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 Chicagos 100-story
John Hancock Center and 110-story Sears Tower (the tallest building
in the United States since its completion in 1974).
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."
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.
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):
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
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
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
After completing undergraduate coursework at the Bengal Engineering
College, University of Calcutta, Fazlur R. Khan received his bachelors
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.
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).
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
1973 he was honored with the top accolade for an engineer in the
United States, election to the National Academy of Engineering.
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).
1983 the American Institute of Architects recognized Fazlur Khan's
contributions with an AIA Institute Honor for Distinguished Achievement.
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.
Structural Engineers Association of Illinois recognized his achievements
with the John Parmer Award in 1987. The SEAOI also commissioned
a sculpture in Fazlur Khans honor by the Spanish artist
Carlos Marinas. The sculpture is located in the lobby of the Sears
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.