floor load rating

[AUtigr]

Hello all,

I am trying to calculate the load rating for a walk-in cooler floor. The floor spans 48" and is assumed to be
1 ft. deep(for the sake of easier calculation). The floor consists of 3/4" plywood spanning 48" and 12" assumed depth(just for the sake of easier calculation). It is supported on each side of the span by 2x4's that run the depth of the floor. This would be a fairly easy calculation, however, the problem is that 20psi foam will be shot under the plywood for added stability.

It is assumed that the load will be uniform across the entire area of the plywood. Since the compression strength of the wood is much greater than that of the foam, the plywood will bend instead of compress since it is supported on both ends.

What mechanical properties will I need for the calculation. I think I will have to set the deflection of the plywood to be an arbitrary tolerance. By the way, the plywood is 4-ply.

Thanks in advance for any help provided,

Thanks in advance,


Quintin (Auburn Engineer)

 

[boo1]

Use a composite section approach. For the mechanical prop of the plywood see:

http://www.fpl.fs.fed.us/documnts/FPLGTR/fplgtr113/Ch10.pdf

http://www.apawood.org/level_c.cfm?content=pub_ply_libmain

 

[AlohaBob]

IBC Table 2304.7(3) Shows plywood capacity for various spans. This plywood looks overstressed at first look.

4 ply is not good. 5 ply would have been better.

 

[jheidt2543]

I've always been under the impression that plywood was fabricated in an uneven number of plys, is this not the case?

 

[AlohaBob]

No