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F.R.KHAN


In step with the abounding vitality of the time, structural engineer Fazlur Rahman Khan (1929 — 1982) ushered in a renaissance in skyscraper construction during the second half of the 20th century. Fazlur Khan was a pragmatic visionary: the series of progressive ideas that he brought forth for efficient high-rise construction in the 1960s and ‘70s were validated in his own work, notably his efficient designs for Chicago’s 100-story John Hancock Center and 110-story Sears Tower (the tallest building in the United States since its completion in 1974).

One of the foremost structural engineers of the 20th century, Fazlur Khan epitomized both structural engineering achievement and creative collaborative effort between architect and engineer. Only when architectural design is grounded in structural realities, he believed — thus celebrating architecture's nature as a constructive art, rooted in the earth — can "the resulting aesthetics … have a transcendental value and quality."

His ideas for these sky-scraping towers offered more than economic construction and iconic architectural images; they gave people the opportunity to work and live “in the sky.” Hancock Center residents thrive on the wide expanse of sky and lake before them, the stunning quiet in the heart of the city, and the intimacy with nature at such heights: the rising sun, the moon and stars, the migrating flocks of birds.

Fazlur Khan was always clear about the purpose of architecture. His characteristic statement to an editor in 1971, having just been selected Construction's Man of the Year by Engineering News-Record, is commemorated in a plaque in Onterie Center (446 E. Ontario, Chicago):




Innovation Follows Program

World population by 1960 was about to burst at the seams. Or so it seemed. Capping the dramatic population increases of the first half of the 20th century, the 1950s' baby boom intensified people’s sense of an earth that was shrinking. Metropolitan centers in particular were pressed for space. Housing was needed for a large number of people — single-family homes were not sufficient — and office space was also wanted for the spiraling numbers of office workers. A healthy economy ensured a sustained demand for office space.

High-rise construction offered the perfect solution. Super-tall buildings could provide large amounts of floor area without having to be densely packed, one building upon the next. A portion of each city block that a high rise occupied could be left available for desirable city plazas and parks.

Despite these apparent advantages, super-tall building construction faced a critical deterrent: expense. Skyscrapers were simply too costly by modern development standards. A tower reaching as high as the Empire State Building could not be justified in economic terms.

It was a generally accepted "fact" of construction that taller buildings cost more to build per square foot of rentable floor area than shorter buildings. A rapid run-up in structure costs resulted from increased wind forces: in order to withstand greater wind effects, a tower's structural framework had to be strengthened and stiffened considerably with increasing building height. Developers, therefore, were dissuaded from building above the thirty-story range by this cost premium. They leaned instead toward constructing bulky, site-consuming edifices. It appeared that conditions in central business districts were bound to worsen, with every building site being completely filled.

It was at this critical moment in the development of the modern urban environment that Fazlur Khan entered the profession.

Filled with both ambition and optimism, and equipped with solid training in structural engineering, Fazlur Khan was undeterred by the mindset and technological difficulties that hindered tall building design. He recognized that the structural systems utilized for high-rise construction were not on a par with the modern scale of architecture, and he took on the challenge of advancing state-of-the-art structural engineering. A decade of revolutionary advances had just begun.

Fazlur Khan's earliest contributions to the field — developing the shear wall frame interaction system, the framed-tube structure, and the tube-in-tube structure — led to significant improvement in structural efficiency: they made the construction of tall buildings economically feasible. The framed-tube structure has its columns closely spaced around the perimeter of the building, rather than scattered throughout the footprint, while stiff spandrel beams connect these columns at every floor level. This structural system was first implemented in 1964 in the construction of the DeWitt-Chestnut Apartments in Chicago, a 43-story reinforced concrete tower designed by Fazlur Khan and his colleagues at Skidmore, Owings & Merrill (SOM). Because of its great relative strength and stiffness, the tubular form immediately became a standard in high-rise design.

