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John Hancock Center

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Projects > Buildings
The John Hancock Center
At a height of 344 meters (1,127 feet), the John Hancock Center is the 16th tallest building in the World, and the 3rd tallest in the city of Chicago (behind the Sears Tower and the Aon Center).[1] When the height of the roof’s antennae are taken into consideration, the John Hancock Center stretches to a height of 457 meters (1,127 feet). Upon completion in 1969, it was the tallest building in Chicago, the third tallest building in the World, and the tallest outside of New York City (behind the Empire State Building and the Chrysler Building).

The John Hancock Center’s 100 stories are used for more than just office space. 49 stories are devoted to residential living[2], with about 700 apartments in total, including the highest residencies in the world.[3] The Center is like a mini-city; amenities include fine dining, a post-office, a supermarket, a gym, and a library.  A John Hancock resident could live comfortably without ever needing to venture outdoors.[4]

The John Hancock Center is currently owned by W2007 Golub Realty, LLC, who purchased the building in 2007 for US$383 million.[5]

Contents

[edit] Construction History

The John Hancock Center was designed by engineer Fazlur Kahn and architect Bruce Graham.[6] Construction began in 1965, and finished in 1970. At one point, more than 2,000 people worked on the project. It is estimated that over 5 million man hours were spent during construction.[7] Total construction costs were US$95 million.[8] This is considered to be a very low price, comparable to the construction costs of a contemporary 45 story office building.[9]

The developers were able to achieve such a low price by employing innovative architectural designs. The exterior of the building features five large steel crosses on each side which provide support in lieu of interior support beams.[10] These external braces required half as much steel as would’ve been needed for internal supports[11], saving an estimated US$15million[12]. An additional benefit of external supports is that they allow for more usable square footage inside.[13]

Besides the five crosses running up the sides of the building, the most distinctive architectural characteristic of the John Hancock Center are the tapered sides. All four sides narrow as you approach the top. The east and west sides narrow by 105 feet, and the south and north sides narrow by 65 feet.[14] This created a technological challenge during construction. Stationary cranes were deemed inappropriate because as the building narrowed near the top, the length of boom needed to reach the building grew too great. The contractor, American Bridge Company, overcame this problem using creeper cranes, which previously were only used in bridge construction.[15] After every three stories were finished, the cranes were elevated three stories themselves using high power hoists. This proved to be a speedy method. On average three stories per week were constructed.

In order to support the vertical load of such a massive building, it was necessary to construct caissons, which are deep cement columns which sit on firm layers of rock. The earth beneath the John Hancock Center proved to be inconsistent and difficult to work with. One caisson in particular required a 197 foot column to be drilled before suitable ground was struck. This is the deepest hole ever dug beneath a building, and required the most powerful drilling apparatus ever assembled.[16]

A major set-back took place in the summer of 1966, when all of a sudden a caisson shifted downwards, with no explanation as to how or why. There was an intense debate among the project’s engineers as to whether or not this was even grounds for major concern. But after tests, it was discovered that the downward shift was due to the cement column having a 14 foot unfilled section. This major flaw brought to concern the structural integrity of the entire building’s foundation, and caused the project to stop for about nine months, while all caissons were tested. In the end, of the 57 caissons supporting the building, a whopping 26 required fixing. The nine-month delay caused financial difficulties for the project’s developer, Jerry Wolman. He sold his share of the project to John Hancock Mutual Life in December, 1966.[17]

[edit] Equipment Used

[edit] Refurbishment/Recent Projects/Renovations

  • 1995: Lower level and garden plaza renovated to reduce the levels of street noise and to make the entrance more welcoming.[18]
  • 1997: 94th floor observatory received a US$2.5million makeover.[19]
  • 2000: Western antenna reduced in size due to lack of use.[20]
  • 2002: Eastern antenna retrofitted, and both antennae are painted white.[21]

[edit] Unique Facts

  • Total square footage: 2,800,000 sq ft.[22]
  • The 94th floor observatory has views of Wisconsin, Michigan, Indiana, and of course Illinois.[23]
  • The 44th floor features the United States’ highest swimming pool.[24]
  • 46,000 tons of steel were used to construct the frame;[25] at the time, this amounted to one tenth of the total monthly steel production of the United States at the time.[26]
  • Each of the four corner columns weighs 100 tons.[27]
  • At the time, the Center had the fastest elevators in the United States, capable of ascending 95 stories in 40 seconds.[28]
  • President Barrack Obama took the future first lady, Michelle Obama, on their first date up to the Center’s 95th floor.[29]
  • On December 18, 1997, Actor Chris Farley was found dead in his 60th floor home from a narcotic-induced heart attack.[30]

[edit] References

  1. John Hancock Center. SkyscraperPicture.com [September 15, 2009].
  2. Property Description. JohnHancockCenterChicago.com [September 15, 2009].
  3. John Hancock Center. SkyscraperPicture.com [September 15, 2009].
  4. The John Hancock Center. GlassSteelandStone.com [September 15, 2009].
  5. Property Description. JohnHancockCenterChicago.com [September 15, 2009].
  6. John Hancock Center. AViewOnCities.com [September 15, 2009].
  7. Construction of iconic John Hancock Center Chicago. Hancock-Observatory.com [September 15, 2009].
  8. John Hancock Center. SkyscraperPicture.com [September 15, 2009].
  9. The John Hancock Center. GlassSteelandStone.com [September 15, 2009].
  10. American Architecture - John Hancock Observatory - Chicago Icon. Hancock-Observatory.com [September 15, 2009].
  11. John Hancock Center. AViewOnCities.com [September 15, 2009].
  12. American Architecture - John Hancock Observatory - Chicago Icon. Hancock-Observatory.com [September 15, 2009].
  13. John Hancock Center. AViewOnCities.com [September 15, 2009].
  14. John Hancock Center. Emporis.com [September 15, 2009].
  15. Construction of iconic John Hancock Center Chicago. Hancock-Observatory.com [September 15, 2009].
  16. Remsberg, Charles. “100 Floors of Modern Living". Popular Mechanics June 1968: pg. 70-71.
  17. Khan, Yasmin. Engineering Architecture: the vision of Fazlur R. Khan. W.W. Norton & Company Ltd: 2004.
  18. The John Hancock Center. GlassSteelandStone.com [September 15, 2009].
  19. The John Hancock Center. GlassSteelandStone.com [September 15, 2009].
  20. John Hancock Center. SkyscraperPicture.com [September 15, 2009].
  21. John Hancock Center. SkyscraperPicture.com [September 15, 2009].
  22. The John Hancock Center. GlassSteelandStone.com [September 15, 2009].
  23. John Hancock Center. SkyscraperPicture.com [September 15, 2009].
  24. John Hancock Center. SkyscraperPicture.com [September 15, 2009].
  25. Construction of iconic John Hancock Center Chicago. Hancock-Observatory.com [September 15, 2009].
  26. Remsberg, Charles. “100 Floors of Modern Living. Popular Mechanics June 1968: pg. 70-71.
  27. Construction of iconic John Hancock Center Chicago. Hancock-Observatory.com [September 15, 2009].
  28. The John Hancock Center. GlassSteelandStone.com [September 15, 2009].
  29. The John Hancock Center. GlassSteelandStone.com [September 15, 2009].
  30. The John Hancock Center. GlassSteelandStone.com [September 15, 2009].