L 形截面部分包覆钢-混凝土组合柱轴压性能试验与承载力计算

To study the axial compression performance of L-shaped partially encased composite steel-concrete (LPEC) columns, axial compression tests of six LPEC short columns were conducted. The influence of critical parameters, such as steel content, link spacing and section aspect ratio, on the load-displacement curve, bearing capacity, stiffness, ductility coefficient and bearing capacity improvement coefficient of LPEC short columns was investigated. The typical failure mode and load-bearing mechanism of LPEC short columns were revealed. Results indicate that the LPEC column has good mechanical performance, and its failure modes are mainly concrete crushing in the middle of the column and local buckling of the section steel flange. Meanwhile, concrete collapse at the end of the column and link breaking around the weld seam also occur in some specimens. Increasing the steel content and decreasing the link spacing can obviously improve the confinement effect of concrete, and then improve the bearing capacity and ductility of the specimen, whereas the influence of the section aspect ratio on the bearing capacity is not significant. In addition, for LPEC columns, the axial compression bearing capacities calculated by the steel-concrete composite column bearing capacity formulas given in the specifications ACI318-14, Eurocode 4 and T/ CECS 719—2020 ‘Technical specification for partially-encased composite structures of steel and concrete’ are conservative due to failing to consider the concrete confinement effect. Based on the superposition principle, a simplified calculation method for the axial compression bearing capacity of LPEC columns considering the confinement effect of concrete was proposed, and the calculated results are in good agreement with the experimental results.