结构基本周期是指结构按基本振型完成一次自由振动所需的时间。
结果表明，筒桩基础桩基相对桩基于桩基有较好的抗震性能，筒桩基础的柔性改善了结构的基本周期。
The result is that cylindrical foundation is more earthquake-resistively than pile foundation, that cylindrical foundation flexibility improves the structural basic cycle.
研究结果表明，考虑地基土、砂砾石垫层、上部结构共同作用时，结构的基本频率明显减小，相应的基本周期明显延长；
The results shows that the fundamental frequency of the model which takes the combined activate into consideration reduced evidently, and the fundamental period prolonged evidently.
首先，当下部结构为整体支承结构时，提出将下部结构按基本周期等效简化为简单框架结构。
Firstly, for holistic substructure, the substructure was simplified as simple frame structure based on principle of equivalent fundamental periods.
应用推荐