Seismic Isolation of Buildings with a New Type of Periodic Foundations

Periodic composite exhibits a unique dynamic character, the so-called frequency band gaps over which there can be no propagation of elastic waves in the composite. Based on the unique character, a new type of layered periodic foundation consisting of concrete and rubber layers is proposed for blocking seismic waves of certain frequencies in the band gaps. Firstly, based on the theory of elastodynamics, the band gaps in the periodic foundations were analyzed by employing the Bloch-Floquet theorem. Subsequently, a parametric study was conducted to achieve a frequency band gap below 20Hz. Finally, we specialize the above concepts and results to a concrete frame on the periodic foundation. The dynamic response of the frame was simulated and the results show that vibration can be attenuated significantly. The results are expected to be useful and helpful for application of periodic isolated foundations in the future.