Quake-proof megatower tops out in Tokyo

Paul Marks, senior technology correspondent

(Image: Kyodo/AP/Press Association Images)

With memories still fresh of Tokyo's skyscrapers swaying scarily as the 11 March 2011 megaquake struck Japan nearly a year ago, it's perhaps not the best time to be preparing to open the country's tallest building. But on 29 February, engineers completed Sky Tree, a 634-metre-high TV transmission and observation tower for the city - with architects Nikken Sekkei promising that it incorporates some of the most advanced earthquake and typhoon-resistant technology. It opens to the public in May.

The ultrahigh transmitter is needed because the city's existing Sky Tower transmitter - a 333-metre-high, red-and-white version of the Eiffel Tower that was built in 1958 - cannot broadcast above much of the city's ever-rising skyline, causing particular problems for lower-power digital terrestrial TV signals.

The Sky Tree has to resist major quakes with an epicentre in Tokyo, not to mention wind speeds of up to 80 metres per second (290 kilometres per hour) for 10 minutes - something the city expects from a typhoon once every 500 years. To get this performance, the architects designed a cylindrical core of reinforced concrete and hung peripheral steel framing from it to form the populated spaces.

Connected to the Sky Tree's core by oil-damped connectors - like the branches of a tree, hence the name - this arrangement cuts the shear forces, and hence the swaying motion, the structure experiences by 40 per cent.

Source: http://feeds.newscientist.com/c/749/f/10897/s/1d1298ad/l/0L0Snewscientist0N0Cblogs0Cshortsharpscience0C20A120C0A30Cquake0Eproof0Emegatower0Etops0Eout0Bhtml0DDCMP0FOTC0Erss0Gnsref0Fonline0Enews/story01.htm

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