Cities

Fazlur Rahman Khan Has Been Called The Einstein Of Structural Engineering

Pop quiz: what do Willis (formerly Sears) Tower and John Hancock Center of Chicago, One Shell Square in New Orleans, U.S. Bank Center in Milwaukee, and the United States Air Force Academy in Colorado all have in common? Fazlur Rahman Khan, a Bangladeshi-American structural engineer without whom the skyscraper may have remained a footnote in history books.

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Elegant Monstrosities

The construction of New York City's Empire State Building in 1931 is often held up as a milestone in the evolution of the modern city: suddenly, architects realized they could build up rather than out, and city skylines took on on new shapes. But that's not exactly true. The building stood alone as the tallest in the world for more than 40 years. That stagnant period was partially due to political circumstances — there was the Great Depression, then World War II — but not entirely.

It was also because skyscrapers were the '57 Chevy of architectural design: elegant and eye-catching, but also expensive and wildly inefficient. The Empire State Building itself required 42 pounds of steel per square foot (206 kg per square meter). The steel required to build anything taller wouldn't be worth the investment, and the taller the structure got, the heavier it needed to be to stand up to wind. All that extra steel and concrete takes up usable space, making every new floor worth less and less.

But Fazlur Khan had a solution. Instead of designing a column, he designed a tube.

United States Air Force Academy

Rise Up

A hollow tube fixed the problems of the heavy buildings that came before it. It helped tall towers withstand horizontal forces like wind and earthquakes, but used less material, making it cost less and have a smaller environmental impact. Khan and his friend and design partner, architect Bruce Graham, tested this tube design on the 42-story DeWitt-Chestnut apartment building to great success. Their next goal? Using it to design what would be the world's second tallest building to that point: the John Hancock Center in Chicago.

They accomplished that feat in 1968, creating their skyscraper with a mere 30 pounds of steel per square foot (145 kg per square meter) to the Empire State Building's 42. And their 100-story tower cost the same as a conventional 45-story building. Four years later, Khan and Graham used the same principles to design the 108-story Sears Tower. This new method proved to be a revolution in building design. It made skyscrapers financially feasible again, and led other architects to follow suit by making other skyscrapers with the same method, including One World Trade Center in New York, Petronas Towers in Kuala Lumpur, Taipei 101 in Taipei, and Burj Khalifa in Dubai. Without Khan's genius, who knows what our skylines might look like?

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