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Skyscrapers in London.
- Modern skyscrapers are often adorned with strange-looking design features, from twisting sides to pointy, tapered ends and gaping holes.
- But these design details aren't for decoration.
- They're among the many features architects use to keep the buildings' residents from getting vertigo, as supertall skyscrapers can sway up to several feet in the wind.
- 432 Park Avenue, New York City's second-tallest residential building, was designed with missing glass in the mechanical floors so that wind could pass through more easily.
- And the twisting design of the 2,073-foot-tall Shanghai Tower in China is meant to withstand typhoon-force winds.
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Many design elements associated with modern skyscrapers - twisting sides, tapered pointy tops, random gaping holes - don't have anything to do with aesthetics.
In fact, many distinctive features of modern supertall buildings are meant to deal with one factor that most people might not consider: the wind.
In heavy wind, supertall skyscrapers can vibrate and even sway up to several feet.
"Back-and-forth movement on top floors can cause serious discomfort for people inside," Christophe Haubursin and Gina Barton wrote for Vox. "To deal with that, modern skyscrapers use a slew of architectural tricks to confuse the wind. Details that might look like decorative flair - like twisted sides, tapered pointy tips, and gaping holes - are actually carefully designed wind reduction techniques that keep buildings still."
Take Chicago's Willis Tower, formerly known as the Sears Tower.
Reuters/Jason Reed
Chicago's Willis Tower, formerly the Sears Tower.
Architect Bruce Graham and structural engineer Fazlur Khan designed the "Windy City" skyscraper using the "bundled tube system," which means the tower is made up of a cluster of nine tubes that are connected to act as a single unit, according to the Chicago Architecture Center.
The structure is stronger because each tube supports the other tubes. And because of the variation in height of the tubes, the force of the wind is disrupted.
As a result, the tower reportedly sways only about six inches in high winds.
At 432 Park Avenue, New York City's second tallest residential building, early tests found that the structure was experiencing significant "vortex shedding" - where wind essentially causes the structure to vibrate - even with relatively low-speed winds, according to WSP, a global infrastructure and transportation consultancy firm.
Xinhua/Li Muzi via Getty Images
Engineers of 432 Park Avenue left out the glass on mechanical floors to let air pass through and reduce vibration and swaying from the wind.
The engineers decided to leave out the glazing - the architectural term for glass - on the uninhabited mechanical floors, allowing wind to pass through the building without meeting so much resistance, WSP reported.
Other elements that seem purely ornamental are actually added with wind in mind.
Hayes Davidson
Terra-cotta panels and bronze latticework were added to the facades of 111 West 57th Street, a 1,428-foot tower in New York.
On the east and west-facing facades of 111 West 57th, a 1,428-foot-tall luxury residential tower in New York, terra-cotta panels and bronze latticework were added to decrease wind forces.
And the spiral design of the 2,073-foot-tall Shanghai Tower in China, the second-tallest completed building in the world, is no accident.
The twist of the tower allows it to withstand typhoon-force winds and reduces wind load by 24%, according to Dezeen.
REUTERS/Aly Song
Shanghai Tower's twisted design allows it to withstand typhoon-force winds.
Many newer skyscrapers, including New York's One57 and 432 Park Avenue, are also outfitted with dampening systems, which act like "massive shock absorber[s]" during high winds, according to The New York Times.
Izak Senbahar, a developer of 56 Leonard, an 821-foot tall tower in New York, told The Times that most people probably won't feel a building swaying unless they're "supersensitive."
"But if you're building a luxury apartment, you have to think about the comfort of every buyer," Senbahar said.