Slab on grade thru doorway

[JStructsteel]

Got a structure that is an open structure (was a enclosed building, now open). there are some man doors where the architect wants to pour the slab continuous thru the door. My comment was its gonna crack.

How would you handle this? a few bars thru the opening to control?

 

[Enable]

No bars unless you reinforce it specifically to control for cracking. What I mean is, if you just throw a couple bars haphazardly you'll be subject to random cracking and you'll be worse off because you cannot control where the crack is going to be. If you put bars you better size and space them to control for crack widths in the various applicable directions.

My preferred approach is no bars and to place a control joint at the start of the projection. It'll crack there and all is well in the world.

 

[dik]

If you're running the slab through, I would add rebar to minimise the cracking that will likely occur... maybe #4x4'-0@12 or 10Mx1200@300 or whatever language you use... but I would definitely reinforce it.

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

-Dik

 

[KootK]

I do it the same as dik. Often the geotech report will say that the slab should be left to float independently but, in my view, architectural trip hazards and such at the threshold trump that requirement locally.

 

[JStructsteel]

Im going to keep the wire mesh continuous, but put a control joint on one side of the opening. I dont see major cracking occurring, just that if there was nothing, it would be worse.

Of all the things to get worked up about, the architect is worried about concrete cracking.

 

[phamENG]

If I have slab on both sides of the door, I put a joint on one side of the threshold and reinforce the other. As dik and KootK have said perpendicular to the door opening (I don't tie it to the foundation wall, though), and diagonals at the re-entrant corners.

If this is a light storage/industrial usage I agree cracking shouldn't be too big of a concern. But if it's getting any sort of finish cracking can be a major problem that shows through to the end product.

 

[dik]

...here we go again. Occasionally run the slab through with a sawcut on the one side to be covered with an extruded threshold...

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

-Dik