EXPRIMENTAL STUDY ON SEISMIC BEHAVIOR OF HIGH-STRENGTH CONCRETE FRAME JOINTS WITH HIGH-STRENGTH STIRRUPS

Four concrete frame joint specimens with high-strength stirrups and one with normal strength stirrups were tested under low cyclic reversed loading to investigate the seismic behavior of high-strength concrete frame joints. The failure pattern, hysteretic behavior, energy dissipation, shear behavior, and stirrup stress of high-strength concrete frame joints were studied. The influence of stirrup yield strength, stirrup volume ratio, and stirrup configuration on the shear bearing capacity, ductility, energy dissipation, and shear deformation of specimens were analyzed. The results indicate that the failure process of specimens with high-strength stirrups are similar to specimens with normal-strength stirrups; increasing stirrup yield strength has limited enhanced effect on bearing capacity of specimens, but the ductility, energy dissipation, and restriction of shear deformation in the joint core are improved effectively. At the ultimate displacement, normal-strength stirrups reach their yield strength, and the stirrup strength is nearly fully developed in specimens with composite high-strength stirrups. The specimens with composite high-strength stirrups show better seismic performance.