Eccoduct

[slickdeals]

We have a high rise project where the architect/MEP want to use an embedded duct in the slab to exhaust air from the bathrooms to the exterior. The slab is a 7" thick post-tensioned slab. Does anyone have experience with this system

http://www.eccoduct.com/

http://www.eccoduct.com/images/ECCODUCT show.pps

How would you approach designing a slab such as this? Seems like for starters, you wouldn't want the duct anywhere other than the middle-third. For example, would you check shear based on a 2.5" slab + void + 2.5" slab? The bigger unknown is the deflections.

So far the Eccoduct folks have been least helpful.

 

[KootK]

The good news: I've seen a gazillion square feet of residential floor slab go up constructed just as you've proposed without incident.

The bad news: I haven't a clue how to make the system calc out in any rational way. As you've rightly surmised, you've got a terrible vierendeel shear panel running across most of your exterior design strip.

Recommendations that you probably don't need:

1) Do your darnedest to steer mechanical away from a layout that is too terrible. You'll meet with limited success here.

2) Keep the ducts away from critical punching shear zones.

3) Ensure that no other trade has any illusions about passing anything else above or below the ducts.

4) Provide small, tightly spaced top and bottom steel over the ducts.

5) Don't let any loved ones purchase units.

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

 

[BAretired]

I have never used that system and would have the same concerns as have been mentioned above. I suspect you would have difficulty in restricting the location of Eccoducts and it would be a constant source of worry during inspection of slabs.

BA

 

[rowingengineer]

the way we have handled this situation is to document allowable zones on our plans that they can have the ducts, generally where the shear stresses are minimal. our slab where 225mm thick.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[CELinOttawa]

Just use hollow core and allow localised breakout. Cheaper and more rational, very common in Scandinavian countries, with this being the normal forced air heating ducting system in some of them (Finland in particular).

That way you also offload the problem to true experts - The precaster's engineers will have access to far more knowledge about this and can customise the units to make it more idiot-resistant.

If it is too late to propose such a change, you've likely got the best possible advice already.