Fazlur Rahman Khan

Fazlur Rahman Khan was born in Dhaka, then in British India, the son of a mathematics teacher. He studied civil engineering in Dhaka, and in 1952 won a Fulbright scholarship to the University of Illinois, where in three years he took two master's degrees and a doctorate. He joined the Chicago architects Skidmore, Owings and Merrill in 1955 and stayed there for the rest of his career.

Tall buildings at the time were held up by a dense internal skeleton of steel, and the taller they went the more steel they needed. Khan's insight was to move the structure to the outside. If the outer walls were built as a stiff tube of closely spaced columns and beams, the whole building resisted wind like a hollow cantilever, and the inside could be open. His first tube building, a 43-storey apartment block in Chicago, was finished in 1965.

He kept refining it. The John Hancock Center of 1969 wore its diagonal braces on the outside. The Sears Tower, completed in 1973, was nine tubes bundled together, rising to different heights, and at 442 metres it was the tallest building in the world until 1998. Both used far less steel per square metre than the Empire State Building. He was also among the first engineers to use computers routinely for structural design.

During Bangladesh's war of independence in 1971 he raised funds and lobbied for his homeland from Chicago. He died of a heart attack in 1982, aged 52.