中文摘要：

为了准确获得钢管混凝土拱肋轴心受压全过程中钢管与混凝土的纵向（拱轴方向）应力水平，揭示钢管混凝土组合作用机理，对钢管混凝土中钢管与混凝土的相互作用机理进行理论分析。基于平截面假定，分析轴心受压不同阶段钢管与混凝土应力状态的变化，根据力学平衡关系，推导钢管与混凝土纵向应力-应变计算表达式，进而得到两者的轴力-应变关系。采用推导公式进行计算，分别与425个钢管混凝土短柱极限承载力和7个短柱荷载-应变试验结果进行对比，并以均布荷载作用下抛物线纯压无铰拱为例，与双单元模型计算结果进行对比。研究结果表明：钢管混凝土组合作用发挥时，钢管与混凝土均处于多向应力状态，三向受压的核心混凝土纵向应力提高，双向受力的钢管纵向应力减小；极限承栽力建议公式计算值与试验值的比值均值为0．969，均方差为0．140，变异系数为0．144，并且建议公式得到的荷载-应变曲线与试验曲线吻合较好，表明提出的算法具有较高的精度，且偏安全；拱肋弹性阶段分析时，建议公式与双单元模型计算结果一致，而进入塑性阶段时，双单元模型计算得到的钢管与混凝土轴力仍按刚度分配，过高地估计了钢管的承载能力，计算结果偏于危险，建议公式计算结果更准确。

英文摘要：

To accurately acquire the longitudinal （axial direction of arch rib） stress level of steel tube and concrete and reveal the composite action mechanism of concrete-filled steel tube （CFST） under compression on axis center of arch rib of CFST, the interaction mechanism between concrete and steel tube was theoretically analyzed. The changes of stress states of steel tube and concrete under compression at different stages were analyzed based on plane section assumption, the longitudinal stress-strain formula was derived and the axial force-strain of steel tube and concrete was further obtained according to equilibrium relation of forces. Comparisons among the calculated results by proposed formulas and the test values of 425 CFST specimens＇ ultimate bearing capacity and 7 CFST specimens＇ results in load-strain curves were carried out. Besides, the calculated values using the proposed formula and the method of double unit model were compared by using the example of the parabolic fixed arch subjected to vertical load uniformly distributed on a horizontal projection. The results show that the steel tube and concrete are in multiaxial stress state when the composite action works. The longitudinal stress of concrete in triaxial compression improves and the longitudinal stress of steel tube in biaxial stress decreases. The mean ratio of calculated values on ultimate bearing capacity by the proposed formula to test values is 0. 969, and its variance and variable coefficient are 0. 140 and 0. 144 respectively. Meanwhile, the calculated results fit well with the load-strain curves of test, which indicates that the proposed method has high precision and high safety. In the analysis of CFST arch rib at elastic stage, the calculated results are in the good agreement with the results by the method of double unit model. However, in the plastic stage, the bearing capacity of steel tube is overestimated by the method of double unit model because of the assumption of axial force distribution according to stiffness, which