Seismic isolation of buildings using composite foundations based on metamaterials

Abstract

Metamaterials can be engineered to interact with waves in entirely new ways, finding application on the nanoscale in various fields such as optics and acoustics. In addition, acoustic metamaterials can be used in large-scale experiments for filtering and manipulating seismic waves (seismic metamaterials). Here, we propose seismic isolation based on a device that combines some properties of seismic metamaterials (e.g., periodic mass-in-mass systems) with that of a standard foundation positioned right below the building for isolation purposes. The concepts on which this solution is based are the local resonance and a dual-stiffness structure that preserves large (small) rigidity for compression (shear) effects. In other words, this paper introduces a different approach to seismic isolation by using certain principles of seismic metamaterials. The experimental demonstrator tested on the laboratory scale exhibits a spectral bandgap that begins at 4.5 Hz. Within the bandgap, it filters more than 50% of the seismic energy via an internal dissipation process. Our results open a path toward the seismic resilience of buildings and a critical infrastructure to shear seismic waves, achieving higher efficiency compared to traditional seismic insulators and passive energy-dissipation systems.

Nonlinear dispersion relation in anharmonic periodic mass-spring and mass-in-mass systems

“…3. The parameters are typical experimental values for spring with low Young Modulus [16]. For this set of parameters, we found a quantitative agreement up to 10 mm ( Fig.…”

“…[7] , [8] Recently the study of nonlinear periodic systems has been faced in several works, [9] for instance considering single nonlinear partial differential equation via a continuum approximation, [10] variational equations, [11] and perturbative approaches. [12] On the other hand, after the experimental demonstration of locally resonant sonic metamaterials [13] there has been a growing interest to apply those concepts in the field of seismic metamaterials in order to filter seismic waves [14] , [15] , [16]. Most of the recent studies on this class of metamaterials deal with linear dynamics and some approaches are based on the use of onedimensional models such as mass-in-mass systems or phononic crystals [16] , [17] , [18] , [19].…”

“…[12] On the other hand, after the experimental demonstration of locally resonant sonic metamaterials [13] there has been a growing interest to apply those concepts in the field of seismic metamaterials in order to filter seismic waves [14] , [15] , [16]. Most of the recent studies on this class of metamaterials deal with linear dynamics and some approaches are based on the use of onedimensional models such as mass-in-mass systems or phononic crystals [16] , [17] , [18] , [19]. Seismic metamaterials can be designed to be integrated directly within the soil, [14] , [20] or, with the standard foundation of a building to protect via the concept of the composite foundation.…”

“…Seismic metamaterials can be designed to be integrated directly within the soil, [14] , [20] or, with the standard foundation of a building to protect via the concept of the composite foundation. The latter has the advantage that the physical space required for the isolation is comparable with the size of the building itself and from a modeling point of view can be described by a periodic chain of massin-mass systems [16]. In addition, compression tests show that the curve stress-strain of the rubber used for the external spring exhibits a nonlinear behavior that can be characterized by an anharmonic energy term.…”

Locally Resonant Metasurfaces for Shear Waves in Granular Media

“…The coupling occurring between the resonators and the waves propagating inside the component induces a bandgap in the subwavelength regime [18]. In civil engineering for instance, arrays of metre-large mechanical resonators embedded in the soil surface [19,20], typically referred to as elastic metasurfaces, or integrated in the building's foundation [21,22] have been recently proposed with the aim of shielding infrastructures from groundborne vibrations and possibly even seismic waves.…”