flatness, levelness and thickness of warehouse slab

[Structures33]

Hey all - I'm reviewing a set of plans for a very large storage warehouse. The owner intends to lease part of it out and they're not sure what the tenants will be storing. Because of this, I'm trying to give suggestions as to how they can keep the warehouse flexible as far as storage allowances go. One of the issues that I don't have much experience with is the flatness/levelness of the slab on grade. Storage can be as high as 36 feet and I know with multi-level rack storage, the flatness will be important. I was thinking of suggesting that they specify at least a flatness of 30 and levelness of 20.
The other issue is the thickness (currently 7" unreinforced). I don't have a problem w/ unr/f - joint spacing is good and compaction of soil will need to be strictly enforced. I am going to suggest using a thicker slab however, in the event that the rack loads are higher (we don't know types of racks, loads or traffic).
Thoughts and recommendations appreciated!

 

[dik]

I would normally spec a floor to be 35/25 for a typical warehouse, so your numbers aren't off the mark. For flatter floors, I usually use 45/35; these are usually OK for more automated storage systems.

Thickness depends on the soil and consolidation as well as conc strength, fatigue, etc. You should look at a program that designs slab thickness for various loads and spacing of loads.

Dik

 

[dougantholz]

Look at WRI, CRSI and even the army corps of engineers. They all have good methods for analyzing SOG. We have successfully used 6" slabs (unreinforced) with up to a 8 kip point load at 8 ft on center.
FL/FF is in the ballpark. I think we use a global 24/20 or a 20/24 I can't remember which way we usually go. Local FF/FL is more along the lines of 24/32.

 

[DonPhillips]

For a speculative warehouse, it is difficult to provide a flat enough floor for pickers intended to run while fully extended. I would think a "superflat" floor would be beyond your current scope and the numbers Douganholz suggested seems appropriate and are close to an old fashioned "class a" finish.

Don Phillips

http://worthingtonengineering.com