Double angle’s back to back 1

[MIStructE_IRE]

Hi,

An architect is looking to use 2.8m long 100x50 Double angle’s back to back as slender columns to support a lightweight canopy. The loads are very light to be fair - but every bit of software I have says this is beyond scope of the particular software which has me wary..

Before I delve into the hand calcs, are there any pitfalls here?! This type of thing doesn’t normally come up!

Thanks

 

[WARose]

If I were you, I'd look at [AISC's] steel manual. They have tables for column loads of double angles.

As far as pitfalls go.....I've gotten some complaints about painting/galvanizing the components. But it's not something that cannot be overcome.

 

[JoelTXCive]

This is one of my favorite tables in the steel manual. If you make sure your angles are non-slender, then life is a lot easier.....

 

[JoelTXCive]

Here is another hidden gem.......check out the 'Stitch Plate' design recommendations in the attached steelwise question........

 

[JoelTXCive]

I'm having difficulties attaching the attachment. Hopefully it is below....

 

[dik]

Thanks, Joel...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[JoshPlumSE]

For light loads, this is not very difficult to do. Lots of small equipment uses single or double angle support frames.

 

[MIStructE_IRE]

Thanks guys. Very helpful stuff

 

[phamENG]

Don't let the software worry you. I've found that most low to mid-level structural analysis software doesn't have an option for angles, or it's so limited it's rarely useful. Entire books have been written on the subject of analyzing steel angles in flexure, so I guess most of them find it too difficult. Though double angles shouldn't be too bad if you handle the stitch plate spacing right.

 

[robyengIT]

metric, angle (equal side), angle (different side)

https://mega.nz/file/UIclmShA#X1gRnVoZMfrrrbBnzL8R6uXyNKl3AW6nY-1vgWRyFM8

 

[Enable]

Please be careful with the detailing near / below grade. While not exactly similar, I was once on a project where welded angles (toe-to-toe) formed columns for a 5 story office structure (HSS was probably uber expensive at the time this thing was built).

Anyways, dirt and such got between the angles and sat there through many freeze thaw cycles. The result was incredible deterioration and local buckling of the members. Again, your back to back situation is much different but make sure you your weld details dont call for a gap between the angles unless it's fully sealed at grade / below.

CWB (W47.1) Div 1 Fabricator
Temporary Works Design

https://www.enable-inc.com/