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BSD wrote:

> Hello:
> I am designing a warehouse slab supporting racks with a Defined Traffic
> Floor and racks.
> The lift truck requires isles without shrinkage joints.  There the slab
> panels will be 15'x150' without any joints
> i ran across a reference referring to designing the slab panel utilizing
> shatter theory, which requires 1/2% steel
> ratio and will limit expected cracking to "micro-cracking" which is
> acceptable for the lift-truck electronics.
> I have designed rack slabs per PCI, WRI and slab drag theory but i haven't
> previously heard of "shatter theory"
> Does anyone no of a reference where I can find any information or other
> opinions
> thanks in advance
> Bill
> bsd


I have never heard of the "shatter" theory before; however, you should use
your sub-grade drag theory to calculate the amount of steel required.  For a
150' joint spacing, 0.5% appears to be acceptable.  For big panels I still
prefer to use post-tensioned, typically unbonded.  I currently have a 300' x
400' warehouse under construction using unbonded PT with only 4 joints; i.e. 8
panels at 150'x100' each.
I was limited to this size joint only because the concrete sub was only
capable of placing 15,000 square foot per day.

Brian K. Smith, P.E.