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试验中设计了4组共12个十二边形中空夹层钢管混凝土柱,通过对其进行轴压试验,研究各试件的受力过程及破坏形态,测得荷载-应变关系曲线,观察内外钢管的局部屈曲现象。研究结果表明:十二边截面中空夹层钢管混凝土柱在轴压作用下,外钢管出现局部屈曲,形态与圆形截面的畸变屈曲类似,没有发生棱角之间的平板部位的局部屈曲;内钢管也发生了局部屈曲,并且只能发生向内的屈曲变形;试件破坏为钢管鼓曲和内部混凝土压碎,表现出良好的延性。建议的十二边截面中空夹层钢管混凝土柱的承载力设计公式能较好预测其轴压承载力。
In the experiment, four groups of 12 doubly-shaped hollow-walled CFST columns were designed. Through the axial compression test, the stress process and failure mode of each specimen were studied, and the load-strain curve was obtained. Local buckling phenomenon. The results show that the local buckling of the outer steel tube is similar to that of the circular cross-section, and the local buckling of the flat part between the corners does not occur. The inner steel tube Local buckling occurred, and only inward buckling deformation occurred. The specimens were damaged by the steel tube bending and internal concrete crushing, showing good ductility. The proposed design formula of bearing capacity of CFST with 12-sided hollow section steel-filled concrete filled steel tubes can predict the bearing capacity of CFST better.