Minimum Flat Plate Thickness
Minimum Flat Plate Thickness
(OP)
Hi,
I need to obtain the minimum thickness of a flat carbon steel plate under the following conditions:
1) Circular bottom plate (radius = r) under uniform pressure P, and the plate is fixed at the periphery.
2) The plate is resting on the soil, and the soil has enough bearing capacity to prevent deflection of the plate.
3) Since I want my deflection to be "0", the plate will be only under simple compression load.
Is there any formula or method to calculate the required thickness under this conditions (compression load) ?
Thank you !
Nikk5
I need to obtain the minimum thickness of a flat carbon steel plate under the following conditions:
1) Circular bottom plate (radius = r) under uniform pressure P, and the plate is fixed at the periphery.
2) The plate is resting on the soil, and the soil has enough bearing capacity to prevent deflection of the plate.
3) Since I want my deflection to be "0", the plate will be only under simple compression load.
Is there any formula or method to calculate the required thickness under this conditions (compression load) ?
Thank you !
Nikk5





RE: Minimum Flat Plate Thickness
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RE: Minimum Flat Plate Thickness
If I define a max allowable deflection "y"= 4", and my flat plate is 0.250 thick, 45' diameter, uniform pressure of 20 psi
How can I verify if thickness is ok ?. I have played with Roark's formulas but since deflection is quite bigger than thickness, they don't seem to fit.
Thanks,
Nikk5
RE: Minimum Flat Plate Thickness
Now equate that deflection to the allowed.
RE: Minimum Flat Plate Thickness
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RE: Minimum Flat Plate Thickness
if the soil is preventing the plate from deflecting, then the plate is merely transferring the pressure load from one face to the other ... 0.001" should be thick enough.
if the soil is not supporting the plate ('cause you're calcuating deflections from Roark) you should be aware that Roark's tables are based on plate bending, and if the defelction predicted is greater than the thickness then the plate is developing membrane loads (hoop stresses) and carryng the pressure as tension. and the fasteners around the edge need to transfer this load into the rst of the structure.
Quando Omni Flunkus Moritati
RE: Minimum Flat Plate Thickness
btw, I entered 45-in as the radius, not the diameter, so the deflection is much smaller, more like 0.775-in, with 50.64-kpsi stress
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RE: Minimum Flat Plate Thickness
RE: Minimum Flat Plate Thickness
Quando Omni Flunkus Moritati
RE: Minimum Flat Plate Thickness
Are you talking about the steel bottom plate of a petroleum storage tank which is 45' in dia.? If so, that is a whole different animal than what everyone here is talking about. It’s basically a tension membrane supported out at the foundation and tank wall. The liquid loads are basically carried by the sub-soil under the floor plate, so there is no real plate bending. There may be some secondary plate bending due to detailing and welded joints however.
RE: Minimum Flat Plate Thickness