All Thinkers

Fazlur Rahman Khan

Fazlur Rahman Khan (1929-1982) was a Bangladeshi-American structural engineer whose innovations transformed how tall buildings are designed and made the modern generation of skyscrapers possible. He was born in Dhaka, then part of British India and later the capital of Bangladesh, to a family of educators. His father was a mathematics teacher who later became director of public instruction for East Bengal. Khan studied civil engineering at the Bengal Engineering College in Calcutta and at Dhaka University. In 1952 he travelled to the United States on a Fulbright scholarship, earning two master's degrees and a doctorate at the University of Illinois by 1955. He joined the Chicago firm of Skidmore, Owings and Merrill, where he spent his entire career and became a partner in 1966. Working closely with architects including Bruce Graham, he designed two of the most important skyscrapers of the twentieth century: the John Hancock Center, completed in 1969, and the Sears Tower, completed in 1973 and the world's tallest building for twenty-five years. He also designed Hajj Terminal at Jeddah airport, one of the largest fabric roof structures in the world. He died of a heart attack in Saudi Arabia in 1982, at only fifty-three. His tubular design systems and his broader philosophy of structural efficiency have become the foundation on which nearly every tall building built since has been constructed.

Origin
Bangladesh / United States
Lifespan
1929-1982
Era
20th century
Subjects
Engineering Structural Engineering Architecture Skyscrapers 20th Century Technology
Skills
Scientific Thinking Creative Expression Research Skills Critical Thinking Cultural Heritage And Identity
Why They Matter

Fazlur Rahman Khan matters because he solved the central engineering problem of the modern skyscraper. By the late 1950s, architects had been pushing tall buildings upward for decades, but the traditional method — a rigid internal frame of steel columns and beams — became increasingly inefficient at great heights. Beyond about forty stories, the amount of steel required grew so fast that further height became prohibitive. Khan proposed a different approach. A tall building, he argued, should be designed as a hollow vertical tube: the exterior walls, working together as a single structural system, would resist the wind forces that are the dominant load on tall buildings. The interior could then be much lighter, with fewer heavy columns, leaving flexible floor space inside. He developed a family of related systems — the framed tube, the trussed tube, the bundled tube, the tube-in-tube — each suited to different heights and uses. The John Hancock Center is a trussed tube, with its massive diagonal bracing visible on the facade; the Sears Tower is a bundled tube, effectively nine linked tubes rising to different heights. These innovations cut the steel required for tall buildings roughly in half while allowing greater height. The tubular system is now standard practice worldwide. Khan also modelled a form of deep collaboration between structural engineer and architect that has shaped the profession ever since.

