On Tue, 20 Mar 2007 06:13:16 -0400, Rikki Nitzkin
<rikkinitzkin@earthlink...> wrote:
Can anyone send me photos/advice about building round roof/base
plates for loadbearing, round SB houses?
Rikki and You're-o-pee'in RoundHeads;
Assuming that you wouldn't try to make a wall-width, monolithic
cast-in-place concrete beam that would be nothing more than a massive
thermal bridge (but would be the easiest to fabricate), box beams
using laminations of 19mm thick (or similar) lumber (staggering the
joints from one lamination to the next, as well as offsetting the
joints in the web material and adding shear plates at those joints) to
construct the cords would be a good choice-- "good" in the sense that
box beams would consume a minimum of lumber while providing the
necessary strength and insulative properties consistent with the SB
walls on which they sit.
The sizing of the chords and webs would need to be determined for the
specific loading conditions.
If bending/laminating 19mm thick lumber into curves is deemed to be
too challenging, then making the beam an octagon (or similar polygon)
would do the trick but wouldn't be a continuous (and hence stronger)
beam as in the case of the former.
The joints would be re-inforced most easily with the use of steel
bands at the outer face to provide the tension to resist outward
thrust (assuming no centre pole or collar ties) and sheet steel or
sheet lumber gussets across both faces of the joints to resist shear.
=== * ===
Rob Tom
Kanata, Ontario, Canada
<A r c h i L o g i c at c h a f f y a h o o dot c a >
winnow the chaff from my edress in your reply
--=== * ===
Rob Tom
Kanata, Ontario, Canada
<A r c h i L o g i c at c h a f f y a h o o dot c a >
winnow the chaff from my edress in your reply
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