DUCTILITY OF STEEL FIBER REINFORCED HIGH-STRENGTH CONCRETE COLUMNS UNDER CYCLIC LOADING

Based on the test of 26 steel fiber reinforced high-strength concrete columns under cyclic loading, the factors affecting the column ductility are analyzed. These factors include the axial compression ratio, the characteristic value of stirrups, the characteristic value of steel fiber, the span to depth ratio and the longitudinal reinforcement. It is demonstrated that the steel fiber has better effects on improving the brittle failure state and increasing the seismic ductility of high strength concrete columns. But the mechanisms of the steel fiber and the stirrups for reinforcing the ductility of high strength concrete columns are different. As a result, the equal seismic ductility cannot be obtained by replacing the stirrups with the equivalent volume ratio of steel fiber. A formula for calculating the displacement ductility coefficient is proposed.