Inside a three-story high-bay structures laboratory, Genda Chen is testing a new maintenance-free adaptive damper to mitigate the vibration of buildings. Unlike the "smart damper" Chen created, this new device requires no external energy.
How does it work? When a tank filled with water and sand is subjected to a weak earthquake, the sand will sink at the bottom of the tank and the water will slosh by itself. As the intensity of the earthquake increases, the sand will move together with the water, increasing the mass of the water-sand mixture that is in motion. "The moving water or water-sand mixture is directly related to the force that can be generated by the tank to counteract the earthquake effects on the building," Chen explains. "As a result, the tank filled with sand functions as an adaptive device for vibration suppression of the building."
The proposed water tank, technically called a mass-variable tuned liquid damper, uses earthquake energy to change its mass according to the intensity of the earthquake. The larger earthquake needs more counterforce, or more water-sand mass in sloshing motion. See the "sloshing" action for yourself.
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