Construction Joint in Columns

[DwayneM]

Hey y'all, In placing columns (26" and 48" dia) with embedded steel rings w/ studs (See Figure), it's necessary to break the concrete placement into two placements, possibly with as much as an hour between the two. Where would you recommend they break the placement, and why? Would it matter? (Longitudinal steel is continuous)
Thanks for the help!

 

[MotorCity]

What is the loading on the overall column (subject to lateral loads, moments, etc?)and on the steel rings? What is the purpose of the rings?

 

[DwayneM]

The columns are main supports for a 2-story commercial structure. The rings are to attach steel framing (w18's, mostly) to the concrete columns. (For example the steel W framing at the second floor level or roof level). Loads are primarily compressive (shear at the face of the cylinders), with some moment.

I'm asking more about if there is any location (A-D) that is preferable over the others to break the pour.

 

[KootK]

Sonotube forms? If so, then I can see how it might be a problem. I'd like to see the pour break high enough anove the top stud so as to not impact it's presumed breakout cone. I don't know that a cold joint across your studs really changes anything but, if you have the choice, why risk it?

You will introduce a cold joint into the column that may need to transfer some shear. It's almost always a non-issue numerically so no big deal.

I'm pretty sure that I've specified this without considering the formwork. No issues that I'm aware of. Your contractor's lucky to have you on the job.




I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KootK]

And hopefully your studs aren't as dense as the sketch shows.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KootK]

Just clued into the 360 ring thing. You might need to forgo stirrups through the height of the embed. Fortunately, the ring itself can probably perform some of the same functions if it's fire proofed. Is this an exposed connection? Could it be a post installed thing?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[MotorCity]

My first preference would be no construction joint, you may want to push for that option since a 2 story column is pretty reasonable to complete in a single pour. If I had to choose a location, I would opt for location "A" so that you minimize the effect a joint would have on the performance of the studs.