875 North Michigan Avenue (formerly John Hancock Center)

With its mixed-use program and bold structural design, the former John Hancock Center transformed Chicago's skyline and set the tone for a new era of high-rise construction.

Project Facts
  • Status Construction Complete
  • Completion Year 1970
  • Design Finish Year 1967
  • Size Site Area: 104,000 square feet Building Height: 1,127 feet Number of Stories: 100 Building Gross Area: 2,800,000 square feet
  • Rental Units 703
  • Awards
    1970, Distinguished Building Award: Office Buildings, AIA – Chicago Chapter and Chicago Association of Commerce and Industry 1971, Architectural Award of Excellence, American Institute Of Steel Construction 1999, National 25 Year Award, American Institute of Architects (AIA) 1992, 25 Year Award, AIA – Chicago Chapter 2015, 50 Significant Structures in 50 Years, Structural Engineers Association Of Illinois
  • Collaborators
    Amman & Whitney Bolt Beranek & Newman Edison Price Weidlinger Walter Holtkamp Rothman, Ammann & Whitney
Project Facts
  • Status Construction Complete
  • Completion Year 1970
  • Design Finish Year 1967
  • Size Site Area: 104,000 square feet Building Height: 1,127 feet Number of Stories: 100 Building Gross Area: 2,800,000 square feet
  • Rental Units 703
  • Awards
    1970, Distinguished Building Award: Office Buildings, AIA – Chicago Chapter and Chicago Association of Commerce and Industry 1971, Architectural Award of Excellence, American Institute Of Steel Construction 1999, National 25 Year Award, American Institute of Architects (AIA) 1992, 25 Year Award, AIA – Chicago Chapter 2015, 50 Significant Structures in 50 Years, Structural Engineers Association Of Illinois
  • Collaborators
    Amman & Whitney Bolt Beranek & Newman Edison Price Weidlinger Walter Holtkamp Rothman, Ammann & Whitney

Mixed-use goes vertical

875 North Michigan Avenue, formerly known as John Hancock Center, the world’s first mixed-use tower, is an architectural icon representing the close collaboration between architect Bruce Graham and structural engineer Fazlur Khan. The building remains an archetype for the collaborative ideal that continues to make SOM a leader in a wide spectrum of design disciplines.

 

Hancock
© Dave Burk | SOM

Known locally as “Big John,” the tower is situated on North Michigan Avenue in a prestigious district with apartments, shops, offices, hotels, restaurants, and art galleries. The wish to continue this mixture initially gave rise to the idea of building a 70-story apartment tower and a 45-story office tower. But the two towers would have occupied most of the site and would have impaired each other’s privacy and daylight conditions. Moreover, the lower-level apartments would have suffered from noise nuisance from the street. It was therefore decided to construct a single tower where the offices would be on the lower floors and the apartments on the higher levels.

The tower’s tapered shape was chosen in order to match the different floor space requirements that decrease from bottom to top — from the entrance and commercial zones at the base to the clusters of small apartments at medium height and finally to the large apartments on top, where relatively less space is needed for ancillary rooms with artificial lighting.

Hancock
© Dave Burk | SOM
Hancock
© Dave Burk | SOM

The John Hancock Center isn’t just important to Chicago; it’s important to city skylines across the world. When it was completed 50 years ago, it changed what architects and engineers thought was possible.


A milestone in structural engineering

The building represents the first use of the exterior diagonalized tube structural system, which was developed specifically for this building. An evolution from the framed tube system, it allows for wider column spacings and, in turn, larger windows typical of steel construction. The exterior frames act as bearing walls, with gravity loads being uniformly distributed among columns, and lateral loads producing uniform forces in the windward and leeward columns. The X-bracing is generally 20 stories high. A secondary spandrel beam system infills the bracing panels.

Hancock
© SOM
Hancock
© SOM

The design proved to be extremely efficient in terms of material use: steel quantities, amounting to about 30 pounds per square foot of floor space, were no greater than for a 50-story conventional tower. Together, the columns, diagonals, and tie members create a clear architectural expression for which the building remains known and relevant decades after its completion.

Hancock