Fazlur Rahman Khan (Bengali: Dhaka, April 3, 1929-Jeddah, March 27, 1982) was a Bangladeshi architect and engineer.
Path
He studied engineering at the Bangladesh University of Engineering and Technology, and received his doctorate in structural engineering in 1952 at the University of Illinois at Urbana-Champaign, as part of a Fulbright Program student exchange.[1].
Between 1952 and 1957 he worked at the American firm Skidmore, Owings & Merrill in Chicago. He then returned to his country, where he joined the Karachi Ordination Service, but in 1960 he returned to the United States and joined Skidmore, Owings & Merrill again. There he developed a fruitful career as a structural engineer, specializing in skyscrapers, where he introduced numerous innovations, such as the use of tubular steel or visible diagonal wind braces, as seen in the 875 North Michigan Avenue skyscraper (1965-1969, with Bruce Graham) and the Willis Tower (1970-1973, with Bruce Graham), both in Chicago. He also intervened in the One Shell Plaza skyscraper in Houston, Texas (1971).[2].
He was responsible for most of Skidmore, Owings & Merrill's projects in the Middle East, including the King Abdulaziz International Airport in Jeddah, Saudi Arabia (1974-1980), which received the Aga Khan Prize for Architecture in 1983.[2].
Structural innovations
Contenido
Khan descubrió que la estructura rígida de acero que había dominado durante mucho tiempo el diseño de edificios altos no era el único sistema adecuado para estos edificios, lo que marcó el comienzo de una nueva era de construcción de rascacielos.[3].
Structural tube systems
The John Hancock Center is the world's first mixed-use tower. When it was built, it was the second tallest building in the world. It demonstrated how much more efficient and feasible the construction of very tall skyscrapers could be, compared to the older design and technology used by skyscrapers up to that time.[4].
Fazlur Khan (Engineer)
Introduction
Fazlur Rahman Khan (Bengali: Dhaka, April 3, 1929-Jeddah, March 27, 1982) was a Bangladeshi architect and engineer.
Path
He studied engineering at the Bangladesh University of Engineering and Technology, and received his doctorate in structural engineering in 1952 at the University of Illinois at Urbana-Champaign, as part of a Fulbright Program student exchange.[1].
Between 1952 and 1957 he worked at the American firm Skidmore, Owings & Merrill in Chicago. He then returned to his country, where he joined the Karachi Ordination Service, but in 1960 he returned to the United States and joined Skidmore, Owings & Merrill again. There he developed a fruitful career as a structural engineer, specializing in skyscrapers, where he introduced numerous innovations, such as the use of tubular steel or visible diagonal wind braces, as seen in the 875 North Michigan Avenue skyscraper (1965-1969, with Bruce Graham) and the Willis Tower (1970-1973, with Bruce Graham), both in Chicago. He also intervened in the One Shell Plaza skyscraper in Houston, Texas (1971).[2].
He was responsible for most of Skidmore, Owings & Merrill's projects in the Middle East, including the King Abdulaziz International Airport in Jeddah, Saudi Arabia (1974-1980), which received the Aga Khan Prize for Architecture in 1983.[2].
Structural innovations
Contenido
Khan descubrió que la estructura rígida de acero que había dominado durante mucho tiempo el diseño de edificios altos no era el único sistema adecuado para estos edificios, lo que marcó el comienzo de una nueva era de construcción de rascacielos.[3].
Structural tube systems
The John Hancock Center is the world's first mixed-use tower. When it was built, it was the second tallest building in the world. It demonstrated how much more efficient and feasible the construction of very tall skyscrapers could be, compared to the older design and technology used by skyscrapers up to that time.[4].
Khan's central innovation in skyscraper design and construction was the idea of the "tube" structural system for tall buildings, which included the variants of framed tube, trussed tube, and bundled tube. His "tube concept", using the entire perimeter structure of a building's exterior wall to simulate a thin-walled tube, revolutionized the design of tall buildings.[5] Most buildings over 40 stories built since the 1960s now use a tube design derived from Khan's structural engineering principles.[6][7].
