residental buidling - RC frame for overhang/large span?

[greznik91]

hELLO

I have been working on the masonry and RC residental building (image bellow). On the top floor I'm dealing with an overhang (1,7 m) and 10 m span - I have been thinking to design this as RC moment frame since I don't have any other idea how to solve this. Frame supports both RC slabs. I have never design something like this so I hope for some suggestions/opinions on this topic. I figured that overhang cant be supported on the cantilever slab since shear and bending forces are far too large for RC slab of 160 mm (or even 200).

What do you suggest? Is RC frame a good design idea in the case like this?
What need special attention in this case?

 

[MIStructE_IRE]

I’d probably go with a simple 325mm cantilever slab - or alternatively, if you have to, cantilever out the blue marked walls below and hang the slab from them.

 

[greznik91]

Thank you for reply.
325 mm slab is too thick so I cant use it. So my solution with RC frame is not (that) sufficient?
I can only use the middle wall since the rest of the walls are lie directly on the slab. Also, walls have to be RC in this case, not masonry

 

[r13]

I don't see you have much choices but to use RC frame system. You may mix some shear walls at where ever possible. The hanging cantilever slab is a good idea though.

 

[MIStructE_IRE]

Keep in mind your disproportionate collapse requirements if you go with the big vierendeel. If someone cuts part of that in the future to say widen a window opening or something you lose the entire cantilever area in spectacular style!

 

[greznik91]

I agree with what you ahve been suggesting.

How about I use the combination of vierendeel RC beam (RC frame) which is also supported in the middle - by 2 x 200 mm RC walls (see attached image)?
Since RC walls 2 x 200 mm will be connected to RC frame in the middle of the span it will act like this anyway since system is pretty stiff this way.

 

[r13]

I would add columns and beams as shown.