Fazlur Khan

Fazlur Rahman Khan
Fazlur Rahman Khan
Born	April 3, 1929 Dhaka, Bengladesh
Died	March 27, 1982(1982-03-27) (aged 52) Jeddah, Saudia Arabia
Resting place	Graceland Cemetery
Nationality	Bangladeshi American
Education	Bengal Engineering and Science University, University of Illinois at Urbana-Champaign
Work
Engineering discipline	Architectural, civil, structural
Significant design	John Hancock Center, Willis Tower, Hajj Terminal, King Abdulaziz University, One Magnificent Mile, Onterie Center
Significant awards	Aga Khan Award for Architecture, Independence Day Award, AIA Institute Honor for Distinguished Achievement

Fazlur Rahman Khan (Bengali: ফজলুর রহমান খ়ান Fozlur Rôhman Khan) (April 3, 1929 - March 27, 1982) was an American Bangladeshi architect and structural engineer. He is a central figure behind the "Second Chicago School" of architecture, and is regarded as the "Father of tubular design for high-rises". Khan, "more than any other individual, ushered in a renaissance in skyscraper construction during the second half of the twentieth century." He has been called the "Einstein of structural engineering" and the "Greatest Structural Engineer of the 20th Century" for his innovative use of structural systems that remain fundamental to modern skyscraper construction. He is widely known for his work on the John Hancock Center and the Willis Tower (formerly Sears Tower), which was the world's tallest building for several decades.

Biography

Fazlur Rahman Khan was born on April 3, 1929 in Dhaka, Bangladesh. He was brought up in the village of Bhandarikandii near Dhaka. His father, Khan Bahadur Abdur Rahman Khan, BES was ADPI of Bengal and after retirement served as Principal of Jagannath College, Dhaka.

Education

Khan received his matriculation from Armanitola Government High School, in Dhaka. He received his bachelors degree from Bengal Engineering and Science University (BESU). He received a Fulbright Scholarship and a Pakistani government scholarship enabled him to travel to the United States in 1952 where he pursued advanced studies at the University of Illinois at Urbana-Champaign. He was able to travel because he finally had enough money. In three years Khan earned two Master's degrees — one in structural engineering and one in theoretical and applied mechanics — and a PhD in structural engineering.

Career

In 1955, employed by Skidmore, Owings and Merrill, he began working in Chicago, Illinois. He was made a partner in 1966 and became a naturalized American citizen in 1967. During the 1960s and 1970s, he became noted for his designs for Chicago’s 100-story John Hancock Center and 108-story Sears Tower, the tallest building in the world in its time and still the tallest in the United States since its completion in 1974. He is also responsible for designing notable buildings in Bangladesh and Saudi Arabia.

Fazlur Khan's personal papers, the majority of which were found in his office at the time of his death, are held by the Ryerson & Burnham Libraries at the Art Institute of Chicago. The Fazlur Khan Collection includes manuscripts, sketches, audio cassette tapes, slides and other materials regarding his work.

Personal interests

Outside of work, Khan enjoyed spending time with his family (wife Liselotte and daughter Yasmin). He enjoyed singing, poetry, and table tennis. He was also heavily involved with creating public opinion and garnering emergency funding for Bengali people during the 1971 Bangladesh Liberation War. He created the Chicago-based organization known as Bangladesh Emergency Welfare Appeal.

Innovations

Khan realized that the rigid steel frame structure that had "dominated tall building design and construction so long was not the only system fitting for tall buildings", marking "the beginning of a new era of skyscraper revolution in terms of multiple structural systems." Khan's design innovations significantly improved the construction of high-rise buildings, enabling them to withstand enormous forces generated on these super structures. These new designs opened an economic door for contractors, engineers, architects, and investors, providing vast amounts of real estate space on minimal plots of land.

Tube structural systems

See also: Tube (structure)

Khan's central innovation in skyscraper design and construction was the idea of the "tube" structural system for tall buildings, including the "framed tube", "trussed tube" and "bundled tube" variations. His "tube concept," using "all the exterior wall perimeter structure of a building to simulate a thin-walled tube, revolutionized tall building design." The constructions of most supertall skyscrapers since the 1960s, including the construction of the World Trade Center, Petronas Towers and Jin Mao Building, employ a tube structural system.

Framed tube

Since 1963, the new structural system of framed tubes became highly influential in skyscraper design and construction. Khan defined the framed tube structure as "a three dimensional space structure composed of three, four, or possibly more frames, braced frames, or shear walls, joined at or near their edges to form a vertical tube-like structural system capable of resisting lateral forces in any direction by cantilevering from the foundation." Closely spaced interconnected exterior columns form the tube. Horizontal loads, for example from wind and earthquakes, are supported by the structure as a whole. About half the exterior surface is available for windows. Framed tubes allow fewer interior columns, and so create more usable floor space. The bundled tube structure is more efficient for tall buildings, lessening the penalty for height. The structural system also allows the interior columns to be smaller and the core of the building to be free of braced frames or shear walls that use up valuable floor space. Where larger openings like garage doors are required, the tube frame must be interrupted, with transfer girders used to maintain structural integrity.

