Building collapse is the primary cause of earthquake-related casualties. With an average of over eight earthquakes with magnitude six or higher every year globally, architects and engineers are constantly looking for better ways to reduce the impact of seismic waves on the structural integrity of buildings. Zeng et al. developed a seismic metamaterial capable of attenuating seismic surface waves between about 0.5 and 22.0 Hz, covering the resonance frequency range of most human-made structures.
When partially buried in the ground encircling a building or a set of buildings, the material isolates seismic surface waves that can cause resonance. According to the authors, a person in the protected buildings during an earthquake will be safe and may not feel the tremor at all.
“This seismic metamaterial can not only protect new buildings, but also protect ancient buildings, because it does not need to change the original structure of the protected objects,” said author Yi Zeng.
The material is made of a series of seismic metamaterial plates formed by horizontally arranging resonance elements, which are then placed atop a soil substrate. To test its damping capabilities, the group compared the impact of a seismic wave with and without interactions with the metamaterial, and found the material effectively blocks the seismic wave’s transmission.
Though large-scale tests and improved manufacturing techniques are needed before applying the seismic metamaterial to real-life structures, it holds promise in protecting vulnerable buildings and metropolises with its simple design. The authors hope it will eventually be used as a replacement or supplement to conventional isolation methods.
Source: “Subwavelength seismic metamaterial with an ultra-low frequency band gap,” by Yi Zeng, Pai Peng, Qiu-jiao Du, Yue-Sheng Wang, and Badreddine Assouar, Journal of Applied Physics (2020). The article can be accessed at https://doi.org/10.1063/1.5144177.
