Fwd: Re: [Cob] dirt bags

[Roselle Milvich]

whoops, I think I just sent this to Nicolas.

--- Roselle Milvich <rosellewind at yahoo.com> wrote:

> Date: Mon, 2 Jan 2006 18:49:45 -0800 (PST)
> From: Roselle Milvich <rosellewind at yahoo.com>
> Subject: Re: [Cob] dirt bags
> To: Nicolás Echániz <nico at rakar.com>
> 
> Hi Nicolas,
> 
> 
> I think a circle is the strongest shape without
> gravity.  If you look in wikipedia under "arch", it
> says "The parabolic and catenary arches are now
> known
> to be the theoretically strongest forms."  Its a
> pretty good article.  It has sketches of different
> types of arches which is interesting to look at for
> ideas on window and door openings.  
> 
> The "dome" entry doesn't give as much information. 
> I'm not sure if the math for the arch would directly
> translate into a dome.  The ending lines of a
> parabola
> do not end vertically, but slightly out.  Into the
> wall if it is a window.  Should it end vertically to
> transfer the weight directly down?  If so,  would
> half
> of an ellipse be the strongest?  
> 
> 
> Just for fun....
> I just learned how to draw an ellipse.  Its pretty
> cool.  You use two thumbtacks for the focus points. 
> Stick them apart from each other on the paper.  Tie
> a
> string between them that is longer than the distance
> between them.  Then pull the string taut with a
> pencil
> as you draw.   Ive got equations if anyone is
> interested.
> 
> 
> Roselle
> 
> 
> 
> --- Nicolás Echániz <nico at rakar.com> wrote:
> 
> > Hi,
> > 
> > I guess this is not exactly the place to ask for
> > help, as dirtbags 
> > buildings are not exactly cob, but I can't think
> of
> > a better place to ask.
> > 
> > I'm planning to build a dirtbag dome (5m diameter)
> > and I need to know 
> > what would be the ideal shape (curve) for this
> kind
> > of corbelled dome. 
> > Does anyone here have relevant information on this
> > subject?
> > 
> > Thanks in advance,
> > 
> > Nico.
> > 
> > 
> > _______________________________________________
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> > 
> 
> 
> 
> 	
> 		
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