Fazlur Rahman Khan

Fazlur Rahman Khan was a structural engineer, born in Dhaka in what was then British India and later Bangladesh, who emigrated to the United States and joined the Chicago firm Skidmore, Owings and Merrill, where he transformed the economics of the tall building. Until the 1960s, tall steel-framed buildings relied on a rigid frame of columns and beams that grew disproportionately heavy and expensive as height increased, because resisting wind load fell mainly on the frame interior. Khan introduced the tubular structural system, concentrating strength in closely spaced columns and deep beams around a building perimeter so the whole building acts as a hollow tube resisting wind like a cantilevered beam, which used dramatically less structural material than a conventional frame at the same height. He applied a reinforced-concrete version of the idea to Chicago DeWitt-Chestnut Apartments in 1963 and a bundled-tube steel version to the Willis Tower, then the Sears Tower, completed in 1973 and the world tallest building until 1998, as well as to the John Hancock Center of 1969, and the tube family of systems he founded remains the standard approach for supertall construction worldwide.