Openings in new slabs with slabs supported by walls

[jbuening]

Unless I'm misinterpreting things, all I can find in the ACI code is openings in new slabs without beams. Essentially it is a continuous slab that is only supported by columns in each corner. What is typically done when you have a slab supported by walls on all four sides? I'm struggling with handling the openings which are occurring in two directions. See attached PDF for slab drawing. It is currently detailed as a continous slab over the center wall. Would anyone care to share some tips on how you would handle this slab design? Thanks

 

[KootK]

Put some beams around your openings! Actually, I was only sort of kidding with that. With reference to the sketch below, here's what I'd do:

1) Abandon all hope of using your top steel for strength design.
2) Use concentrated reinforcing at the heavy red lines to create simple span in-slab beam elements.
3) Rationalize your slab as a bunch of one way spanning panels. The blue hatching below represents the span direction. Choose your span direction in a way that minimizes the loads delivered to the in-slab beams. They're hard enough to make work without adding any extra load.
4) Add top steel for crack control wherever you expect to have negative moment (walls/columns/in-slab beam supports)

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.

 

[Guastavino]

Do you have access to a finite element program like RISA? I would model it as plates in that and then "check" it by doing something similar to what KookK was saying. I'd make sure that the moment/shears made sense. RISA has a program called RISA Floor ES that does two way slabs specifically. Likely overkill for what you show, but for something like what you show, I'd do it a complex way and then simple hand "checks" to make sure it made since.