带翼缘十字形截面轴心受压构件的扭转失稳极限承载力分析

ANALYSIS OF TORSIONAL INSTABILITY ULTIMATE BEARING CAPACITY OF FLANGED MEMBERS WITH CRUCIFORM SECTION SUBJECTED TO AXIAL LOAD

带翼缘十字形截面构件轴心受压时,极有可能发生扭转失稳。对于此类构件的扭转失稳,相关研究相对较少,设计时很容易被忽略,在工程应用时存在安全隐患。采用有限元方法,计入残余应力的影响,对带翼缘十字形轴心受压构件的失稳承载力进行了研究,考察了初始扭转角、扭转长细比、翼缘宽度、腹板高度、腹板厚度等参数对带翼缘十字形截面构件扭转失稳承载力的影响。结果表明:带翼缘十字形截面轴心受压构件在扭转失稳后不具备后屈曲性能;初始扭转会加速截面塑性区的发展,降低截面的刚度;在给定初始扭转缺陷和残余应力的前提下,构件的扭转失稳极限承载力仅与扭转长细比λω有关,与翼缘宽度、腹板高度、腹板厚度等几何参数没有直接关系。

Torsional instability of flanged members with cruciform section is very likely to occur when they are subjected to axial compression.For the torsional instability of such members,there are relatively few research,and it is easy to be ignored in design.Besides,there are potential safety hazards in engineering applications.Finite element method was used to study the instability bearing capacity of the flanged members with cruciform section considering residual stress when they were subjected to axial compression.The effects of initial torsion angle,torsion slenderness ratio,flange width,web height,web thickness and other parameters on the torsional instability of flanged members with cruciform section were investigated.The results showed that flanged members with cruciform section under axial compression did not have post-buckling properties after torsional instability occurred.The initial torsion accelerated the development of the plastic zone of the section and reduced the stiffness of the section.Under the premise of the given initial torsion imperfections and residual stress,the torsional instability ultimate bearing capacity of the member was only related to the torsion slenderness ratioλω,and was not directly related to the geometric parameters such as flange width,web height and web thickness.