Novel locally resonant and widely scalable seismic metamaterials for broadband mitigation of disturbances in the very low frequency range of 0–33 Hz

Abstract

Most current shielding mechanisms against seismic disturbances fail in protecting structures from low-frequency vibrations typically in the range of 1–10 Hz. This paper proposes a novel locally resonant Zero-Frequency Stop Band (ZFSB) metamaterial in the form of cylindrical resonators clamped to a 0.5 m thick concrete bed. This concept is convenient for practical implementation, and yields effective broadband wave inhibition in the ultra-low frequency range of 0–33 Hz. Through numerical simulations validated first against published experimental data, the concept is shown to achieve an attenuation zone due to the local resonance occurring between surface waves and the metamaterial features. Dynamic response- and transient time-analyses are used to gain insight into phononic dispersion in the proposed metamaterial, allowing the authors to demonstrate the working of the proposed concept. The effect of the material properties of the clamping bed on the performance of the proposed seismic metamaterial is also studied. The numerical results are then further validated through 1:40 scaled-down laboratory experiments. The proposed metamaterial when combined with soil with layered material properties, is later shown to nucleate wider ZFSB. The concept proposed is widely scalable for practical implementations and thus of much interest for isolation and protection of civil structures from low-frequency seismic disturbances.