Shanghai Tower's 1,000-tonne pendulum that tames typhoon winds

In the teeth of Typhoon Dolphin, Shanghai's tallest building swung into action.

Destructive winds and torrential rainfall stirred a massive 1,000-tonne pendulum near the top of Shanghai Tower .

The 632-meter skyscraper is designed to sway.

But when the wind pushes one way, the suspended mass swings the other – a giant pendulum counters the tower’s movement and keeps people inside from feeling the motion.

The system, known as an eddy-current tuned mass damper, can cut wind-induced movement by up to 60%, according to a 2017 study by Tongji University.

Controlling a 1,000-tonne pendulum is no breeze.

Shanghai Tower uses electromagnetic damping: as the mass moves, magnets and conductive plates generate opposing forces that slow it down, without the wear and tear of mechanical contact.

The pendulum is just one part of the tower's defense.

Its twisting, tapered shape, refined through wind-tunnel tests, also helps reduce motion.

The principle at work is simple: Don't fight the wind.

Use controlled motion to counter it. (Cover: The "Shanghai Eye" installation, part of the damping system on the 126th floor of Shanghai Tower in Shanghai, China, April 27, 2019. /VCG)