矢跨比对弦支穹顶整体稳定性的影响

Influence of Rise-to-Span Ratio on Global Stability of Suspen-Dome Structures

随着弦支穹顶在我国的逐步应用,其整体稳定问题日益突出。以两种矢跨比弦支穹顶为例,得出不同矢跨比弦支穹顶的缺陷敏感性规律。研究表明:进行特征值分析时,应不断调整外部荷载使结构的第一阶特征值为1.0,否则将产生虚假的特征值和屈曲模态,以及对结构的极限承载力的过高估计;矢跨比为1/10的弦支穹顶为缺陷敏感性结构,预应力的引入不足以改变其初始后屈曲性状,应严格执行网壳规范对其进行分析;矢跨比为1/15的弦支穹顶为缺陷不敏感结构,但在计算时结构不会自动进入分支路径,应以其特征值为参照,判断其失稳类型,并加入初始扰动使其进入分支路径。

Along with the gradual application of suspend-dome structures, the global stability of this kind of structure is becoming increasingly pronounced. In this paper, taking two different rise-to-span ratio suspen- dome structures as examples, imperfection sensitivity of different rise-to-span ratio suspen-dome structures was obtained. Design guidelines were also given to refer for practical projects. The calculation results show that the load should be adjusted continuously so that the first eigenvalue becomes 1.0, otherwise erroneous eigenvalues and modes would be produced and the limit bearing capacity would be over-estimated. Suspen-dome structures with rise-to-span ratio of 1/10 are imperfection sensitive ,with the introduction of prestressed cable ,their post- buckling property is not to be changed,while suspen-dome structures with rise-to-span ratio of 1/15 are imperfection insensitive, but they would not enter into bifurcation path by themselves, then initial geometric imperfection is demanded to be introduced.