Seismic Behavior of Concrete Columns with CRB735 High-Strength Steel Reinforcement

Four concrete columns reinforced by CRB735 high-strength longitudinal steel reinforcement and stirrups were tested under cyclic loading to investigate its seismic behavior. And one concrete column with HRB400 normal strength longitudinal steel reinforcement and stirrups as a referring column was also tested. Changing parameters of tested columns included stirrup spacing and axial load ratio. Test results showed that all the concrete columns encountered concrete compression crash failure. Compared with the referring column with HRB400 reinforcement, the lateral yielding load of the column with CRB735 reinforcement increased by 17% and the lateral ultimate load increased by 15%; the stiffness degradation, the ductility and energy dissipation capacity were nearly unaffected. For the concrete column reinforced by CRB735 reinforcement, when the stirrups spacing increased from 50 to 100 mm, the ductility and energy dissipation capacity only decreased by 5% and 1%, respectively; and when the axial load ratio increased from 0.3 to 0.5, the ductility and energy dissipation capacity also decreased by 5% and 1%, respectively. The ratio between tested seismic shear capacities of the concrete columns with CRB735 reinforcement and those calculated by the design equation in GB50010 were 1.77, which should the design equation could be used to predict the shear capacity of concrete columns with CRB735 high-strength steel reinforcement on the safety side with a 1.77 safety margin.