Preliminary study on the periodic base isolation effectiveness and experimental validation

Periodic material possesses distinct characteristics that can block some certain frequency waves propagate through the structure, which can be used to reduce the unwanted seismic waves in civil engineering. Base on the Bloch-Floquet theory, the certain frequencies, terms frequency band gaps, are theoretically presented and derived. A numerical model of 1D periodic foundation is established to investigate the filtering effects of elastic waves. The dynamic response and filtering effects of a three-storey steel frame with a 1D periodic foundation and concrete foundation are performed and compared through the numerical method and shaking table tests. Ambient vibration, earthquake ground motions, and sine waves are applied as the input waves. The results show that the seismic waves cannot propagate in the 1D periodic foundation when the frequencies of the waves fall into the frequency band gaps of the foundation. Simultaneously, a single unit cell has proven to possess the same frequency band gaps as those with an infinite number of unit cells and has enough response reduction inside the frequency band gaps of the periodic foundation. Consequently, the proposed periodic foundation can be used to apply in isolating environmental vibration or seismic waves in civil engineering through adjusting the frequency band gaps enveloping the exciting frequencies of the waves.

Automated summary

Periodic materials can block specific frequency waves, reducing unwanted seismic waves in civil engineering. Adjusting frequency band gaps can help isolate environmental vibrations or seismic waves in civil engineering.