Nested-mass locally resonant metabarriers for seismic wave mitigation

Seismic metamaterials (SMs) have garnered significant attention in earthquake engineering due to their exceptional ability to manipulate waves. Originating from the fields of electromagnetics and acoustics, these SMs consist of periodic arrays of engineered structures embedded in the soil to protect buildings from seismic waves. In this paper, we propose a nested-mass metabarrier, which can produce a low-frequency band gap utilizing the local resonance phenomenon of its inner core. Based on analytical studies, parametric analysis, and construction feasibility, the developed metabarrier comprises a concrete core inside a plywood shell and is interconnected by soft polyethylene foam. Dispersion analysis shows the proposed metabarrier can generate a low-frequency band gap of 0.8–3.2 Hz, which falls within the frequency range of seismic waves (below 10 Hz). Lab-scale experiments and numerical simulations further verify the performance of the metabarriers in attenuating propagating P-waves in sand at frequencies within the band gap. The proposed metabarrier design is therefore shown to have desired wave attenuation and is feasible for construction, demonstrating its potential for practical application in seismic protection.