Integrity reo in a transfer slab 2

[JSorr]

Hi all,
First time poster so please go easy on me. Because integrity reo is relatively new to Australian standards my supervisors are not a lot of help for me here.

I have a 850 flat plate slab which I'm struggling to fit the integrity reo into the column cores. I had the idea of stacking the bottom bars in multiple layers and have drawn up two different arrangements which I think may be acceptable for this.

Option 1 is by far the easiest for the fixers on site. The idea is to stack the bars in the long edge of the column and separate using N20 spacers (to suit 20mm aggregate) in the short edge. My concern with this is that the reo will not be evenly divided on all edges, particularly since the slab mainly spans on the short edge of the columns (Typical for carpark transfers). The other concern is whether the stacked bars will realistically be able to contribute to the failure ductility in this arrangement.

Option 2 I believe remedies some of my concerns above by evenly distributing the integrity reo amongst each edge - but adds a lot of complexity which I don't trust the guys on site to do properly.

I'm open to exploring other options if my sketches are not within the intent of the code, however the slab is irregularly shaped so I can't get a beam grid in this particular case and the columns are limited by the carpark/traffic dimensions so I don't have a lot of wiggle room there either.

 

[rapt]

It should be distributed in the 2 directions approximately in accordance with the load coming into the connection from each direction.

Stopping the stirrups above it is not much use.

How much force are you trying to transfer?

 

[JSorr]

Thanks Rapt.

It makes sense to distribute the bars based on load coming in, but it seems hard to practically achieve this with a typical carpark column.
Also noted regarding the stirrups, I was trying to simplify the detail and may have tipped it a bit too far.

Ultimate reaction from the slab is 8500kN with dimensions currently 1000x350, load would be roughly distributed evenly from x and y direction.

 

[rapt]

Yes, blade columns cause problems with this.

So you need about 9500mm2 in each direction if distributed evenly by my calculation. Not too difficult on the long faces, but definitely not easy on the short faces.

 

[JSorr]

Rapt,

In your opinion could I do an arrangement similar to my 'option 1' except flip it to the short face. If I do 3 layers of 3/N36 with N20/N24 spacers I can get close to even distribution. My concern would be whether the stacked bars are too high from soffit to contribute to ductility during failure.

Thank you for your helpful responses so far.

 

[Just Some Nerd]

For an 850 plate I'd wager you can get a couple of extra layers in while still being in the "bottom" say ~1/4 of the slab (1/4 has been pulled out of thin air while typing this for transparency). I'm not sure how to establish quantitatively how high integrity reinforcement can be placed while still functioning but I imagine that with >600mm of concrete above there's not much likelihood of it ripping out of the top of the slab like top reo will.

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Why yes, I do in fact have no idea what I'm talking about

 

[rapt]

As long as the bottom reinforcement is low enough to be in the compression zone it should comply. So it would depend on the neutral axis depth for any design.

Bars could be bundled with increased development length!

I would have thought the minimum space if not bundled was bar diameter.

 

[JSorr]

Thanks JSN & Rapt.

You have given me more than enough to solve this!