Test on axial compression performance and bearing capacity calculation of GFRP bars reinforced coral aggregate marine concrete columns exposed to tidal area

In order to solve insufficient durability of steel bars and shortage of offshore construction materials, a new type of glass fiber reinforced polymer (GFRP) bars reinforced coral aggregate marine concrete column was proposed. 28 columns in marine tidal area were tested under axial compression. Firstly, the failure process of the specimens was observed, the load-displacement curves and the stress-strain data were obtained. Then, the failure mechanism of the specimens and the influence of various parameters on the mechanical properties were analyzed. At last, the bearing capacity calculation of this new type of member in the tidal area was discussed. The results show that the failure modes of GFRP bars reinforced coral aggregate marine concrete columns include wide and sparse cracks on the surface, coarse aggregate fracture and cover concrete divided into strips. Compared with the reinforced concrete (RC) specimen, the bearing capacity of GFRP bars reinforced coral aggregate marine concrete specimen decreases by 38%, and the strain of characteristic points is smaller. For GFRP specimens, increasing the reinforcement ratio of longitudinal bars or spiral stirrups can’t effectively improve the bearing capacity of specimens, but can improve their deformation performance. In the short-term tidal environment within 270 days, the bearing capacity of specimens first decreases and then increases, and the ductility shows a fluctuating trend with a variation amplitude of 25%. Finally, the calculation formulas for calculating the bearing capacity of the GFRP bars reinforced coral aggregate marine concrete columns in the tidal area were proposed by fitting and introducing variation parameters of material property.