中文摘要：

考虑内、外钢管对混凝土的双重约束作用,分析复式钢管混凝土的轴压应力状态,采用双剪统一强度理论分析混凝土和钢管各自的极限轴压强度,得出复式钢管混凝土轴压承载力公式;通过推导钢管在极限状态的强度折减系数及钢管与混凝土之间的紧箍力值,计算出的轴压承载力与试验数据进行对比,吻合较好,验证了双剪统一强度理论在复式钢管混凝土轴压承载力计算中的适用性;并给出了内圆钢管的径厚比和直径与轴压承载力提高系数的关系,为复式钢管混凝土的优化设计提供理论依据.

英文摘要：

With consideration of the double confinement to the concrete from the twin tubes,the stresses in the concrete and the steel tubes were analyzed,and the ultimate compressive strength was calculated based on the twin shear unified strength theory.The strength reduction factor（βf） was deduced according to plasticity theory,and the confining force between the steel and the concrete was also obtained.Then,the ultimate load capacities of the concrete filled twin steel tubes under axial compression was computed.In comparison with the corresponding experimental results,it is shown that the twin shear unified strength theory can be used in the calculation of the axial capacity.The axial compressive strength of composite column was shown to be influenced by the diameter-to-thickness ratio and the diameter of the inner circular steel tube.The optimal design of the inner steel tubes is presented for the engineering application of these composite columns.