The first building to apply the tube-frame construction was the DeWitt-Chestnut Apartments building that Khan designed and was completed in Chicago in 1963. This laid the foundations for the framed tube structure used in the construction of the World Trade Center.

The John Hancock Center, designed by Skidmore, Owings and Merrill with chief designer Bruce Graham and structural engineer Fazlur Khan. The building was completed in 1969.

Trussed tube and X-bracing

Khan pioneered several other variations of the tube structure design. One of these was the concept of X-bracing, or the "trussed tube", first employed for the John Hancock Center. This concept reduced the lateral load on the building by transferring the load into the exterior columns. This allows for a reduced need for interior columns thus creating more floor space. This concept can be seen in the John Hancock Center, designed in 1965 and completed in 1969. One of the most famous buildings of the structural expressionist style, the skyscraper's distinctive X-bracing exterior is actually a hint that the structure's skin is indeed part of its 'tubular system'. This idea is one of the architectural techniques the building used to climb to record heights (the tubular system is essentially the spine that helps the building stand upright during wind and earthquake loads). This X-bracing allows for both higher performance from tall structures and the ability to open up the inside floorplan (and usable floor space) if the architect desires. Original features such as the skin, pioneered by Fazlur Khan, have made the John Hancock Center an architectural icon.

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.

Sears Tower (now Willis Tower), designed by Bruce Graham and Fazlur Khan and completed in 1974, was the tallest building in the world at the time of its construction

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.

Influence

The influence of Khan's tube structure design can be seen in numerous buildings built since the 1960s. Tube structures have since been used in many skyscrapers, including the construction of the World Trade Center, Petronas Towers, Jin Mao Building, and most other supertall skyscrapers 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:

Khan invented a new way of building tall. [...] So Fazlur Khan created the unconventional skyscraper. Reversing the logic of the steel frame, he decided that the building's external envelope could – given enough trussing, framing and bracing – be the structure itself. This made buildings even lighter. The "bundled tube" meant buildings no longer need be boxlike in appearance: they could become sculpture. Khan's amazing insight – he was name-checked by Obama in his Cairo University speech last year – changed both the economics and the morphology of supertall buildings. And it made Burj Khalifa possible: proportionately, Burj employs perhaps half the steel that conservatively supports the Empire State Building. [...] Burj Khalifa is the ultimate expression of his audacious, lightweight design philosophy.

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 and Taipei 101. 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. This was the first time that people could have the opportunity to work and live "in the sky".

Professional milestones

List of buildings

Some the most famous buildings Khan was responsible for performing as structural engineer include the following:

• DeWitt-Chestnut Apartments, Chicago, 1963
• John Hancock Center, Chicago, 1965–1969
• Sears Tower, Chicago, 1970–1973
• Hajj Terminal, King Abdulaziz International Airport, Jeddah, 1974–1980
• King Abdulaziz University, Jeddah, 1977–1978
• One Magnificent Mile, Chicago, completed 1983
• Onterie Center, Chicago, completed 1986
• U.S. Bank Center, Milwaukee, 1973
• Burj Khalifa, Dubai, completed 2010

Other honors

Among Khan's other accomplishments, he received the Wason Medal (1971) and Alfred Lindau Award (1973) from the American Concrete Institute (ACI); the Thomas Middlebrooks Award (1972) and the Ernest Howard Award (1977) from ASCE; the Kimbrough Medal (1973) from the American Institute of Steel Construction; the Oscar Faber medal (1973) from the Institution of Structural Engineers, London; the International Award of Merit in Structural Engineering (1983) from the International Association for Bridge and Structural Engineering IABSE; the AIA Institute Honor for Distinguished Achievement (1983) from the American Institute of Architects; and the John Parmer Award (1987) from Structural Engineers Association of Illinois (Engineering Legends, Richard Weingardt).

Death

Khan died of a heart attack on March 27, 1982 while on a trip in Jeddah, Saudi Arabia. He was only 53. He was a general partner in SOM, the only engineer holding that high position at the time. His body was returned to the USA and was buried in Chicago.

Further reading

• Weingardt, Richard G. "Engineering Legends: Great American Civil Engineers." ASCE Press, 2005.
• Khan, Y. S. "Engineering Architecture: the vision of Fazlur R. Khan." New York: W. W. Norton & Company, 2004.

External links

• Website dedicated to Fazlur Rahman Khan
• "Evolution of Concrete Skyscrapers". http://www.civenv.unimelb.edu.au/ejse/Archives/Fulltext/200101/01/20010101.htm. Retrieved 2007-05-14. 
• Fazlur Rahman Khan information at Structurae