[提要]  论述了变截面梁单元有限元线弹性分析方法，以及不同类型梁单元（等截面梁单元、普通位移模式变截面梁单元、积分位移模式变截面梁单元）对变截面刚架内力分析的差异。在大量算例分析的基础上，给出两段变截面梁（远端铰接）等效转动惯性矩的计算公式，供设计人员参考。
[关键词]  门式刚架 变截面梁 有限元 等效刚度

The authors present a finite element formulation of a portal frame with tapered members, and demonstrate the convergent difference of three types of finite elements used in the analysis. A lot of numerical studies are carried out to investigate the behavior of the portal frame and conduct a set of design formula for evaluating the equivalent stiffness of the beams with tapered sections.
Keywords: portal frame tapered members; finite element method; equivalent stiffness