Fazlur Rahman Khan Tube structural systems What was the tube structural system? His "tube concept", using all the exterior wall perimeter structure of a building to simulate a thin-walled tube, revolutionized tall building design. Did this system do well? Most buildings over 40 stories constructed since the 1960s now use a tube design derived from Khan's structural engineering principles. Was this system used for anything else? Tubular systems allow greater interior space and further enable buildings to take on various shapes, offering added freedom to architects. Was there anything else interesting about the article? Another important feature of the tubular systems is that buildings can be constructed using steel or reinforced concrete, or a composite of the two, to reach greater heights. What else can you tell me about the tubular systems? They not only make the buildings structurally stronger and more efficient, but also significantly reduce the structural material requirements.
Do buildings last longer using this system?
Do buildings last longer usingTube structural systems?
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 variants. His "tube concept", using all the exterior wall perimeter structure of a building to simulate a thin-walled tube, revolutionized tall building design. Most buildings over 40 stories constructed since the 1960s now use a tube design derived from Khan's structural engineering principles.  Lateral loads (horizontal forces) such as wind forces, seismic forces, etc., begin to dominate the structural system and take on increasing importance in the overall building system as the building height increases. Wind forces become very substantial, and forces caused by earthquakes, etc. are important as well. The tubular designs resist such forces for tall buildings. Tube structures are stiff and have significant advantages over other framing systems. They not only make the buildings structurally stronger and more efficient, but also significantly reduce the structural material requirements. The reduction of material makes the buildings economically more efficient and reduces environmental impact. The tubular designs enable buildings to reach even greater heights. Tubular systems allow greater interior space and further enable buildings to take on various shapes, offering added freedom to architects. 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. Khan was among a group of engineers who encouraged a rebirth in skyscraper construction after a hiatus of over thirty years.  The tubular systems have yet to reach their limit when it comes to height. Another important feature of the tubular systems is that buildings can be constructed using steel or reinforced concrete, or a composite of the two, to reach greater heights. Khan pioneered the use of lightweight concrete for high-rise buildings, at a time when reinforced concrete was used for mostly low-rise construction of only a few stories in height. Most of Khan's designs were conceived considering pre-fabrication and repetition of components so projects could be quickly built with minimal errors.  The population explosion, starting with the baby boom of the 1950s, created widespread concern about the amount of available living space, which Khan solved by building upward. More than any other 20th-century engineer, Fazlur Rahman Khan made it possible for people to live and work in "cities in the sky." Mark Sarkisian (Director of Structural and Seismic Engineering at Skidmore, Owings & Merrill) said, "Khan was a visionary who transformed skyscrapers into sky cities while staying firmly grounded in the fundamentals of engineering." CANNOTANSWER
forces caused by earthquakes, etc. are important as well. The tubular designs resist such forces for tall buildings.
Fazlur Rahman Khan (, Fozlur Rôhman Khan; 3 April 1929 – 27 March 1982) was a Bangladeshi-American structural engineer and architect, who initiated important structural systems for skyscrapers. Considered the "father of tubular designs" for high-rises, Khan was also a pioneer in computer-aided design (CAD). He was the designer of the Sears Tower, since renamed Willis Tower, the tallest building in the world from 1973 until 1998 and the 100-story John Hancock Center.

A partner in the firm Skidmore, Owings & Merrill in Chicago, Khan, more than any other individual, ushered in a renaissance in skyscraper construction during the second half of the 20th 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 design and construction. In his honor, the Council on Tall Buildings and Urban Habitat established the Fazlur Khan Lifetime Achievement Medal, as one of their CTBUH Skyscraper Awards.

Although best known for skyscrapers, Khan was also an active designer of other kinds of structures, including the Hajj airport terminal, the McMath–Pierce solar telescope and several stadium structures.

