Gradient V-Shaped and N-Shaped Seismic Metamaterials

Area of Science:

• Earthquake Engineering
• Materials Science
• Wave Physics

Background:

• Seismic metamaterials offer a promising approach to mitigate earthquake hazards by reducing seismic wave impacts.
• Existing seismic metamaterial designs often struggle to achieve a broad bandgap at low frequencies, a critical requirement for effective seismic wave reduction.

Purpose of the Study:

• To propose and analyze two novel seismic metamaterial designs, V-shaped and N-shaped, for enhanced low-frequency seismic wave attenuation.
• To investigate the effect of geometric modifications and gradient arrangements on the bandgap properties of seismic metamaterials.
• To develop cost-effective seismic metamaterial solutions using readily available materials like concrete.

Main Methods:

• Finite element transient analysis was employed to simulate the seismic wave propagation and attenuation characteristics of the proposed metamaterial designs.
• Band structure calculations were performed to determine the frequency ranges (bandgaps) where seismic waves are significantly attenuated.
• Gradient patterns were implemented by arranging metamaterials of varying heights to broaden the overall bandgap.

Main Results:

• Both V- and N-shaped seismic metamaterials demonstrated effective attenuation of surface waves over a broad range of low frequencies.
• The N-shaped design, achieved by adding a line to the V-shape, exhibited a broadened bandgap compared to the V-shaped design.
• Gradient arrangements of these metamaterials successfully combined individual bandgaps, leading to wider frequency attenuation ranges.
• Numerical simulations using finite element analysis were validated against band structure results, confirming their accuracy.

Conclusions:

• The proposed gradient V- and N-shaped seismic metamaterials are effective in attenuating low-frequency surface waves, offering a viable solution for earthquake hazard reduction.
• The N-shaped design provides an improvement in bandgap width over the V-shaped design.
• The use of concrete as the base material ensures a cost-effective and practical implementation for seismic protection of existing structures.