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Re: CONC Slab Uplift

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Don't you need Fres=1.5*Fuplift?

Regards,
Bill Allen

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> From: Jim Dane <jimdane(--nospam--at)ix.netcom.com>
> To: seaoc(--nospam--at)seaoc.org
> Subject: Re: CONC Slab Uplift
> Date: Thursday, July 31, 1997 11:17 AM
> 
> > 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
> > 
> I would never try to resist a 2.5 kip uplift with a 4" slab.  You would
> need 50 square feet of slab to have enough mass to resist the force.  I
> don't know the details but it seems you need to have a foundation poured
> or a caisson drilled to resist the 2.5 kip force.
> 
> Jim Dane, P.E.
> 
>