Design of Metamaterials for Seismic Isolation

Abstract

This study assesses the implementation of locally resonant metamaterials in seismic isolation applications, by investigating their potential feasibility in low frequency bands. To this end, via adoption of both Blochs Theorem and classical vibration analysis, both one-dimensional and two-dimensional mass-in-mass lattices are analyzed in overlapping subbands and corresponding relations for the structural parameters are derived. The lattices are first examined in an infinite setup, for determining the arrangement of the resulting band gaps. Subsequently finite lattice configurations are investigated in the frequency and time domain. In this work, previous results are corroborated and additionally expanded to the 2D case. The parametric study that was carried out reveals interesting properties, particularly for low external-to-internal stiffness ratios of the unit cells comprising the lattices. Further investigation is required for confirming the feasibility of application of the resulting setups in full scale.

Seismic mitigation performance of periodic foundations with inertial amplification mechanism considering superstructure-foundation interaction

“…Equation (26) indicates that the total concentrated mass of the periodic foundation is less than the mass of the superstructure m i , and equation (27) indicates that the height of the periodic foundation is controlled within 9 m.…”

“…However, these two current attenuation mechanisms for periodic isolation foundations have two non-negligible disadvantages: (a) the frequency attenuation zone of the periodic structure based on Bragg scattering mechanism is obviously higher than the main frequency band of ground motions from 0.1 to 10 Hz, unless larger periodic unit cell size is adopted. This makes it difficult to realize the engineering application; (b) the periodic structure based on local resonance mechanism often adopt simplified one-dimensional multi degree of freedom spring resonator model, by increasing the mass ratio (referring to the ratio of the mass of the resonator to the mass of major structure, namely m 2 /m 1 in the resonator model in figure 1) for low frequency attenuation zone, but the smaller bandwidth of the attenuation zone follows [26,27].…”

On the feasibility of structural metamaterials for seismic-induced vibration mitigation

“…This study overviews outcomes of previous works of the authoring team Wagner et al, 2016) with the purpose of providing guidelines toward feasible designs, and in order to provide a critical discussion with respect to open-ended questions, and future directions. To this end: 1 we investigate requirements for seismic isolation in low frequency bands 2 we derive a conceptual design for a technologically feasible unit cell configuration in support of this pursuit 3 we offer a discussion on the inherent intricacies and the critical parameters that must be carefully considered prior to engaging in detailed analysis, including FE modelling, optimisation and testing of experimental prototypes.…”