One genius design, more than 5 million man hours.
It began with architects who were ahead of their time
Designing and building John Hancock Centre was never going to be an easy job. But the developers were lucky enough to start as they meant to continue - with a team of architects who were ahead of their time in engineering and design aesthetics.
The team was headed by Bruce Graham (Architect and Design Partner) and Fazlur Khan (Chief Structural Engineer) of Skidmore, Owings & Merrill. SOM was driven by the principal made famous by Mies van der Rohe's motto 'less is more'. '
Interpreting the brief
"The design of the John Hancock Center, in Chicago, was influenced by its unique site. Just off Lake Shore Drive, it is surrounded by huge, residential high-rise buildings and yet faces one of the city's most attractive commercial streets.
(The developers) insisted on producing a tall building with residences above, offices and commercial uses below. The search for a new kind of structure which would accommodate multiple uses and also express the scale and grandeur of a one-hundred-story tower, lead Dr. Kahn and me to the diagonal tube.
It was as essential to us to expose the structure of this mammoth as it is to perceive the structure of the Eiffel Tower, for Chicago, honesty of structure has become a tradition."
Bruce Graham in "Bruce Graham of SOM."
New York: Rizzoli International Publications, 1989.
Architectural/design highlights
- Gutsy, masculine design in the tradition of industrial Chicago.
- Building design eliminated the need for inner support beams, greatly increasing amount of available floor space.
- Design also minimized the use of steel, saving an estimated $15 million.
- The design concept allows only five to eight inches of sway in a 60mph wind; tested to withstand winds of 132 miles-per-hour.
- John Hancock Center is characterized by the distinctive X-shaped external bracing that has made it an architectural icon. And for that we can thank engineer, Fazlur Khan. He pioneered this system to derive higher performance from tall structures and open up the usable floor space (the X-bracing virtually eliminates the need for interior columns).
- The center occupies only 40% of site space, creating rare open space on a bustling thoroughfare.
- The outer skin of high-density black aluminum contrasts with 11,459 extra-thick, glare-proof, bronze glass windowpanes.
- The building is shaped like a wedge, creating the illusion that it is even taller. This was drafted to balance the need for extra parking/commercial space below, and, smaller residential areas above.
Engineering/construction highlights
- At the peak of construction, more than 2,000 people worked on the project; some five million man-hours were required to complete the development.
- Enough steel to make 33,000 cars was used to make the frame, which took three years to complete and weighs 46,000 tons.
- Its four corner columns weigh up to 100 tons each.
- The building's 1,250 miles of wiring carries enough power to supply a city of 30,000 people.
- There's enough aluminum in the building to cover 12 football fields.
- Its 11,459 extra-thick, bronze windows contain enough glass to produce a single, 5ft sheet 13 miles long.
- Because of John Hancock Center's lakeside location, caissons had to be sunk into 10ft holes drilled 190ft into bedrock.
- The unusual design required innovative construction methods, including the use of "creeper cranes," previously used only in bridge construction, to hoist steel beams into place.
- Pre-fabrication of the immense corner joints meant construction proceeded at a rapid pace - up to three floors a week.
