中文摘要：

以核心膨胀混凝土的膨胀效应等效为普通混凝土与温度场耦合产生的膨胀效应，借助有限元分析软件ABAQUS，考虑材料本构关系的非线性以及受力过程中材料Poisson比的变化等因素，建立了方钢管膨胀混凝土短柱在轴心压力作用下的非线性有限元计算等效模型，讨论了钢管与核心膨胀混凝土之间的接触压力、荷载对核心膨胀混凝土纵向应力分布的影响以及钢管对核心膨胀混凝土的约束效应等问题。研究结果表明，当轴压荷载接近极限荷载时，钢管对核心混凝土开始产生约束效应，约束压力迅速增大，且约束效应主要集中在两对角区域。

英文摘要：

The nonlinear finite element equivalent model for axially-loaded square expansive concrete-filled steel tube （CFST） short columns is proposed based on the guidance that the expansive effect of the core expansive concrete is equivalent to the one of coupling common concrete with the temperature field, considering the effect of material nonlinear constitutive relation and the variation of Poisson＇s ratio under loading. The contact press between the tube and the expansive core concrete, the axial stress distribution of the core expansive concrete under loading, and the confinement of the tube to the core expansive concrete are analyzed. The results show that the confinement of the tube to the core expansive concrete is produced when the axial load closes to the ultimate load, the constraint press increases rapidly, and the confinement is mainly concentrated in the two diagonal areas.