Lateral loads (horizontal forces) such as wind forces, seismic forces, etc., begin to dominate the structural system and assume increasing importance in the overall building system as the height of the building increases. Wind forces become very substantial and forces caused by earthquakes, etc. They are also very important. Tubular designs resist such forces in tall buildings. Tube structures are rigid and have significant advantages over other framing systems. Not only do they make buildings structurally stronger and more efficient, they also significantly reduce structural material requirements. Material reduction makes buildings more economically efficient and reduces environmental impact. Tubular designs allow buildings to reach even greater heights. Tubular systems allow for greater interior space and allow buildings to take on a variety of shapes, offering greater freedom to architects.[8][9] These new designs opened an economic door for contractors, engineers, architects and investors, providing large amounts of real estate space on minimal plots of land. Khan was part of a group of engineers who encouraged a renaissance in skyscraper construction after a hiatus of more than thirty years.[10]
Tubular systems have yet to reach their limits when it comes to height. [28] Another important feature of tubular systems is that buildings can be constructed using steel or reinforced concrete, or a composite of the two, to achieve greater heights. Khan pioneered the use of lightweight concrete for high-rise buildings,[11] at a time when reinforced concrete was primarily used for construction only a few stories high.[12] Most of Khan's designs were conceived with consideration for prefabrication and repetition of components so that projects could be built quickly with minimal errors.
More than any other engineer of the century, Fazlur Rahman Khan made it possible for people to live and work in "cities in the sky." Mark Sarkisian (Director of Earthquake and Structural Engineering at Skidmore, Owings & Merrill) said, "Khan was a visionary who transformed skyscrapers into sky cities while remaining firmly rooted in engineering fundamentals."[13].
Framed tubes
Since 1963, the new structural system of framed tubes became very influential in the design and construction of skyscrapers. Khan defined the framed tube structure as "a three-dimensional spatial 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-shaped structural system capable of resisting lateral forces in any direction by cantilevering from the base."[14] Closely spaced interconnected exterior columns form the tube. Horizontal loads, for example wind and seismic, are supported by the structure as a whole. Approximately half of the exterior surface is available for windows. Framed tubes allow for fewer interior columns and therefore create more usable floor space. The bundled tube structure is more efficient for tall buildings, reducing the height penalty. The structural system also allows for smaller interior columns and the core of the building to be free of braced frames or shear walls that use up valuable floor space. Where larger openings are required, such as garage doors, the tube frame should be interrupted and transfer beams used to maintain structural integrity.
The first building to use framed tube construction was the DeWitt-Chestnut Apartment Building, which was renamed DeWitt Plaza, a building Bruce Graham designed and engineered by Khan, which was completed in Chicago in 1963. This laid the foundation for the framed tube structure used in the construction of the World Trade Center (1973-2001).
Tube with reinforcement and X bracing
Khan pioneered several other variants of the tube structure design. One of them was the concept of applying X-bracing to the outside of the tube to form a reinforced tube. X-bracing reduces lateral loading on a building by transferring the load to exterior columns, and the reduced need for interior columns provides greater usable floor space. Khan first employed exterior X bracing in his engineering of the John Hancock Center in 1965, and this can be clearly seen on the exterior of the building, making it an architectural icon.[16].
In contrast to earlier steel frame structures, such as the Empire State Building (1931), which required about 206 kilograms of steel per square meter, and One Chase Manhattan Plaza (1961), which required about 275 kilograms of steel per square meter, the John Hancock Center was much more efficient, requiring only 145 kilograms of steel per square meter.[17] The tube-frame concept was applied to many later skyscrapers, including the Onterie Center, the Citigroup Center, the Hotel Arts and the Bank of China Tower.[18].
Bundled tubes
One of Khan's most important variants of the tube structure concept was bundled tubes, which was used for the Willis Tower and the One Magnificent Mile. The bundled tube design was not only the most economically efficient, but was also "innovative in its potential for the versatile formulation of architectural space. Efficient towers no longer had to be box-like; tube units could take various shapes and could be grouped into different types of clusters."
