EXPERIMENTAL STUDY ON ASEISMIC BEHAVIOR OF REINFORCED CONCRETE COLUMNS WITH GRADE 600 MPa STEEL BARS

To investigate the aseismic behavior of RC columns with grade 600 MPa steel bars, five RC columns with grade 600 MPa steel bars and one RC column with conventional steel for comparison were tested under cyclic loading. The effects of steel bar strength, stirrup spacing and axial compression ratio on failure model, hysteretic behavior, bearing capacity and ductility, dissipation capacity, and degradation of stiffness and strength were analyzed. The test results showed that:the failure pattern of specimens is the bending failure, and the bond failure between the grade 600 MPa longitudinal bars and concrete and the fracture of longitudinal bars were observed. The bearing capacity and energy dissipation of specimens increased significantly with the improvement of steel bar strength, while the ductility and energy dissipation capacity of specimens decreased. Increasing the stirrup spacing decreased the ductility and energy dissipation capacity and accelerated the strength degradation of specimens in late loading, but there was little effect on bearing capacity of specimens. It is concluded that the RC columns with grade 600 MPa steel bars has a good aseismic behavior and can be used in aseismic structures by reasonable design.