Three dimensional periodic foundations for base seismic isolation

Abstract

Based on the concept of phononic crystals, periodic foundations made of periodic materials are investigated in this paper. The periodic foundations can provide low frequency band gaps, which cover the main frequency ranges of seismic waves. Therefore, the periodic foundations are able to protect the upper structures during earthquake events. In this paper, the basic theory of three dimensional periodic foundations is studied and the finite element method was used to conduct the sensitivity study. A simplified three-dimensional periodic foundation with a superstructure was tested in the field and the feasibility of three dimensional periodic foundations was proved. The test results showed that the response of the upper structure with the three dimensional periodic foundation was reduced under excitation waves with the main frequency falling in the attenuation zones. The finite element analysis results are consistent with the experimental data, indicating that three dimensional periodic foundations are a feasible way of reducing seismic vibrations.

Effective Negative Mass Nonlinear Acoustic Metamaterial with Pure Cubic Oscillator

“…An acoustic frequency branch is a lowfrequency dispersive curve while an optical frequency branch is a high-frequency dispersive curve. On this basis, we can obtain linear dispersive curve Equations (14) and (15). 8, is expressed as u (1) j,1…”

“…In civil engineering, acoustic metamaterials with the band characteristics were also created to replace the traditional seismic designs for isolating seismic waves from buildings. Shi and his coworkers [10][11][12][13][14] proposed a novel concept of foundation, periodic foundation, to isolate civil structures from seismic wave with frequencies that might resonate with the structures, which has been investigated in a number of comprehensive theoretical, numerical, and experimental studies. In particular, Brûlé et al [15] carried out the large-scale test of seismic metamaterials [15] such as seismic metawedge capable [16] capable of creating seismic waves and studied the attenuation effect of seismic waves by using finite periodic lattices of mass-in-mass barriers [17].…”

Composite periodic foundation and its application for seismic isolation

“…Considering the fact that the frequency content/region of earthquake excitation in the horizontal direction is different from that in the vertical direction, it is expected that periodic foundations with DAZs that target the earthquake excitation frequencies in the corresponding directions will be effective in reducing the vibration in both directions. While most existing research studies mainly focused on complete attenuation zone (CAZ) and periodic foundations with highly symmetric unit cells, the current paper studies the directional frequency attenuation zones of the 2 dimensional 3‐component LRPFs with unit cells that are not highly symmetric. Since a LRPF composed of one type of unit cell only has one major local resonant attenuation zone, to isolate seismic waves in both horizontal and vertical directions, a novel 2‐dimensional 3‐component LRPF is proposed by combining 2 types of local‐resonant unit cells with one type targeting the earthquake excitations in the horizontal direction and the other targeting the earthquake excitations in the vertical direction.…”

“…For instance, Shi and his coworkers proposed a novel concept of foundation, periodic foundation, to isolate structures from seismic wave with frequencies that might resonate with the structures. The feasibilities and effectiveness of one‐dimensional periodic layered foundation, and 2‐dimensional and 3‐dimensional periodic foundations in reducing structural responses have been investigated in a number of comprehensive theoretical, numerical, and experimental studies . Similar studies have also been conducted by other researchers .…”

Attenuation zones of initially stressed periodic Mindlin plates on an elastic foundation

“…Waves with frequencies in the AZs cannot propagate through the periodic structures. Hence, the AZ characteristic makes periodic structures a potential candidate in many engineering applications, such as mechanical filters, acoustic suppression and seismic isolation [3][4][5][6][7].…”