Asymmetrical cold-formed angle cantilever beam lateral buckling

[JeanLucPicard]

Hi all,

I'm having some specific problem with lateral buckling. I have a asymmetrical cold-formed "uneven angle" cantilever bar. The section and the system is shown here.
The EuroCode gives methods for doubly symmetrical sections, so, I can't use them. There are some SN guides for cantilevers and channel bars.

The ideas I'm considering:
[ol 1]
[li]The angle between the "neutral" and principal axis is small α=6°, hence, try and work with the SN guides for channel - mono symmetric section... [/li]
[li]The only thing I can think of is to make a FEM out of shell elements using Autodesk Robot and get the Mcr. I have an idea how to model it, but I have no idea how to be sure I reached Mcr? [/li]
[/ol]

If you have some answers, different ideas or tips for my ideas please share. Every tip is welcomed!

Thank you in forward!


Live long and prosper!

 

[MikeHalloran]

Angles make terrible beams.


The idea of using them as such is so fluorescently bad that no one who could possibly be the target of legal action will knowingly encourage or facilitate your folly.


Mike Halloran
Pembroke Pines, FL, USA

 

[JeanLucPicard]

@MikeHalloran yes they are. From shear flow to this. EC 1993-1-3 says that one should do experimental testing rather than calculation... But I'm not designing, it's already there...

Live long and prosper!

 

[MikeHalloran]

Do your experimental testing as part of the demolition?

Mike Halloran
Pembroke Pines, FL, USA

 

[MikeHalloran]

ISTR using a program called CUFSM to work on a somewhat related problem.
It's specifically designed to deal with rolled sections, and gave credible results on a real world problem.
I don't recall it being particularly hard to learn and use, and it didn't crash, which these days is a huge accolade.



Mike Halloran
Pembroke Pines, FL, USA

 

[XR250]

I would be surprised if you could get any useable capacity out of that

 

[JeanLucPicard]

Guys thanks for the replys. I've done some hand calculations like here:
[ul]
[li] Thimoshenko uneaqual leg angle bar critical moment[/li]
[li] Steel structures report cirtical moment [/li]
[li] Eurocode provisions for obtaining critical moment for monosymmetric sections [/li]
[/ul]

From there I calculated slenderness. All calculations have shown similar slenderness. BC the cantilever was short and had lateral supports, the LTB had no significant influence on the stability overall.

Live long and prosper!

 

[XR250]

A return lip on your web to form a bottom flange would greatly increase the capacity.
The program CFS could then likely calculate this for you and would be cheaper than hand calcs by the time you are done.