Biography
Fazlur Rahman Khan  was born on 3 April 1929 in the Bengal Presidency of British India,  now Bangladesh. He was brought up in the village of Bhandarikandii, in the Faridpur District near Dhaka. His father Abdur Rahman Khan was a high school mathematics teacher and textbook author. He eventually became the Director of Public Instruction in the region of Bengal and after retirement served as Principal of Jagannath College, Dhaka.

Khan attended Armanitola Government High School, in Dhaka. After that, he studied Civil Engineering in Bengal Engineering and Science University, Shibpur (present day Indian Institute of Engineering Science and Technology, Shibpur), Kolkata, India, and then received his Bachelor of Civil Engineering degree from Ahsanullah Engineering College, (now Bangladesh University of Engineering and Technology). He received a Fulbright Scholarship and a government scholarship, which enabled him to travel to the United States in 1952. There he studied at the University of Illinois at Urbana–Champaign. 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 with thesis titled Analytical Study of Relations Among Various Design Criteria for Rectangular Prestressed Concrete Beams.

His hometown in Dhaka did not have any buildings taller than three stories. He also did not see his first skyscraper in person until the age of 21 years old, and he had not stepped inside a mid-rise building until he moved to the United States for graduate school. Despite this, the environment of his hometown in Dhaka later influenced his tube building concept, which was inspired by the bamboo that sprouted around Dhaka. He found that a hollow tube, like the bamboo in Dhaka, lent a high-rise vertical durability.

Career

In 1955, employed by the architectural firm Skidmore, Owings & Merrill (SOM), he began working in Chicago. He was made a partner in 1966. He worked the rest of his life side by side with fellow architect Bruce Graham. Khan introduced design methods and concepts for efficient use of material in building architecture. His first building to employ the tube structure was the Chestnut De-Witt apartment building. During the 1960s and 1970s, he became noted for his designs for Chicago's 100-story John Hancock Center and 110-story Sears Tower, since renamed Willis Tower, the tallest building in the world from 1973 until 1998.

He believed that engineers needed a broader perspective on life, saying, "The technical man must not be lost in his own technology; he must be able to appreciate life, and life is art, drama, music, and most importantly, people."

Khan's personal papers, most of which were 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 life
For enjoyment, Khan loved singing Rabindranath Tagore's poetic songs in Bengali. He and his wife, Liselotte, who immigrated from Austria, had one daughter who was born in 1960. In 1967, he elected to become a United States citizen.

Innovations
Khan discovered that the rigid steel frame structure that had long dominated tall building design was not the only system fitting for tall buildings, marking the start of a new era of skyscraper construction.

Tube structural systems

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 variants. His "tube concept", using all the exterior wall perimeter structure of a building to simulate a thin-walled tube, revolutionized tall building design. Most buildings over 40 stories constructed since the 1960s now use a tube design derived from Khan's structural engineering principles.

Lateral loads (horizontal forces) such as wind forces, seismic forces, etc., begin to dominate the structural system and take on increasing importance in the overall building system as the building height increases. Wind forces become very substantial, and forces caused by earthquakes, etc. are important as well. The tubular designs resist such forces for tall buildings. Tube structures are stiff and have significant advantages over other framing systems. They not only make the buildings structurally stronger and more efficient, but also significantly reduce the structural material requirements. The reduction of material makes the buildings economically more efficient and reduces environmental impact. The tubular designs enable buildings to reach even greater heights. Tubular systems allow greater interior space and further enable buildings to take on various shapes, offering added freedom to architects. 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. Khan was among a group of engineers who encouraged a rebirth in skyscraper construction after a hiatus of over thirty years.

The tubular systems have yet to reach their limit when it comes to height. Another important feature of the tubular systems is that buildings can be constructed using steel or reinforced concrete, or a composite of the two, to reach greater heights. Khan pioneered the use of lightweight concrete for high-rise buildings, at a time when reinforced concrete was used for mostly low-rise construction of only a few stories in height. Most of Khan's designs were conceived considering pre-fabrication and repetition of components so projects could be quickly built with minimal errors.

