Axial Load–Moment Interaction Diagram of Fibrous SCC Bridge Compression Members Reinforced with GFRP Bars and Spirals

While the bridge design codes and standards provide provisions for designing concrete bridge members reinforced with fiber-reinforced polymer (FRP) bars, the axial–flexural behavior of fibrous self-consolidating concrete (FSCC) columns reinforced with glass-FRP (GFRP) bars remains underexplored. To address this gap, 10 full-scale FSCC columns—each 1,500 mm in height and 305 mm in diameter—were tested under four eccentricity levels: 0%, 16%, 33%, and 66% of the column size. The study investigated longitudinal reinforcement ratios and eccentricity levels on the axial–flexural performance of GFRP-reinforced FSCC columns. Test results revealed that FSCC significantly enhanced the axial and flexural performance of GFRP-reinforced columns, particularly under high eccentric loading. The fibers improved strain capacity, delayed cover spalling, and enhanced ductility. Columns with higher longitudinal reinforcement ratios exhibited improved ductility and maintained structural integrity under high eccentric loads. A load–moment interaction model was developed for FSCC-GFRP columns and validated against the experimental results, showing closer agreement than approaches that neglect FSCC effects. The findings underscore the benefits of incorporating FSCC in design models and provide a basis for refining code provisions for GFRP-RC bridge members.