Ligth Gage Cold Formed Steel frames

[Jonathan Monge Cubillo]

Hi:

Does anyone knows if there is a way to use cold formed steel framing beams and columns like in a moment frame?
I know there is a prequalified beam to column detail in the AISI using the HSS column and the framing beam, but i have a complex project where HSS steel is not an option. Also I´m in Costa Rica, where the cost of something like Hardy Frame or Siimpson lateral force systems are likely to take down the project.

I can perform the math and detail everithing to comply with seismic lateral forces, but I´m really concern about code compliance and the real life behaviour of such a system. Especially in the conections, because there´s a high seismic risk in the country.

Thanks,

 

[Celt83]

You'll be hard pressed to get the moment connection you'd require for a moment resisting frame in Cold-Form. Typically Cold Form lateral resistance is achieved with strapped wall panels that act pretty similarly to a steel "X" braced frame. the "X" is usually tension only members using plate material. The biggest headache is end attachments to develop the forces Simpson and The Steel Network have some products that can help on this end.



Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

 

[GC_Hopi]

I have seen moment frames done using cold formed steel and the design is similar to AISI detail. I have no idea what it would be good for so you would need to run some numbers. Attached is a picture.

 

[milkshakelake]

This is the only article I could come up with:

https://www.structuremag.org/wp-content/uploads/2014/08/C-CS-Uang-Feb111.pdf

Some of my clients are asking for cold formed steel moment frames to save money. I'm based in NYC, a low seismic zone. I always say no because there hasn't been enough research on it. I could probably find a way to justify it with AISI code, but it's very theoretical and not really based on real life studies. It's a bigger problem in a high seismic zone.

I think about how steel moment frames were theoretically great in seismic, but after real earthquakes, they found that the way it was typically welded with backer plates caused huge stresses. So the welding codes and AISC evolved, and now moment frames are safer. I don't see that happening with cold formed steel and AISI; it's not as well researched and there might be unintended effects if you just use the code without real life testing. I agree with Celt83, x-bracing is more common.

 

[MotorCity]

Any chance you have sheathing that you could take advantage of as a shear wall instead of a moment frame?

 

[Jonathan Monge Cubillo]

Hi milkshakelake:


Thanks for the information. Sure as Celt83 and MotorCity say´s X bracing or steel sheating are a more common solution, we design all of our projects that way, but in this case we have no walls complying the base to heigth relations in one of the building directions.
I´ll go back to my traditional solution, using a hybrid hot rolled and cold formed steel building intead.