Fazlur Rahman Khan

Creating new possibilities for mid-20th-century architecture, Fazlur Rahman Khan's designs were economical, requiring far fewer rigid building materials than traditional designs. More than that, Khan's innovative approach freed architects to literally reach for the skies: buildings he designed or those designed using his principles set new records for height. The dividing line between architecture and structural engineering was fuzzy in Khan's work, which married technical ingenuity to creative artistic understanding and produced iconic, instantly recognizable buildings. Khan spent his career at the Chicago architecture firm of Skidmore, Owings & Merrill and was involved in the construction of the Windy City's two landmark skyscrapers: the John Hancock Building and the Sears Tower (now the Willis Building).

Khan was born on April 3, 1929, in the village of Bhandarikandii, near Dacca in British-ruled India (now Dhaka, Bangladesh), where his father was a school mathematics teacher. A special influence, according to daughter Yasmin Khan (as quoted on a Princeton University website), was a grandfather who was a public education administrator and math textbook author. Khan's grandfather not only helped him with homework but devised additional problems for him to solve and challenged him to find new ways of looking at questions posed in the homework. “I always had a feeling,” Khan recalled in his interview with Yasmin, that “I was somehow enjoying it beyond the curriculum requirement.” Majoring in civil engineering, Khan graduated from the Bengal Engineering College in Shibpur, India.

After his home region became part of Pakistan in 1947, Khan became one of the academic stars of the new nation, as well as a carrier of its high hopes. He enrolled at the Ahsanullah Engineering College at the University of Dhaka, studying structures and applied mechanics. After graduating in 1950, he stayed on briefly as a teacher. He learned that he could inspire others, and this talent would serve him in the future even though he did not pursue a career as an educator. Khan won a Fulbright scholarship that, augmented by a grant from the Pakistani government, enabled him to move to the United States for graduate study in the early 1950s. Within three years, he had earned three graduate-level degrees from the University of Illinois at Champaign-Urbana: a master's degree in structural engineering, a master's degree in theoretical applied mechanics, and a Ph.D. in structural engineering.

In 1955, Khan joined the staff of leading Chicago architectural firm Skidmore, Owings & Merrill. With the exception of a two-year stretch from 1957 to 1959, he would remain there for the rest of his career, being promoted to participating partner in 1961, associate partner in 1966, and general partner in 1970. When Khan began work, the tallest building in the United States was New York City's Empire State Building; opened in 1931, it was still the tallest building in the world. Like other skyscrapers built at that time, its internal structure was a steel frame: a grid of vertical and horizontal steel beams. It was this design that had made the first skyscrapers possible in the early 20th century, but Khan, with his varied academic background, realized that other principles of construction were possible.

Khan's investigation into the structure of airplane wings had taught him that hollow structures might, counterintuitively, be as strong as solid ones as well as being more flexible in resisting lateral forces such as wind. Thus, he reasoned, instead of being supported by a central steel tower, a building could be held up by an exterior frame. This approach became known as tube design: the entire building was essentially a giant vertical tube.

Khan devised several variations on his tube design idea: the framed tube, the tube-in-tube, the bundled tube, and the trussed tube. His first projects to make use of the tube design included the 35-story Brunswick Building (1965, now the Cook County Administration Building), whose exterior columns and column-free interior set the pattern for future Khan designs. Another was the 43-story DeWitt Chestnut Apartment Building, built in 1966 and now called the Plaza on DeWitt.

Khan served as the architect on his next building, Chicago's landmark Sears Tower. Renamed the Willis Tower in 2009, the building was 110 stories high and became the tallest building in the world upon its completion in 1973, surpassing New York City's World Trade Center. (It held that distinction until 1998, when the Petronas Twin Towers opened in Kuala Lumpur, Malaysia.) The observation deck of the Sears Tower not only offered an unparalleled view of the Chicago area but also exposed visitors to the strengths of Khan's tube design: the building could sway in strong winds without damage. The building, an example of the bundled tube design, remains the second-tallest skyscraper in the United States, exceeded only by Manhattan's One World Trade Center. Khan was also involved in the construction of Chicago's One Magnificent Mile, working as the structural engineer.

Buildings using Khan's tube design were hailed as engineering marvels. For one thing, they were economical: where the Empire State Building used 206 kilograms of steel per square meter, Khan's John Hancock Center required only 145. These buildings were also visually striking, offering architects more flexibility than earlier designs, and they often became landmarks in the cities where they were constructed.

As Khan's career progressed, the list of his projects expanded to include One Shell Square in New Orleans, First Wisconsin Center (now the U.S. Bank Center) in Milwaukee, the U.S. Air Force Academy in Colorado Springs, the Hajj Terminal at Jeddah, Saudi Arabia's King Abdulaziz Airport, and the Hubert H. Humphrey Metrodome in Minneapolis, Minnesota. While the last two buildings were not skyscrapers, they relied on structural ideas similar to those Khan employed in his skyscraper designs. During the 1970s and early 1980s, he was honored with professional awards from organizations such as the American Society of Civil Engineers, the American Concrete Institute, the American Institute of Steel Construction; and London's Institution of Structural Engineers as well as honorary degrees from Northwestern University and Lehigh University. Several awards followed posthumously, including Khan's 1996 induction into the Illinois Engineering Hall of Fame.

In a century that saw dramatic changes in technology, Khan was one of the first architects to make extensive use of computer-aided design (CAD) in his work; the technology was in its infancy when he began to employ it, but he persuaded Skidmore, Owings & Merrill to invest in a mainframe computer for the purpose. CAD would soon become commonplace in architecture and structural engineering work. His most lasting legacy, however, remains the tube design, which is still used in most skyscraper construction, including Dubai's Burj Khalifa, a Skidmore, Owings & Merrill–designed structure that ranks as the world's tallest building.

Although Khan became a U.S. citizen in 1967, he continued to maintain ties to his homeland. During the 1971 war that resulted in the independence of Bangladesh from Pakistan, he organized emergency relief operations in Bangladesh. Khan died suddenly from a cardiac episode in Jeddah, Saudi Arabia, on March 27, 1982.