EXPERIMENTAL STUDY ON SEISMIC BEHAVIOR OF HIGH-STRENGTH CONCRETE COLUMNS WITH HIGH-STRENGTH STIRRUPS

The experiments of six high-strength concrete columns confined with composite stirrups were performed under high axial compression forces and low cyclic reversed loading. The failure process,failure modes,hysteresis characteristics, ductility and energy dissipation are investigated, and the stress level of the transverse reinforcement is evaluated. The results of the comparison between high-strength stirrup columns and normal-strength stirrup columns indicates that increasing stirrup strength is not helpful to the increase in the lateral bearing capacity of specimens, however, it can improve the ductility and energy dissipation of specimens significantly. At the ultimate displacement, the core concrete confined with high-strength stirrups was not crushed obviously, furthermore, stirrups did not reach the yield strength and could supply efficient confinement to the core concrete. At a given stirrup ratio, the aseismic behavior of columns with small stirrup spacing and stirrup diameter is better than those with large stirrup spacing and stirrup diameter.