analysis of submerged flat plate

[frostrobn]

I'm looking for a little help in determining the proper bending equation to use in the analysis of 1/2" plate welded out around it's perimeter to a structural frame. The frame is submerged and is used to isolate a gate on a hydroelectric dam for maintenance. I was able to analyze the structural members, but what about the plate? Fixed-fixed ends using the longest dimension for (l) is way too conservative.

 

[frostrobn]

Miecz, I understand that the coeff. is unitless. So p is (psi) and a is (in)? You said the moment in my case is 1.90 k'/ft. Do you mean 1.90 kip-ft? I'm tripping up on the units in the formula on Figure 34, Moment = Coeff. x (p x a^2). What are the units for Moment, p, and a? I know this sounds really fundemental, but I was taught to always question the units, especially with new formulas.

 

[frostrobn]

Once I am satisfied with the stiffeners, I just want to be able to show that I concidered what the peak stress is in the plate between the stiffeners. Yes, stiffeners are more efficient (in terms of material used). Consideration #2, cost and time to fabricate $$$$. Stiffeners take more time in the shop to fabricate.

I just want to make sure I am applying the correct formulas for the analysis of a plate under a UDL with its edges supported or even fixed. I know the DL is actually decreasing with the decrease in submerged depth, which I will account for in higher sections of the panel I am designing.

Thanks.

 

[miecz]

frostrobn-

By 1.90 k'/ft, I meant 1.90 kip-ft per foot. (It could also have been 1.90 kip-inch per inch.) That is, there is 1.90 k-ft of bending moment for each foot of support length. For 1.90 k'/ft, when you calculate your section modulus, "b" is one foot. For 1.90 k-in/in, "b" would be one inch.

 

[rb1957]

p = pressure in psi, or MPa
a = length in in, or mm

resulting in moment in lbs*in or N*mm

consistent units yield intelligent results !

if you're trying to minimise weight and build costs and all those good things, sharpen your pencil and use the tapered pressure distribution.

 

[frostrobn]

OK. How about the units used for p and a? in, psi, ???? Are you telling me that the equation from Figure 34 is spitting out kip-ft/ft?

 

[frostrobn]

Sorry, rb1957, you posted as I was writing my last post. I think I'm all set now. I will go after the tapered loading and try to optimize the stiffener use to meet all the objectives. Thank you sincerely for you patience and help.