"Ned Simmons" wrote in message
...
On Tue, 17 Jun 2014 18:18:02 +0000, Jim
wrote:

I'm erecting a shade sail over a patio and planning to use
4"x4"x1/4"
steel tubing on the four posts that will carry the fabric. The
fabric
will be tensioned so that it barely flaps in anything but a very
strong
wind. I'm told there will be between 2000 & 3000 # pull at the
connection
points.
The tube steel will be embedded in concrete 3' or more below grade
depending on the height out of the ground. Two of the tubes will be
9'
above grade and opposite from one another. Another will be at 10'
above
grade and the opposite one, the highest, at 11' above grade.
Can anyone tell me if A500 B grade 4"x4"x1/4" tubing will do the
job?

If I'm interpreting your description properly (that's a big if), the
tubing is nowhere close to strong enough, even if the footings are
adequate.

--
Ned Simmons

If you curve the edges inward a little like this, the bolt rope
tension you need to minimize flapping decreases enormously.
http://www.structureflex.com.au/PVCMembranes.php
:
http://www.mossinc.com/

-jsw