高层建筑抗震设计振型数目选取原则

Criterion of mode number selection in seismic design for high-rise building structures

针对《建筑抗震设计规范》中高层建筑结构抗震设计时振型数目选取规定不明确的问题,研究了高层建筑结构抗震计算中诸多影响因素与振型选取的关系。经过动力学分析,认为不同的高振型会影响基底剪力沿结构高度的分布;振型参与质量是基于基底剪力等效得到的反映各阶振型对基底剪力贡献大小的参数;高层建筑抗震计算的振型数目选取与振型参与质量有关。研究结果表明:高层建筑结构抗震设计中高振型的影响不容忽视,在底部剪力和顶端位移误差小于5%的情况下,累计质量参与系数应大于90%;对于不规则结构,动力荷载参与系数应大于95%。

Based on selecting mode number in seismic design of high-rise building structures in Chinese current code for seismic design of building has not express provision, the relationship between mode and many influences in seismic calculation of high-rise building structures is studied. This paper puts forward that the different high mode influences the distribution of base shear along the height of structure. Modal participating mass is a parameter, which effects the contribution to the base shear by each mode based on equivalent to the base shear. Mode number selection in seismic calculation of high-rise building structures relates to modal participating mass. The research result indicates that the influence of high mode should not be neglected in the seismic design of tall building structures. The decision principle of mode number is： when the error of base shear and top displacement are both below 5 %, the sum of modal participating mass ratio should exceed 90 % ; for the irregular structure, the dynamic load participation ratio should exceed 95 %. 3 tabs, 3 figs, 8 refs.