strengthening techniques on the flexural behavior of damaged reinforced concrete (RC) beams and concrete elements. The research consists of two phases: (i) epoxy injection was applied to flexurally damaged small-scale concrete specimens of varying strength classes; (ii) large-scale RC beams were first damaged under four-point flexural loading and then repaired using epoxy injection, GFRP, CFRP, and their combinations. All specimens were re-tested to evaluate strength and deformation recovery. The results showed that epoxy injection restored up to 97–118% of the original flexural strength in concrete samples and significantly increased flexural toughness. In RC beams, GFRP wrapping increased toughness by 365%, while the highest strength gains were obtained from GFRP wrapping (128.44%) and the CFRP wrapping combined with epoxy injection (127.5%). In conclusion, the findings indicate that various repair and strengthening methods can significantly improve strength and deformation capacity, offering effective solutions for post-earthquake structural rehabilitation.</p>