Chicago Skyscraper Leaves 83rd Floor Empty For Wind To Blow Through

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A 95-story skyscraper under development in Chicago is making room for the wind. The engineers of the new Vista Tower were concerned that the building would sway in the wind — possibly enough to make its future inhabitants feel sick. So architects opted to leave the 83rd story of the building empty, creating a tunnel for the wind to rush through nearly 1,000 feet above the street.

Here & Now's Jeremy Hobson talks with Juliane Wolf, one of the building's designers.

Interview Highlights

On conceiving the design

"Well, it wasn't just us, I have to admit, we had a great team of engineers working with us. During our design phase, one of the steps we take is to do wind-tunnel testing. We did that for the Vista Tower as well, and during wind-tunnel testing, the results showed that we had to mitigate the wind forces via several measures that we could develop further. We tested different options, and the most effective was doing a blow-through floor, which means taking out a level within the tower. It proved to be very effective and it worked well with the design, so that's the strategy we moved forward with."

On the sway of the building without the blow-through floor

"It would sway enough to make people uncomfortable, potentially nauseous — of course, it depends on how strong the wind blows, so it's not a constant sway or movement, but during storms, there certainly would have been a level of movement that would make people too uncomfortable. [Blow-through floors] get rid of the sway to acceptable levels. There's actually a norm that dictates what is acceptable. There is a little movement, always, but it is at a level that does not make people uncomfortable."

On losing money by taking out a floor

"That is true, I'm sure the developers would have rather kept the floor there, but it's one of the wind-mitigating measures that had to be taken, so they understood it of course."

On whether or not these adjustments mean we're building skyscrapers too high

"I don't think so, I think that to deal with wind forces is a very common part of tall-building engineering, and the blow-through floor is one of these measures that has a great effect. There are other measures, one of which is to have a pool filled with water that mitigates the sway of the tower. So, there are different measures, and the blow-through floor is just one of them, so I don't think it means anything about going too far."

This article was originally published on July 31, 2017.

This segment aired on July 31, 2017.



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