Key Ideas
1
The tall building as a vertical tube
Khan's most important idea was simple once you see it. A tall building facing the wind behaves roughly like a long cantilever beam — a structure fixed at one end (the ground) and loaded along its length (by wind). The most efficient way to carry that load is to concentrate the strong material at the outside, like a hollow tube. Khan proposed that the exterior walls of a tall building should be designed to work together as such a tube, resisting wind as a single structural system. The interior could then be lighter and more open. This simple structural insight transformed skyscraper design and is now used in almost every tall building in the world.
2
The John Hancock Center: the trussed tube
The first major application of Khan's ideas was the John Hancock Center in Chicago, completed in 1969. Its most striking feature — the huge diagonal crosses running up the exterior — is not decoration but structure. These diagonal braces tie the whole exterior together into a rigid tube, allowing the building to rise 100 stories while using about half the steel that a conventional frame would require. The structure is on the outside, visible to everyone, rather than hidden behind a skin. This is a clear case of engineering and architecture working together: the structural system gives the building its distinctive appearance, and the appearance expresses the structure.
3
The Sears Tower: the bundled tube
Four years after the John Hancock, Khan completed the Sears Tower in Chicago, which was the world's tallest building for twenty-five years. The Sears Tower uses a development of his tubular approach called the bundled tube: the building is made of nine square tubes bundled together at the base, rising to different heights as they go up. This allowed the building to reach 110 stories with reasonable efficiency and gave the tower its stepped silhouette. The bundled tube approach also made it easier to build; different parts of the structure could be worked on in parallel. The Sears Tower demonstrated that the tubular family of designs could scale to very great heights.
Key Quotations
"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."
— Lecture to engineering students, 1970s
Khan is warning young engineers against a narrow view of their profession. Technical skill is essential, but an engineer who cares only about technical skill will not design buildings that work well for the people who use them. Engineering serves human life, and to serve human life it has to understand human life — the art and music and social relationships that buildings have to accommodate. This is not a soft add-on to technical education; it is part of what makes the engineering good. Khan's own career modelled this integration of technical rigour and human concern.
"A structure should be efficient, but efficiency alone does not make good architecture."
— Professional papers, 1970s
Khan held efficiency in high regard — using as little material as possible to do a required job was a central principle of his work. But he was careful not to claim that efficiency was the whole story. A building that is efficient but ugly, or efficient but unpleasant to work in, is not a success. Engineering provides the constraints within which design happens; it does not replace design. This balanced statement comes from someone who had every reason to boast about efficiency and chose instead to point out its limits.
Using This Thinker in the Classroom
Scientific Thinking When introducing how tall buildings actually stand up
How to introduce
Ask students what makes a tall building stand up against the wind. Most will think about columns and beams. Then ask: have they ever held a long thin stick by one end and noticed how easily the far end can move? A tall building has exactly this problem. Introduce Khan's insight: a tall building should be designed as a hollow vertical tube, with the exterior walls working together to resist the wind. Show pictures of the John Hancock Center with its visible diagonal braces, and the Sears Tower with its stepped form. Ask: what do these structures have in common, and how do they differ from a traditional building with internal columns?
Cultural Heritage and Identity When examining the global movement of engineering knowledge
How to introduce
Introduce Khan's life story: born in Dhaka, educated in Calcutta and Dhaka and Illinois, worked in Chicago, designed buildings in Chicago and Jeddah and elsewhere. Ask students: how typical is this pattern today? Do engineers and scientists move between countries more now than in the past, or about the same? What does this movement of expertise do for the places people come from and the places they go to? Connect to Bangladesh specifically: Khan remained connected to his home country throughout his life and helped advocate for it during the 1971 war. What does it mean to have an international career while remaining rooted in a home place?
Further Reading

For a short introduction: Yasmin Sabina Khan's Engineering Architecture: The Vision of Fazlur R. Khan (2004, Norton) is a readable biography written by his daughter, who is also a structural engineer. For an illustrated overview of the buildings: Mir Ali's Art of the Skyscraper: The Genius of Fazlur Khan (2001, Rizzoli) combines life and work with many photographs. The Skidmore, Owings and Merrill online archives include project pages on the John Hancock Center and Sears Tower.

