design of cold formed column base plate connection

[Islem]

Hello everyone,

can i please find any example of a cold formed base plate connection ?

in my case i have a back to back column using C section shape .

Many thanks.




islem

 

[Lomarandil]

Is it reasonable to connect the Cs to a section of base track instead? If the loads are small and concentric (I would hope you aren't looking for fixity with cold formed steel) I'm imagine that is easier.

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The name is a long story -- just call me Lo.

 

[Islem]

Hi Lo;

the column is back to back there is no track section at bottom, but it is connected with a base plate which has a thickness of 20mm,i provided a fixed connection because i have already designed the model ,and the column status engineering passed normally.
i am just trying now to design the base plate considering the rods embedded in concrete.
thanks

Islem

islem

 

[Celt83]

If you intend to weld your column to the plate make sure to check for the reduced allowable stresses, as far as I know most software does not do this.

Open Source Structural Applications:

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

 

[Lomarandil]

Which directions see moments at the base plate? And what magnitudes?

It's hard for me to imagine any effective fixed connection except welded assuming that a 20mm thick base plate is needed for strength. And that might cause issues as Celt pointed out.

(Question for other contributors: does weld distortion cause issues in cold formed steel?)

Is the fixed connection really required for structural stability? I understand that's what was modeled, but if you can't achieve a practical physical connection, the model isn't worth much.

As for designing the base plate itself, following AISC design guide 1 (free online) and treating your column like a hot-rolled W-shape will be fine.

----
The name is a long story -- just call me Lo.

 

[Islem]

it will be bolted to the plate welded to the base plate i can't attach the picture to explain more for you

thanks Lo

islem

 

[XR250]

Islem,

Here are my thoughts..

1) Trying to weld light gage to a 3/4" plate is going to be challenging. You will likely melt the light gage before you can get enough heat in the steel for a reliable connection.

2) if you are trying to resist overturning with that plate using a fixed connection, I would re-think your lateral stability strategy.

 

[Islem]

@Lomarandil

exactly it's what was modeled , fixed bases culummns, i will try to treat it as a hot rolled and see what will brings

thanks so much

islem

 

[Lomarandil]

I'll say it again -- what was modeled doesn't mean anything if you can't make it happen in the real world. Models are only a tool. They can be useful or they can be dangerous.

Please, check that the connection between the column and base plate works before you go any further.

----
The name is a long story -- just call me Lo.

 

[TLHS]

This is not a good condition if you can avoid it.

If you can't, have you investigated pre-engineered connectors? Simpson manufacturers connections intended for cantilevered partial height walls. Other manufacturers probably do too

https://embed.widencdn.net/pdf/plus/ssttoolbox/2ljnlbm1hq/F-CF-RCKW18.pdf?u=cjmyin

 

[Agent666]

Fully fixed in your model is not representative of the foundation flexibility that's usually present. This combined with second order effects can have a huge impact on the distribution of the moment in a flexible frame (less base moment, more knee moment, more drift).

Now for back to back sections the company I used to work for used to use a single fin plate (with similar bending capacity to the sections) extending between the sections with sufficient overlap length for the number of bolts required, this was then welded to a cast in plate. Sometimes the baseplate was simply bolted down, sometimes the fin plate would be a hot rolled channel slightly larger than the cold formed sections.

 

[Islem]

@Agent666

I already do the same with my case, a fin plate welded with base plate the fin plate bolted between back to back column ,just in my case I left a gap of 150mm between the two sections , i means that i have two fin plate spaced 1500 mm.

Thank you

islem

 

[Islem]

sorry 150 mm

islem

 

[Agent666]

Your links don't work?

 

[Islem]

yes i don't know what's the issue i can't attach links

islem