某切边不规则凯威特单层球壳结构非线性屈曲分析

Nonlinear buckling analysis for a trimmed irregular Kiewitt single-layer spherical shell structure

以某切边不规则凯威特单层球形网壳作为研究对象,研究由于开洞而造成的不规则、支承拱梁水平刚度和竖向刚度的变化、活载的非对称分布、初始几何缺陷、几何非线性以及材料弹塑性对网壳非线性屈曲性能的影响,并采用有限元软件ANSYS对此结构进行非线性的荷载-位移全过程分析。研究结果表明:与完整球壳相比,切边球壳的稳定性能大幅度下降;与水平刚度相比,拱梁的竖向刚度对稳定性的影响较大;按一致缺陷模态法得到的稳定承载力系数,往往不是最小;初始几何缺陷值取跨度的1/400较适宜;材料非线性对切边球壳稳定性的影响较大;活载的非对称分布对本结构的稳定性并无不利影响。

The nonlinear buckling behavior of a trimmed irregular Kiewitt single-layer spherical shell structure was investigated by introducing the irregularity caused by the openings of the dome, the changes of vertical and horizontal stiffness of the support arch beams, unsymmetrical distribution of live loads, initial geometric imperfection, geometric nonlinearity and material elastic-plasticity. The nonlinear load-displacement whole process of this structure was analyzed by using the finite element software ANSYS. The results show that compared with perfect spherical latticed shell, the stability of this trimmed spherical shell is considerably reduced. The vertical stiffness of the support arch beams has greater influence on the stability of this structure than the horizontal stiffness. Using the consistent imperfect buckling analysis method, the coefficient of stable bearing capacity usually is not minimal. A 1 /400 of the span can be appropriately taken as the maximum value of initial geometric imperfection. The material nonlinearity might have significant effects on the stability of this trimmed spherical shell. The unsymmetrical distribution of live loads does not have adverse impact on the stability of the structure.