Where Do We Stand on Metamaterial-Based Seismic Design of Engineering Structures?

Conventional seismic isolation systems for engineering structures are effective in reducing the damaging effects of the horizontal components of a vibration, but they are not well suited for protection against the vertical components of dynamic loads. They are also prone to rocking, further complicating the design. Metamaterial-based seismic isolators are very attractive because they can overcome the disadvantages existing in conventional seismic isolation systems. These metamaterial-based seismic isolators use the foundation of engineering structures to block or reflect the damaging seismic motion being transmitted to the engineering structures. This paper presents both the analytical and experimental studies to demonstrate the feasibility and effectiveness of the metamaterial-based seismic isolators. To date, where we stand on metamaterial-based seismic design of engineering structures is critically examined. Guided by solid-state physics, the seismic isolators can be made by the metamaterial to exhibit frequency band gaps that are useful in resisting the seismic waves imposed on engineering structures from earthquake disturbances. Possessing distinct frequency band gaps, this metamaterial will block, or reflect, the incoming seismic motion with the frequencies falling between these gaps. We properly designed the frequency band gaps to match the fundamental frequency of an earthquake, so that its dynamic response is greatly reduced.