coil spring. Coil springs translate linear motion along their axis into
torsion of the coils. It doesn't sound like you will have a
torsion-resisting section unless you can box the thing somehow. Are you
creating a spiral box-beam? That should work. Or at least be
analyzable.
Bob Garner, S.E.
-----Original Message-----
From: Michel Blangy [mailto:mblangy@satco-inc.com]
Sent: Tuesday, September 02, 2008 12:57 PM
To: Seaint@Seaint. Org
Subject: Site Built Spiral Stair Case
An Architect wants to use a method I've never seen before to construct
site
built spiral stair cases. We do a lot of tight radius spiral staircases
here
in southern California residences. Typically, the outer and inner
supports
of the treads are continuously supported by tightly spaced studs. The
idea
now is to line the inside face of the spiral with multiple layers of
plywood, glued and screwed in place and then, after the glue has had
time to
cure, the plywood and interior support studs are to be cut parallel to
the
tread nose line at some depth creating a spiraling plywood beam. I have
no
clue as to how to calc this out, but the architect has seen several
constructed and swears they are quite solid. How might one spec a load
test
for such a thing and does this test indemnify the EOR? What other
concerns
if any would you have?
Thanks in advance,
Michel
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