Elastic metamaterial-based seismic shield for both Lamb and surface waves

Abstract

Controlling the propagation of seismic waves to protect critical infrastructure via metamaterial is of new topical interest. This approach can be implemented by remote shielding of incoming waves rather than with vibration isolating structures. In this paper, a two-dimensional elastic metamaterial with periodically square concrete-filled steel piles embedded in soil is proposed to achieve a seismic shield for guided Lamb waves and surface waves. Its properties are numerically investigated using the finite element method. For Lamb waves, we first identify complete bandgaps appearing in a periodic composite with cylindrical piles. By comparison, it is found that if the shape of the pile is replaced with the square shape, the bandgaps become wider and shift to the lower frequencies, which is more suitable for practical applications. Furthermore, it is demonstrated that a complete low frequency bandgap also exists for surface waves. The vibration modes for both types of waves at the bandgap edges are computed and analyzed to clarify the mechanism of the bandgap generation. The study focuses on realistic structures that can be effective in the frequency ranges for seismic waves. Although we have focused on the geophysical setting, elastic waves are also very important in applications involving acoustic wave devices.

A Review of Research on Seismic Metamaterials

“…In 2017, Achaoui et al buried periodic cylindrical columns and cross-shaped inclusions in the bedrock under the soil layer, [37] and Du et al investigated the protective effect of H-shaped fractal pillars and square concrete-filled piles which are better than hollow cylinder or square piles. [38,39] In 2018, Geng et al considered 1D binary SMs with two contrasting constituent materials, [40] and Zeng et al inspected I-shaped pillars arranged on a 2D ground surface. [41] Khlopotin et al studied the effect of a physically realizable cloak built up by unrestricted micropolar elastic media in the 2D form subjected to incident Rayleigh waves pertinent to seismic loading in 2015.…”

“…In recent years, significant research has introduced the local resonance mechanism in the construction of SMs. [6][7][8]14,[21][22][23][24][25][26][27][30][31][32][33][34][35][36]38,39,41,[47][48][49]55,56,61,62,64] The local resonance bandgap is the result of coupling between the long traveling wave property and the resonance characteristic of the periodic local oscillator in the matrix. The existence of coupling is the key factor to determine whether the bandgap is generated.…”

“…[55,56,61,62,64] Du et al also studied a three-component resonance structure and pointed out that the scatterer can be regarded as an oscillating rigid body and the connector as a spring between adjacent scatterers. [39] Du et al, Zeng et al, and Muhammad et al studied the inhibition of seismic wave propagation by the local resonance of H-shaped, I-shaped, and built-up structural steel pillars with periodic arrangements, respectively. [38,41,47] Torres-Silva and Cabezas introduced negative bulk modulus using a chiral structure which can excite rotation resonance and then cause the imaginary wave vector to attenuate the seismic wave.…”

“…Although some scholars have conducted 3D structural research considering waves in any given direction, [16,24,31,32,55,61,62,108,129] most of the existing studies are based on the 2D simplified model to analyze the propagation of waves. [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]55,56,58,59,[61][62][63][64][65][66]68,70,[106][107][108]110,[112][113][114][116][117][118]…”

Mechanical modeling of superelastic tensegrity braces for earthquake-proof structures

“…There is a growing scientific interest toward the design and engineering of nonlinear acoustic and mechanical metamaterials with tunable properties and advanced functionalities that are not found in conventional materials [1,2,3,4,5,6,7]. Seismic metamaterials are peculiar; they protect buildings and infrastructures from seismic waves, either by creating a shadow zone around the structure to be protected [8,9,10,11] or by applying seismic isolation devices based on lattice metamaterials at the foundation level [12,13]. Nonlinear metamaterials are progressively emerging as structured materials that can tune their responses to the level of the applied stress/strain or the amplitude of traveling waves [3,14,15,16,17].…”