Fazlur Khan

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Fazlur Khan : biography

03 April 1929 – 27 March 1982

In contrast to earlier steel-frame structures, such as the Empire State Building (1931), which required about 206 kilograms of steel per square metre and Chase Manhattan Bank Building (1961), which required around 275 kilograms of steel per square metre, the John Hancock Center was far more efficient, requiring only 145 kilograms of steel per square metre. The trussed tube concept was applied to many later skyscrapers, including the Onterie Center, Citigroup Center and Bank of China Tower., pg 34, Introduction to Tall building Structures, Dr. D.M Chan

Bundle tube

One of Khan’s most important variations of the tube structure concept was the "bundled tube," which he used for the Sears Tower and One Magnificent Mile. The bundle tube design was not only the most efficient in economic terms, but it was also "innovative in its potential for versatile formulation of architectural space. Efficient towers no longer had to be box-like; the tube-units could take on various shapes and could be bundled together in different sorts of groupings."

Concrete tube structures

The last major buildings engineered by Khan were the One Magnificent Mile and Onterie Center in Chicago, which employed his bundled tube and trussed tube system designs respectively. In contrast to his earlier buildings, which were mainly steel, his last two buildings were concrete. His earlier DeWitt-Chestnut Apartments building, built in 1963 in Chicago, was also a concrete building with a tube structure. The Brunswick Building, a 35 stories tall building built in 1965 also used this structural system.http://www.som.com/content.cfm/brunswick_building

Influence

Khan’s seminal work of developing tall building structural systems in structural steel and reinforced concrete based on building height are still used today as starting point when considering design options for tall buildings. Tube structures have since been used in many skyscrapers, including the construction of the World Trade Center, Aon Centre, Petronas Towers, Jin Mao Building, Bank of China Tower and most other buildings in excess of 40 stories constructed since the 1960s. The strong influence of tube structure design is also evident in the world’s current tallest skyscraper, the Burj Khalifa in Dubai. According to Stephen Bayley of The Daily Telegraph:

These pioneering structural systems shaped skyline of cities around the world. Khan is the foremost structural engineer of the 20th century whose contributions to the design of tall buildings have had a profound impact on the profession of architecture and engineering. In his short life, Khan re-shaped the concept of super-tall buildings and man’s ability to live and work in the sky. His developments are among today’s "conventional" systems for skyscraper design. Khan never acquired a household name, but a quarter-century after his death, his legacy lives on in the lives and work of a new generation of structural engineers.

Sky lobby

The first sky lobby was also designed by Khan for the John Hancock Center. Later buildings with sky lobbies include the World Trade Center, Petronas Twin Towers, Taipei 101 and the Burj Khalifa. The 44th-floor sky lobby of the John Hancock Center also features the first high-rise indoor swimming pool, which remains the highest in America., Emporis This was the first time that people could have the opportunity to work and live "in the sky".

A sky lobby is an intermediate floor, where people change from an express elevator that stops only there to a local elevator that stops at every floor within a segment of the building. When designing very tall buildings supplying enough elevators is a problem. Travellers wanting to reach a specific higher floor may conceivably have to stop at a very large number of other floors on the way up to let other passengers off and on. This increases travel time, and indirectly requires many more elevator shafts to still allow acceptable travel times – thus reducing effective floor space on each floor for all levels. To resolve this issue he invented the sky lobby.