Structural behavior of HPC columns reinforced with CFRP bars under axial loading

This study investigates the axial compressive behavior of high-performance concrete (HPC) columns reinforced with carbon fiber-reinforced polymer (CFRP) bars, motivated by CFRP's high strength, fatigue resistance, and corrosion immunity. Despite these advantages, limited research has constrained its practical use. Eight HPC columns (150 × 150 mm cross-section, 1200 mm height) made of M50-grade concrete with 8% silica fume and superplasticizer were tested under axial loading. Key parameters included axial load capacity, deformation, failure mode, and ductility. Results showed that CFRP-reinforced columns exhibited only a slight 5.7% reduction in ultimate load compared to steel-reinforced counterparts. However, CFRP specimens absorbed approximately 8% more energy while maintaining comparable ductility. No CFRP bar rupture occurred during testing; the maximum strain recorded in the longitudinal CFRP bars reached approximately 65% of their ultimate tensile strain capacity (2600 μm/m out of 4000 μm/m). Theoretical strength predictions using existing confined-concrete models aligned with experimental data. Overall, the study demonstrates that CFRP longitudinal bars and stirrups offer a viable alternative to conventional steel reinforcement in HPC columns. The minor reduction in load capacity is offset by improved energy absorption and environmental benefits, including corrosion resistance and potentially longer service life. These findings support broader application of CFRP in concrete structures, particularly where durability under aggressive conditions is critical. The work contributes valuable experimental data and validates analytical models, helping to bridge the knowledge gap hindering wider adoption of CFRP reinforcement in real-world construction.