World Guide – Tuned Mass Damper of the Shanghai Tower

World Guide List Item – Investigate the Magnetic Tuned Mass Damper of the Shanghai Tower

From Gizmodo:

This is where the ‘tuned mass’ damper system of the 2,073-foot Shanghai Tower comes into play. The physics of the damper work exactly as normal — a 1,000 ton weight hangs from steel cables. But two systems prevent the weight from moving too far or two fast: hydraulic rams, and a ‘tunable’, self-generated magnetic field.

The iron weight hangs above 10m x 10m copper plate, which is studded with 125 powerful magnets. As the iron swings over the magnets, it induces an electrical current in the copper plate, which in turn is enough to limit the motion of the mass. The beauty is in the simplicity: there’s no outside power source, and it’s a completely self-regulating system. The faster the weight moves, the stronger the magnetic field containing it.