设计特征周期

对于短周期结构，延性需求随场地土变软而增大，同类场地随设计分组特征周期增大而增大。

For structures with short period , the mean ductility demand will increase when soil becoming softer and the design characteristic periods growing longer .

我国现行抗震规范中设计反应谱特征周期的取值偏低，可能是偏于不安全的；

The predominant periods in our current seismic design code is smaller than the results of calculation , and our design code is probably unsafe .

竖向与水平向地震动分量卓越周期的比值在0.7-0.9之间，竖向设计反应谱的特征周期应有单独规定。

The ratio of vertical and horizontal predominant period is 0.7-0.9 , so independent characteristic period of vertical design response spectrum should be defined .

结果表明，现行抗震设计规范中设计谱的特征周期和长周期谱值明显偏小。

The characteristic periods and the spectral values for long period portion of the design spectra in the code for seismic design of buildings ( GB50011-2001 ) of China are obviously lower than those from the statistical results .