初应力和黏结滑移对钢管混凝土长期变形的影响

利用ANSYS程序建立考虑钢管初始应力、屈服和黏结滑移效应的钢管混凝土长期变形分析三维实体有限元模型.对模型中钢管初始应力和黏结滑移效应模拟方法的正确性进行验证；通过算例系统研究上述3种因素对钢管混凝土收缩徐变变形及应力重分布的影响.结果表明：对收缩徐变后钢管仍处于弹性阶段的钢管混凝土构件，初始应力不会对其应力重分布产生影响；若收缩徐变后钢管屈服，则应力重分布不再发生，但变形速率增加，设计人员需引起重视；钢管混凝土的长期变形计算应根据不同约束条件选择是否考虑黏结滑移效应；其中底部钢管与混凝土全部约束构件的完全黏结假定成立，但对仅约束管内混凝土的构件收缩徐变计算，应考虑其黏结滑移效应.
Abstract: A three-dimensional finite element model of concrete filled steel tube (CFST), considering initial steel stress, yield and bond-slip effect, was established by the ANSYS program to analyze the time-dependent behavior of CFST. The correctness to simulate the initial stress and bond slip effect of the steel tube was verified; the influence of the above three factors on the shrinkage and creep deformation and stress redistribution of the CFST was studied with several examples. All the results show that the initial stress does not affect the stress redistribution of CFST if the steel is in elastic stage after the concrete shrinkage and creep, and if the steel tube yields after the concrete shrinkage and creep, the stress redistribution stops, but the deformation rate increases. Therefore, more attention should be paid to the deformation. Before calculating the time-dependent behavior of CFST, whether the bond slip effect between the steel tube and core concrete should be considered or not is according to constraint conditions. If the bottom of CFST is constrained both in core concrete and steel tube, the complete bond assumption is reasonable; if it is only confined in core concrete, the bond-slip effect should be taken into consideration.