Wide band-gap seismic metastructures

Abstract

Metamaterials exploit local resonances to reflect acoustic signals with wavelengths well above the characteristic size of the material's structure. This has allowed obtaining materials that present low-frequency (albeit narrow) band gaps or devices for optical and acoustic cloaking. In this work, we propose to use an array of resonating structures (herein termed a "metastructure") buried around sensitive buildings to control the propagation of seismic waves. These seismic metastructures consist of arrays of cylindrical tubes containing a resonator suspended by soft bearings. To obtain broadband attenuation characteristics, each resonator in the array is designed to exhibit a different eigenfrequency. We study the response of these systems using numerical analysis and scaled (1:30) experiments. We target wave mitigation in the infrasound regime (1–10 Hz), a range of frequencies relevant for the protection of large buildings.

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