Tower
John Hancock Center
Skidmore, Owings & Merrill | Chicago, USA | 1968-70
Image of John Hanco...
Aerial oblique view, John Hancock building in the distance.

ProjectJohn Hancock Center
ArchitectSkidmore, Owings & Merrill
CityChicago
CountryUSA
AddressJohn Hancock Center
Building TypeTower
Number of Dwellings700
Date Built1968-70
Dwelling Types1,2, & 4 bra. flats
No. Floors100
Section Typeflats
Exterior Finish
Materials
anodized aluminum glass curtain wall
Construction Typesteel frame
Ancillary Servicesmixed use commercial, office, and residential, including parking

When it was built, the John Hancock Building in Chicago was advertised as the only building in the world where people lived above the 60th floor. A mixed use building, 100 stories in height, the apartments start at the 44th floor, extending through the 92nd floor. The bottom 42 floors are commercial and office space and parking. Residents transfer to a separate bank of elevators at the Sky Lobby on the 42nd floor where there is a lobby for the apartments, a restaurant, health club and swimming pool for the residents. The top 7 floors contain mechanical spaces in addition to another restaurant and observation floor. Twin television antenna reach upward for another 350 feet. Originally the project was conceived of as two separate towers of more-or-less equal height, one an office building and the other an apartment building creating much the ambiance of Mies van der Rohe's twin towers at 860 Lake Shore Drive. Later the apartment tower was stacked on top of the office tower.

The tapered form resulted from structural concepts to reduce cost and decrease the "sail effect" of wind loads. The tapered form is also accredited to the zoning of building functions with offices, which require more open floor area on the lower levels, then a zone of efficiency apartments that require a deeper plan than the multi-bedroom dwellings at the top that have more rooms requiring exterior frontage. The unique diagonal bracing, an idea used earlier by SOM in the Alcoa Building in San Francisco of the same year, is the result of a structural concept to achieve maximum wind bracing with minimum steel. The idea is a rectangular "trussed tube" made up of vertical trusses where lateral loads are taken up by the diagonal members as compared to a conventional steel frame of vertical vierendeel trusses where lateral loading is taken up in the connections between column and beam. The choice of this system resulted in a significant savings in steel from a typical steel building requiring 45-50 pounds of steel per square foot to about 30 pounds per square foot here. The bigger exterior columns emphasize the structural concept. Tube caissons were sunk 140 feet to bedrock. In addition, a grid of grade beams extending down 28 feet, anchor lateral forces into the clay removing any lateral loads from the caissons.

There are two typical apartment floors, both central core arrangements with an internal corridor wrapping the service areas. In typical fashion, dwellings are arranged with kitchens and baths in a zone along the corridor and major rooms in a deeper zone along the exterior of the building. The efficiency studio apartments which are deeper are all located in the lower portions of the residential zone where the building footprint is larger. In these floors, larger apartments are placed at prime corner locations. Most of the larger apartments, however, occur above the 60th floor where the building area is less. With 700 dwellings housing 1700 people, office space for 4,000 people, plus restaurants, health clubs, shopping and parking, the John Hancock Center is virtually a self-contained city. The skyscraper paradigms so popular in the earlier years of the century have been built here and residents live an encapsulated existence virtually on top of the world that is occasionally even in the clouds.

Architectural Record, Jan. 1967, pp. 137-44

Architectural Forum, July/Aug., 1970, pp. 36-45.

Architecture of Skidmore, Owings & Merrill, 1963-73, Architectural Book Pub. Co., New York, 1974, pp. 162-9.

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