劲性支撑穹顶结构模态特性参数分析

Modal characterristics parameter analysis of rigid bracing dome

模态特性分析是结构动力特性分析的基础。选用杆元和索元建立有限元模型,采用分块Lanczos模态方法,分析了劲性支撑穹顶结构不同荷载工况下结构的模态特性,讨论了初始预应力、杆件截面面积及高度、跨度、矢高、荷载等参数对结构自振频率的影响。算例分析表明:劲性支撑穹顶结构自振频率较小且分布密集,出现大小相近或相同的频率对及相互对称的振型;环向等分数和杆件截面面积对劲性支撑穹顶结构的自振频率影响较小;荷载作用使结构的自振频率变小;预应力、跨度及矢高对自振频率影响较大,应在结构设计阶段给予充分考虑。

Modal characteristics analysis is the basis of the structural dynamic characteristics analysis. The finite element model of the rigid bracing dome was built by the truss elements and cable elements. Through adopting the block Lanczos modal analysis method, modal characteristics of the structure under different loads condition are analysed. The influences of structural parameters, such as initial prestress, span, load, etc. on the structural natural frequencies is concluded. The analysis of numerical example indicates rigid bracing dome appear similar or identical to the size of the frequency of and mutual symmetry vibration mode, whose natural frequency is small and inten- sively distributed; Equal division of ring direction and bar section area have little influences on the structural natural frequencies ; Under the action of load, structural natural frequencies become smaller; Prestress, span, rise have larger influence on the structural natural frequencies, which should give full consideration in the structural design stage.