The population explosion, starting with the baby boom of the 1950s, created widespread concern about the amount of available living space, which Khan solved by building upward. More than any other 20th-century engineer, Fazlur Rahman Khan made it possible for people to live and work in "cities in the sky". Mark Sarkisian (Director of Structural and Seismic Engineering at Skidmore, Owings & Merrill) said, "Khan was a visionary who transformed skyscrapers into sky cities while staying firmly grounded in the fundamentals of engineering."

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 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 Apartment Building, since renamed Plaza on DeWitt, building that Bruce Graham designed and Khan did the engineering for was completed in Chicago in 1963. This laid the foundations for the framed tube structure used in the construction of the World Trade Center.

Trussed tube and X-bracing

Khan pioneered several other variants of the tube structure design. One of these was the concept of applying X-bracing to the exterior of the tube to form a trussed tube. X-bracing reduces the lateral load on a building by transferring the load into the exterior columns, and the reduced need for interior columns provides a greater usable floor space. Khan first employed exterior X-bracing on his engineering of the John Hancock Center in 1965, and this can be clearly seen on the building's exterior, making it 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 meter and One Chase Manhattan Plaza (1961), which required around 275 kilograms of steel per square meter, the John Hancock Center was far more efficient, requiring only 145 kilograms of steel per square meter. The trussed tube concept was applied to many later skyscrapers, including the Onterie Center, Citigroup Center and Bank of China Tower.

Bundle tube
One of Khan's most important variants of the tube structure concept was the bundled tube, which was used for the Willis Tower and One Magnificent Mile. The bundled 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."

Tube in tube
Tube-in-tube system takes advantage of core shear wall tubes in addition to exterior 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 in One Shell Plaza. Later buildings to use this structural system include the Petronas Towers.

Outrigger and belt truss
The outrigger and belt truss system is a lateral load resisting system in which the tube structure is connected to the central core wall with very stiff outriggers and belt trusses at one or more levels. BHP House was the first building to use this structural system followed by the First Wisconsin Center, since renamed U.S. Bank Center, 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. Later buildings to use this include Shanghai World Financial Center.

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. Trump Tower in New York City is also another example that adapted this system.

Shear wall frame interaction system
Khan developed the shear wall frame interaction system for mid high-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-stories Brunswick Building. The Brunswick building was completed in 1965 and became the tallest reinforced concrete structure of its time. The structural system of Brunswick Building consists of a concrete shear wall core surrounded by an outer concrete frame of columns and spandrels. Apartment buildings up to 70 stories high have successfully used this concept.

Legacy
Khan's seminal work of developing tall building structural systems are still used today as the 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 Center, 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:

Life cycle civil engineering
Khan and Mark Fintel conceived ideas of shock absorbing soft-stories, for protecting structures from abnormal loading, particularly strong earthquakes, over a long period of time. This concept was a precursor to modern seismic isolation systems. The structures are designed to behave naturally during earthquakes where traditional concepts of material ductility are replaced by mechanisms that allow for movement during ground shaking while protecting material elasticity.

The IALCCE established the Fazlur R. Khan Life-Cycle Civil Engineering Medal.

Other architectural work

Khan designed several notable structures that are not skyscrapers. Examples include the Hajj terminal of King Abdulaziz International Airport, completed in 1981, which consists of tent-like roofs that are folded up when not in use. The project received several awards, including the Aga Khan Award for Architecture, which described it as an "outstanding contribution to architecture for Muslims". The tent-like tensile structures advanced the theory and technology of fabric as a structural material and led the way to its use for other types of terminals and large spaces.

Khan also designed the King Abdulaziz University, the United States Air Force Academy in Colorado Springs and the Hubert H. Humphrey Metrodome in Minneapolis. With Bruce Graham, Khan developed a cable-stayed roof system for the Baxter Travenol Laboratories in Deerfield, Illinois.

