纤维增强混凝土外包钢管组合柱轴压性能的试验与理论研究OA

To address corrosion issues in traditional concrete-filled steel tubular columns under extremely cor-rosive environments,a novel fiber-reinforced concrete-encased circular steel tubular composite column was proposed,and the experimental and theoretical research on its axial compression behavior was conducted.Four specimens were designed,including pure steel tube(ST),normal concrete-encased steel tube(NC-ST),high-performance concrete-encased steel tube(HPC-ST),and ultra-high toughness cementitious composite-encased concrete-filled steel tube(UHTCC-CFST).Based on experimental and theoretical analyses,an axial compressive bearing capacity calculation model considering local buckling of the inner steel tube was devel-oped.Test results show that ST yields at the load of 1 552 kN.NC-ST exhibites a 45.8%higher yield load(2 264 kN)but 50%lower yield strain than ST.HPC-ST achieves the highest peak load(5 921 kN),but failes rapidly after the peak.After reaching the peak load(5 020 kN),the UHTCC-CFST exhibites a slow de-crease in bearing capacity.The axial strain corresponding to the point where the bearing capacity reaches 0.85 times the ultimate load exceeds 1.54%,which is 4.53 times the ultimate strain,demonstrating excellent ductility reserve.The proposed theoretical calculation model for axial compressive bearing capacity can pro-vide a design basis for the engineering application of composite columns with externally wrapped steel tubes.