（1 香港理工大学土木及环境工程学系， 香港 999077； 2 中山大学土木工程学院， 广州 519082）

［摘要］变截面构件具有造型优美、自重轻及用料省等特点，被广泛应用于幕墙、厂房、桥梁、网壳等大跨度结构。传统变截面构件的设计方法采用一阶线性分析理论，无法反映构件在复杂结构中的真实内力与变形。基于有限元理论，提出适用于大变形、大转角等非线性问题的变截面构件直接分析法。推导出构件最不利几何缺陷模型及包含该缺陷的高阶变截面欧拉-伯努利梁柱单元，提出用于稳定设计的变截面构件承载力计算公式。验证算例表明，该一单元一构件的分析设计方法准确高效，可应用于任意变截面结构形式的分析与设计。

［关键词］变截面构件； 直接分析法； 梁柱单元； 初始缺陷； 弯曲失稳； 二阶效应

中图分类号：TU318-1文献标识码：A文章编号：1002-848X(2019)16-0065-07

Theory and application of the direct analysis method for tapered members with I sections

Bai Rui1, Liu Siwei2, Liu Yaopeng1, Chan Siulai1

(1 Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China; 2 School of Civil Engineering, Sun-Yat-Sen University, Guangzhou 519082, China)

Abstract:Due to the material efficiency and the aesthetic appearance, the tapered members have been widely used in long-span structures, such as the portal frame, facade, bridge and reticulated shell. The conventional design method of tapered members is developed based on the empirical linear analysis approach with the effective length assumption and is only applicable to the web-tapered members. Moreover, the analysis method may incorrectly evaluate the member deflection and internal forces in complicated structures. To remedy the insufficiencies, the direct analysis method (DAM) with one-element-pre-member modeling approach was developed. Based on the theory of the finite element method, an advanced tapered Euler-Bernoulli beam-column element was derived. The function to represent the most critical initial geometric imperfection was presented. The flexural buckling design of tapered columns with the proposed method was demonstrated. Compared to the conventional method, the advanced method is more reliable and efficient and can be applied to the tapered members with any tapering scenarios.

Keywords:tapered member; direct analysis method; beam-column element; initial geometric imperfection; flexural buckling; second-order effects

*中山大学科研启动金（76140-18831105），香港教育资助委员会（PolyU 152039/18E）。

通讯作者：刘思威，博士，副教授，Email: liusw8@mail.sysu.edu.cn。