tube in tube
The tube-in-tube system takes advantage of the core shear wall tubes in addition to the outer tubes. The inner tube and outer tube work together to resist gravity loads and lateral loads and to provide additional rigidity to the structure to prevent significant deflections at the top. This design was first used at One Shell Plaza.[19] Later buildings that used this structural system include the Petronas Towers.[20]
Stabilizer and belt structures
The beam and belt truss system is a lateral load resisting system in which the tube structure is connected to the central core wall with very rigid stabilizers and belt trusses at one or more levels. The BHP House was the first building to use this structural system followed by the First Wisconsin Center, since renamed U.S. Bank Center "U.S. Bank Center (Milwaukee)"), in Milwaukee. The center rises 601 feet, with three belt trusses at the bottom, middle and top of the building. The exposed belt trusses serve aesthetic and structural purposes.[21] Later buildings include the Shanghai World Financial Center.[22]
Concrete tube structures
The last major buildings designed by Khan were One Magnificent Mile and the Onterie Center in Chicago, which employed his bundled tube and trussed tube system designs respectively. In contrast to its previous buildings, which were primarily steel, its last two buildings were concrete. The DeWitt-Chestnut Apartments building, built in 1963 in Chicago, was also a tube-frame concrete building.[16] Trump Tower in New York is also another example that adopted this system.[23].
Shear Wall Frame Interaction System
Khan developed the shear wall frame interaction system for mid-rise buildings. This structural system uses combinations of shear walls and frames designed to resist lateral forces. The first building to use this structural system was the 35-story Brunswick Building,[21] which was completed in 1965 and became the tallest reinforced concrete structure of its time. The structural system of the Brunswick Building consists of a concrete shear wall core surrounded by an exterior concrete frame of columns.[24] Apartment buildings up to 70 stories high have successfully utilized this concept.[25].
List of buildings
Buildings on which Khan was a structural engineer include:[26].
References
[1] ↑ Midant, 2004, pp. 484-485.
[2] ↑ a b Midant, 2004, p. 485.
[3] ↑ Ali, Mir M.; Moon, Kyoung Sun (2007-09). «Structural Developments in Tall Buildings: Current Trends and Future Prospects». Architectural Science Review 50 (3): 205-223. ISSN 0003-8628. doi:10.3763/asre.2007.5027. Consultado el 22 de marzo de 2021.: https://dx.doi.org/10.3763/asre.2007.5027
[5] ↑ Weingardt, Richard (2005). Engineering legends : great American civil engineers : 32 profiles of inspiration and achievement. American Society of Civil Engineers. ISBN 0-7844-0801-7. OCLC 60419905. Consultado el 22 de marzo de 2021.: https://www.worldcat.org/oclc/60419905
[10] ↑ Council on Tall Buildings and Urban Habitat. World Congress (2001). Tall buildings and urban habitat : cities in the third millennium : 6th World Congress of the Council on Tall Buildings and Urban Habitat, 26 February to 2 March, 2001. Spon Press. ISBN 0-203-46754-X. OCLC 51782388. Consultado el 22 de marzo de 2021.: https://www.worldcat.org/oclc/51782388
[12] ↑ Sev, Aysin (2005). "Tubular Systems for Tall Office Buildings with Special Cases from Turkey" (PDF). In Cheung, Y. K.; Chau, K. W. (eds.). Tall Buildings: From Engineering to Sustainability. Sixth International Conference on Tall Buildings, Mini Symposium on Sustainable Cities, Mini Symposium on Planning, Design and Socio-Economic Aspects of Tall Residential Living Environment, Hong Kong, China, 6 – 8 December 2005. World Scientific. p. 361. doi:10.1142/9789812701480_0056. ISBN 978-981-256-620-1.
[20] ↑ Lee, P. K. K. (1997). Structures in the new millennium : proceedings of the fourth International Kerensky Conference on structures in the new millennium, Hong Kong, 3-5 September 1997. A.A. Balkema. ISBN 90-5410-898-3. OCLC 39016527. Consultado el 27 de marzo de 2021.: https://www.worldcat.org/oclc/39016527
[26] ↑ National Academy of Sciences (1993). Biographical memoirs. Volume 62. National Academy Press. ISBN 0-585-14673-X. OCLC 45729831. Consultado el 22 de marzo de 2021.: https://www.worldcat.org/oclc/45729831
Khan's central innovation in skyscraper design and construction was the idea of the "tube" structural system for tall buildings, which included the variants of framed tube, trussed tube, and bundled tube. His "tube concept", using the entire perimeter structure of a building's exterior wall to simulate a thin-walled tube, revolutionized the design of tall buildings.[5] Most buildings over 40 stories built since the 1960s now use a tube design derived from Khan's structural engineering principles.[6][7].
