Strength of materials and designs for space habitat

>>I look at suspension bridges and consider the loads they can bear. It
>>makes me wonder about how an O'Neill habitat would actually be
>>constructed. In this spacesettlers group, I read that O'Neill calculated
>>the maximum size for a titanium sphere would be about 19KM.
>> Where can I find discussions of
>the forces on the hulls of space habitats with 1G environments?
>>I don't want to read too much about miraculous
new material. But I would like to see some simple discussions of the
centrifigal forces an how current materials measure up to the requirements.

I'm not at all interested in unobtanium results. Even the solid titanium
result is useless to me except as a simple illustration. Especially since I
was converted to concrete...;-) The mass of solid metal is ridiculous. A
colony with a standard metal hull plus inert un-spun shell is still ~85%
rock. Concrete uses maybe 1/2 to 2/3 the amount of metal, in the form of
cables; cable get maybe 5 times the stress rating of beams or plates or
pressure shells of solid metal -comparing mass of metal to acceptable
stress.

My earlier posting here-- Article Review: "Concrete Space Colonies" #931
(3/26/2001)

As I recall, the biggest colonies they could build with acceptable known
methods was about 12km diameter, while the biggest they ever worked out in
detail is the Island 3 at ~7km.

>>Is it better to have cables radiating out from central support? Would a
>>torus or sphere be able to sustain the force vectors resulting from a 1G
>>spin?
>>How does the amount of "soil" or shielding affect the calculations?
>>I guess I am looking for links and pointers as much as answers...
>
>It's interesting that your raise the comparison of suspension bridges
>because that is the engineering example that was used in the original
>studies.
>
>Don't look for the cables within the Habitat: look outside. The cables are
>used to wrap the cylinder, torus or sphere and contain the loads.

I learned a lot about that from the "Concrete Space Colonies" article. The
colony is built with no spin, and the cables around the circumference are
only tightened up a bit during construction. As it's finished, they're
"tuned up" together. The cables provide a permanent crush, forcing the parts
together. The compression is comfortably greater than the total load -plus-
for a safety margin. The mass of soil and shielding is included in that
figure.

See also the original space colony studies online. The appendices have a lot
to say.
1975 studies, maintained by Al Globus
http://makeashorterlink.com/?O1E6612A6

>For the specifics on at least some of your questions, you can play with
>them in this spreadsheet I wrote. It calculates the rotation, atmospheric
>compositon, material loads, metal thickness, etc.
>
http://f5.grp.yahoofs.com/v1/EFjBP-
vvFvyxE4Qev9rcYJjvwR5Y7sRy2tBKTNDVEV91UxVkSByxTVC5oJamcsFqlEu67NGdftu
Hw5enFXl65TY6YE5vBVImEjc3v9wl/TangoMan%27s%20Design%20Criteria%20for%
20Space%20Station.xls

That link will never come through on a yahell group mailing. Try re-posting
it, but go through this site:
http://makeashorterlink.com

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