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Re: CONC Slab Uplift

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Sickler wrote:
> First, thanks to all who responded to my request for repeat of
> information on concrete slabs for machinery.  I received exactly
> the information I needed.
> I have another concrete slab question that I could use some
> help with:
> I am evaluating a 4" slab on grade with no edge beams or footings.
> At one column location, there is an uplift load of 2.5 kips.
> Given that the slab is thin and flexible, it would appear that
> the uplift load would engage a portion of the slab in bending.
> The highest uplift reaction occurs in the middle of the slab, away
> from the edges; but I am also interested in behavior near the edges.
> How would you determine what portion of the slab resists the uplift
> load and then how would you evaluate the design moments in the slab?
> Any suggestions or references would be greatly appreciated.
> Thanks,
> Nina Sickler

For that kind of uplift, I would suggest that you make the footing
deeper and wider and use the dead load of the soil to counteract the
uplift.  IT is not standard practice to use slab-on-grade to resist
uplift.  The concept will be similar to anchor bolt embedment.

Good luck,

Thomas Chiu, SE
Thomas Engineering