As the reach of tall buildings extended, Fazlur Khan resolved to discover structural systems appropriate for each new scale of architecture. Crafting rational architecture in cooperation with Bruce J. Graham, chief design architect in SOM's Chicago office, he united an exceptionally efficient "trussed-tube" structural system with an articulate, graceful form for Chicago's 100-story John Hancock Center. A few years later he introduced another groundbreaking structural system, the "bundled tube." This design for Chicago's 110-story Sears Tower was structurally efficient and economic: at 1,450 feet, it provided more space and rose higher than the Empire State Building, yet cost much less per unit area. Equally important, the new structure type was 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.

When one looks at a text on tall-building design today, one finds these recognizable structure types: the framed tube, the shear wall frame interaction, the trussed tube, the bundled tube, and the composite system (also developed by Fazlur Khan). Though Khan developed structural systems for particular project needs, he based his innovations on fundamental structural principles that allowed them wide application. His developments are among today’s “conventional” systems for skyscraper design.

As the building boom in the West came to an abrupt halt in 1974, new demands surfaced that thrust designers into unfamiliar settings. Clients in the Middle East and Asia, for example, were anxious and now financially able to construct housing, offices, and other facilities in large scale. SOM took on this design work, and Fazlur Khan responded to needs and situations as he perceived them.

For the immense roof of the Hajj Terminal of the new airport in Jeddah, Saudi Arabia — intended to shelter 80,000 pilgrims at a time, waiting for up to 36 hours — he searched for a coherent scheme that was both efficient and honored the spirit of the Hajj pilgrimage. The fabric roof structure melds a traditional concept, that of the Bedouin tent, with sophisticated technology. Twenty years after the airport's opening, this fabric roof and the space that it creates continue to awe as well as comfort terminal users.


Professional Milestones

After completing undergraduate coursework at the Bengal Engineering College, University of Calcutta, Fazlur R. Khan received his bachelor’s degree from the University of Dacca in 1951 while placing first in his class. A Fulbright Scholarship and a Pakistani Government Scholarship subsequently enabled him to travel to the United States in 1952 where he pursued advanced studies at the University of Illinois, Urbana. In three short years Khan earned two masters’ degrees — one in structural engineering and one in theoretical and applied mechanics — and a PhD in structural engineering.

A Bangladesh postal stamp honors Fazlur Rahman Khan.
He received an Alumni Honor Award from the University of Illinois, Urbana (1972), an Honorary Doctor of Science from Northwestern University (1973), and an Honorary Doctor of Engineering from Lehigh University (1980).

 

In 1961, Fazlur Khan was made a Participating Associate in Skidmore, Owings & Merrill; in 1966 he became an Associate Partner and in 1970 a General Partner – the only engineer partner at the time.

In 1973 he was honored with the top accolade for an engineer in the United States, election to the National Academy of Engineering.

He was cited five times among "Men Who Served the Best Interests of the Construction Industry" by Engineering News-Record (for 1965, 1968, 1970, 1971, and 1979); and in 1972 he was named "Construction's Man of the Year." He was posthumously honored with the International Award of Merit in Structural Engineering from the International Association for Bridge and Structural Engineering and a Distinguished Service Award from the AIA Chicago Chapter (both in 1982).

In 1983 the American Institute of Architects recognized Fazlur Khan's contributions with an AIA Institute Honor for Distinguished Achievement.

That same year he was honored with the Aga Khan Award for Architecture "for the Structure of the Hajj Terminal, An Outstanding Contribution to Architecture for Muslims," which was completed over the last years of his life.

The Structural Engineers Association of Illinois recognized his achievements with the John Parmer Award in 1987. The SEAOI also commissioned a sculpture in Fazlur Khan’s honor by the Spanish artist Carlos Marinas. The sculpture is located in the lobby of the Sears Tower.

In 1998 the city of Chicago named the intersection of Jackson and Franklin Streets (located at the foot of the Sears Tower) “Fazlur R. Khan Way.”

 
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