Round-ended concrete-filled steel tube columns under impact loading: Test, numerical analysis and design method

This paper reports experimental and numerical investigations on the behaviours of round-ended concrete filled steel tube (RE-CFST) columns under combined pre-axial and impact loadings. Twelve RE-CFST specimens were tested to assess the influences of the cross-sectional aspect ratio, impact velocity and pre-axial loading on the impact-resisting performance. The failure patterns, impact force and mid-span deflection histories were obtained and analyzed. Test results showed that increasing pre-axial loading led to a decrease in the plateau impact force and an increase in the mid-span deflection. In addition, the finite element (FE) models were developed and calibrated with the experimental data, and then employed for evaluating the working mechanism of typical RE-CFSTs during the whole impact process and performing parametric investigations. According to the experimental and numerical results, empirical formulae were proposed for predicting the plateau impact force of RE-CFST columns subjected to lateral impact.