工字钢梁弯扭屈曲的计算模型和屈曲方程的求解

The Bending Twist Computational Model of Steel H—Beams and to Solve Twist Equations

钢结构设计规范ＧＢＪ１７－８８中梁的整体稳定临界弯矩计算公式［１］是依据能量法原理并再进行某些简化而推导出的，使得荷载作用点至弯曲中心距离ａｙ和截面不对称系数βｙ的力学含义变得不明确。本文采用“拉弯比拟法”［２］，理顺各力学量的关系，并采用“逆算单元长度法”［３］，快速、简捷地求解薄壁构件弹性阶段的一般微分方程式。

In the steel structure design code GBJ17 88 the formula which is used to caluclate critical bending moment of steel beams in the state of global stable is deduced according to the energy theory and has been simplified in some cases.These simplification lead to uncertainty of the mechanical quantities such as“a y”—the distance from load action point to the bending center of the section;“β y”—the parameter to describle the asymmetric property of the beam section.This paper try to use the method of comparison pull with bend to define the relation ship among mechanic quantities.A new method called inverse cauclation of finite element is introduced to solve the differential equation quickly for thin walled member in elastic state.