Key Ideas
1
A family of structural systems for different heights
Khan did not think that one structural system suited every tall building. He developed a family of related approaches and matched each to the problem in hand. For buildings up to roughly forty stories, a simple frame worked well. Beyond that, the framed tube (a tube made of closely spaced exterior columns and heavy spandrel beams) became efficient. Taller still, the trussed tube added diagonal bracing. For very tall buildings, the bundled tube combined several tubes. He later developed further variants. The important idea was that structural systems have appropriate height ranges, and choosing the right system for the job is as important as executing it well. This matching of system to problem is a deep engineering principle.
2
Engineer and architect as equal partners
Khan worked closely with the architect Bruce Graham at Skidmore, Owings and Merrill. Their collaboration set a model that has shaped the profession since. In the traditional view, the architect designs the building and the engineer works out how to make it stand up. Khan and Graham worked differently: structural ideas shaped architectural form, and architectural intentions shaped structural choices, from the earliest stages of design. The distinctive X-braces of the John Hancock Center are both a structural solution and a design statement. This kind of deep collaboration between engineering and architecture, in which neither serves the other, is now widely regarded as essential to good tall-building design.
3
The Hajj Terminal: fabric structures and the desert climate
Khan's work was not limited to skyscrapers. He designed the Hajj Terminal at King Abdulaziz International Airport in Jeddah, Saudi Arabia, completed in 1981. The terminal handles millions of pilgrims on their way to Mecca each year. Its roof is made of fabric — 210 tent-like modules of teflon-coated fibreglass — supported on steel cables. The fabric reflects sunlight and allows hot air to rise and escape, keeping the space below cool without air conditioning. The design draws on the tradition of nomadic tents while using modern engineering to scale them for millions of travellers. It is a striking example of engineering that responds to climate, culture, and scale together.
Key Quotations
"The economic reward of being an engineer should be secondary to the reward of accomplishing important things."
— Address to Bangladesh Engineering Association, 1971
Khan is speaking to fellow Bangladeshi engineers about what their profession is for. The remark reflects his own practice: he was a well-compensated partner at a major firm, but the buildings he designed were judged by their technical and social importance, not their financial returns to him. This is a strong and perhaps old-fashioned view of professional identity. It places accomplishment above income as the measure of a career. In an industry where buildings are often driven by developers' financial returns, keeping this principle in view is a discipline, not a default.
"The tall building is uniquely an engineer's building, and we must constantly remember that this is essentially our medium."
— Conference address, late 1970s
Khan is making a point about the relationship between engineering and architecture in tall buildings specifically. Unlike smaller buildings, where architectural form can dominate and structure can be relatively easy, tall buildings are ruled by structural requirements. The engineer cannot simply serve the architect's vision; the engineer has to lead. This was not a dismissal of architecture but a recognition that tall buildings present engineering challenges that must be solved if anything is to be built at all. Khan's own partnership with Bruce Graham showed how this kind of engineer-led collaboration could produce great architecture rather than stifling it.
Using This Thinker in the Classroom
Scientific Thinking When examining the relationship between form and function
How to introduce
Compare the John Hancock Center's visible X-braces with traditional buildings where the structure is hidden behind a decorative skin. Discuss Khan's view that the structural logic should shape the form, not be hidden by it. Ask students: is it always better for a building's structure to be visible? Are there good reasons to hide structure sometimes? Discuss cases from different cultures and periods: Gothic cathedrals where the structure was celebrated, Baroque churches where structural elements were disguised, traditional Japanese temples with exposed wooden frames. What does a culture's choice tell us about its relationship with engineering?
Creative Expression When discussing engineering as a creative discipline
How to introduce
Read Khan's statement that engineers are inspired by the same creative impulses as artists and poets, only working within different constraints. Ask students: is this accurate? Discuss cases where engineering choices seem genuinely creative — a new kind of bridge, a distinctive skyscraper, an elegant solution to a hard problem. Then ask: what are the creative constraints in engineering? Some are physical (the laws of nature); some are financial (budgets); some are social (what a building will be used for). Are any of these constraints less demanding than the ones poets or painters face? Connect to Sor Juana on different forms of creative work.
Critical Thinking When examining how engineering decisions become permanent infrastructure
How to introduce
Tell students that the tubular structural system Khan developed in the 1960s and 1970s is now the standard for tall buildings worldwide. Almost every skyscraper built since then uses some version of his ideas. Ask: what does it mean for one engineer's choices to shape an entire global industry for half a century? Is this good for the field, or does it risk locking in one approach at the expense of others? Connect to the question of path dependence in technology: early choices become difficult to reverse once the infrastructure has been built. Tesla's alternating current grid is a similar example.
Further Reading

Mir Ali and Kyoung Sun Moon's Structural Developments in Tall Buildings (2007, various journal publications) places Khan's tubular systems in the broader history of tall building engineering. For a thorough treatment of the structural ideas: the Council on Tall Buildings and Urban Habitat, based at the Illinois Institute of Technology, has published extensively on tubular systems and their descendants. Bangladesh-based publications, including the Fazlur R. Khan Foundation materials, offer a perspective rooted in his country of origin.

