Fazlur Rahman Khan, a Bangladeshi-American structural engineer and architect, revolutionized skyscraper design with his innovative tube structural system, which enabled the construction of taller, more efficient, and safer buildings
In the 1970s, the discovery of oil revolutionised the United Arab Emirates (UAE) and triggered a construction boom. The 39-storey Dubai World Trade Centre (WTC) symbolised this boom as the UAE’s first high-rise in 1978 and an ambition of an aspiring economic power. The high rises multiplied over the next four decades. In 2020, the UAE joined Japan in having the world’s third-largest skyscrapers after the United States (US) and China.
Almost two dozen highrises in Dubai are twice the size of WTC, or over 300 meters high, including Burj Khalifa, an engineering marvel and the tallest globally. Burj Khalifa is double the Empire State Building’s height, representing the realisation of a vision of building the UAE from the ground up.
The UAE’s transformation from a desert land to a landscape with striking skyscrapers would not have been possible without structural engineer and architect Fazlur Rahman Khan (1929-1982). Khan, the son of a maths teacher from Bhandarikandii village near Decca (now Dhaka in today’s Bangladesh), paid special attention to aesthetics as he developed the bundled-tube configuration that revolutionized tall building structures and redefined the limits of the skyscraper.
The Pioneer
Fazlur Rahman Khan pioneered advances in large-scale design. His tube structural system, which is used to build tall buildings around the globe, earned him the title of Einstein of structural engineering. His system enabled taller structures with increased efficiency and safety at reduced costs.
Fazlur Rahman Khan passed away in Saudi Arabia in 1982 at 52. But his legacy has lived on in the form of the famed skyscrapers erected using his systems, including the Burj Khalifa, Petronas Towers in Malaysia’s Kuala Lumpur, Hong Kong’s Bank of China Tower, and Shanghai’s Jin Mao Tower. In April 2017, Joe Sommerlad wrote in the Independent that Khan sculpted the modern cityscape as Google Doodle celebrated what would have been the structural engineer’s 88th birthday. Khan equipped skyscrapers to withstand the impact of horizontal forces—high winds or earthquake vibrations, etc.
Fazlur Rahman Khan used perimeter walls like thin tubes rather than designing buildings around a solid central core. The innovation revolutionised the urban landscape, reducing the materials required to build structures and the environmental impact. It proved a game-changer beginning with Chicago’s 43-storey DeWitt-Chestnut Building and 35-storey Brunswick Building, the first projects to use the tubular system in the 1960s. The system’s success led to its use in the John Hancock Center, an iconic 100-storey mixed-use skyscraper.
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The Hancock Center, with a sloping black steel form, was completed in 1970, and remains one of the most recognizable structures in Chicago’s skyline. It has a tapered rectangular tube with trusses on each of the four sides supporting it. The X-bracing on its exterior reduced the need for internal support columns and increased available floor space. It enabled the structure to resist wind loads.
Two buildings were planned to be built on the site of the John Hancock Center. But a casino club’s refusal to sell its space to the developers meant a smaller space was incapable of housing them, prompting Fazlur Rahman Khan and architect Bruce Graham to opt for a trussed single tower as the most cost-effective alternative for the 100-storey high and the second-tallest building in the world in 1968.
Rise And Rise
Graham and Fazlur Rahman Khan also designed and built the Sears Tower, Chicago’s tallest, now known as Willis Tower, overlooking Lake Michigan. The Sears Tower was his first skyscraper to employ the bundled tube structural system, consisting of narrow steel cylinders clustered together to form a thicker column.
The system minimized the amount of steel needed for towers. It did away with internal wind braces as the perimeter columns bore the weight of the winds. In 1998, Khan’s sculpture was unveiled at the 108-storey Sears Tower in recognition of his contribution to the field of structural engineering. Lehigh University set up the Fazlur R Khan Endowed Chair of Structural Engineering and Architecture in 2016, honouring the memory of the man credited with revolutionizing the skyline of Chicago with his engineering designs.
The US Air Force Academy (Colorado), US Bank Center (Milwaukee), One Shell Square (New Orleans), 140 William Street (Melbourne, Australia), and King Abdulaziz International Airport’s Hajj Terminal in Saudi Arabia’s Jeddah are Khan’s other notable structures. The Hajj Terminal for Muslims making the annual pilgrimage to Mecca is made of Teflon-coated tents suspended from high-strength cables. The tents are designed to direct hot desert air up and out to keep the terminal cool.
Sky As The Limit
The ever-taller towers in the UAE demonstrate how Khan’s innovation ensured the sky was the limit in building skyscrapers. A visionary, he adopted computer-aided design in architecture when the technology was in its infancy. In 1972, Khan explained to American weekly magazine Engineering News-Record that he puts himself in the place of a building when thinking about its design, feeling every part and visualizing in his mind the stresses and twisting a building undergoes.
Regarded as the ‘father of tubular designs’, he initially attended the University of Calcutta‘s Bengal Engineering College in what was then British India. The violence in the aftermath of India’s partition forced him to leave the college in his final year. He eventually graduated in engineering from the Ahsanullah Engineering College in East Pakistan (now Bangladesh).
His academic excellence earned him a Fulbright Scholarship to the US and a Pakistan government grant in 1952 to study at the University of Illinois. Fazlur Rahman Khan received his master’s degrees in applied mechanics and structural engineering and a PhD in structural engineering in the US. Khan returned to Pakistan to become the Karachi Development Authority’s executive engineer before returning to the US and joining the architectural firm Skidmore, Owings & Merrill (SOM) in Chicago in 1955. He became a partner in the firm in 1966 and distinguished himself with the innovative new design for high-rise buildings, the tube concept.
Mark Sarkisian, an American structural engineer and the Partner of seismic and structural engineering at SOM, has credited Khan with leading a renaissance in skyscraper construction by tuning buildings to the dynamic forces of gravity, wind, and earthquake. In his 2007 lecture as part of the Fazlur Rahman Khan Lecture Series at Lehigh University, Sarkisian said Khan mastered structural engineering principles by giving unprecedented freedom to the architects he collaborated with.
Sarkisian noted Khan showed engineers how to group beam-column frames into bundles to strengthen a tower, reducing the amount of steel and concrete necessary to support it, and creating open space in a building’s interior. Khan learned to offset the impact of wind by tapering tall buildings and fitting them with strategic indentations. Khan introduced exposed and diagonal braces for aesthetic purposes and as structural support. Sarkisian said Khan helped transform the urban environment by making it possible to live, work, and dream in cities in the sky.
In his famous June 2009 speech at Cairo University, US President Barack Obama paid Khan a fitting tribute by counting him among icons such as Malcolm X and Muhammad Ali, as the builder of America’s tallest building, emphasizing how Muslims have enriched the US since its founding.
Sameer Arshad Khatlani is a journalist and the author of the Penguin Random House book The Other Side of the Divide
