SB: RE: [Fwd:] SB Vault Questions

[JOHN SALMEN <terrain@shaw.ca>]

this is in the realm of where it would be quicker to create a design for an
interior arch (conc. (or stucco mix) and steel) for support rather than to
model the infill material unless you have a lot of beer and your engineer
friend has a lot of time and lack of any other kind of life and/or a lot of
software. I can think of all kinds of ways to approach this but like Rob my
back is getting sore at the prospect of going into it. The basic gist of it
is that so little material is required to create the interior arch
structurally without using complicated hypothetical straw properties that in
terms of a compliance with structural requirements it would probably be the
simplest approach to use the straw not as a material that is transmitting
stress between skins but as a material that can hold everything roughly in
column and carrying some exterior loads (that is bad enough but simpler to
model)


---Original Message-----
From: Robert W. Tom [mailto:archilogic@yahoo.ca]
Sent: November 23, 2002 10:34 AM
To: strawbale@crest.org
Cc: Swearingen, John; Lerner, Kelly
Subject: SB: [Fwd:] SB Vault Questions



I'm afraid that my back won't let me sit-up for long enough to answer
Doug's questions so perhaps others could ?  I don't know if Doug is
on the SB List so it'd probably be a good idea to copy him directly.
--- * ---
Rob Tom
Kanata, Ontario, Canada
<ArchiLogic@CHAFFyahoo.ca>
(winnow the "chaff" spamguard from my edress in your reply)

Please visit http://www.theHungerSite.com daily

------- Start of forwarded message -------
From: Doug  Nuttall <dnuttall@rcii.com>
To: "'archilogic@yahoo.ca'" <archilogic@yahoo.ca>
Subject: Fwd: More curiosity about straw bales
Date: 11/22/02 11:31:12 AM

About a year ago I dropped you a line at a different email address,
asking
about straw bale construction, and you replied that I should do some
research at CMHC.  I've done some research on permeability and
structural
elements, and I know I have to learn a lot more about all of this.  I am
currently trying to research straw bale arches & vaults, and I am
having
problems finding an appropriate buckling theory for straw bales, with
plaster on the inside, and steel mesh on the outside.

Do you know of any specific research on arch buckling, composite
buckling,
and/or straw bale buckling theory?  Thus far I've found theory on
circular
arch buckling, but I'm thinking of either parabolic or catenary arches,
and
the theory falls apart if the arch deviates significantly from the circular.

I've asked a friend who is a structural engineer to run a straw bale
vault
through his S-Frame software, using straw, steel, and plaster
elements, but
I don't know things like how much tension to put in the steel & how
thick to
make the plaster on the inside to maximize the span and minimize the
cost.
I may be able to get him to run a variety of models, but I don't want
to owe
him that much beer.

I've looked at the circular arch designed and tested by Skillful Means,
and
although it produced some spectacular results, I'm envisioning a
different
concept.  I want to do an arch that has tapered bales, so there is no
plaster between the bales, and use pure tension on the outside, pure
compression on the inside, just to keep it simple.  Get the angles right,
and the whole thing should work well.


Douglas Nuttall, P.Eng.
ROBINSON CONSULTANTS INC.
Kanata, ON.

-------- End of forwarded message --------




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