Lateral loads (horizontal forces) such as wind forces, seismic forces, etc., begin to dominate the structural system and assume increasing importance in the overall building system as the height of the building increases. Wind forces become very substantial and forces caused by earthquakes, etc. They are also very important. Tubular designs resist such forces in tall buildings. Tube structures are rigid and have significant advantages over other framing systems. Not only do they make buildings structurally stronger and more efficient, they also significantly reduce structural material requirements. Material reduction makes buildings more economically efficient and reduces environmental impact. Tubular designs allow buildings to reach even greater heights. Tubular systems allow for greater interior space and allow buildings to take on a variety of shapes, offering greater freedom to architects.[8][9] These new designs opened an economic door for contractors, engineers, architects and investors, providing large amounts of real estate space on minimal plots of land. Khan was part of a group of engineers who encouraged a renaissance in skyscraper construction after a hiatus of more than thirty years.[10]
Tubular systems have yet to reach their limits when it comes to height. [28] Another important feature of tubular systems is that buildings can be constructed using steel or reinforced concrete, or a composite of the two, to achieve greater heights. Khan pioneered the use of lightweight concrete for high-rise buildings,[11] at a time when reinforced concrete was primarily used for construction only a few stories high.[12] Most of Khan's designs were conceived with consideration for prefabrication and repetition of components so that projects could be built quickly with minimal errors.
More than any other engineer of the century, Fazlur Rahman Khan made it possible for people to live and work in "cities in the sky." Mark Sarkisian (Director of Earthquake and Structural Engineering at Skidmore, Owings & Merrill) said, "Khan was a visionary who transformed skyscrapers into sky cities while remaining firmly rooted in engineering fundamentals."[13].
Framed tubes
Since 1963, the new structural system of framed tubes became very influential in the design and construction of skyscrapers. Khan defined the framed tube structure as "a three-dimensional spatial 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-shaped structural system capable of resisting lateral forces in any direction by cantilevering from the base."[14] Closely spaced interconnected exterior columns form the tube. Horizontal loads, for example wind and seismic, are supported by the structure as a whole. Approximately half of the exterior surface is available for windows. Framed tubes allow for fewer interior columns and therefore create more usable floor space. The bundled tube structure is more efficient for tall buildings, reducing the height penalty. The structural system also allows for smaller interior columns and the core of the building to be free of braced frames or shear walls that use up valuable floor space. Where larger openings are required, such as garage doors, the tube frame should be interrupted and transfer beams used to maintain structural integrity.
The first building to use framed tube construction was the DeWitt-Chestnut Apartment Building, which was renamed DeWitt Plaza, a building Bruce Graham designed and engineered by Khan, which was completed in Chicago in 1963. This laid the foundation for the framed tube structure used in the construction of the World Trade Center (1973-2001).
Tube with reinforcement and X bracing
Khan pioneered several other variants of the tube structure design. One of them was the concept of applying X-bracing to the outside of the tube to form a reinforced tube. X-bracing reduces lateral loading on a building by transferring the load to exterior columns, and the reduced need for interior columns provides greater usable floor space. Khan first employed exterior X bracing in his engineering of the John Hancock Center in 1965, and this can be clearly seen on the exterior of the building, making it an architectural icon.[16].
In contrast to earlier steel frame structures, such as the Empire State Building (1931), which required about 206 kilograms of steel per square meter, and One Chase Manhattan Plaza (1961), which required about 275 kilograms of steel per square meter, the John Hancock Center was much more efficient, requiring only 145 kilograms of steel per square meter.[17] The tube-frame concept was applied to many later skyscrapers, including the Onterie Center, the Citigroup Center, the Hotel Arts and the Bank of China Tower.[18].
