Impact of High-Strength Reinforcement on Ductility of Normal-Strength Reinforced Concrete Column

The ductility of reinforced concrete columns can be significantly influenced by the configurations and material properties of the confining bars. Extensive research is required to comprehend the limitations on yield strength imposed by certain building codes, particularly concerning high-strength reinforcement. AS 3600:2017 and ACI 318-19 codes restrict the yield strength of confinement reinforcement to 800 MPa and 700 MPa, respectively. This study investigates the ductility of reinforced concrete columns using five different confining bar configurations, two concrete compressive strengths (30 MPa and 50 MPa), two longitudinal reinforcement yield strengths (420 MPa and 500 MPa), and four transverse reinforcement yield strengths (420 MPa, 500 MPa, 700 MPa, and 1000 MPa). The diameter of the confining bars is adjusted to meet the required area estimates from ACI 318-19 and AS 3600:2017 codes. Additionally, finite element analysis is conducted using the 3D-NLFEA package. The results demonstrate the safety and adequate ductility provided by high-strength steel in reinforced concrete columns. Furthermore, a simple formulation for column ductility, which integrates the confining bar configurations, is proposed based on the numerical study.