High-Strength Concrete Circular Columns with TRC-TSR Dual Internal Confinement

The standard requirements for transverse steel reinforcement (TSR) confinement in reinforced-concrete (RC) columns are mainly to provide the following: ductile behavior, minimum axial load capacity of the column’s core, and prevention of longitudinal bars buckling. It is well-known that the passive confinement due the TSR action is less effective in high-strength concrete (HSC) compared to normal-strength concrete (NSC). Therefore, the TSR amounts required by the standards for HSC columns are high, and in some cases, especially in the lower stories columns of high-rise buildings, are impractical. This paper presents a new construction method using textile-reinforced concrete (TRC) as internal confinement together with reduced TSR amounts. Moreover, comparison of the proposed method with RC columns casted in fiber-reinforced polymer (FRP) stay-in-place forms as additional external confinement, is presented. Eleven large-scale column specimens were tested under axial compression. The results give an insight on the application feasibility of the proposed construction method. It is shown that the TRC-TSR dual internal confinement action can be an option to reduce the standard required TSR amounts while maintaining similar levels of ductile behavior.