Bundled tubes
One of Khan's most important variants of the tube structure concept was bundled tubes, which was used for the Willis Tower and the One Magnificent Mile. The bundled tube design was not only the most economically efficient, but was also "innovative in its potential for the versatile formulation of architectural space. Efficient towers no longer had to be box-like; tube units could take various shapes and could be grouped into different types of clusters."
tube in tube
The tube-in-tube system takes advantage of the core shear wall tubes in addition to the outer tubes. The inner tube and outer tube work together to resist gravity loads and lateral loads and to provide additional rigidity to the structure to prevent significant deflections at the top. This design was first used at One Shell Plaza.[19] Later buildings that used this structural system include the Petronas Towers.[20]
Stabilizer and belt structures
The beam and belt truss system is a lateral load resisting system in which the tube structure is connected to the central core wall with very rigid stabilizers and belt trusses at one or more levels. The BHP House was the first building to use this structural system followed by the First Wisconsin Center, since renamed U.S. Bank Center "U.S. Bank Center (Milwaukee)"), in Milwaukee. The center rises 601 feet, with three belt trusses at the bottom, middle and top of the building. The exposed belt trusses serve aesthetic and structural purposes.[21] Later buildings include the Shanghai World Financial Center.[22]
Concrete tube structures
The last major buildings designed by Khan were One Magnificent Mile and the Onterie Center in Chicago, which employed his bundled tube and trussed tube system designs respectively. In contrast to its previous buildings, which were primarily steel, its last two buildings were concrete. The DeWitt-Chestnut Apartments building, built in 1963 in Chicago, was also a tube-frame concrete building.[16] Trump Tower in New York is also another example that adopted this system.[23].
Shear Wall Frame Interaction System
Khan developed the shear wall frame interaction system for mid-rise buildings. This structural system uses combinations of shear walls and frames designed to resist lateral forces. The first building to use this structural system was the 35-story Brunswick Building,[21] which was completed in 1965 and became the tallest reinforced concrete structure of its time. The structural system of the Brunswick Building consists of a concrete shear wall core surrounded by an exterior concrete frame of columns.[24] Apartment buildings up to 70 stories high have successfully utilized this concept.[25].
List of buildings
Buildings on which Khan was a structural engineer include:[26].
References
[1] ↑ Midant, 2004, pp. 484-485.
[2] ↑ a b Midant, 2004, p. 485.
[3] ↑ Ali, Mir M.; Moon, Kyoung Sun (2007-09). «Structural Developments in Tall Buildings: Current Trends and Future Prospects». Architectural Science Review 50 (3): 205-223. ISSN 0003-8628. doi:10.3763/asre.2007.5027. Consultado el 22 de marzo de 2021.: https://dx.doi.org/10.3763/asre.2007.5027
[5] ↑ Weingardt, Richard (2005). Engineering legends : great American civil engineers : 32 profiles of inspiration and achievement. American Society of Civil Engineers. ISBN 0-7844-0801-7. OCLC 60419905. Consultado el 22 de marzo de 2021.: https://www.worldcat.org/oclc/60419905
[10] ↑ Council on Tall Buildings and Urban Habitat. World Congress (2001). Tall buildings and urban habitat : cities in the third millennium : 6th World Congress of the Council on Tall Buildings and Urban Habitat, 26 February to 2 March, 2001. Spon Press. ISBN 0-203-46754-X. OCLC 51782388. Consultado el 22 de marzo de 2021.: https://www.worldcat.org/oclc/51782388
[12] ↑ Sev, Aysin (2005). "Tubular Systems for Tall Office Buildings with Special Cases from Turkey" (PDF). In Cheung, Y. K.; Chau, K. W. (eds.). Tall Buildings: From Engineering to Sustainability. Sixth International Conference on Tall Buildings, Mini Symposium on Sustainable Cities, Mini Symposium on Planning, Design and Socio-Economic Aspects of Tall Residential Living Environment, Hong Kong, China, 6 – 8 December 2005. World Scientific. p. 361. doi:10.1142/9789812701480_0056. ISBN 978-981-256-620-1.
[20] ↑ Lee, P. K. K. (1997). Structures in the new millennium : proceedings of the fourth International Kerensky Conference on structures in the new millennium, Hong Kong, 3-5 September 1997. A.A. Balkema. ISBN 90-5410-898-3. OCLC 39016527. Consultado el 27 de marzo de 2021.: https://www.worldcat.org/oclc/39016527
[26] ↑ National Academy of Sciences (1993). Biographical memoirs. Volume 62. National Academy Press. ISBN 0-585-14673-X. OCLC 45729831. Consultado el 22 de marzo de 2021.: https://www.worldcat.org/oclc/45729831