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Steel Structure Trivia: View from Above
Posted by Tasha Weiss on May 25, 2012 at 8:59 AM.


Here’s MSC’s May Steel Structure Trivia question! This photo is a different take on our “Steel Shots,” showing the photographer’s perspective from atop an American landmark. Your challenge is to correctly identify the steel tower from which this photo was taken. Photo: Geoff Weisenberger



Answer: This shot was taken from the north side of the 99th floor of Willis Tower in Chicago. (Click the thumbnail for a larger view of the full photo; AISC’s building is just outside of the shot, to the right.) Congratulations to Matt Lombardo, a structural engineer with McPherson Design Group in Norfolk, Va., for being the first (and only) person to supply the correct answer! And thanks to all who participated.


Willis Tower (formerly Sears Tower) was the tallest building in the world from its completion in 1973 until 1998, when it was surpassed by the Petronas Twin Towers in Kuala Lumpur, Malaysia. That structure has a total height of 1,483 ft, but this includes the architectural spires; the towers’ roofs are actually 1,242 ft. Willis Tower’s roof is 1,450 ft and its twin antennae–not considered architectural features–reach 1,729 ft. (Both buildings were surpassed in height in 2004, when Taipei 101 opened.)


Sears SmallAn icon for the Chicago ever since it was built, Willis Tower–designed by Skidmore, Owings and Merrill, with Fazlur Khan as the structural engineer–consists of nine separate 225-ft by 225-ft square “tubes” in a 3×3 grid, up to the 50th floor. Starting at level 51, two tubes end and the remaining seven continue up to level 66. From floors 67-90, there are five tubes, and then the number of tubes is reduced to two from floors 91-108.


The building used 76,000 tons of structural steel in its construction. Thanks to advancements in the domestic steelmaking process and an increase in the strength of structural steel, if it were built today versus 1973, the steel package would be much more efficient. It could be done with approximately 16,000 fewer tons of steel, 876,000 fewer labor hours, a 58% lower carbon footprint and 74% less embodied energy.


You can test your steel structure knowledge right here on our MSC website on the last Friday of each month, where a new photo showing only a detailed portion of a steel structure will be posted to the Steel in the News section as our weekly “Steel Shot.” Your challenge is to correctly answer the trivia question provided in the news post, based on what you see in the photo. The next question will be posted at 10 a.m. (CDT) on Friday, June 29.



The first three people who supply the correct answer will receive a MSC-branded stainless steel back scratcher! You’ll need it to successfully tackle those pesky itches after the trivia pressure subsides. (And check out that telescoping action! Wow!) Its five-fingered curved design reaches from 7 in. to 20 3/4 in. in length.

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