The “surprising” swaying motion in the world’s thinnest skyscrapers

Posted by Derek Mason

16th August 2022

Photo credit: Jermaine Ee on Unsplash

The quest for bigger and better skyscrapers continues, but now there’s a new superlative in the mix. The world’s skinniest skyscraper opened this year in New York City. Dubbed “the Coffee Stirrer,” Steinway Tower is more than a quarter of a mile tall, and its width is the exact length of a standard bowling alley.

As with any building over a certain height, high winds can potentially cause noticeable swaying. A building as tall and slim as the Steinway Tower, which comes in at 435m (1,428ft), could move as much as 0.9m (3ft) on the upper floors. This could be nausea-inducing, until you get used to it!

Built at 111 West 57th Street, also known as Billionaire’s Row, the tower’s proportions mean the residential tower is the thinnest in the world, with a height-to-width ratio of 24:1.

Tall buildings are effectively very long cantilevers. It’s possible to reduce the swaying effect, and most structural engineers will push to have bigger stair cores and lift cores to stabilise the building. But architects and developers often prefer to have more floor space for retail, residential and office space. This means the cores must work a lot harder. Swaying in certain weather conditions will be inevitable.

The 82-floor tower is made up of 5 floors of recreation and retail space, plus 77 floors of residential space. Each one of the 46 apartments takes up at least one floor, giving residents panoramic views of Central Park, the Upper East Side and the Upper West Side.

Apartments in this £1.5 billion tower are listed between £6 million for the smallest flat and £50.7 million for the penthouse, so maximising the space has presumably been profitable. It’s the third tallest building in NYC, after One World Trade Centre and Central Park Tower.

The tower uses the “air rights” of Steinway Hall, an attractive, historic building that housed Steinway & Sons’ piano showrooms and concert halls. The building is perfectly aligned with the axis of Central Park, providing a symmetrical view to apartment owners.

There’s just the slight issue of getting used to any swaying. Neighbours in nearby 432 Park Avenue, which comes in at 425.5m (1,396ft) have a similar issue, and visitors to the tower have spoken of being “super nauseated”. With a height-to-width ration of 15:1, 432 Park is also more slender than the average skyscraper.

The media has commented on the swaying as if it’s a surprise, but anyone who’s spent time in very tall buildings will be aware that swaying is a natural side effect of the height, especially on a windy day.

For most of us, it’s not a problem we’re likely to have. Aside from the cost, there doesn’t seem to be the same appetite for tall, skinny, residential skyscrapers in London. We do, however, have Brighton’s tallest building – the i360 tower – which won a place in the Guinness World Records as the “most slender tower” in 2016.

At a diameter of 3.9m (12.7ft) and a height of 162m (531ft), this tourist attraction would also make a good coffee stirrer. Unlike the Steinway Tower, visitors expect it to move, with a doughnut-shaped glass pod carrying people up and down the tower to enjoy panoramic views.

It’s also a feat of engineering, designed to weather “50 year” storm conditions – with 76 “sloshing liquid dampers” fitted to help prevent lateral movements.

And it has a more disparaging nickname than “the Coffee Stirrer”. Locals who were against the construction have nicknamed it the iSore.

At Super Structures Associates, we’ve worked on a wide range of projects, from buildings squeezed into tight spaces, the narrowest house being only 1.8m wall to wall, to ones with a more ordinary width. If you need assistance with the structural elements of an upcoming project, please do get in touch.

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