Eccentrically loaded corroded RC columns repaired with advanced composites: Experimental testing and analytical modeling

This study provides direct experimental evidence comparing carbon fiber-reinforced polymer (C-FRP) and carbon fabric-reinforced cementitious matrix (C-FRCM) systems for rehabilitation of short reinforced concrete (RC) columns. Fifteen RC columns were tested under eccentricity-to-depth ratios ( e/h ) of 0.0–0.3. Corroded columns were pre-damaged through accelerated corrosion, resulting in steel losses of 22% in longitudinal bars and 42% in ties. Corrosion reduced the load capacity by 41% under concentric loading and by an average of 17% under eccentric loading. Both repair systems effectively restored the load capacity of the corroded columns. C-FRP repairs increased the load capacity by 80–167%, while C-FRCM achieved load capacity gains of 49–86%. The lower effectiveness of C-FRCM was ascribed to a premature debonding at the fabric–mortar interface. A new analytical model was developed to predict the load capacity, incorporating material nonlinearities, corrosion-induced degradation, and combined confinement from internal steel ties and external composite wraps. Model predictions were validated using experimental results from this study and additional literature data. The model produced P–M interaction diagrams consistent with experimental trends, confirming its reliability and practical use as a simple, accurate tool for structural evaluation and retrofit design.