Hysteretic Behavior Of Steel Fiber-Reinforced High-Strength Concrete Columns With High-Strength Steel Bars

In this paper, an innovative column reinforced with HRB 600 MPa reinforcements and ultrahigh-strength (UHS) steel bars with low bond strength was proposed. To study the cyclic behavior of the proposed column, three square cantilever columns were designed and tested under constant axial load and cyclic lateral load. The main parameter was the area proportion of the UHS longitudinal bars in the column section. Under the principle of equal area design, three proportions of 35%, 65% and 100% were selected. As the test results showed, with the increase in the UHS reinforcement area proportion, the columns had an improvement in reducing the residual displacement. Employing the UHS steel bars in the column can make the lateral deformation distribution of the column more uniform in the plastic hinge zone, which means a lower deformation curvature and mitigated concrete damage, thus leading to a corresponding small damage index. Numerical models were established and verified by comparison with the experimental hysteretic response of the three columns under cyclic loading. Additionally, parametric studies consisting of the axial load ratio (ALR) and stirrup arrangement (SA) were conducted. The effects of these parameters on the seismic behavior of the proposed columns were further investigated.