人字形密肋式折板拱壳的动力特性分析

针对人字形密肋式折板拱壳结构，采用有限元理论和子空间迭代法求得了结构的自振频率，分析了结构的振型特点，详细讨论了矢跨比、脊线刚度、边梁刚度和柱上肋梁的刚度对结构基频的影响，还讨论了建筑构造做法所产生的外加质量对结构自振特性的影响。分析表明，结构的低阶振型主要表现为竖向振型，横隔是结构整体刚度的薄弱环节，结构基频随矢跨比的降低而增加，这与传统认识不符。建议结构的矢跨比不宜小于1／6，脊线和边梁刚度对基频的影响很小，边梁的跨高比可取1／20—1／16，提高柱上肋的刚度有利于改善结构的整体刚度，结构动力特性分析时应计及建筑构造做法所产生的外加质量的影响。分析结论可为类似工程应用提供参考。

Dynamic Character Analysis of Herring-bone Folded-plate Ribbed Shell

The natural frequency of vibration for herring-bone folded-plate ribbed shell are provided by finite element method theory and method of sub-space iteration, the peculiarities of mode shapes is summarized. The influ- ences of height-to-span, rigidity of ridge and side beam, rigidity of restrained rib beam are discussed for structure first frequency, Furthermore, the influences of additional mass of construction is discussed for free vibration char- aeteristic. The results show that anterior mode shaper of the structure is behaved with vertical vibration ,the rigidity of end truss is unsubstantial, the first frequency is increased when the height-to-span diminishes and this is inconsistent with conventional cognition. This paper proposes height-to-span of structure not less than 1/6, the change on first frequency is very small with rigidity of ridge and side beam, span-to-height of side beam can adopt 1/20- 1/16, structural rigidity can strengthen by accretion of restrained rib beam, the influences of additional mass of construction can not ignore when free vibration characteristic is analyzed. The conclusion can give some references to similar project application.