Concrete ramp slab intersection
Concrete ramp slab intersection
(OP)
I'm wondering how engineers typically handle crossing ramp/column interactions in solid slab/PT parking garages.
Attached is a 3D pdf showing the condition I'm talking about and some generic sketches below.


Attached is a 3D pdf showing the condition I'm talking about and some generic sketches below.
- Architects seem to want to do it as shown in the attached PDF where one slab goes to the opposite side of the column and the other is only touching one face but I don't like this at all.
- I've seen details let the slabs overlap such that each slab touches 3 faces of the column. This leads to an issue in the location where the slabs are crossing and they are near the same elevation.
- I've also seen details showing the slabs terminate at the midpoint of the columns, which works pretty well as long as the punching shear pencils out. Seems like a nightmare to build though.
- One must also consider what is going to create the barrier between the slabs. Cable rail, concrete wall, CMU wall, or other.
- I've always been able to have a concrete wall running up the intersection, which solves all of this, but in this case the architect doesn't want that.








RE: Concrete ramp slab intersection
RE: Concrete ramp slab intersection
Dik
RE: Concrete ramp slab intersection
The building is a multi story flat plate concrete building with a few underground parking levels.
The second attachment is a 3D pdf version of the second photo in the original post.
RE: Concrete ramp slab intersection
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: Concrete ramp slab intersection
Dik
RE: Concrete ramp slab intersection
Run each slab edge to the midpoint of the column such that the slab is touching 50% of the column perimeter.
Koot, a beam would be my preference as well (or Dik's comment about corbels) but the architect doesn't want that so I'm doing my due diligence first. If it comes down to it, I'll do a beam but I want to be sure I'm doing my best to accommodate.
RE: Concrete ramp slab intersection
Dik
RE: Concrete ramp slab intersection
Yes you're right. I think all methods will create issues forming the slab (other than corbels on both sides with the slabs entirely separated by the width of the column).
RE: Concrete ramp slab intersection
Dik
RE: Concrete ramp slab intersection
RE: Concrete ramp slab intersection
Something akin to a beam or drop panel is almost unavoidable at that location I'd think. Unless your up against headroom issues, I think the natural thing to do would be to carry the lower slab sofit through to the other side for a bit.
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: Concrete ramp slab intersection
Koot, a shear key or couplers aren't required since the slab will be placed top of the (short length of) column, then the next (half) level of column will be placed on top of that. Repeat up the parking levels.
RE: Concrete ramp slab intersection
Yeah, I'd not do that with the no overlap option. Mechanically, it's pretty much identical. And I'd rather have the shear key in both scenarios as I'd be concerned that shrinkage would tend to cause the slab to pull away from the column and compromise the shear capacity. Although I suppose that there'll be so much moment at that joint that a pull away on the compression side is unlikely. Either way, since the monolithic pour helps little in my opinion, I'd let the contractor pour the columns full height.
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.