Computers for structural engineering and architecture
In the 1970s, engineers were just starting to use computer structural analysis on a large scale. SOM was at the center of these new developments, with undeniable contributions from Khan. Graham and Khan lobbied SOM partners to purchase a mainframe computer, a risky investment at a time, when new technologies were just starting to form. The partners agreed, and Khan began programming the system to calculate structural engineering equations, and later, to develop architectural drawings.

Professional milestones

List of buildings
Buildings on which Khan was structural engineer include:

 McMath–Pierce solar telescope, Kitt Peak National Observatory, Arizona, 1962
 DeWitt-Chestnut Apartments, Chicago, 1963
 Brunswick Building, Chicago, 1965
 John Hancock Center, Chicago, 1965–1969
 One Shell Square, New Orleans, Louisiana, 1972
 140 William Street (formerly BHP House), Melbourne, 1972
 Sears Tower, renamed Willis Tower, Chicago, 1970–1973
 First Wisconsin Center, renamed U.S. Bank Center, Milwaukee, 1973
 Hajj Terminal, King Abdulaziz International Airport, Jeddah, 1974–1980
 King Abdulaziz University, Jeddah, 1977–1978
 Hubert H. Humphrey Metrodome, Minneapolis, Minnesota, 1982
 One Magnificent Mile, Chicago, completed 1983
 Onterie Center, Chicago, completed 1986
 United States Air Force Academy, Colorado Springs, Colorado

Awards and chair

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 and Illinois Engineering Hall of Fame from Illinois Engineering Council (2006).

Khan was cited five times by Engineering News-Record as among those who served the best interests of the construction industry, and in 1972 he was honored with ENR Man of the Year award. In 1973 he was elected to the National Academy of Engineering. He received honorary doctorates from Northwestern University, Lehigh University, and the Swiss Federal Institute of Technology Zürich (ETH Zurich).

The Council on Tall Buildings and Urban Habitat named one of their CTBUH Skyscraper Awards the Fazlur Khan Lifetime Achievement Medal after him, and other awards have been established in his honor, along with a chair at Lehigh University. Promoting educational activities and research, the Fazlur Rahman Khan Endowed Chair of Structural Engineering and Architecture honors Khan's legacy of engineering advancement and architectural sensibility. Dan Frangopol is the first holder of the chair.

Khan was mentioned by President Obama in 2009 in his speech in Cairo, Egypt when he cited the achievements of America's Muslim citizens.

Khan was the subject of the Google Doodle on 3 April 2017, marking what would have been his 88th birthday.

Documentary film
In 2021, director Laila Kazmi began production on a feature-length documentary film to be called Reaching New Heights: Fazlur Rahman Khan and the Skyscraper on the life and legacy of Khan. The film is produced by Kazmi's production company Kazbar Media, with development support from ITVS, which provides co-production support to independent documentaries on PBS. The film is helmed by director and producer Laila Kazmi, with associate producer Arnila Guha, and New York-based art director Begoña Lopez. It is fiscally sponsored by Film Independent.

Charity
In 1971 the Bangladesh Liberation War broke out. Khan was heavily involved with creating public opinion and garnering emergency funding for Bengali people during the war. He created the Chicago-based Bangladesh Emergency Welfare Appeal organization.

Death
Khan died of a heart attack on 27 March 1982 while on a trip in Jeddah, Saudi Arabia, at the age of 52. He was a general partner in SOM. His body was returned to the United States and was buried in Graceland Cemetery in Chicago.

