Fazlur Khan - Illinois Section of the American Society of Civil

Structural Engineer
In step with the abounding vitality of the time, structural engineer
Fazlur Rahman l{han (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 1960's and 70's were validated in his own work, notably his
efficient designs for Chicago's 100-story John Hancock Center and
1lO-story Sears Tower (the tallest building in the world for over 20
years).
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 consfuctive
- the earth can "the resulting aesthetics ... have a
art, rooted in
ffanscendental 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
The Sears Tower is 1,454 feet (443 meters) high, and reaches 1,7O7 leel (520 meters) including the antenna towers.
From its sþ deck on a clear day you can see 40 to 50 miles including portions of lllinois, lndiana, Wisconsin and
Michigan. This huge attraction for Chicago draws 1.5 million tourists each year. Yet without the vision of one individual,
Fazlur Khan, this magnificent monument of engineering might never have become a reality. Photo by Skidmore, Owings
& Menitt(SOMI
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selected Construction's Man of the Year by Engineering
News-Record, is commemorated in a plaque in Onterie
Center at446 E. Ontario, Chicago that reads: "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."
Innovation Follows Program: V/orld 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 1950's 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 healtþ economy
ensured a sustained demand for office space.
High-rise construction offered the perfect solution. Supertall 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 'ofact" 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
withstand greater wind effects,
a
forces: in order to
tower's structural framework
had to be strengthened and stiffened considerably with
increasing building height. Developers, therefore, weie dissuaded from building above the 30 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.
Chicago's 100-story John Hancock
Center utilizes Fazlur Khan's
"trussed tube" structural system.
Photo by Skidmore, Owings
&
Merrill(SOM).
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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
unimaginative 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 stateof-the-art structural engineering. A decade of revolutionary advances hadjust begun.
developing the shear wall frame
Fazlur Khan's earliest contributions to the field
led to
interaction system, the framed-tube structure and the tube-in-tube structure
significant improvementin structural efEciency; they made the consffuction 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 fooþrint, 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
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Chicago, a 43-story reinforced concrete tower designed by Fazlur Khan and his colleagues
at Skidmore, Owings & Merrill (SOM). Because of its greatrelative 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 "ûussed-tube" structural system with an aficulate, glacefirl
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 1,454 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 ofgroupings.
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
Bundl¡d Tubc Slruclurul Sy¡rr¡n
For Scor¡ Torrcr
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Schematicof Chicago'sSearsTower developed by Fazlur Khan). Though Khan
shows Fazlur Khan's concept of the
developed structural systems forparticularproject
,,bundted tube,,
structu;Jili#:
oøÃgt à
Menill(SOM).
Drawing by Skidmore,
needs, he based his innovations on fundamental
structural principles that allowed them wide
application. His developments are among
today's "conventional" systems for sþscraper
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 andnow 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 Haj 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 Haj pilgrimage. The
fabric roof structure melds a fraditional concept,
that of the Bedouin tent, with sophisticated
technology. Tlventy years after the aþort's
opening, this fabric roof and the space ttrat 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 civil engineering bachelor's degree from the Ùniversity
of Dacca in 1951 while placing first in his class. A Fulbright Scholarship and a Pakistani Government
Scholarship subsequently enabled him to ûavel to the United States in 1952 where he pursued advanced
studies at the University of Illinois, Urbana. In three short years Khan earned two master" d"gr""r
one in
structural engineering and one in theoretical and applied mechanics
and a doctor of philosóphy degree in
structural engineering. He received an Alumni HonorAward from the University of trlinois, Urbana
eglZ),
an Honorary Doctor of Science from Northwestern University (1973),and an Honorary Doctor of Engineering
from Lehigh University (1930). In 1961, Fazlur Khan was made a Participating Àssociate in Stidmore,
Owings & Merrill; in 1966 he became an Associate Partner and i n t97 0 a General Partner the only engineer
partner at the time. ln 1973 he was honored with the top accolade for an engineer in the United Strt"r,
election to the National Academy of Engineering. He was cited five times among "Men Who Served the Best
Interests of the construction Indusüry" by Engineering News-Record (for I 965 1968 !g7 0 tg7 I and, 1g7 g);
,
,
,
and in 1972 he was named "Construction's Man of the Year." In 1983 the American Institute of
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Fazlur Khan's Haj Terminal at the
airport in Jeddah Saudi Arabia.
Photo by Skidmore, Owings &
Merrill(SOM).
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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.
Fazlur Khan was honored posthumously as well by the Structural Engineers
Association of Illinois with the John Parmer Award in 1987 and with the
commissioning and creation of a sculpture 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 Sfreets (located at the
foot of the Sears Tower) "Fazlur R. Khan Way."
Above: When looking at the Sears Tower from street level, the pedestrian can easily notice the appearance of the modular sections or "bundled tube" segments
which make up the building. One interesting note is that the average sway of the build¡ng is calculated to be about 6 inches (152 millimeters) from true center'
This is small when consideiing the enormouã height of the building at 1,454 feet. On some occasions, "SkydecK' visitors can even enjoy a view above the clouds
as the Sears Tower protrudeJtnrougn the overcast sky. On other occasions it can be snowing when looking out from the upper floors and raining below as the
public can be seen walking down the streets with open umbrellas. Photo by Skidmore, Owings & Menill (SOM).
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Resources
"This article is an excerpt of th.e information presented at the website prepared
by Mr. Khan's daughter, yasmin
Byron' More information regarding Mr. Khan's life and career can be foünd at www.fazlurrkhan.com.,,
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