The Willis Tower, as referred to on the official website willistower.com, is a prime corporate office building in Chicago (Illinois) in the United States. The tower is home to more than 100 businesses, including law firms, insurance companies, transportation companies, and financial institutions. Architect Bruce Graham and structural engineers Srinivasa and Fazlur Khan of Skidmore, Owings & Merrill, [SOM] designed the iconic building for Sears, Roebuck & Company. When Willis Group Holdings Ltd bought the building in 2009 with naming rights, it renamed it the Willis tower from Sears Tower as it’s commonly known in downtown Chicago. The tower is 527,3m high, weighs +225.000tn, has a top floor height of 412.69m, a roof height of 422.14m, 104 elevators, and costs USD 175.000.000.
Site Location
Before deciding on its current location, a two-block area bounded by Franklin Street on the east, Jackson Boulevard on the south, Wacker Drive on the west, and Adams Street on the North, the Sears company hired a law firm” Arnstein, Gluck, Weitzenfeld & Minow” to find a location. The company proposed a site on the western edge of Chicago’s Loop, the main section of Downtown Chicago and the city’s main business district. This proposed site which was eventually rejected was located on Goose Island, a 60 acres artificial island northwest of Downtown Chicago. The building footprint occupies the entire block, 12,140,57sqm
Design and Concepts
Nine square tubes make up the Willis Tower, each a building complex of its own. The tubes form a 3 by-3 framework with 225-foot (69 meters) sides that is supported by a square base. This inventive way of developing the Universal Fashion building made the tower way more productive than the more seasoned high-rises that were built. It rose higher than the Empire State Building, given more space, and cost a lot less per unit area. In that sense, the development of the Willis Tower stamped one of the foremost noteworthy minutes in the history of high rises. Its interesting plan at the time would be reproduced for various other supertalls in the future, counting the Burj Khalifa. Construction commenced in 1970 with the first steel bundled tubes being put in place in April 1970. Construction was however halted after reaching the 50th floor with the main concern being from the television watchers who feared that the tower would disturb the signal in the area. The case was dismissed on May 17, 1972. Construction resumed and in May 1973, the tower was completed.
The design of the project was inspired by an advertisement for a package of cigarettes and the notion of “the higher, the greater the effect of the wind on the structure”. The “father of tubular designs” Engineer Fazlur Rahman Khan created a new structural concept known as “screen tubes” as a response to the new alternative new structural concept after the already existing concept of bracing X to prevent deformation or displacement by the outside or with walls of reinforcement around the vertical communication core was too expensive in a steel structure high-rise and the client didn’t want reinforcement X on the front of his building. For these “tubes”, the Sears (Willis) tower appears to the eye as a series of independent towers joined together at different heights.
Structures and Materials
The tower is the tallest all-steel structure (columns and beams) in the world. The structure is made up of nine square modules without internal supports and suspended floors. The building is composed of all the nine square 22.86 * 22.86m modules (tubes) at the base to the 50th floor. The tubes are inserted into reinforced concrete caissons reaching bedrock and also joined by a concrete mat layer.
The building materials include structural steel for the columns and beams and reinforced concrete for the slabs. The tower has a black anodized aluminum exterior with tinted glass in bronze black lines to highlight the tubes.
Program
The Sears Tower has a total floor area of 418.64 square meters of which 353.961 square meters are rentable. The tower contains a total of 110 apartments, 108 above ground accessed with 104 elevators of which 16 are double height. The reverse icon design of the structure was conceptualized as a result of the space requirements. The idea was to design a building that incorporates both extremely large offices and small to medium size companies. The tower is also divided vertically into three zones of between 30-40 floors, each with a double-height lobby and three mechanical floors. In front of the tower is a separate entrance for tourists who use the sky deck Pavilion, a viewing platform located on the 103rd floor at a height of 412.69m high. The platform was incorporated as an additional innovative idea in line with the design concept. Minimum glass balconies allow five-sided views in all directions and provide an experience that approximates feeling suspended in the air. The projections are roughly 1.22m deep, 3m high, and 3m wide. They are made of laminated glass panels 3.81cm thick hanging from a steel frame that rides on rails, permitting them to be withdrawn into the building for cleaning and upkeep.
Other services include a platform for the dissemination of world-class conference centers and health facilities, all with exceptional technical features.
Tourism and Pop Culture
The tower has the highest observation deck in the United States named the Skydeck. On some clear days, the states of Illinois, Michigan, Indiana, and Wisconsin can be seen. The Skydeck attracts around 1.3 million tourists a year.
Because of its status as an icon skyscraper in America, the tower has been featured in several TV shows, movies, video games, etc. such films include Transformer: Dark of the moon, Transformer: Age of Extinction, Jupiter Ascending and so many more.
Facts by the Numbers
- 12th tallest building in the world
- 2nd tallest building in North American/Western Hemisphere
- 110 floors high (443 meters)
- (520 meters) including the building’s twin antennae
- 76,000 tons of steel with a combined weight of the building is 222,500 tons
- Average sway is approximately 6 inches from the true center
- The tower has 16,100 bronze-tinted windows
- 25,000 miles of electrical cable
- 25 miles of plumbing
- 80 miles of elevator cable
- 145,000 light fixtures
- 43,000 miles of telephone cable
- Construction cost of more than $175 million
- 104 elevators moving 1,200 feet per minute
- More than 16,000 square feet of conference rooms
- 99-floor event space
- 3 main entrances
Reference List:
Willis Tower: An American Icon with a rich history [online] Available at: https://www.willistower.com/history-and-facts [Accessed date: 18 October 2022].
The ledge: Facts about the ledge. [Online] Available at : https://theskydeck.com/the-tower/facts-about-the-ledge/ [Accessed date: 18 October 2022].
Sears Tower- Willis Tower [online] Available at https://en.wikiarquitectura.com/building/sears-tower willis-tower/ [Accessed date: 22 October 2022
Art fact: 33 Great Facts About The Willis Tower [online] Available at:https://art-facts.com/facts-about-the-willis-tower/ [Accessed date: 18 October 2022].
Just Fun Facts: Interesting facts about the Willis Tower. [online] Available at : https://thetowerinfo.com/buildings-list/willis-tower/ [Accessed date: 18 October 2022].
