阻尼对周期性隔震基础滤波特性的影响研究

Periodic isolation foundation is a new kind of seismic isolation system drawing the attention of more and more researchers. Ignoring the effect of damping, the isolation mechanism of periodic isolation foundation has been studied clearly in previous works. However, because of the limitation of the theoretical model, the effect of material damping on the filtering performance of periodic isolation foundation has not yet been considered. Considering the effect of damping, this project aims to make a systematic study on the method of analyzing the dispersion relationship of periodic structure and on the influences of damping on the filtering performance of periodic isolation foundation. The main research contents of this project are: 1) considering the effect of damping, novel numerical methods to calculate the dispersion relationship for different kinds of periodic structure will be established, and simplified theoretical models for analyzing the filtering effects and the dissipation performance of periodic structures will be developed; 2) the interaction between the filtering attenuation and the dissipation attenuation will be studied by through energy flow property analysis of finite periodic structure; 3) considering the effect of different factors like the scale of earthquakes, the characteristic of the upper-structure and so on, the influences of the damping on the filtering characteristic of the periodic foundation will be investigated, and the simplified design method for periodic foundations will be given. Through a comprehensive study proposed in this project, efficient numerical methods to calculate the dispersion relationship of different periodic structures including the effect of damping will be given and the influences of the material damping on the filtering effect of periodic isolation foundation will be clarified, which will be a great progress for the theoretical models and design methods of periodic isolation foundation.

作为一种新型隔震措施，周期性隔震基础已得到研究者越来越多的关注。在不考虑材料阻尼情况下，周期性隔震基础的隔震机理已较明晰。然而，由于理论分析上的困难，材料阻尼因素对周期性隔震基础滤波特性的影响一直未能考虑。本项目将系统研究计入阻尼因素后周期性结构频散关系分析方法以及阻尼因素对周期性隔震基础滤波特性的影响。研究内容主要包括：1）考虑阻尼因素，寻求周期性结构频散关系的求解方法，建立周期性结构滤波特性与耗能特性简化分析模型；2）研究有限周期性结构的能量流动特性，揭示滤波衰减作用和耗能衰减作用的影响机理；3）针对不同地震动、上部结构特性等因素，研究阻尼对周期性隔震基础滤波特性的影响，提出考虑阻尼后周期性隔震基础的简化设计方法。通过本项目研究，可望给出计及阻尼时周期性结构频散关系的有效求解方法，揭示材料阻尼对周期性隔震基础滤波特性的影响，进而丰富和完善周期性隔震基础的计算理论和设计方法。

周期结构对弹性波具有选择性透过作用，利用这种滤波动力特性学者们提出了一种新型隔震策略，即周期隔震基础。已有理论、数值及试验研究验证了周期基础隔震应用的有效性。基于已有研究，本项目重点研究考虑阻尼之后周期基础的复频散特性计算理论及考虑阻尼后周期基础的隔震性能。首先，项目提出三种复频散特性计算方法并研究了不同周期结构的复频散动力特性，揭示了周期结构频散差异性和一致性；其次，项目提出滤波减振机理与耗能减振机理的参数分析模型，数值模拟研究两种减振机理的相互影响；第三，项目提出复合周期基础模型，研究了复合周期基础在核电站结构隔震中的应用可行性。