Running Conduit Horizontally Thru Concrete Slab
Running Conduit Horizontally Thru Concrete Slab
(OP)
My project features a cast-in-place, two-way flat plate concrete slab ranging from 10"-14" thick. The contractor wishes to run conduit horizontally through the slab. The structure was not specifically designed for this allowance. Does anyone have any experience with this? If we allow it, to what parameters should we limit the conduit? Any code guidance on this subject? I'm located in the United States.






RE: Running Conduit Horizontally Thru Concrete Slab
Will pull out the ACI code later and check...I am fairly certain I remember seeing it in there.
RE: Running Conduit Horizontally Thru Concrete Slab
RE: Running Conduit Horizontally Thru Concrete Slab
RE: Running Conduit Horizontally Thru Concrete Slab
Too low and the conduit takes a tension load, too high and it displaces compression concrete.
It's not ideal, but if you only have a couple of pieces of conduit in a large slab, it shouldn't be a problem.
RE: Running Conduit Horizontally Thru Concrete Slab
Also keep conduit AWAY from columns and high shear areas - I think 6.3 might talk about that.
RE: Running Conduit Horizontally Thru Concrete Slab
RE: Running Conduit Horizontally Thru Concrete Slab
You bring up a good point. ME's always like to run up a conduit adjacent to the column which means they have a 90 degree elbow close to the face of the column and kills you in punching shear.
Sometimes I wish they had a little bit more well rounded knowledge of how they affect other disciplines.
RE: Running Conduit Horizontally Thru Concrete Slab
RE: Running Conduit Horizontally Thru Concrete Slab
RE: Running Conduit Horizontally Thru Concrete Slab
Anytime the conduits enter the slab from an electrical room the number of conduits is large, this always tends to be a problem area as well. For this I have them run the conduits under the slab until they are spread out enough.
Other items that i put in my notes:
No conduit In the shear cone
Not conduits larger than 2" or ¼" the slab thickness, whichever is less.
No crossing of conduit (again always a problem to get the sub to comply)
No displacement of tendons or rebar
No conduits in parking slabs
No aluminum conduits.
Some limit on center to center spacing, ie 3xDia
Some limit on the number of adjacent conduits in a slab, ie only 3 in a 6' width
I have also provided additional top and bottom steel in instances where the above rules could not be followed.
RE: Running Conduit Horizontally Thru Concrete Slab
Then there is the sparky who wants to put his conduit on top of the top mat....
RE: Running Conduit Horizontally Thru Concrete Slab
You have not stated what type of building it is. The worst ones are hospitals and hotels where the conduits can be very numerous and clumped together like crazy.