Until recently, linear analysis has been considered sufficient for the static analysis of structural frames. Nonlinear effects, if included, have tended to be considered at the element level rather than at the complete structure level. However, recent changes in codes of practice have been introduced that require a more complete nonlinear analysis to be performed. While these requirements should lead to a more accurate analysis, there has been little guidance given to the type and implementation of such an analysis. Moreover, different implementations have been adopted by various commercial software. In this paper, we discuss the use of mixed finite elements for the large deflection analysis of two-dimensional frames including shear deformation. In particular, we develop a family of elements that can be combined with different nonlinear models and discuss the effects of various assumptions and approximations that are commonly used to simplify the analysis. Examples are given to illustrate the various issues discussed.

直到最近，线性分析已被认为足以用于结构框架的静态分析。如果包括非线性效应，则倾向于在元素级别而不是在完整结构级别考虑。然而，最近引入了实践规范的变化，需要执行更完整的非线性分析。虽然这些要求应该导致更准确的分析，但几乎没有对此类分析的类型和实施提供指导。此外，各种商业软件采用了不同的实现方式。在本文中，我们讨论了混合有限元在包括剪切变形在内的二维框架的大变形分析中的应用。尤其是，我们开发了一系列可以与不同非线性模型结合的元素，并讨论了通常用于简化分析的各种假设和近似值的影响。举例说明所讨论的各种问题。