螺栓单面连接不等边角钢轴压承载力试验研究

EXPERIMENTAL STUDY OF UNEQUAL-LEG-ANGLES CONNECTED WITH ONE LEG OF BOLTS UNDER ECCENTRIC COMPRESSION

角钢输电铁塔中大量构件采用单面连接,由于两主轴刚度不同,如采用不等边角钢可有效节约钢材。目前国内设计方法中关于单面螺栓连接不等边角钢的规定不足,对扭转在构件失稳中占的比例数值有分歧,因此选取两组14个截面分别为90×56×6和140×90×8构件进行试验和有限元计算,长细比范围30~180。试验和有限元模型中螺栓孔布置、构件两端连接方式均与工程实际一致;有限元模型考虑螺栓、螺栓孔等相互作用。结果表明:试验和有限元计算结果基本一致,所有长度的构件都发生弯曲屈曲,扭转屈曲不是主要屈曲模式;当长细比较小时,由于截面平均应力较大,连接肢出现局部皱褶变形;长细比较大的构件屈曲时弯曲变形较大,中间截面角钢两肢夹角会发生变化。通过与现有设计方法对比,发现相关规范不能很好地预测单面连接不等边角钢构件破坏模式和承载力,建议进一步进行参数分析以完善计算方法。

Plenty of members in the angle steel transmission tower were single-sided connected. Due to the different stiffness of the two bending axes,unequal-leg angle can effectively save steel. Available design methods provide limited information for unequal-leg angles connected with one leg of bolts at both ends,and there are no consistent view on the effect of torsional buckling in such kind of members. For this reason,14 unequal leg members,with cross-section of 90 × 56 × 6 and 140 × 90 × 8,were tested under eccentric compression,and the slenderness ratio（λ） was within the range of 30 - 180. In the tests and the finite element model,the bolt holes arrangement and the connection modes of the two ends of the members were all consistent with the actual project. The interaction between bolt and bolt hole was considered in the finite element model. The results from tests and finite element calculation were in good agreement. The test and FEA results showed that torsional buckling was not the dominant failure mode,almost all of members occurred flexural buckling. If λ was small enough,local fold buckling occurred in connecting leg because the average stress of the section was large; Due to the members with large λ had a large bending deformation,the angle between two legs changed in intermediate cross-section after loading. Current design methods are incapable of calculating the failure mode and bearing capacity of unequal leg angles connected with one leg of bolt,a parameter analysis is necessary for improving the current methods.