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?

11', 3000# = 33,000 ft-lb at the base of the tallest post.

Go look up what that tubing can withstand, and let us know.

I think you need to worry more about your anchors pulling out of the
ground with that much bending moment being exerted on a post with only a
three foot deep base.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com