Concrete Column Above a Steel Beam with no support bellow?

[EdgarPeriera]

Good Morning all,

Please help me with the image bellow. The engineer Is proposing a steel column HEA260 at "Pórtico4". The Columns P5, P6, P7, P23, P24 and P9 are ALL CR columns with 250x250mm. As a constructer I have a great deal of difficulty accepting this solution but the engineer was quite insulting and said that there is no problem with this solution. I requested construction details that he didn't provide so far. I do not like to question the technical knowledge of the engineering but I've never done or seen something like that in 20 years of construction. My particular concern is with the columns P23 and P24 with no support underneath and the connection of the steel beam to the edge columns P5 and P9. This beam is at the second floor residential area with a flat concrete roof above. Could someone help me clarify this problem and probably elaborate a response to the engineer? Thank you very much for all your help.

 

[EdgarPeriera]

Morning all,

I was really hoping to have some clarity on the subject but so far that is not the case. One thing you all somehow agree (and I also agree for that matter), it's feasible... but..
I might as well share the hole project, for obvious reasons I removed the name of the Engineer.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1705236038/tips/JR_pmhitw.pdf[/url]

On sheet 5 you may see some details but they are generic details that has nothing to do with what's happening on the drawings. But like @dik suggested he might be thinking bolting the rebar to the steel beam. On the bottom left corner of sheet 5 is a generic detail for the slab encasement.

 

[dik]

I was only joking about bolting <Sarky></Sarky> font... I would never bolt! The welded rebar can be something similar to the attached. With rebar, if using fillet welds, the rebar has to be weldable.

https://weldingweb.com/vbb/threads/111151-Welding-rebar-and-Nelson-stud!

Your detail is similar to what I've drawn except the entire beam is not encased. The 4" of concrete cover on the top is better, but not sufficient to develop a hook for rebar. Welding would still be my preference.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

Updated detail like

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[EdgarPeriera]

Well, @dik I really apreciate your inputs. I have no problem with that detail. Hoping that the detail (that I'm still waiting, hopefully next week) will be similar and includes the type of steel and weld requirements. But that will solve one question. The interruption of the concrete columns is still something a bit strange. And the connecton/stress at the columns p5 and p9. I'm getting a little bit obsessed about finding a actual photo of a real case with a equal solution. I'm still dry on that quest.

 

[dik]

Something like... Using angle clips with bolts or welds to the steel beam. Column reinforcing using normal vertical bars from lower column to upper column.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[EdgarPeriera]

Good morning all,
You are giving me good inputs and drawings, I might as well draw what I see and what you are telling me.
There is a lot of mixed ideas but bare with me on this one. I'm drawing mostly what the designer represented:
The steel beam is a HEA 260 (260x250mm)
The RC columns are (not bigger than) 250x250mm
The RC beams are(where occurs on drawing) 250x400mm
The ribbed concrete floor is supported at a continuous welded L angle.

on top of that there is the WWF 150x150mm and the poured in place concrete.
What can I say? Too much appending for too little. That's my first thought.

 

[EdgarPeriera]

attached SketchUp file

https://files.engineering.com/getfi...9ac-a129556e1f4c&file=Something_like_this.skp

 

[dik]

I'd attach the steel beam to the face of the column/beam as shown in my sketch. Proposed is likely unworkable.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[jayrod12]

Agree with Dik. Weld plate at the location you show. otherwise the detailing for the reinforcing for both the columns and that RC beam become too convoluted.

 

[phamENG]

Since it was stated that ceiling height and clearance is an issue, I'd bet the designer is trying to ensure continuity of the beam to keep the depth of the steel beam as low as they can get away with. The result is this...thing.

My biggest concern is the concrete beam framing in orthogonally to this joint. I think you could make the continuous steel beam work...but there are better ways to skin that cat. Best way is probably to do an extended end plate on the beams and through bolt through the column (cast in, otherwise your core drill will eviscerate the bars in the joint). May require a higher strength concrete to get the bearing capacity to keep the fixed end on the steel beam from crushing the column.

 

[dik]

With the end plate, you can likely develop whatever moment you require... just a matter of not using clip angles... similar detail, but different. I would not consider using through bolts... just looking for trouble. The concrete beam can be continuous over the concrete column with the embedded plate case in the side of the concrete beam.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[EdgarPeriera]

Good morning, Thank you all again for your various inputs.
Just have one question @dik. I'm not sure what you have saying when (sic.) "I would not consider using through bolts... just looking for trouble. The concrete beam can be continuous over the concrete column with the embedded plate case in the side of the concrete beam." I interpreted something like this:

 

[phamENG]

Edgar - that's not an extended end plate. It will give some fixity, but not much. The plate has to be quite thick and extend above and below the beam with 8 through bolts, 4 per flange.

dik - I don't think there'd be much trouble. As long as the holes are accurately placed in the form work, you can pass threaded rod of appropriate size and strength through and use nuts to secure it in place for concrete placement. To have continuity, embedded weld plates would need continuous studs welded to both plates in any case, unless you're trying to use the concrete in tension or develop bars with 180 degree hooks in that small space, which I'm pretty sure you're not.

 

[dik]

I include the clipboard post from an earlier reply.


I've encountered too many misaligned holes in past. With the small size and reinforcing (beam and column), remedy may not be so easy. It's far easier and more positive to cast a headed stud plate into the mess. Just my personal choice. In any event the beam has to be excluded.

End plate connections can be designed to be pretty stiff. I do it all the time.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[EdgarPeriera]

Sometimes the technical jargon just go over my head I'm not a native English speaker. But I think Dr. Google helped me on this one. I see all the points and most definably this end solution must be properly sized and calculated and not thrown to the constructor with some generic details. The concept that you've presented seems solid (way more understandable that the minimalistic project that I received). I'm still waiting for a proper reply from the engineer/designer. Then I would level his approach with more in-depth reasoning of the solution/problems according with your inputs. Don't fill this is a end on situation but this could be a problem grabber. Hope for the best, expect the worst. Thank you all.

 

[dik]

Edgar... with respect to your latest detail with the through bolds... looks pretty good, but I would pour the concrete to the finished floor level and cast the new concrete column founded at that elevation.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik