Plate for a man hole

[ccking1]

I have to design a plate acting as a cover for a man hole. It is 24"x24" supported on all sides. There is going to have heavy circulation over it. I know there is biaxial bending an torsion but dont know how to design it. Have any info on this design?

 

[SperlingPE]

Order a manhole cover from a supplier.

 

[swearingen]

First, I'll assume you're stuck with square, otherwise you really need to consider making it round so it can't be dropped in the hole.

For maximum moments and shears, check out Roark's Formulas for Stress and Strain. They have that case in there (uniform load, pinned on 4 sides).

I think SperlingPE stated it best, however. Find a Neenah catalogue and buy one. It will probably be lighter than the one you come up with.

 

[macmet]

gotta agree, just buy one.

 

[ccking1]

Thing is that I work for a steel fabricator. A simple plate for that use would be a lot cheaper than buying one from a supplier. It's more a well cover at the end of a floor gutter in an industrial building. I would like to replace the traditional grating.

 

[UcfSE]

Try Roark's, or design it for one-way bending.

 

[JedClampett]

There's a reason that you don't see steel covers in roadways. Steel will tend to absorb energy by deforming. Covers have to be fitted just right and overdesigned to handle the traffic load plus impact. If either don't happen, the cover will warp, make a lot of noise and get worse.
If there isn't a problem with leveling and the grating is in good shape, weld a plate to that.