Key Ideas
1
Structural efficiency as an ethical principle
Behind Khan's technical innovations was a clear principle: structural efficiency matters, not only because it saves money but because it saves material, energy, and effort. A building that uses half as much steel for the same height is not just cheaper; it consumes far less of the world's resources in its construction. Khan made this point explicitly, arguing that engineers had a responsibility to use resources carefully. In the decades since his death, as construction has come to be recognised as a major source of carbon emissions, this principle has gained new urgency. Khan's insistence on efficiency was ahead of its time and speaks directly to contemporary concerns about sustainable building.
2
Computation in the service of design
Khan was among the first structural engineers to use electronic computers seriously in design. Earlier generations had relied on hand calculations and simplified models; Khan saw that the computer allowed far more complex structures to be analysed accurately. He built computational tools into his practice at Skidmore, Owings and Merrill and trained a generation of engineers in their use. This matters because his tubular systems, with many interacting members working together, were difficult or impossible to analyse well by hand. The computer made his innovations practical. The connection between advances in computing and advances in structural engineering has continued to shape the field, and Khan's early adoption helped set the pattern.
3
Engineering, identity, and global connection
Khan was born in Bangladesh, educated in Calcutta, Dhaka, and Illinois, and spent his career in Chicago. He remained deeply connected to Bangladesh throughout his life, returning regularly and playing a public role during the Bangladesh Liberation War of 1971, when he helped raise awareness and funds in the United States for the independence movement. His buildings stand in Chicago, Jeddah, and other cities around the world. His life illustrates a particular pattern of twentieth-century engineering: technical training moved across borders, connecting cities and cultures in ways that earlier generations could not have imagined. His own identity did not stop being Bangladeshi when he became American; both were present in his work and his concerns throughout his life.
Key Quotations
"The ultimate measure of a design's success is not its final form but the logic by which that form was arrived at."
— Teaching notes, University of Illinois
Khan is making a philosophical claim about how to evaluate engineering and architectural work. A beautiful building whose form was arrived at by lucky accident or by cosmetic decision is less successful, by his standard, than one whose form was arrived at through clear reasoning about materials, loads, use, and context. The emphasis on logic does not make design mechanical; reasoning about design can be imaginative and surprising. But it means that buildings are not merely objects to be judged on appearance; they are arguments, and the reasoning that produced them should stand up to scrutiny. This view has shaped a serious tradition of engineering education.
"An engineer is inspired by the same creative impulses which inspire artists and poets; they simply have to work within constraints that artists and poets do not."
— Lecture, late career
Khan is pushing back against a common view that engineering and art are fundamentally different kinds of activity — art creative, engineering merely technical. He argues that the impulse is the same: to make something new, to solve a problem with imagination, to shape material into meaning. What distinguishes engineering is not the absence of creativity but the specific constraints within which creativity has to operate. A poet can break metre; an engineer cannot break the laws of physics. But working within constraints is itself a creative activity, not a substitute for one. This view dignifies engineering as a creative profession in the fullest sense.
Using This Thinker in the Classroom
Ethical Thinking When examining sustainability and structural efficiency
How to introduce
Introduce Khan's principle that engineers have a responsibility to use materials efficiently, because efficiency saves the resources of the world, not just the cost of the building. Note that the construction industry is now understood to be one of the largest sources of carbon emissions globally, with cement and steel production particularly significant. Ask: how does Khan's principle speak to contemporary debates about sustainable building? Does structural efficiency alone solve the climate impact of construction, or are other changes needed — different materials, different ways of designing cities, different attitudes toward height? Connect to Vandana Shiva and Rachel Carson on the environmental costs of infrastructure.
Research Skills When examining the role of collaboration in technical work
How to introduce
Introduce the long partnership between Khan and the architect Bruce Graham at Skidmore, Owings and Merrill. Their work challenges the myth of the solitary genius in both engineering and architecture: the best results came from deep, sustained collaboration between people with different skills. Ask students: what does good collaboration between people with different expertise look like? What goes wrong when collaboration is shallow, or when one side dominates? Discuss the specific skills of working well with people whose training and language differ from your own. Connect to the broader question of how modern complex work almost always involves collaboration and what makes it succeed.
Common Misconceptions
Common misconception

Khan designed the architectural appearance of the John Hancock and Sears Towers.

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What to teach instead

Khan was the structural engineer; the architect of both buildings was Bruce Graham, also at Skidmore, Owings and Merrill. In traditional terms, architects design the appearance and function of buildings, and engineers work out how to make them stand up. What makes Khan's work distinctive is that the appearance of these buildings — the visible X-braces on the Hancock, the stepped form of the Sears Tower — comes directly from the structural system he developed. The architecture and the engineering are inseparable. But calling him the architect overstates one role and understates another. The collaboration between Khan and Graham is the accurate story.

Common misconception

The tubular structural system is a single invention Khan made once.

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What to teach instead

Khan did not invent one system; he developed a family of related systems, each suited to different heights and uses. The framed tube, the trussed tube, the bundled tube, the tube-in-tube, and later variants all belong to the family. Khan and his colleagues matched each system to specific problems. This is important because it shows his engineering as an ongoing practice of analysis and response, not a single brilliant idea. The range of tubular systems also reflects a general truth about engineering: most real problems are solved not by one system that handles everything but by a toolkit of approaches matched to specific situations.

Common misconception

Because Khan was Bangladeshi, his work was ignored during his lifetime.

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What to teach instead

Khan was recognised as a major figure in structural engineering during his lifetime. He was a partner at one of the world's leading architecture and engineering firms, designed two of the tallest buildings in the world, received major professional awards, and was consulted on projects internationally. His background as a Bangladeshi and Muslim professional in mid-twentieth-century America undoubtedly involved obstacles and slights. But the claim that he was ignored obscures the real story, which is that he succeeded at the highest level of his profession. It is fair to note that his name is less widely known to the general public than the buildings he designed, but this is true of most structural engineers.

