Experimental Study on the Seismic Behavior of Concrete Columns with 630 MPa High-Strength Stirrups

The widespread adoption of high-strength steel reinforcement in China has driven a growing demand for 600 MPa grade and higher-strength stirrups in engineering applications. This study experimentally investigates the seismic performance of concrete columns reinforced with 630 MPa high-strength steel stirrups. Six concrete columns were designed and fabricated, incorporating key variables including concrete strength, stirrup strength, and stirrup spacing ratio. Low-cycle reversed loading tests were subsequently conducted on these specimens, enabling a thorough evaluation of their seismic characteristics. Additionally, the study examines the cumulative damage effects and confining influence of 630 MPa high-strength stirrups on the core concrete. The findings reveal that concrete columns with a low ratio of 630 MPa high-strength stirrups exhibit enhanced seismic performance when the concrete strength is relatively low. However, with increasing concrete strength, the confinement efficiency of 630 MPa ultra-high-strength stirrups diminishes, leading to accelerated damage progression and reduced ductility. Both low- and high-strength concrete columns benefit from a high stirrup ratio, which provides effective confinement. Furthermore, 630 MPa high-strength stirrups help mitigate damage accumulation while enhancing yield displacement, peak displacement, ultimate displacement, ductility, and energy dissipation capacity. The use of 630 MPa high-strength stirrups not only ensures superior seismic performance but also reduces reinforcement requirements and improves construction efficiency.