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?

--
posted from
http://www.polytechforum.com/metalwo...pa-598712-.htm
using PolytechForum's Web, RSS and Social Media Interface to
rec.crafts.metalworking and other engineering groups

Jim fired this volley
in roups.com:

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?

Look up beam load tables for ASTM500 grade resistance welded square
tubing.
There are many on the web, but the links are ugly to post. Like this:

http://www.google.com/url?sa=t&rct=j...ource=web&cd=6
&cad=rja&uact=8&ved=0CDkQFjAF&url=http%3A%2F%2Fwww .pirate4x4.com%2Ftech%
2Fbillavista%2FPDFs%2FHollow%2520Structural%2520Se ctions%
2520LRFD_Beam_Load_Tables.pdf&ei=H4qgU8_kEsrNsQT9r 4D4CQ&usg=AFQjCNENcs3
_ZcMBrsNCKXgrhSmJdp6cpA&sig2=kNVIcdG4-LkJez8mY_KxGw&bvm=bv.68911936,d.cWc

Lloyd

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

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

"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

On Tue, 17 Jun 2014 13:38:34 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Jim fired this volley
in roups.com:

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?

Look up beam load tables for ASTM500 grade resistance welded square
tubing.
There are many on the web, but the links are ugly to post. Like this:

http://www.google.com/url?sa=t&rct=j...ource=web&cd=6
&cad=rja&uact=8&ved=0CDkQFjAF&url=http%3A%2F%2Fww w.pirate4x4.com%2Ftech%
2Fbillavista%2FPDFs%2FHollow%2520Structural%2520S ections%
2520LRFD_Beam_Load_Tables.pdf&ei=H4qgU8_kEsrNsQT9 r4D4CQ&usg=AFQjCNENcs3
_ZcMBrsNCKXgrhSmJdp6cpA&sig2=kNVIcdG4-LkJez8mY_KxGw&bvm=bv.68911936,d.cWc

Lloyd, here is the output from that link:
Redirect Notice

The previous page is sending you to
http://www.pirate4x4.com/tech%%202Fb... ad_Tables.pdf.

If you do not want to visit that page, you can return to the previous
page.

--
There is nothing more frightening than ignorance in action.

--Johann Wolfgang von Goethe

On Tue, 17 Jun 2014 16:22:19 -0400, Ned Simmons wrote:

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.

Come to think of it, the tension on the tube walls at the base of the 11'
section is something over 100,000 psi. Even if it didn't buckle on the
compression side, it'd bend right over.

--

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

On 6/17/2014 1:18 PM, 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?



I use 4" sch 40 galvanized pipe in 3' diameter hole 5' deep. They have
standing and doing well for over 5 years.

--


___________________________________

Keep the whole world singing . . .
Dan G
remove the seven

On Wed, 18 Jun 2014 14:05:52 -0400, Jim Wilkins wrote:

"Tim Wescott" wrote in message
...

Come to think of it, the tension on the tube walls at the base of the
11'
section is something over 100,000 psi. Even if it didn't buckle on the
compression side, it'd bend right over.

Tim Wescott

Where did you locate the neutral plane?
-jsw

I figured that for a quick calculation that was going to say "it'll break
anyway", I'd rearrange the walls of the pipe so that they're 8" long, 4"
apart. =

1/4" thick walls gave me (1/4")(8") = 2 sq in.

That's going to result in an overestimate of the strength of the pipe --
but if the stronger pretend thing breaks, then surely the real, weaker,
thing will break.

I put the neutral plane half way between the walls, so the force from the
moment is

(33,000 ft-lb) / ((2")/(12 in/ft)) = 198,000 lb

Dividing this by the area gave me 99,000 psi, which is close enough to
100,000 given all the wild approximations.

--

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

In article s.com,
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?

Weight is easy. You also need to calculate the wind loading effects.
The overturning moments can be quite large, and the footings have to be
big enough not to be uprooted.

Joe Gwinn