Structural steel help--Engineers. (kinda on topic)

[james]

I hope this isn't too far off topic, but this could be used as structure in a garage or stuff--but I know there's someone here that'll have the know how...
I just got a call to build a structure for a local museum to hang large mesh banners from. Attached is a quick sketch I made for them. They were using two aluminum flag poles, but a storm folded them in half. The banners are mesh, but big. I'm sure this would be more than sufficient, but what wall woulf the uprights half to be? Does anyone see any major flaws in my design?

[38Chevy454]

I'm not a structural engineer, but your truss design is more than strong enough. The cross braces are what add the strength, by triangulating the tubing. Combined with your tringulated design for the posts, that would survive a tornado. I think the upright poles could be 1/8 or 3/16 wall and still be overkill.

You could probably get by with less cross-braces, or at least make them longer and angles more, that would be less in number and still provide the triangulating effect. Your truss is going to be very stiff and will not have any problems.

[Andy]

I could run the numbers but need more info on the banners. Size, openings. Wind speed?

[james]

The banners are roughly 14' x 16'. They are pure mesh, not vinyl with a couple windholes. Imagine bugscreen times 10. It's in an open area about two blocks from the gulf, but they'll take the banners down next big storm.

[james]

actually, here's a pic I found online. I belive the mesh let's about 25% airflow.

[HotRodHon]

I am an engineer http://www.jalopyjournal.com/ubbthreads/images/graemlins/tongue.gif and your design looks more that adequate. http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif
The only question is how they are mounted to the ground. http://www.jalopyjournal.com/ubbthreads/images/graemlins/shocked.gif http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif I don't see guide wires so I have to assume they are free standing. If so, make sure the cement blocks are deep enough and the bolts to hold them down are sufficient http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif
Be sure to use tubing not rod for the uprights.
Looks good though. http://www.jalopyjournal.com/ubbthreads/images/graemlins/tongue.gif

[DrJ]

[ QUOTE ]
...
The only question is how they are mounted to the ground. http://www.jalopyjournal.com/ubbthreads/images/graemlins/shocked.gif http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif ...

[/ QUOTE ]

He's in FLA.
The caissons aren't mounted in ground, they are floating in quicksand and Atlantic Ocean water... http://www.jalopyjournal.com/ubbthreads/images/graemlins/wink.gif

So, you're concern is that same one I had looking at it.
(And no I'm not an engineer, I'm a Sculptor, and Sculptors have to deal with this very thing when installing their larger work.)

[james]

They are going to have the pads poured--4' deep by 2' around. It's good solid ground, and we're on the gulf side, not atlantic. http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif They're having the pads poured, so I'm not too worried ( no liability as I only am contracted for building the towers and bolting them down).

[FEDER]

James I build ALOT of structure on boats with AL.
First off DONT buy tubing buy pipe,sch 40 will do fine.
Youre not going to bend so get 6061.A little stronger not as floppy in length.Next with all the diagonal supports you will have its goona want to pull like crazy. Tack it all together first then dog it down. Move around when welding. If it were Me I wouldnt use round bar for the cross supports too much welding and to close together. Ide use plate with artsy cutouts in it.That would keep the unit straight plus You would only have to skip weld it. This would be much stronger And easier to build with less tools.
Dont forget to put some chocks from the pipe to the baseplates. Also use 3/4" plt for the base.PM Me if I can help. --- FEDER

[james]

They want steel after the bad experience with the alum flagpoles. As for the sides, they want it simple and fairly light visually, so plate won't work, but that is a good idea. I'm not worried about the process as much as making sure it'll be strong enough. Looks like everyone seems to think it will... http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[Unkl Ian]

The weak link,right now,is the attatchment to the ground.

If it's a public installation,
I think they need an Engineer to sign off on the design,
which would include all the specifications.

[zman]

Do yourself a favor and just take yourself to the local theatrical lighting supply and get a couple of trusses. Use those for the uprights and make the cross piece....