Response of seawater sea sand coral aggregate concrete columns reinforced with hybrid glass fiber reinforced polymer and stainless steel bars under axial compression

The potential application prospects for concrete structure in island engineering and marine structures are increasing through the utilization of concrete composed of seawater, sea sand and coral aggregates (SSCC) combined with hybrid reinforcement. This innovative approach effectively addresses the diminishing availability of freshwater and river sand resources, as well as steel corrosion. This study explores the axial load carrying capacity and ductility of columns reinforced with combination of stainless steel bars and GFRP bars. The study conducted tests on 36 columns, varying in strengths (30 MPa, 40 MPa, 50 MPa), reinforcement types (GFRP bars (G group), stainless steel bars (S group), GFRP bars-stainless steel bars (GS group)), and reinforcement ratios (1.01%, 1.56%, 2.26%). The results exhibit positive correlation between the axial load carrying capacity of the column and both the strength grade and reinforcement ratio. In general, SSCC columns reinforced with stainless steel bars (S-SSCC) exhibit the highest axial load carrying capacity, followed by those reinforced with combination of GFRP bars and stainless steel bars (GS-SSCC), and SSCC columns reinforced with GFRP bars (G-SSCC) exhibit the lowest axial load carrying capacity. Furthermore, the axial load carrying capacity was determined utilizing ACI 440, CSA S806 and the finite element software ABAQUS. The results derived from the analytical model exhibited strong agreement with those obtained experimentally. Ductility analysis results suggest that columns with hybrid reinforcement can significantly improve ductility compared to those with only GFRP bars.