CONCRETE
constructionmanagermagazine.com
Left: 111 West 57th Street (middle tower) overlooks Central Park
Last year, Taylor Grange Developments announced that it had obtained planning permission for 211 Broad Street in central Birmingham. What makes this building special is its dimensions. Were it to be built, it would be the UK’s first super-slender skyscraper (see box, p29). Though plans to start construction on the Birmingham site are paused while the country wrestles with covid-19, across the pond in New York a record-breaking example of this genre is nearing completion: the world’s most slender tower, 111 West 57th Street (see box, p30). It takes a particular set of circumstances to make these freakishly skinny buildings viable. They come with their own costly engineering and design challenges, which means that only a handful of cities boast them.
GOING SUPER SKINNY WITH CONCRETE NEW YORK, HONG KONG, MELBOURNE AND NOW… BIRMINGHAM? KRISTINA SMITH EXPLORES THE TECHNOLOGY BEHIND THE SUPER-SLENDER SKYSCRAPER
What is slender? The slenderness of a building is expressed as the ratio of its width to its height. “Any building with a slenderness ratio greater than 1:10 is considered slender, with very slender buildings having ratios of 12 to 15 and even more,” explains Giorgio Bianchi, a director at engineer Robert Bird. Birmingham’s 211 Broad Street would have a slenderness ratio of 1:12. Manhattan’s 111 West 57th Street’s ratio is a waif-like 1:24. The reason to construct such unusual buildings comes down to one thing: land values. When the market price of apartments is high enough
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