Submerged plate design

[wag2483]

In lieu of stop logs a contractor has proposed a plate to retain water. The plate would drop into vertical notches that were originally cast into an 8' x 8' concrete conduit. The design approach is to treat the plate in horizontal strips acting simply supported. To be determined, but anticipated that the plate may require stiffeners, angles welded horizontally at a given space on center. Preliminary calcs confirmed that when the angles are positioned on the tension side of plate, opposite water pressure, both the PNA and ENA fall within the plate thickness, meaning the angles will only see tension. Is it then acceptable to design in accordance with AISC steel const. spec F11? Thanks for any suggestions.

 

[HTURKAK]

Your sketch implies a hydraulic gate. If this is a sluice open or closed , you may follow typical plate engineering formulas.
However, if the gate will be used for regulating the flow , that will be a different story due to flow induced vibrations .
I will suggest you to look industry standards ( in this case AWWA ) rather than AISC and a reference book ; Design of
Hydraulic Gates by ERBISTI .

If i were , i would simply reject this proposal and ask to provide stop logs.
Say my opinion..
..

He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[ldeem]

How wide of a plate strip are you using to calculate the composite section properties? I have always found this to be a challenge. When I have designed similar items I lean toward a narrow strip and then look at plate bending between stiffeners. In this case, assuming it is a critical item to hold back water, I would ignore composite action and design it with Channels or wide flange to span the width then set the stiffener spacing based on plate bending between stiffeners.

 

[JoelTXCive]

IES Web offers a plate analysis program that will do this design (with or without composite action).

The software is super cheap and they have a free 30 day trial.

It's called Visual Plate. You can do a plain plate, or add stiffeners to the back of it. The analysis results will give you stresses in the plate, and the moment in the stiffeners.

https://www.iesweb.com/vp/

Or Youtube playlist:

https://youtube.com/playlist?list=PL520061D84CB5623F&si=zW4RqJ5LMOfVsS3R

I'm not a salesperson for the company, but I am a big fan of their products. You could learn to use the software and get a design in under 30 minutes. It's really easy to use.

Good Luck!