初始扭转轴压杆弹性弯扭屈曲性能研究  

ELASTIC FLEXURAL-TORSIONAL BUCKLING BEHAVIOR OF PRE-TWISTED BAR UNDER AXIAL PRESSURE

作　　者：陈昌宏[1,2] 单建[2] 黄莺[3] 

机构地区：[1]西北工业大学力学与土木建筑学院,陕西西安710129 [2]东南大学土木工程学院,江苏南京210096 [3]西安建筑科技大学土木工程学院,陕西西安710055

出　　处：《工程力学》2009年第6期166-171,共6页Engineering Mechanics

基　　金：国家自然科学基金项目(50678036)

摘　　要：根据初始扭转轴压杆的变形规律导出了相应的弹性弯扭屈曲方程。方程表明:由于初始扭转角的存在,两抗弯主轴方向上的弯曲屈曲变形相互耦合;且由于截面剪心和形心不重合,弯曲屈曲变形与扭转屈曲变形也相互耦合。而对于具有双轴对称截面的初始扭转轴压杆,弯曲屈曲变形与扭转屈曲变形相互独立。同时,对不同初始扭转角的轴压杆进行有限元分析,指出Frisch-FayR错误的分析假定,验证了双轴对称截面的初始扭转轴压杆弹性弯曲屈曲变形曲线是一条空间曲线,且随着初始扭转角的增加,该曲线对平面曲线的偏离变大。最后,进行了初始扭转杆的有限元参数分析,得出初始扭转轴压杆弹性弯曲屈曲承载力与初始扭转角和截面抗弯刚度比参数的变化关系。初始扭转角的存在使强轴对压杆绕弱轴的屈曲位移产生"抵抗"作用,从而提高了杆的弹性弯曲屈曲临界承载力;截面抗弯刚度比μ越大,初始扭转角使这种"抵抗"作用越强,弹性屈曲承载力越高。According to deformation features of pre-twisted bar, the governing equation for elastic flexural-torsional buckling is deduced, which indicates that the bending buckling deformations in two main bending directions are coupled, as well as bending and twist buckling deformations due to the noncoincidence of shear center and shape center of the cross-section. On the other hand, if the cross section is dual-axis symmetric, bending buckling deformations are independent of the twist buckling deformation. At the same time, finite element analysis of pre-twisted bar with different pre-twisted angle is performed, which demonstrates that the assumption in Frisch-Fay R about a plane elastic bending buckling deformation curve is not correct, the larger the pre-twisting angle, the more significant deviation of the curve from a plane. Finally, the finite element parameters analysis is carried out on the relationships between elastic bending buckling critical capacity with pre-twisted angle and with bending rigidity ratio. The existence of the pre-twisted angle leads to ＇resistance＇ effect of the stronger axis on buckling deformation in the direction of weaker axis, and enhances the elastic bending buckling critical capacity. The ＇resistance＇ effect is getting stronger and the elastic buckling capacity is getting higher as the cross section bending rigidity ratio increases.

关 键 词：初始扭转杆 弯曲屈曲 扭转屈曲 耦合 有限元 

分 类 号：TU318[建筑科学—结构工程]