有约束梁的整体稳定

OVERALL STABILITY OF BEAMS WITH RESTRAINTS

探讨两种约束对梁整体稳定的影响,并提出用于设计工作的实用方法。其一是梁在平面内的端部约束,以框架梁为代表。现行钢结构设计规范没有这方面的规定,需要加以补充;其二是梁跨度范围内的侧向支承点对梁稳定提供的约束。计算这类梁的稳定,需要考虑各段之间的相互约束。现行规范只给出支承点为等间距时的等效临界弯矩系数,缺少不等间距时的计算方法。所推荐的用计算长度表现约束效应的计算方法既具有普遍性,又概念清晰。还论述了承受端弯矩梁段的非弹性影响,并提出相应的计算公式。

The influence on the overall stability of beams and girders form two kinds of restraints is discussed and practical approaches for routine design work are suggested. The first one is end restraint in the beam plane, as occurring in frame girders. In the current design code for steel structures, relevant provisions are lacking and need be added. The second issue is the restraint provided by intermediate lateral supports. Mutual restraint in beam segments has to be considered in the stability calculation of this kind of beams or girders. The current design code specifies coefficient of equivalent critical moment only for the case of equidistant lateral supports, without any instruction for the case of unequal spacing. The approach of effective length for taking account of restraining effect, as recommended in this study, has not only the merit of generality but also of clarity in idea. Also the influence of inelasticity on beam segments subject to end moments is discussed and relevant formula is recommended as well.