Hysteretic behavior of the corroded recycled aggregate concrete columns with ultra-high strength bars

The seismic behavior of six corroded recycled aggregate concrete (RAC) columns with ultra-high-strength bars (UHSB) was investigated through quasistatic test and numerical analysis. The main parameters include different corrosion ratios, axial load ratios (ALR), and stirrup ratios. The results revealed that: The damage development of the corroded specimen sped up with increasing corrosion ratio and ALR, and the corroded specimens suffered brittle shear failure due to the stirrup fracture or the concrete failure. The difference in carrying capacity of the specimens with low corrosion ratios and ALR was relatively small, while the deformation capacity was significantly reduced with increasing corrosion ratios and ALR. Reinforcement corrosion had a minor effect on the strength and stiffness degradation but would reduce the maximum cumulative energy dissipation capacity. By combining residual drift and residual crack width, the corroded specimens all could meet the limit of repairable residual drift and crack width before 4% drift, showing satisfactory resilient performance. Based on the modified corrosion models of materials, the numerical analysis showed the detrimental and coupling impact of the high ALR, high corrosion ratio, and low stirrup ratio on the carrying and deformation capacity. Through numerical analysis data, an equation was proposed that can satisfactorily predict the peak drift of the corroded columns with UHSB.