Hysteresis performance of steel fiber-reinforced high-strength concrete-filled steel tube columns

The hysteresis performance of steel fiber-reinforced high-strength concrete-filled steel tube (SFHCFST) columns was investigated through experimental and numerical analysis. Quasi-static tests were conducted on eight SFHCFST columns and one high-strength concrete-filled steel tube column, subjected to constant axial and cyclic lateral loads. The seismic performance of the SFHCFST columns was experimentally studied, considering the effects of axial compressive load ratio (n), steel fiber volume content (Vf), thickness of steel tube (t), and concrete strength. The test results revealed that an increase in concrete strength led to improved lateral strength but weakened plastic energy-dissipation capacity and ductility. Adding steel fibers to the concrete not only enhanced the lateral strength of columns, but also improved ductility and deformability, mitigating the negative impact of brittleness resulting from high concrete strength. The seismic performance of SFHCFST was significantly enhanced as the thickness of steel tube increased. However, an increase in axial load led to a decrease in ductility and an increase in lateral strength. A finite element (FE) model was established and verified based on experimental results, followed by a parametric analysis considering steel yield strength, length-to-diameter ratios and concrete strength.