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CONSTRUCTION KNOWLEDGE BLOG

July 19, 2008

What will Those Crazy Structural Engineers Think of Next?
Filed under: Design — Tags: — nedpelger

I came across an article in BLDGBLOG that discussed an earthquake dampening system for skyscrapers. Usually I only need to hear the word “Earthquakes” and I lose interest, because we really don’t have earthquakes where I live and build. When I saw the graphic of this huge steel ball suspended near the top of a skyscraper, I was intrigued. I think you will be too.

For whom the bell tolls

[Image: Diagram of Taipei 101’s earthquake ball via the Long Now Foundation].

Earlier this week, the Long Now Foundation looked at earthquake dampers inside skyscrapers, focusing specifically on Taipei 101 – a building whose unanticipated seismic side-effects (the building’s construction might have reopened an ancient tectonic fault) are quite close to my heart.
As it happens, Taipei 101 includes a 728-ton sphere locked in a net of thick steel cables hung way up toward the top of the building. This secret, Piranesian moment of inner geometry effectively acts as a pendulum or counterweight – a damper – for the motions of earthquakes.

[Image: The 728-ton damper in Taipei 101, photographed by ~Wei~].

As earthquake waves pass up through the structure, the ball remains all but stationary; its inertia helps to counteract the movements of the building around it, thus “dampening” the earthquake.
It is a mobile center, loose amidst the grid that contains it.

[Image: Animated GIF via Wikipedia].

However, there’s something about discovering a gigantic pendulum inside a skyscraper that makes my imagination reel. It’s as if the whole structure is a grandfather clock, or some kind of avant-garde metronome for a musical form that hasn’t been invented yet. As if, down there in the bedrock, or perhaps a few miles out at sea inside a submarine, every few seconds you hear the tolling of a massive church bell – but it’s not a bell, it’s the 728-ton spherical damper inside Taipei 101 knocking loose against its structure.
Or it’s like an alternate plot for Ghostbusters: instead of finding out that Sigourney Weaver’s New York high-rise is literally an antenna for the supernatural, they realize that it’s some strange form of architectural clock, with a massive pendulum inside – a great damper – its cables hidden behind closet walls and elevator shafts covered in dust; but, at three minutes to midnight on the final Halloween of the millennium, a deep and terrifying bell inside the building starts to toll.
The city goes dark. The tolling gets louder. In all the region’s cemeteries, the soil starts to quake.

(Thanks to Kevin Wade Shaw for the link!)