冷弯薄壁型钢卷边槽形截面构件畸变屈曲控制研究

Distortional buckling controlling of cold-formed thin-walled steel members with lipped channel section

基于部分加劲板件的畸变屈曲和局部屈曲的稳定系数比较,提出了冷弯薄壁型钢卷边槽形截面构件畸变屈曲发生于局部屈曲之后或畸变屈曲不发生的临界控制条件;给出了通过构件畸变屈曲计算长度控制畸变屈曲的临界条件;提出一种控制畸变屈曲的构造措施,即在卷边间加设缀板,并通过已有试验对其有效性进行验证,同时推导了卷边间缀板的刚度需求。结果表明:通过构件截面尺寸控制畸变屈曲不发生或发生在局部屈曲之后,可以不考虑构件畸变屈曲的影响,简化冷弯薄壁型钢卷边槽形截面构件承载力的计算;计算长度小于畸变屈曲半波长一半的构件不发生畸变屈曲;通过在卷边间加设缀板的构造措施能有效阻止部分加劲板件的转动,构件的畸变屈曲荷载和承载力都有很大的提高,缀板布置间距不同,构件承载力的提高幅度也不同,缀板间距越小,构件承载力提高幅度越大。算例分析表明,满足一定间距和刚度需求的缀板能够提高构件的畸变屈曲承载力或避免畸变屈曲的发生。

Based on comparison of stability coefficient between distortional buckling and local buckling,the critical condition without distortional buckling or distortional buckling occurring after local buckling for cold-formed thin-walled steel members with lipped channel section was put forward. At the same time,the critical condition for controlling distortional buckling by corresponding calculation length of members was presented. Furthermore,a countermeasure to avoid distortional buckling of cold-formed thin-walled steel members with lipped channel section by setting batten sheets between two lips was presented. A series of tests were carried out to show its validity,and the stiffness requirement of the batten sheets was proposed. The results show that,calculation of distortional bucking load-carrying capacity of cold-formed thin-walled steel members with lipped channel section can be avoided if the distortional buckling occurs after the local buckling or the distortional buckling does not occur by controlling the section sizes of members; distortional buckling doesn't occur when the calculated length is less than half of half-wave length of distortional buckling; the suggested countermeasure by setting batten sheets between two lips is valid to prevent the rotation of flanges,which leads to an evident increase of the elastic distortional buckling strength,and the loadcarrying capacity of axial compression members as well; with different spacing of batten sheets,the corresponding increase of load-carrying capacities is obviously different. Generally,the spacing is smaller,increase of load-carrying capacity is higher. The example show that the batten sheets with a certain spacing and stiffness can increase the distortional buckling strength or avoid the occur of distortional buckling.