开口薄壁杆件的塑性极限承载力研究

Analyses of the plastic limit bearing capacity of thin-walled beams with open profile

为了研究开口薄壁杆件的塑性极限承载力,采用空间杆件广义屈服准则定义单元承载比、结构的承载比均匀度及基准承载比的概念和计算表达式,据此建立了弹性模量调整的计算公式,进而提出了薄壁杆件结构的极限承载力分析的弹性模量缩减法。算例结果表明,弹性模量缩减法具有良好的计算精度和计算效率。算例分析表明,工字形薄壁杆受偏心荷载作用时,对结构破坏影响最大的内力是弯矩,其次是扭矩;工字型薄壁杆的极限承载力随翼板厚度或腹板厚度的增加而提高,且对前者的变化更敏感。

The elastic modulus reduction method （EMRM） is proposed for the plastic ultimate load bearing capacity evaluation of thin-walled beams, based on the element bearing ratio （EBR） and the equilibrium of strain energy. The EBR is defined for discrete elements by the generalized yield criteria of space bar. The concept and expression of uniformity of EBR and the reference of EBR are presented for adjustment of the elastic modulus of elements. The numerical examples presented in this paper demonstrate the flexibility, accuracy and efficiency of the proposed method. It also shows that the ultimate bearing capacity of the thin-walled bar increase with the thickness of flange or web, and is more sensitive to the variation of the thickness of the flange than the web.