See also
 Chicago school
 Engineering Legends, a 2005 book
 List of Bangladeshi architects

Notes and references

Notes

References
 
  Ali, Mir M. (2001). Art of the Skyscraper: The Genius of Fazlur Khan. Rizzoli International Publications, Inc., New York, NY,

External links
 
 Fazlur Rahman Khan Collection in the South Asian American Digital Archive (SAADA)
 Fazlur Rahman Khan Documentary Project
 Fazlur Khan Lifetime Achievement Medal
 Letter from Bill Clinton

 Exhibition at Princeton University

1929 births
1982 deaths
20th-century American architects
American Muslims
Bangladeshi diaspora
American people of Bangladeshi descent
Bangladesh University of Engineering and Technology alumni
20th-century Bengalis
Burials at Graceland Cemetery (Chicago)
Civil engineers
Pakistani emigrants to the United States
Recipients of the Independence Day Award
Structural engineers
University of Dhaka alumni
Grainger College of Engineering alumni
20th-century engineers
Skidmore, Owings & Merrill people
Australian Antarctic Building System  or  AANBUS  is a modular construction system used by the Australian Government Antarctica Division for buildings in Antarctica.  The individual modules resemble shipping containers.  Each module is approximately 3.6 metres by 6 metres by 4 metres high.

Buildings built using the AANBUS modules are placed on concrete footings anchored into the ground and do not need external guy wires to anchor and support them.  The modules are built of steel with attached insulation and vapor barriers.

The modular design provides improved shipping, speed of assembly in the short Antarctic summer and better testing before shipping.  The ability to test the assembled modules allows corrections to be made in the convenience of construction sites in temperate climates with easy access to parts and equipment, rather than at remote Antarctic locations where shipping in of replacement parts is an arduous undertaking.

Further reading

External links 
History of AANBUS
Characteristics of the Australian Antarctic Building System

Architecture of Australia
Australian Antarctic Territory
Technology related to buildings in Antarctica Postal codes in Singapore have consisted of six digits since 1995, replacing the four-digit system introduced in 1979. They are administered by Singapore Post.

6-digit postal code
The 6-digit postal code is made up of the sector code and the delivery point. The sector is represented by the first two numbers of the postal code. The remaining four numbers define the delivery point within the sector. e.g.
53 Ang Mo Kio Avenue 3
Singapore 569933
56 is the sector code; 9933 is the delivery point, i.e. house or building.

For Housing and Development Board (HDB) residential blocks, the block number is included in the postal code. e.g.
Blk 145 Lorong 2 Toa Payoh
Singapore 310145
HDB residential blocks with the same number in the same postal sector are differentiated by their postal codes as follows:
Blk 147 Simei Street 2
Singapore 520147

Blk 147 Tampines Avenue 5
Singapore 521147
Similarly, for a HDB residential block sharing the same number as another block in the same postal sector, but have an added suffix behind are differentiated by their postal codes as follows:
Blk 150 Bishan Street 11
Singapore 570150

Blk 150A Bishan Street 11 
Singapore 571150
The postal codes for private residential, commercial and industrial houses and buildings are assigned based on the alphabetical sequence of the street names in each sector. This means that the codes for a particular postal sector have been assigned first to houses and buildings located along street names beginning with 'A', followed by 'B' and so on. The postal codes for such properties do not contain the corresponding house or building numbers included in the postal code. HDB industrial and commercial blocks also use this system.

Postal districts
This table lists the postal districts:

History 

Singapore was originally divided into 28 postal districts on 6 March 1950, with a number being allocated to each district. For example, the Orchard Road area was in District 9.
277 Orchard Road
Singapore 9

This was superseded by a new four-digit system on 1 July 1979, with the last two digits representing a sector in each district. There were in total 81 sectors.
277 Orchard Road
Singapore 0923
On 1 September 1995, this was replaced by a six-digit system, in which every building was given its unique postcode, the first two digits of which represented the old sector, i.e. 23.
277 Orchard Road
Singapore 238858
Although the old districts are no longer used by Singapore Post, they are still widely used to refer to locations of properties for sale or rent.

Addressing from overseas
SingPost recommends the following format for addresses: 

Generally, the last line SINGAPORE is omitted when posting within the country.

References

External links 
 SingPost

Singapore
Postal system of Singapore