冷弯薄壁卷边槽钢弹性畸变屈曲分析中的转动约束刚度

WEB ROTATIONAL RESTRAINT IN ELASTIC DISTORTIONAL BUCKLING OF COLD-FORMED LIPPED CHANNEL SECTIONS

畸变屈曲是冷弯薄壁卷边槽钢的重要屈曲模式,腹板提供给翼缘板的转动约束刚度是影响其畸变屈曲性能的关键因素之一。该文对冷弯薄壁卷边槽钢弹性畸变屈曲分析中腹板提供给翼缘板的转动约束刚度取值进行了全面深入的研究。首先推导了腹板在8种不同应力情况与变形形状下的转动约束刚度理论计算公式;接着利用这些公式详细讨论了腹板变形形状的影响;最后提出了计算简便且精度较高的转动约束刚度统一近似公式。研究成果为解析法分析卷边槽钢的弹性畸变屈曲、进而提出畸变屈曲荷载的实用计算公式提供了依据和方便。

The distortional buckling is one of important buckling modes for cold-formed lipped channel sections and the distortional buckling load depends significantly on the rotational restraint provided by the web to the flange during buckling deformation. So the thorough study on the rotational restraint for elastic distortional buckling analysis is presented. Analytical expressions for the rotational restraint are first derived for eight cases representing different combinations of stress states and deformation shapes of the web. Based on these analytical expressions, the effect of the deformation shape of the web is discussed in detail. Finally, an accurate simplified expression for the rotational restraint is proposed. The results of the present study are expected to be useful for the future development of a simple approximate formula for the distortional buckling load of cold-formed lipped channel columns for design use.