H型钢弦支穹顶结构弹塑性稳定性分析

Elastic-plastic stability analysis of H-beam suspendome

在圆钢管弦支穹顶结构中,构件在壳体曲面内外的计算长度不同,造成材料性能无法在两个方向上均得到充分利用.本文提出以H型钢为杆件形式的弦支穹顶结构克服了上述不足.首先通过一则算例对比分析了圆钢管和H型钢两种杆件形式在弦支穹顶曲面内外的轴心受压稳定性差异,随后建立了同时考虑节点域、节点刚度、杆件初弯曲的精细化数值模型,探讨了H型钢弦支穹顶结构杆件的初始几何缺陷施加方式,得到了节点域、节点刚度、杆件初弯曲等参数对结构稳定承载力的影响规律.结果表明:H型钢轴心受压稳定应力在弦支穹顶曲面内外可以达到平衡且在曲面外低于同截面面积圆钢管的稳定应力,材料在两个方向上均得到了充分利用;随强轴抗弯刚度系数的降低,结构稳定承载力下降趋势较为明显;H型钢杆件的几何缺陷尤其是弱轴方向的几何缺陷,对结构的稳定承载力将产生较大影响,在杆件加工时应尽量避免H型钢沿弱轴方向的初弯曲.

In suspendome structures using circular steel tubes,the effective length of the member inside and outside the shell surface is different,so that the material properties cannot be fully utilized in both directions.The H-beam suspendome proposed in this paper overcomes the above deficiency.Firstly,through an example,the difference of axial compressive stability inside and outside the shell surface between the circular steel tube and the H-beam is compared and analyzed.Then,a refined numerical model considering the joint region,joint stiffness and initial bending of members is established.The application method of geometric imperfections of members in H-beam suspendome structure is discussed.The effects of joint region,joint stiffness,initial bending of members and other parameters on the structural stability bearing capacity are obtained.Results show that the stability stress of the H-beam under axial compression can be balanced both inside and outside the curved surface of the shell.Outside the curved surface,the stress of H-beam is lower than the circular steel tube with the same cross-sectional area.The material is fully utilized in both directions.With the decrease of the bending stiffness coefficient of the strong axis,the decrease trend of the ultimate load is obvious.The geometric imperfections of the H-beam,especially those in the weak axis direction,will have a great impact on the stability bearing capacity of the structure.The initial bending of H-beam along the weak axis direction should be avoided when the members are processed.