大矢跨比单层球面网壳动力试验模型弹塑性稳定分析

为了解水平地震作用下具有不同失效机制的单层球面网壳结构在静力荷载作用下的弹塑性稳定性能,利用有限元软件ANSYS,对两个矢跨比为1/2的单层球面网壳结构试验模型进行双重非线性全过程分析,获得结构的弹塑性极限承载力,比较二者的失稳模态,初步了解二者之间的差异。考察结构杆件屈曲、初始缺陷等因素对结构稳定性能的影响,并分析各因素对结构极限承载力的影响规律。结果表明,地震作用下,具有强度破坏特征的网壳结构在静力下的失稳模式表现为结构的整体失稳,而发生动力失稳破坏的结构则表现为局部失稳破坏。杆件失稳和初始缺陷使结构的临界荷载大幅度降低,且地震作用下属于强度破坏的单层球面网壳结构在静力下对初始缺陷的敏感性大于动力失稳破坏结构。

ELASTIC-PLASTIC STABILITY OF DYNAMIC TEST MODELS OF LARGE RISE-SPAN RATIOS SINGLE-LAYER RETICULATED DOMES

In order to further understand the elastic-plastic stability behaviors of single-layer reticulated domes under static loads, which had different kinds of failure mechanisms subjected to horizontal earthquake actions. Based upon geometrical and material nonlinear complete-process analysis, two dynamic test models of single-layer reticulated domes with the rise-span ratios equal to 0.5 were analyzed by finite element method software ANSYS for elastic-plastic ultimate bearing capacity and differences of the instability modes of the structures were compared. The influences on the stability of the buckling of the members and the initial geometric imperfections were also considered during the analysis. It is shown that the structures which the failure mechanisms were strength failure and dynamic instability under horizontal earthquake action appeared global instability and local instability under static load respectively. The buckling of members and the initial geometric imperfections made the critical load of the structures significantly decrease. The strength failure structure was more sensitive to the initial imperfections than the dynamic instability structures under static load.