Balcony (Cantilever Slab) Suspended on Beam DETAIL

[DavAD]

Dear all,

Thank-you for your time,

I am currently detailing a balcony to be cast in concrete in an already existing apartment.
I plan to cast a beam internally which will be inserted in walls on each side, and a cantilever slab externally hanging from this beam (beam also acting as a counter weight)

My question is re. detailing of the reinforcement.
Internally the beam is a 1000mm x 345mm beam with top/bottom reinforcement 8H20 and H15 Links at 150mm
Bent U-Bars H20 at 150mm will be inserted in the beam and will hang to the outside overhang.
Transverse steel H16 at 200mm is added externally.
Width of slab is 175mm.

Loads considered are normal externally loaded slabs/balconies as per EC2.
Could you knidly let me know if in your opinion there is anything missing from this detail?

Kind regards

 

[dik]

Just some thoughts... Why a 7" slab, unless the interior slab is 7"... can you taper it to 5" at the end? little much for a 3'3 balcony and why a curb... weight, and you have to drain it then. Guardrail attached directly to the cant slab and let it drain off the end... no scuppers. why the beam... treat the slab at right angles to the balcony as fixed end each end and reinforce like a regular slab. Does the slab step at the buiding face to prevent rainwater from flowing in?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[StrEng007]

Is there a bearing condition for this slab? Is it possible to bring the exterior slab over the wall line?

I agree with Dik, slope the slab to the exterior edge to create positive drainage. If you can bring your slab over the bearing wall, you can incorporate a little bump-up in order to step down to the exterior. It would be nice to hook the horizontal bars over the steel that runs parallel to the free end of the slab. I like to think that helps the 'delegated engineer' when they come along and design for a guardrail (confines the free edge).

 

[HTURKAK]

Dear DavAD (Structural),

Eurocode 2 is for Design of concrete structures. ( General rules and rules for buildings etc...)
You are expected to look EC-1 for actions.

EC 1 suggests Uniformity distributed load qk 2.5 kN/m2 and Concentrated load Qk 2 kN for residential balconies.

My suggestions will be,

- Use tapered slab 150mm to 120 mm.. ( Fine for 1.0 cantilever and 175 mm is overkill)
- Extend the top H 20 /150 bar to tip of the balcony and make bend
- Provide compression reinf. cage at the bottom of balcony ( min. H12/150 etc)
- Check the existing FRS ( load bearing walls ? ) for the new extra loads .