Rebar cages for concrete filled hollow section (CFHS) columns

[user277418]

Hi

Are here factory guys who worked with CFHS columns?

Can you tell me how rebar cages are usually fixed within concrete filled hollow section (CFHS) columns to achieve the required concrete cover between the reinforcement and inner surface of the hollow section? As far as I am imagining the rebar cages should be preinstalled into shaft of the column at a factory. And then the fixing should be able to ensure the required concrete covers during transportation and installation on site. As far as I understand welding of something from inside of the hollow profile is impossible due to lack of space (possible only at edges of the hollow profile) and weld something through the profile wall may be forbidden due to durability issues.

While we are at it. Do the CFHS rebar cages need some special attention compering to rebar cages for precast RC columns for example? Rebar cages for precast columns usually installed from above into formwork located horizontally, but, my guess, the CFHS rebar cages installed by sliding the cage into the steel profile from side while the profile is laying horizontally. If I am right, seems to me, the CFHS rebar cage should be able to keep straightness for convenience of the installation. Thus need to be less flexible than usual PC column rebar cage.

Best regards

 

[SteelTubes]

This article doesn't necessarily answer your question but it provides practical considerations for concrete filled HSS columns and may point you in the right direction.

https://steeltubeinstitute.org/resources/practical-guidance-for-concrete-filled-hss-columns/

 

[user277418]

Thank you SteelTubes. Indeed a good article. I am aware of those issues. Chapter 4.2.1 of CIDECT design guide 7 is also a good reading for those who are interested.

 

[CDLD]

There is a video from AISC on youtube:

https://www.youtube.com/watch?v=1fzqBwZKLJQ&t=3053s

Not sure if it helps.

 

[user277418]

@CDLD thanks. watched it when it was published

 

[user277418]

I have found answer to the 1st question. So simple

 

[user277418]

For those who might be interested to see how concreting is done
A link to a video