半刚性连接钢框架整体结构屈曲荷载计算模型

Computational Model of Buckling Load of Plane Steel Frames with Semi-rigid Connections

在综合考虑梁柱任意半刚性连接及弹性支撑特性的基础上,建立了单层多跨平面钢框架结构整体失稳的线弹性屈曲荷载的解析计算模型,并同时考虑了所有柱脚的半刚性特征,使模型的适用范围更为广泛.本模型中的半刚性连接特性通过在所有梁柱连接处设置虚拟约束弹簧实现,弹性支撑则通过在柱顶引入具有任意刚度参数的水平弹簧实现.基于上述的基本模型,通过对所有构件建立失稳状态的控制方程并引入相应的连续性条件和边界条件,建立了平面单层任意多跨框架结构整体失稳的临界荷载解析计算方法,并研制了相应的计算程序.分析结果表明,半刚性连接特性和水平支撑效应对框架结构整体稳定性的影响极为显著,而且作用于多跨框架结构柱顶竖向荷载的分布特征对结构的整体稳定性有不可忽视的影响.另外,结构的支撑刚度及节点的半刚性连接特性对单层框架整体稳定性的影响具有明显的界限性和区间效应,对此需进一步开展深入研究。

Taking into consideration the combined effects resulting from joint flexibility and elastic bracing system, a generalized analytical model is established for the buckling load of steel plane frames with multiple spans and single story, and the flexibility of column-to-bases joints are considered together with that of column-to-beam connections. All the semi-rigid connections in this paper are modeled using virtual rotational springs set at joints, and the elastic bracing system is modeled with the horizontal spring with arbitrary stiffness at the top of columns. Tile method for computing the buckling load of the frames is obtained through establishing differential equations for each element satisfying the condition set for buckling of the framed structure, and using all the boundary conditions and displacement compatibility conditions. From the computational results, it concludes that the buckling load or the equivalent buckling length factor of the plane steel structures is greatly influenced by stiffness of bracing elements and semi-rigid connections. It is also found that the effect is limited in a sense that the stiffness of bracing elements or the semi-rigid connections has no effect on the buckling length when the stiffness of bracing elements or semi-rigid connections exceeds a threshold. Further investigation is needed for the collateral effect of the distribution of loads or ratio of loads on the buckling load of the whole structure.