Physics Question on PressuVessels

--- In spacesettlers@yahoogroups.com, "ANTIcarrot"
wrote:
> > From: victoriatangoman [mailto:tango_dancer@h...]
>
> > Besides, will the human habition mass be distributed evenly or will
> > there be clusters of different mass densities throughout the
> > Habitat? If so, how will this mass loading be distributed according
> > to pressure vessel design theory?
>
> Stanford torus solved the problem by ensuring the buildings weren't more
> than two stories stll in any one place and building them out of
light weight
> materials, similar to like warehouses or hangers. They also put larger
> buildings up against the walls, where the structure could directly
support
> thier weight.
>
> In larger habitats you could always put a cable on the top of the
building
> and attach it to the other side of the colony. Or just build two (or
more)
> 'spoke' towers that meet in the center. Suspension bridges,
remember. ;) Or
> balance the mass out with a swimming pool. Such a 'flat' structure
can still
> weigh hundreds of tonnes.

I learned in college engineering that building a dam can cause
earthquakes. Build a dam and the space behind it fills up with
millions of tons of water. The ground below, depending on what it is,
will compress some beneath the weight. Then, if it can, it will move
sideways.

And there is your earthquake.
>
> Whatever shape we end up building them, the major structural and
internal
> elements will likely be designed using the same slicing technique
used in
> ship design. That is you divide the ship/colony up into small thin
sections
> along the long/rotational axis and balance the forces on each slice
> seperately. In torus habitats you can also slice though the, um,
> circumfurence of the torus, if that makes sense.
>
> Beyond that it gets complex, but since it works for ships it should
work for
> colonies.
>
> ANTIcarrot.

These things are complex enough so that engineering practice is to
carefully calculate the stresses on the object being built then make
the structure strong enough to withstand about twice as much.

In engineering terms, this is called a fudge factor. Safety being
more important than economics.

As a structure ages, the material it is made of will usually become
less stress resistant. These calculations can get quite complex.

The quick and dirty answer is to make it much stronger than what was
thought to be necessary.

I started college almost 40 years ago. A friend had an elderly
foreign car. He popped the hood, I looked in, and my jaw dropped.
The damn thing had at least one I-beam running the length of the car.

Certainly stronger than usually needed.

Rick Brooks