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micsim (Industrial) (OP)
22 Sep 06 14:20
Hi,
I am working on a project to utilize an existing mezzanine 12'x40' for storage.  Safety regulations require Load Limits to be posted in total or psf.  The mezzanine is rated at 100psf.  My question is that what does this 100psf acctually mean all by itself?  Even if it was rated at 250psf, I would not be able to stand on the mezzanine carrying 50lbs, if it meant I can't have more than 250lbs on 1 square foot.  

What would be the proper way to use this value, 100psf or say even 350psf, to determine the maximum weight that I can safely store on a rack and isle configuration?  I am assuming that the psf rating is refering to the structures strength, but does not tell you anything about how the decking distributes concenctrated loads.  

Thanks for any and all help.
gotwood (Structural)
22 Sep 06 14:45
According to IBC the floor has to be designed for:

Residential: 40 psf (yours is way over this)
Storage LIGHT : 125 psf (slightly higher)
Storage Heavy : 250 psf (more for large commercial storage with heavy equipment)

so you should post 100 psf on the sign.  If you have more than 100 psf, it doesnt mean its going to fail.  It just means it will deflect more than comfortable deflection.

Having one 300 lbs line backer in the middle is no where closed to 100 psf covering the whole floor.  100 psf is very high.
gotwood (Structural)
22 Sep 06 14:51
I guess the total load u can have would be 100psf X 12' X 40' =48000 lbs!!!!  Thats HUGE!!!  If I were you I would put 100 psf limit and put nothing over 2000 lbs (from IBC for concentrated load).
gotwood (Structural)
22 Sep 06 14:56
put nothinng over 2000 lbs concentrated load I meant. So if you put a car in there, each wheel cannot be more than 2000 lbs.  Not that you are going to put a car in there.
micsim (Industrial) (OP)
22 Sep 06 15:35
Thank you for the help.

I plan on storing about 8000lbs on the mezzanine, including the shelving.  I planed to have two rows of 3' deep shelves running on each side of the mezzanine for 24' with a 6' aisle down them middle.  This is only 55psf if the storage is evenly distibuted.  

What if someone load one of the shelving units to 4000lbs, the shelves are 3'x6'.  This would be 222psf below the shelf, not factoring the shelves are only touching the deck on four legs. Say all the selves end up fully loaded, that would be 32000lbs, still less than 48000lbs of the mezzanine.  

If I post 48000lbs it doesnt mean much because it would be bad to put consentrated load anywhere near that much, and if I post (48000/480) 100psf it doesnt tell me much either because if you just say, well load divided by area of the load, then you can even walk on it.  

Just looking for informaiton on how I might use the psf value or the total load limit to safetly design my storage racks and aisle.  

I read some where that I should use my aisle to calculate the load in psf. eg. 3'x6' with 3' aisle is 4000lbs/36sf is 111psf.     
gotwood (Structural)
22 Sep 06 15:49
Just to be easy to understand, do not store anthing more than 2000 lbs.  So if you store stuff on the shelf, dont go over 8000 lbs (2000 per leg).

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