In the narrowest skyscraper in the world

She is only three years old, but already, she is an icon. The Steinway Tower, in new York, is the narrowest skyscraper in the world. Located a few steps from Central Park, this architectural feat rises over 84 floors.

This morning, our team has an appointment to visit it. As guides, we can count on two engineers and an architect who have signed his design.

From the outside, the silhouette of the Steinway Tower impresses. Our office, shop architects, does not create simple cold and impersonal glass cubesinsists archivette tuts.

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Indeed, the skyscraper is not straight.

On the south side, the upper floors are narrower than the previous ones. They sketch the profile of a celestial staircase.

It is in tribute to the Empire State Building and the Chrysler Building, explains the architect. They too have a staircase silhouette.

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At 111 57th rue Ouest – The address of the Steinway Tower -, the facade is not a modern construction.

We find ourselves in front of a heritage building, built in the 1920s. It was the Steinway Hall, former head office of the famous pianos manufacturer.

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When the property developer approached us in 2013 to build here, we scraped our headsrecalls Scot Teti.

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It was obviously impossible to destroy this heritage building, and the plot of land that was free behind the Steinway Hall was tiny.

To rise on this pocket handkerchief, the Scot Teti team designed a 435 -meter tower, but whose grip on the ground is only 18 meters wide. A ratio of 24 to 1.

Unheard of!

Build the impossible

Make sure that such a skyscraper could stand up is Silvian Marcus’ job.

This structural engineer is a summacy in the world of real estate in New York. His WSP cabinet team has signed engineering plans for the highest towers in the city, whether it is the One World Trade Center or the skyscrapers supertalls (higher than the State Building Empire) which make up theBillionaires alley -This Manhattan area, south of Central Park, known for its ultra high and ultra luxurious residential skyscrapers.

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The thinner a tower, the more difficult it is to guarantee its stabilityunderlines the engineer, which has about fifty years of experience.

The first step was to securely anchor the tower on the ground. We installed 192 anchors in the rock, up to 25 meters deep, explains Silvian Marcus. These are like the roots of a tree. In the event of strong winds, they prevent the building from overthrowing.

The time has come to visit the interior. But do not enter who wants in the Steinway Tower. Buyers, who pay up to $ 110 million to live there, do not want to meet journalists in the elevator. Fortunately for us, Silvian Marcus is not used to being told no. It only takes a few phone calls for the doors to open.

The entrance is by the Steinway Hall, fully restored and now integrated into the skyscraper.

We then enter the new tower to take the elevator, which goes to the 82nd floor.

The doors open directly in an apartment that occupies two entire floors. This unit is not yet sold.

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What immediately strikes is the spectacular view of Central Park that we have from the show. The north facade is entirely glazed to put your eyes full.

Ditto for the southern facade. On this side, it is the view of the Empire State Building and the new Tours of Midtown Manhattan which are available to us.

We have reduced the structural elements to the essentials so as not to obstruct the viewssouligne Silvian Marcus.

The framework of the building is made up of the east and west facades as well as the central nucleus, where the elevators are located. These are walls two meters thick. The engineers also increased the thickness of the floors to add mass to the building and allow it to resist the wind.

Wind test

The wind is the number one enemy of architects and engineers who design the skyscrapers supertalls. It is here that between the Canadian engineer Derek Kelly, of the RWDI firm, between the scene. In his blower, located in Guelph, Ontario, he tested the aerodynamics of the highest towers in the world, be it Burj Khalifa, in Dubai, or the One World Trade Center, in New York.

The Steinway Tower was no exception. The Derek Kelly team reproduced it on a reduced scale (1: 400). She also made models of all the buildings that surround her. The engineers then simulated an episode of strong winds in the blower.

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The first version of the tower offered by the architects did not have a very good aerodynamic performance, known as Derek Kelly. So we worked together to reshape the building.

On the upper floors, if aerodynamics are not well controlled, building oscillations can be a problem. Movements can affect the inner ear and cause sensations similar to seasickness or vertigo. People who buy this type of apartment are extremely demanding, notes Silvian Marcus. They don’t want to feel anything.

To reduce the gap of the wind on the skyscraper, Derek Kelly offered to leave three floors completely open, up of the tower. It is a bit like making holes in the sail of a ship.

For the summit, engineers and architects have designed what they call a crown. It breaks the formation of vortexes and makes them less powerfulexplains Derek Kelly.

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A giant counterweight

The day of our visit, the winds border on the 45 kilometers an hour in Manhattan. In the 82nd floor apartment, no movement is detected. Our team rises a few floors above, above the last apartments, to discover another secret of this amazing stability.

It is here that the mass shock absorber is located, a huge steel structure whose role is to counterbalance the movements of the building. It works like a giant pendulum that oscillates at the opposite frequency of building movements.

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This structure was entirely designed and built in Ontario by the engineering firm Motioneering and its partner, the manufacturer A&H. Together, they made mass shock absorbers for skyscrapers worldwide, including the famous steel ball at the top of the Tapei 101 tower.

That of the Steinway Tower caused some headaches to engineers.

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The building narrows a lot towards the top, which means that the surface of the floors is very smallexplains engineer Andy Smith, technical director at Montioneling. Our shock absorber weighs 800 tonnes and it must oscillate by more than a meter and a half in each direction. We didn’t have much margin.

In Manhattan, the race towards the sky is far from over. In the coming months, Derek Kelly plans to test eight new supertalls New Yorker in his blower. We have rarely been so busyhe said, before going back down to the ground floor to run at his next meeting.

Scot Teti stays with us for a few more minutes to admire the view from the 82nd floor apartment. There is a fun saying that says that New York will be great once they have finished building it, he recalls. We haven’t finished yet.

A report by Dominique Forget and Yanic Lapointe on this subject will be presented to the program Discovery Sunday at 18 h 30 (Hae) on here TV.

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