Performance of seawater sea sand coral aggregate concrete columns reinforced with hybrid glass fiber reinforced polymer and epoxy‐coated steel bars under axial compression

To improve the ductility of fiber reinforced polymer reinforced concrete structures while addressing the corrosion of steel bars and promoting the utilization of local materials, seawater sea sand coral aggregate concrete (SSCC) columns reinforced with hybrid glass fiber reinforced polymer (GFRP) bars and epoxy‐coated steel bars (ECSB) provide a viable solution for marine structures and island engineering. This innovative solution combines GFRP bars and ECSB to ensure axial load carrying capacity while improving ductility. In addition, considering local materials, ecological benefits, and good durability, it provides the possibility for large‐scale construction of marine engineering. This study considered three research variables, namely strength grades (C30, C40, and C50), reinforcement ratios (1.01%, 1.56%, and 2.26%), and reinforcement types (GFRP bars [G group], ECSB [E group], and GFRP bars and ECSB [GE group]). A total of 36 concrete columns were studied to evaluate their mechanical properties, including axial load carrying capacity and ductility. Regarding axial load carrying capacity, with the same reinforcement ratios and strength grades, the SSCC columns reinforced with ECSB exhibit the highest axial load carrying capacity, followed by SSCC columns reinforced with hybrid GFRP bars and ECSB, while SSCC columns reinforced with GFRP bars (G‐SSCC) show the lowest. Regarding ductility, the hybrid reinforcement type significantly improves the ductility of the column compared to G‐SSCC columns. Furthermore, the axial load carrying capacity and ductility of columns were predicted using American Concrete Institute 440.1R‐15, Canadian Standards Association S806‐12 (R2021), and the finite element software ABAQUS. The analysis results show good agreement with the experimental results.