Applying unified formula for stress - strain relations of concrete under unixial load, ABAQUS was used to establish the 3D finite element model and to analyze the behavior of concrete - filled circular steel tubular (CFST) dumbbell shaped stub columns under axial compression. The elasto- plastic method was also used to analyze the load -deformation curve of CFST dumbbell shaped stub columns when the CFST dumbbell shaped stub column was simplified as superposition with the two CFST stub columns, the two steel webs and the concrete inside the steel web space. The load - axial strain behavior of CFST dumbbell shaped stub columns was analyzed by both finite element method and elasto - plastic method. The analysis results are in good agreement with the experiment results from references. Analytical results by elasto -plastic method are slightly lower than that by finite element method. Then based on the two methods, the axial stress and perimeter stress of steel tube, the longitudinal and perimeter stress of steel web, the axial stress and radial stress of concrete core, and the longitudinal stress of concrete inside the steel web space in CFST dumbbell shaped stub columns were discussed. At yield state, the axial stress of section steel was slightly lower than its yield stress because of the confinement effect for concrete. The analytical stresses in CFST dumbbell shaped stub columns by the two methods were almost the same, and the finite element model could reflect that the longitudinal stress of the concrete inside the steel web space increases lightly for the concrete confined by steel webs. Based on the limit equilibrium method, simplified formula for the axially loaded CFST dumbbell shaped stub columns was proposed. The analysis results by limit equilibrium method are close to those by finite element method, and both are in safe range compared with the experiment results from references.%采用混凝土单轴受力应力-应变关系统一计算公式,应用ABAQUS有限元软件建立哑铃型钢管混凝土轴压短柱三维有限元实体模型.将哑铃型钢管混凝土轴压短柱的荷载-变形曲线简化为2圆钢管混凝土轴压短柱、钢腹板和腹腔内混凝土的荷载-变形曲线简单叠加,建立弹塑性法.对比了有限元法和弹塑性法计算结果与试验结果,2种方法与试验结果较吻合,且弹塑性法计算结果略低于有限元法计算结果.采用2种方法对哑铃型钢管混凝土轴压短柱的钢管的轴向应力与环向应力、钢腹板纵向应力与横向应力、核心混凝土的轴向应力与径向应力以及腹腔内混凝土的纵向应力进行数值分析,指出2种方法对上述各种应力的计算基本接近,且有限元法可合理反映腹腔内混凝土受约束而使得纵向承载力提高的规律.基于极限平衡理论建立了哑铃型管混凝土轴压短柱承栽力计算公式,由该公式所得计算结果与有限元计算结果相近且与试验结果相比都偏于安全.
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