John Hancock Center

The John Hancock Center is an International Style skyscraper designed by Skidmore, Owings & Merrill, with Bruce Graham as lead architect, and built between 1965 and 1969 in Chicago, IL.

John Hancock Center is not the only name you might know this building by though. It is common for companies to want to attach their names to iconic buildings when they move in, or for the general public to come up with nicknames, and this one is no exception. The building has changed names several times over the years, and is also known as:

• John Hancock Center between 1969 and 2018.
• 875 North Michigan Avenue from 2018 until this day.

Its precise street address is 875 North Michigan Avenue, Chicago, IL. You can also find it on the map here.

The building is one of the most famous examples of structural expressionist architecture, and one of the most iconic landmarks in Chicago's skyline.

The silhouette of the building is that of a truncated pyramid, which makes the Hancock Center one of the most distinguishable buildings not only in Chicago's skyline, but in the world.

Private access to the condominiums is provided through a separate entrance at 175 Delaware.

The building underwent a major restoration in 1995.

Skidmore, Owings & Merrill, with Bruce Graham as the lead architect, was the architecture firm in charge of the architectural design.

That being said, architecture is a complex discipline involving many professionals from different fields, without whom this building would have not been possible. We will surely be leaving out a lot of names here, but here is a list of the people we do know also played their part in making the John Hancock Center a reality:

• Fazlur Rahman Khan, and Srinivasa Iyengar in charge of Structural Engineering
• Tishman Construction Co as the Main Contractor
• Otis as the company in charge of the elevators system
• John Hancock Mutual Life Insurance Company as the Main Developer

The John Hancock Center can be categorized as an International Style building.

The John Hancock Center was completed in 1969. By 1969 the International Style movement had already left its early days behind and could be considered a mature movement, which does not mean it was loved and accepted by everyone, on the contrary. The International Style was accepted by the architecture community way before it was by the general public, and it is therefore likely that the John Hancock Center was not well received by everyone at the time.

The John Hancock Center uses a trussed tube-in-tube structure , with steel columns and concrete slabs.

A trussed tube-in-tube structure uses a central core, known as inner tube, which usually holds stairs, lifts and installations, and a perimeter of columns around it, which form the exterior tube. The interior tube is tipically more massive (often made of reinforced concrete), and the exterior tube is "lighter" (made of steel or concrete columns). Both tubes are conencted via horizontal elements which make up the floors and also transmit any horizontal froces from the facade to the core.

The facade of the building is load bearing. This is a direct consequence of the integration of the exterior "tube" into the facade, something which most trussed tube-in-tube buildings do in order to liberate the interior space from structural elements and achieve a more flexible interior.

So the facade of the builing is techinically load-bearing, yes, however, in between the load-bearing colums we find a window-wall type of facade, which by itself would not be cosnidered load-bearing.

The John Hancock Center was an engineering pioneer, as it was the first to utilize the exterior structural system of diagonal tubes, developed specifically for this building, and which we now refer to as trussed structure. It is an evolution of the framed tube system, which allows for wider column spacings and, in turn, larger windows.

At the Hancock Center, each pair of diagonally braced tubes spans 18 floors, providing structural support. The columns, beams, and diagonal tubes are connected by heavy steel reinforcement plates

From an aesthetic point of view, the facade features dark tinted glass in anodized aluminum frames, and the trussed structure we already mentioned, painted in black.

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