From: Gina Miller (nanogirl@halcyon.com)
Date: Tue Jul 20 1999 - 02:17:57 MDT
I didn't mean a building, merely a structure in its smallest capability and
furthest reaching height possible.
Gina "Nanogirl" Miller
>> Ron Kean wrote: If cost is no object, other materials which have
>> a higher strength to weight ratio than steel could be used, such as
>> titanium or perhaps carbon fiber composites. Doubtless much taller
>> buildings could be constructed using steel than already have been...
>
>Ron I may have misinterpreted Gina's original question. Assuming
>she did not restrict herself to a *building* as we know it, but meant
>*any* structure, practical or otherwise, in a 1 G field, how high could
>it go? Lets ignore wind loads, since everyone would have different
>assumptions on that, plus the aero drag on circular cross sections
>are approximation-ey. Also, lets forget fiber composites, since they
>tend to be lousy in compression, and ignore soils restrictions (assume
>an infinitely rigid infinitessimally flat base).
>
>Surprise: for this kind of application, good old common steel does
>as well as titanium. The ratio of the sheer moduli (Ti/steel) is almost
>the same as their density ratio (in fact steel is *slightly* better than
Ti.
>Steel beats aluminum and magnesium too). So assume a steel tower
>and a solid round cross section since making it hollow doesnt allow you to
>go any higher.
>
>Lets assume a steel tower, minimum diameter of one meter at the
>top, maximum diameter of 200 m at the base, sheer modulus of
>8.3E4 MPa and a density of 7.8 g/cm^3. Come back tomorrow
>with an answer, see if we get the same. spike
>
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