钢管混凝土圆弧桁架拱平面内徐变稳定分析

摘要

For concrete-filled steel tube arch ribs ,the creep of concrete w ould increase the pre-buckling deformation which will reduce the in-plane buckling resistance significantly ,therefore only included in the influence of pre-buckling deformation on the stability behavior ,creep stable bearing capacity can be accurately obtained of concrete filled steel tube arches .In this paper ,based on the theory of nonlinear buckling of shallow arch ,the nonlinear in-plane equilibrium and buckling equations for CFST truss ar-ches are established by using the principle of virtual work .By solving these equations ,a-symmetric bifur-cation buckling and symmetric snap-through bucking creep stability load are proposed of pin-ended ar-ches and fixed arches ,and the effect of core concrete creep on the stability of CFST arches has been stud-ied .In addition ,the influence of modified slenderness ,central and creep coefficient on creep buckling be-haviors has been investigated ,providing theoretical basis for long-term design of concrete filled steel truss arches .%核心混凝土的徐变会增加钢管混凝土拱肋的屈曲前变形，降低结构的稳定承载力，因此只有计入屈曲前变形的影响，才能准确得到钢管混凝土拱的徐变稳定承载力。基于圆弧形浅拱的非线性屈曲理论，采用虚功原理，建立了考虑徐变和剪切变形双重效应的管混凝土圆弧桁架拱的平面内非线性平衡方程，求得两铰和无铰桁架拱发生反对称分岔屈曲和对称跳跃屈曲的徐变稳定临界荷载。探讨了钢管混凝土桁架拱核心混凝土徐变随修正长细比、圆心角和加载龄期对该类结构弹性稳定承载力的影响，为钢管混凝土桁架拱长期设计提供理论依据。