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设计制作了8根复式薄壁方钢管混凝土轴压长柱试件,通过试验,研究了长细比和截面类型对复式薄壁方钢管混凝土轴压长柱承载力的影响。试验发现:构件的承载力随着长细比的增大而下降;内置圆钢管高强混凝土后组合柱的承载力提高了33%;内置空钢管后构件的承载力下降了约14%;实心复式薄壁方钢管混凝土柱具有较高的剩余承载力和延性。基于ABAQUS软件和相关的本构模型,建立了复式薄壁方钢管混凝土轴压长柱的有限元模型,有限元计算结果与试验结果吻合良好。基于该有限元模型进行受力性能影响因素分析和参数分析。分析表明:焊接残余应力和钢管弯角效应对轴压承载力的影响均小于1.5%,且二者相互抵消,受力分析时可以忽略;实心复式薄壁方钢管混凝土长柱的稳定系数随着内钢管屈服强度、混凝土强度或径宽比的增大而减小。提出了复式薄壁方钢管混凝土长柱轴压承载力的简化算式,计算值与实测结果吻合较好。
Eight composite thin-walled square CFST columns were designed and manufactured. The effects of slenderness ratio and cross-section type on the bearing capacity of double-walled concrete-filled square steel tubular long columns were studied. The test results show that the bearing capacity of components decreases with the increase of slenderness ratio, the bearing capacity of composite columns increases by 33% after built-in high-strength concrete filled circular tubes, and the bearing capacity of the components decreases by about 14% Thin-walled square steel tube columns have higher residual capacity and ductility. Based on the ABAQUS software and the related constitutive model, the finite element model of the composite thin-walled square steel tube (CFST) long columns with axial compression is established. The calculated results are in good agreement with the experimental results. Based on the finite element model, the influencing factor analysis and parameter analysis of the force performance are carried out. The analysis shows that the influence of welding residual stress and steel tube bending angle on bearing capacity of axial compressive strength are all less than 1.5%, and the two cancel each other out and can be neglected in force analysis. The stability coefficient of solid double- Yield strength, concrete strength or aspect ratio decreases. A simplified calculation method for bearing capacity of long-section CFST long columns under axial compression is put forward. The calculated values are in good agreement with the measured results.