高阶振型对建筑结构层间位移的影响

Influence of Higher Modes on Inter-Story Drift of Multistory Buildings

建筑结构层间位移是抗震设计的研究重点。本文基于广义层间位移谱,分析高阶振型对结构最大层间位移角以及对结构层间位移沿无量纲高度分布的影响,并通过调整结构侧向刚度比,分析高阶振型对结构层间位移变形类型的影响。结果表明:随着结构固有周期的增加,仅取一阶振型进行分析将会显著低估结构的最大层间位移角,高阶振型的影响决不能忽视;从结构层间位移沿无量纲高度分布的角度分析,高阶振型将会显著增加结构中上部位的层间位移需要;高阶振型将增加长周期结构的剪切变形和中上部位的弯曲变形需求,但对中下部位弯曲变形的影响并不明显;针对长周期结构的设计和分析,除计算最大层间位移角外,建议考虑层间位移沿结构高度的分布情况。

Inter-story drift ratio is the research emphasis of seismic design on multistory buildings.Based on generalized inter-story drift spectrum,the influence of higher mode on maximum inter-story drift ratio is analyzed.In the meantime,the influence on the deformation types is investigated by adjusting the lateral stiffness ratio.It is illustrated in this paper that with the increase of fundamental period of structure,the maximum inter-story drift ratio will be underestimated seriously if the fundamental vibration mode is just considered,and the influence of higher modes cannot be ignored; the deformation demands of the upper part will be increased obviously in the analysis of inter-story drift demands distribution.Furthermore,for the buildings with long fundamental period,the flexural deformation of the upper part and shear deformation increase significantly if higher modes are considered.More attention should also be paid that,for long-period structures,the inter-story drift demand distribution should be considered as well as the inter-story drift ratio.