concrete beams supported by steel column? 1

[mats12]

Hi,

What is the best way to make this connection? Should there be a steel plate integrated in concrete beam so you can later weld steel column to it?

Or is it better to weld steel plate on column first and then anchor the whole thing to concrete beam (before starting the second floor)?
I havent seen this in practice yet. Any detail, photo, suggestion will be appreciated.

 

[phamENG]

Interesting. I'd put the column in place first with a top plate, headed studs welded to the top plate strong enough to stabilize the column. Then form and pour the concrete.

 

[KootK]

1) Is it possible to query the contractor for their preference?

2) I have no real preference in terms of structural performance other than that casting around the column and embed would produce a perfectly mated interface.

3) Installing the column later has the distinct advantage of not requiring a penetration through your contractors for work. That won't mater much if it's one off, hand built stuff though.

4) if this will be exposed to the elements or exposed to view, I might embed nothing at all and use post installed anchors when the column is installed. That way, the look would be clean and you'd not have to touch up any of your corrosion protection measures on the steel after welding.

 

[phamENG]

Given the size of the building and apparent short span of your beams on that corner, I'd hesitate to specify the form first install column later ideas. I'm not sure they're "constructable." To remove the form work to install the column, you'll have to remove the shoring for the form work. If the shoring is removed prior to installing the column, what's holding up the beams?

I suppose you could detail it to support its own dead weight and then install the column before proceeding with the second floor, but that feels overly complicated for a small building.

Like KootK said, check with the contractor if they're already on board.

 

[dik]

KootK did it... talk to the contractor first.

Dik

 

[KootK]

To remove the form work to install the column, you'll have to remove the shoring for the form work. If the shoring is removed prior to installing the column, what's holding up the beams?

I'd imagined something like this:

1) Set up shoring and form work as usual.

2) Cast beam and slab.

3) Move beam form work shoring over to the slab beside the beam. Obviously, this is not something that one would do if there were 50 stories of concrete stacked above.

4) Remove beam form work.

5) Reinstate shoring under the beams sans form work.

6) Install steel column.

The viability of all that depends on the nature of the form work system employed naturally of course.

I suppose you could detail it to support its own dead weight and then install the column before proceeding with the second floor, but that feels overly complicated for a small building.

My impression is that there's a healthy back span on at least one of the beams coming into this joint. That might be exploited to advantage.

 

[r13]

It is not unusual to install the steel post after construction is done. I and my friend designed and built the first cantilever building in town some 40 years ago. The entire building consisted of 10 units, the owner of the corner unit just couldn't live with it, and added a steel pipe at the tip of where the two cantilever met (a situation similar to the picture shown). 40 years later, everything is fine, including the steel pipe.

Wasn't the beam designed for DL+LL? Just leave a few vertical shoring posts on each side to be safe.

[Second thought] Are the concrete beams are continuous from end to end, or only sized up in the corner?

 

[Tomfh]

We use steel post with heavy cap plate already attached, with U bars or studs welded to the cap.

It’s always worked quite well.

I suppose you could do it the other way around, but it involves site welding, shoring considerations, etc.

 

[JLNJ]

Ask your architect whether or not the structure needs to be rated.