Behavior of concrete columns reinforced and confined by high-strength steel bars

With the rapid development of high-rise buildings and mega structures such as long span bridges and mega dams, etc. in recent years, the need of high strength structural materials becomes urgently required. For structural concrete, reinforcement from steel bars is a mandatory. Therefore, this paper investigate the effect of high-strength reinforcing steel bars in concrete columns. According to ACI 318M-14, the yield strength of steel bars used as longitudinal and shear reinforcement in structural concrete is limited up to 420 MPa, particularly for special seismic systems. Furthermore, the characteristics of high-strength steel bars particularly in terms of ductility (elongation) is one of the main issues. There is an assumption that the higher the strength of the material, the more brittle it is. Thus, high-strength steel bars with the grade of 550 MPa (above 420 MPa) were used as both longitudinal and transverse steels to study their effects on column capacity and ductility, respectively. The results show that high-strength steel bars are promising to be introduced for structural members, particularly concrete columns.