New RC slab + existing RC beam
New RC slab + existing RC beam
(OP)
Hello, i got a problem.
i dont know what to do about this:
existing slab is 200 mm thick, existing beam is 250/500 mm
new slab is 200 mm thick
i have to connect new RC slab to existing slab - which is pretty standard (view A-A: rebars anchoring in the middle of a slab and control reabars for shear forces). But in this case I also have an opening in the existing slab (for staircase), so I have to connect my new slab to existing beam (view B-B). i dont know how to do that since beam is only 250 mm wide. I havent done that before. What do you suggest/do in case like this? I have to connect new slab to existing - i m not allowed to do new support (wall, column) next to existing structure.

i dont know what to do about this:
existing slab is 200 mm thick, existing beam is 250/500 mm
new slab is 200 mm thick
i have to connect new RC slab to existing slab - which is pretty standard (view A-A: rebars anchoring in the middle of a slab and control reabars for shear forces). But in this case I also have an opening in the existing slab (for staircase), so I have to connect my new slab to existing beam (view B-B). i dont know how to do that since beam is only 250 mm wide. I havent done that before. What do you suggest/do in case like this? I have to connect new slab to existing - i m not allowed to do new support (wall, column) next to existing structure.







RE: New RC slab + existing RC beam
Your bars will only have 50mm of cover at the top of the slab, the bottom of the slab, and the top of the beam. With such a small edge distance, I think that increasing the embedment of the bar would hurt more than it would help.
Personally, I`m not a huge fan of this type of detail due to the small edge distances mentioned above. I prefer to bolt an continuous steel angle into the side of the beam to provide a bearing connection rather than a shear connection. Perhaps you'd be comfortable with a similar detail at the beam.
RE: New RC slab + existing RC beam
RE: New RC slab + existing RC beam
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.
RE: New RC slab + existing RC beam
RE: New RC slab + existing RC beam
RE: New RC slab + existing RC beam
It's a fine solution that has some advantages but it probably wouldn't be my choice here for the following reasons:
1) You may need to fireproof the angle.
2) If it's exposed sofit, someone may have to look at the fireproofing on the angle.
3) If you've got no other structural steel on the job, I'd hate to add just this one piece.
4) If you've got form work elsewhere, it's not a big deal to use form work here.
5) The dowels are pretty easy and 100 mm edge distance is plenty.
Obviously, I'm making some assumptions about the nature of your project and your construction environment.
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.
RE: New RC slab + existing RC beam
My usual hesitation with direct dowel from the slab is any top steel in the beam cross section may be getting close to that 100 mm mark depending on how its detailed, especially at that interior column.