Steel-Concrete-Steel Landing Slab

[Valstone]

I have a 2-1/2" concrete slab that spans between fin plates at a stair landing. The fin to fin spacing is 21". There are #6 reinforcing steel bars that spans between the fin plates and are welded to the fins with a 1/4" fillet weld all around. The reinforcing steel bars are located mid-depth of the slab.

What is the correct way to transfer the shear from the 2-1/2" concrete slab to the steel fin plates. The slab can span based on plain concrete shear and flexure. I am just not real sure how the slab transfers the shear to the fin plate.

Thanks,
Val

 

[ishvaaag]

If supported in the fins, one first would look at Vc capacity without shear reinforcement. If not enough, enter dowel action. A 3D model will help to establish if the deformations are small enough for the thing working properly; even so maybe one can expect some visible crack.

This is the proble with uncommon designs, one can't be as sure of good behaviour by lack of testing enough. And some designers are not just looking for novelty but irrationality. Even if we must not repress all times these intents, for that would stifle innovation, the designer should always know that some things are made along some precise ways for some reasons.

 

[Valstone]

ishvaaag,

The way the landing is constructed is that the rebar is welded to the fins and then the concrete slab is placed. A cross section of the landing is as follows:


- -
| | | |
| | | |
| | | |
| |--------------------------------| |
| |________________________________| |
| | | |
- -------------------------------- -

The horizontal dotted lines = Edge of concrete
The horizontal cont. lines = rebar

The remaining thickness of the fins is filled in with a finished topping slab. Also, the slab is placed with formwork on the bottom and sides.

Val