Flexural behavior of reinforced concrete T-beams strengthened with AA/CFRP hybrid systems

This study presents a comprehensive experimental and analytical investigation into the flexural behavior of reinforced concrete (RC) T-beams strengthened with hybrid Aluminum Alloy (AA) and Carbon Fiber Reinforced Polymer (CFRP) systems. The research program involved sixteen RC T-beams, including fourteen strengthened specimens utilizing AA plates, CFRP laminates, and their hybrid configurations, along with two control specimens for baseline comparison. All specimens were subjected to four-point bending tests to evaluate their structural performance. The experimental results demonstrated that all specimens exhibited flexural failure modes, with laminate debonding emerging as the predominant failure mechanism. The strengthened beams showed significant improvements in load-carrying capacity, with enhancements ranging from 18% to 77% for low reinforcement ratio specimens and 10% to 44% for high reinforcement ratio specimens. The findings suggest that an optimized hybrid system configuration can substantially increase beam strength while maintaining satisfactory ductility characteristics. Notably, specimens with higher reinforcement ratios exhibited less pronounced ductility reduction compared to their lower reinforcement ratio counterparts. Analytical predictions of load-carrying capacity were developed and compared with experimental results. The study revealed that the ACI-440.02R-19 provisions provided unconservative estimates for beams strengthened with AA plates, highlighting the need for refined design methodologies for such hybrid strengthening systems.