Experimental study on flexural behavior of RC beams strengthened with prefabricated UHPFRC panels using EBR and grooving methods

This study investigates the flexural performance of reinforced concrete (RC) beams strengthened with precast ultra-high-performance fiber-reinforced concrete (UHPFRC) panels using externally bonded techniques. A key innovation is the application of a grooving method to enhance interfacial bond strength and stress transfer between the UHPFRC panels and the RC substrate. An experimental program was conducted on four beams, including a reference specimen, a beam strengthened using the conventional externally bonded reinforcement (EBR) technique, and two beams strengthened using different groove classes. The experimental results demonstrate that both strengthening techniques improve the flexural response of RC beams; however, the grooving method provides superior performance in terms of load capacity, ductility, crack distribution, and energy dissipation compared to the conventional EBR approach. The optimized grooving class increased flexural capacity by approximately 45% compared to the reference beam, accompanied by substantial improvements in ductility and energy dissipation. In addition, a simplified analytical model based on sectional analysis was developed to estimate the flexural capacity of the strengthened beams, and the predictions show good agreement with the experimental results. Overall, the findings indicate that the grooving method, when properly configured, provides an effective and reliable solution for strengthening RC beams using precast UHPFRC panels.