Thickened Slab - Footing
Thickened Slab - Footing
(OP)
See attached sketch.
There are some site restraints and the contractor is proposing to use a thickened slab edge to support a 14' tall fence. With posts at 8' or 6' on center. I have a couple of questions:
1. Should there be an expansion joint between the thickened slab and the 8" s.o.g.? If so is it acceptable to have some uplift on one side of the footing?
2. Instead of an expansion joint can the thickened slab and slab have a dowel between them so that the slab helps resist overturning and any theoretical uplift (as shown in the attached sketch)?
Thanks
There are some site restraints and the contractor is proposing to use a thickened slab edge to support a 14' tall fence. With posts at 8' or 6' on center. I have a couple of questions:
1. Should there be an expansion joint between the thickened slab and the 8" s.o.g.? If so is it acceptable to have some uplift on one side of the footing?
2. Instead of an expansion joint can the thickened slab and slab have a dowel between them so that the slab helps resist overturning and any theoretical uplift (as shown in the attached sketch)?
Thanks
EIT






RE: Thickened Slab - Footing
What type of loads are you designing your fence for? I am getting a 1.37k loading at the top of the post to get a net bearing of zero at one corner.
RE: Thickened Slab - Footing
Moment at base for 8'o.c. spacing M=15.68k
max bearing for 8' long footing x 2 wide approx 2,194psf but the pressure diagram terminates before the other end of the footing (if that makes sense)
So are you saying you would dowel them "together"?
EIT
RE: Thickened Slab - Footing
Mike McCann
MMC Engineering
RE: Thickened Slab - Footing
Good call on the stirrups, I should have thought about that...
that sounds like a good though.
Would you say it is ok to have uplift on one end of the footing (meaning the pressure distribution on the footing terminates before the other end of the footing)?
Thanks again.
EIT
RE: Thickened Slab - Footing
Mike McCann
MMC Engineering
RE: Thickened Slab - Footing
If the moment is below the allowable torsion permitted by the section (ACI - T=phi*sqrt(f'c)*Acp^2/Pcp).
Would you omit the stirrups or keep them regardless?
Thanks
EIT
RE: Thickened Slab - Footing
The slab and thickening should be poured together. Stirrups are a good idea even if not strictly required by code.
I don't think you need to extend the thickened portion so far beyond the fence...just leave enough room to make a proper connection at the base of the posts.
BA
RE: Thickened Slab - Footing
Mike McCann
MMC Engineering