Common misconception

Tall buildings are dangerous because they are so high, and Khan's work made them more dangerous by pushing them higher.

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What to teach instead

This reverses the actual relationship. Khan's engineering made tall buildings safer as they grew taller, not less safe. A hundred-story building using 1960s conventional framing would have required vastly more material and would have performed worse in wind, earthquake, and fire conditions than a building of the same height using Khan's tubular systems. The analysis of how tall buildings perform under extreme loads has continued to advance in the decades since Khan, partly because his work made the question urgent. Tall buildings designed with proper engineering are not inherently dangerous; their safety record is generally better than that of many ordinary structures.

Intellectual Connections
Develops
Nikola Tesla
Tesla and Khan both solved central infrastructure problems of their respective centuries. Tesla's alternating current system made it possible to electrify entire cities. Khan's tubular structural systems made it possible to build very tall buildings efficiently. Each worked at the scale of infrastructure — the systems that shape how cities actually function. Each combined technical breakthrough with practical engineering that could be applied at large scale. Reading them together reveals the pattern by which a single engineering insight, properly developed and deployed, can shape the built environment for generations.
In Dialogue With
Al-Jazari
Al-Jazari and Khan both worked in Islamic engineering traditions separated by eight centuries. Al-Jazari designed machines for the Artuqid court in twelfth-century Upper Mesopotamia; Khan, a twentieth-century Bangladeshi Muslim, designed buildings for twentieth-century Chicago and Jeddah. The Hajj Terminal at Jeddah, in particular, draws on the tent forms of traditional Arabian architecture while using modern engineering. Reading them together traces a long Islamic engineering tradition and resists the common habit of treating modern engineering as an exclusively Western achievement. Khan stood in a long lineage that included Al-Jazari and many others.
Complements
Rabindranath Tagore
Tagore and Khan are two figures of Bengali intellectual and creative life who pursued very different kinds of work — Tagore in literature, music, and education, Khan in engineering — while sharing a broadly humanist orientation. Khan's insistence that engineers must care about art, music, and most importantly people would have been congenial to Tagore's sensibility. Both retained deep connections to Bengal even as they worked on international stages. Reading them together resists a narrow view of Bengali culture as purely literary or purely technical, and points instead to an integrated tradition of thought and making.
In Dialogue With
Amartya Sen
Sen and Khan are both Bengali-born figures whose work took them across the world while remaining connected to their origins. Sen's capabilities approach to development economics emphasises what people are actually able to do and be; Khan's buildings created the urban environments in which much contemporary life is lived. Both worked on questions about how resources should be deployed for human benefit. Sen operated at the level of economic theory; Khan operated at the level of steel and concrete. Reading them together shows the range of serious intellectual work that has come out of the Bengali tradition and entered the wider world.
Anticipates
Wangari Maathai
Maathai's work on the relationship between environment, community, and built landscape, developed in Kenya decades after Khan, intersects with Khan's concern for structural efficiency and responsible use of materials. Maathai focused on trees, soil, and grassroots organisation; Khan focused on steel, concrete, and the design of tall buildings. The common thread is the conviction that physical infrastructure — whether buildings or ecosystems — should be designed and cared for with human wellbeing and resource responsibility in mind. Reading them together draws environmental consciousness and engineering ethics into the same frame.
In Dialogue With
Thomas Kuhn
Kuhn's account of how scientific and technical fields develop through the establishment of shared frameworks applies neatly to Khan's career. By the late 1960s, the framework of conventional steel framing for tall buildings had reached its limits. Khan's tubular systems offered a new framework for thinking about tall-building structure, and once demonstrated through the John Hancock and Sears Tower, this framework was adopted across the field. This is close to what Kuhn called a paradigm shift, though in engineering practice rather than basic science. Khan's career shows how a single engineer, working with particular projects, can nonetheless reshape the shared framework of an entire profession.
Further Reading

For technical papers

Khan's own papers in the Journal of the Structural Division of the American Society of Civil Engineers, published from the late 1960s through the 1970s, lay out the tubular systems in detail.

For later scholarly treatment

Antony Wood and Dario Trabucco's writings through the Council on Tall Buildings and Urban Habitat are authoritative.

For the Hajj Terminal specifically

Chuck Thornton's accounts of working with Khan on that project provide close views of his design process.