| ABSTRACT:Periodic structures exhibit a unique dynamic character, the so-called attenuation zone in which the waves can’t propagate. It is also proved by the research of layered periodic foundation. However, the foundation bears the gravity of the upper structure in the practical engineering. The gravity will be translated into the initial stress of the foundation. The influence of initial stress on the attenuation zone is studied in this paper, which has never been considered by the researchers before. The dynamic characteristics of the composite layer periodic foundation are simulated by using ANSYS. This paper includes the following aspects:1. The basic theory of the Transfer matrix (TM) method is introduced in detail, and the attenuation zone of layered periodic foundation with initial stress is studied by this method.2. Concrete and rubber are selected as the component materials of layered periodic foundation, and the attenuation zone of this foundation is calculated in this paper. The influential factors (geometric parameters and initial stress) on attenuation zones are studied comprehensively. At last, two kinds of layered periodic foundation model are designed.3. By setting up combined layered periodic foundation model and using ANSYS to analyze its frequency response, it is found that the combined periodic foundation with initial stress has stronger attenuation and much wider attenuation zone than that without initial stress.4. The transient response of a structure with periodic foundation is conducted by ANSYS, the results show that the structure with initial stress has displacement and acceleration attenuation, compared with the layered periodic foundations without initial stress. In addition, the structure with attenuation zone can isolate vibration, which is proved through analyzing the time history of displacement.5. Through the seismic response analysis, it indicates that the composite layered periodic foundation with initial stress can attenuate the seismic response. |
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