From: Dani Eder (firstname.lastname@example.org)
Date: Wed May 03 2006 - 16:53:23 MDT
> Look at skyscrapers -- 4x increase in record
> skyscraper height in the 40
> years leading up to the Empire State Building in
> 1931. Then no increase in
> record height in the next 40 years.
But skyscrapers aren't a technology. They are a
complex application of multiple technologies. The
ESB itself had it's size and shape determined as
much by the size of the lot it is sitting on and
the zoning requirements for setbacks in tall
buildings as anything else.
The height you can build with a given material can
be scaled by dividing the strength by the density
and then reducing by a factor for safety margin.
For steel it is 70,000 psi/0.3 lb/in^3 = 233,333 in
= 19,400 ft/ 2-4 safety factor = ~5-10,000 ft.
For concrete it is 14,000 psi/0.087 lb/in^3
= 13,400 ft/2-4 = 3350-6700 ft.
Other factors than the strength of structural
materials has limited building heights to well
below what is possible.
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