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Originally Posted by joemustardo
Sorry. I meant the steel for the structure of the building. In the image of FMC, the red crane is basically going straight sure the steel structure. Why is that?
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Presumably because the site is so tight, and the structure will take up most--if not all--of the site. While the CITC site is obviously much bigger than that for the FMC Tower, the structure will similarly occupy most, if not all, of the site.
Also, and more significantly, the eventual height of these buildings--and hence the tower cranes--requires that the cranes be supported by more than just their intrinsic steel towers. That occurred to me overnight, and a quick bit of Googling just now revealed the following:
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A typical tower crane has the following specifications:
Maximum unsupported height - 265 feet (80 meters) The crane can have a total height much greater than 265 feet if it is tied into the building as the building rises around the crane.
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http://science.howstuffworks.com/tra...wer-crane2.htm
And of course, anchoring them to the core would maximize their support as they continue to climb.