The metamaterial can resist propagation of the waves generated by earthquakes, thus making buildings safer. Credit: Getty Images Plus

A computer model has shown that a building frame made of two-dimensional metamaterial can attenuate the intensity of waves generated by an earthquake1. The metamaterial can also resist propagation of the waves through its frame.

Metamaterials are structures made by placing unit cells in a specific order. They exhibit unusual properties that don’t occur in natural materials. Researchers at the Indian Institute of TechnologyMandi, Himachal Pradesh, simulated a metamaterial structure with two different types of unit cells.

The cells were square-shaped with a circular inner structure that can scatter waves. The outer layers of both unit cells were made of rubber, while the inner circular core of one unit cell was made from steel and the other from lead.

When exposed to three transient pre-recorded earthquake excitations, the metamaterial didn’t allow waves of a certain frequency to pass through it.

The researchers then compared the response of a metamaterial-based building frame to earthquake excitations with that of a concrete foundation. The frame vibration of the former was significantly less than the concrete frame. The metamaterial-based foundation could attenuate waves between 2.6 and 7.8 Hz.

Increasing the number of unit cells in the array of metamaterial increases attenuation of seismic waves. The desired array can be determined based on this.

This study offers a means to design new materials for building earthquake-tolerant houses, the researchers say.