Concrete Column Bracing (Compatiblity Issue) 1

[moyseh]

Hi Guys,

I have a situation where I have sets of concrete columns which are supporting steel UBs and I want to provide some lateral support.

Would diagonal cross braces (tension only) work here or do we have a compatibility issue, whereby the column is too stiff to deflect enough to engage the braces?

Cheers

 

[KootK]

I think that steel braces could be used to brace concrete columns against in plane buckling. It doesn't take a ton of strength or stiffness for a brace to perform the bracing function and I would consider steel to be compatible with concrete in that regard. I suppose that you could use slip critical bolting to reduce any slop in the steel system but I wouldn't normally bother with that.

 

[moyseh]

Thanks for the reply - not sure you fully understand my question though. Have snipped an image outlining the situation

 

[jayrod12]

I believe he understood perfectly. His answer still stands.

Essentially he's indicating you can do that, but also warning that there's potentially a stiffness mismatch. It's possible your concrete columns may be stiffer as cantilevered columns than the bracing will be.

 

[moyseh]

Right, understood. How would I go about investigating checking the difference in stiffness between the two elements?

 

[jayrod12]

You could check your column deflection as a pure cantilever for the required bracing load and compare that to brace elongation. See where that ends up.

As Koot also sort of indicated, it's likely not an issue many people would concern themselves with.

 

[HTURKAK]

The use of steel bracing for precast structures although not common , is an option. But with heavy tubular elements not with rods ( which could be viable for PEMB) ..

Just for info. one example , Bouwhuis bldg (which is mixed precast construction with tubular steel bracing) in Netherlands.

https://commons.wikimedia.org/wiki/File:Bouwhuis.jpg

https://upload.wikimedia.org/wikipedia/commons/4/44/Bouwhuis.jpg