中文摘要：

在已有恒高温后混凝土单轴受压和钢材单轴拉伸力学性能研究的基础上，建立了恒高温后混凝土轴对称三轴受压应力一应变关系和复杂受力下的钢材多轴应力一应变关系。应用连续介质力学，建立了恒高温后钢管混凝土同时受压的同心圆柱体计算模型，采用弹塑性全过程分析理论，建立了恒高温后钢管混凝土轴压组合弹性模量理论计算公式和组合应力一应变关系全曲线的理论表达式，并编制相应的计算程序对恒高温后钢管混凝土轴压短柱受力性能进行弹塑性全过程分析，计算结果与试验结果吻合较好。

英文摘要：

Based on the research of the mechanical properties of concrete at uniaxial compression and steel at uniaxial tension after constant high temperature, the axisymmetric triaxial compressive stress-strain relationships of concrete and multiaxial stress-strain relationships of steel after constant high temperatures were suggested. Based on continuum mechanics, the mechanical model of concentric cylinders of circular steel tube with concrete core of entire section loaded after constant high temperature was determined. Applying elasto-plastic analysis method, theoretical calculation formulas for composite elastic modulus and composite stress-strain relationships of concrete-filled circular steel tube （CFST） stub columns were proposed and a FORTRAN program was developed, and the load-axial strain relationships of CFST stub columns after constant high temperatures were analyzed. The analysis results are in reasonable agreement with the experiment ones.