Large Cantilever

[tclat]

Hi All,

I'm analyzing a five storey hotel that has 16 foot cantilever balconies. Floor to floor height is 10 feet. The good thing is there are reinforced concrete party walls at 15'0 centers between each room which also extent out to almost the end of the balcony. The party walls extend 30 feet inside (full bearing down to the ground) although a couple of them have doors linking t40 rooms together (15 foot from the balcony). I'm running some preliminary calcs to advise the architect if this system is possible.

I'm considering spanning the slab 15 foot to the party walls and using the walls as deep cantilever beams.

If I consider that the cantilever depth is 4 x 10' = 40 feet, then a 16 foot cantilever really doesn't seem that bad both for strength and serviceability. Obviously, this deep beam will be cast in 10 foot sections as the building progresses so I will have to check the the shear flow at each construction joint but even 10 foot beam depth seems fine for long term deflections. I also need to consider temporary loading during the construction stage.

Any thoughts/comments?

Thanks

 

[hokie66]

Sounds good to me. 16 foot cantilevers are just too much for "normal" construction. The walls should work fine. Hopefully, you won't have issues with the balcony extending around corners.

 

[rapt]

If the walls are there and connected to the slabs, they are going to carry all of the load no matter what you assume anyway, relative to the stiffness of a 15' cantilever slab.