Cantilever Wall Supported by Concrete on Deck

[FishTheStructure]

Does anyone have any (Canadian) design examples of a wall supported by concrete on deck? The wall will be orientated both parallel and perpendicular to the deck flutes. The wall will not be supported at the top and thus will be imparting moment to the concrete on deck at the base of the wall.

My concern is mainly due to bending moment in the concrete on deck when the wall is parallel to the deck flutes.


Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein

 

[BAretired]

No examples to show you. Doesn't sound like a good idea to me, particularly walls parallel to the flutes.

BA

 

[msquared48]

I agree with BA here.

Mike McCann, PE, SE (WA)

 

[KootK]

I take it this is a partial height wall that can't be braced by the ceiling above? What's the context? Could it be a concrete wall? If it's concrete and the loads are light, I might have some ideas. I've had to get creative attaching guardrails to metal deck slabs in the past.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

 

[CELinOttawa]

I've seen this type of construction designed as a balcony once, but that is foolish - while you may be able to cantilever VicWest XX## out across a supporting wall, it is not a good idea. The pans will rust like mad, and the overall durability will not be anywhere near what is required.

If this is internal, on a well supported span of concrete covered deck, fine. It won't be easy, but you can make it work with through fastening and additional reinforcement in the topping slab. This has been done in a Police station I am aware of... But I don't think it saved any money. It was done not to vary the construction, and was only one isolated location. The rest were CMU boxes sitting on deck pan, all with an open end (ie: Cells).

 

[haynewp]

I would look into spanning the wall between perpendicular wall segments at each end if possible.

 

[Once20036]

When you're perpendicular to the flutes, I'd add some supplement members (angles?) below the concrete deck and anchor your verticals into the supplemental framing. Depending on where you are in construction maybe this means vertical bars welded to an angle, or threaded bars drilled through an angle. A similar scheme may also be good when you're parallel to the flutes.

This way, your vertical loads aren't relying on a thin concrete deck to develop their capacity.

 

[FishTheStructure]

Thanks for the thoughts so far, more or less in line with what I have been thinking.

Some more context:
Yes this must be a free standing wall; if it could be supported at the top I would not have a problem.
The concrete on deck is existing 90 mm concrete on 75 mm deck.
The new wall is going to be a glass wall cantilevering out of a supporting U-shaped shoe.

My current design utilizes plates above and below the concrete on deck to engage a larger portion of the concrete on deck and thus minimize local failures.
My original post arose from thoughts regarding if I could simply anchor the wall to the concrete on deck and avoid the plate below. My thinking was that removing the plate below from my design would shrink the failure area in the concrete on deck and reduce the capacity. I am curious to see if anyone else has completed an analysis like this before.

The alternative is providing new beams below the existing concrete on deck to provide positive support at discrete locations along the length of the wall.


Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein

 

[KootK]

I've seen glass guard rails attached to metal deck floor slabs using just fasteners installed within the shoe. CR Lawrence has details online. I don't know how they make the numbers work but they seem to perform fine for whatever loads they see in service.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

 

[FishTheStructure]

These are 2.4 m tall walls so they have around 4 times greater moment than the average glass handrail...

Great spirits have always encountered violent opposition from mediocre minds - Albert Einstein