Chicago’s Vista Tower To Have ‘Blow-Through’ Floor

CHICAGO (CBS) — The sight of it is intended to move you, but a new Marquis skyscraper in Chicago had the potential to much too much.

When complete, the city’s future 94-story development, the Vista Tower, will stand at nearly 1,200 feet — making it Chicago’s third tallest building.

But in the Windy City, the winds are blowing through the architect’s design.

“In some of our wind tunnel testing, we discovered the building had a little too much sway on the top,” said Sean Linnane, who’s with the Magellan Development Group. “Not necessarily that the building would fall over, but it would be uncomfortable if you were at the top.”

A model of the building was placed in a wind tunnel and, thus, the problem was discovered. However, it also led to a solution, which was that a place for wind to pass through was needed.

What’s now being called a “blow-through floor” is a first for Chicago.

“We take the portion of the building and we raise it up, and we have a portion where the wind can come right through the building,” Linnane said.

A blow-through hole exists at 515 N. State, but it’s only an aesthetic feature. The Council on Tall Buildings and Urban Habitat said the Willis Tower can sway up to six inches daily, and added that it’s surprisingly not alone.

“Probably the vast majority of them [skyscrapers] that you would see on the skyline actually do sway and are built to do so,” said Daniel Stafarik, who’s with the council.

To reduce sway, some buildings have dampers on the roof, which is a solid piece of concrete or a water tank that helps to weigh down the building.

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