Round Tube Column with Spiraling hole pattern up column

[MidwestSE]

Hi All,

I've got a potential design coming up that might involve a large round column (48" OD w/ +/- 1" thick walls) that will have a series of 12" diameter holes spaced 5' vertically and spirally arranged around the pipe(assembly will be roughly 60' tall).

My first thought is to design it similar to a stack w/ a series of reinforced breech openings (following ASME standard for stack design).

Anybody else encountered something similar before? Or have any other ideas to design or validate the design?

Thanks!

 

[KootK]

My first thought is to design it similar to a stack w/ a series of reinforced breech openings (following ASME standard for stack design).

Me too. Could be pretty conservative for some applications though.

What is the application here? Industrial? Public art? What goes in/through the holes? How close to maxing out M/Sx will you be?

Kinda sound like you're building a giant flute. To that end, at least cursory consideration might be given to cross wind and stack effects.

 

[MidwestSE]

It'll be industrial for short term use until a facility can be upgraded (a year or 2 max - it's a short term solution until a capital expansion occurs) - grain will be dumped in the top and flow down through the tube, out the holes, forming a grain storage pile on the ground. Once the pile is started, the tube will undergo less and less flexure as the grain pile grows up around the tube (essentially a lightweight soil surround).

I'm thinking M/S won't be too high. I certainly won't be pushing it to 99%. With how tall it is, a reasonable lateral deflection at the tip will control the design - I was thinking around H/300 as the equipment isn't very sensitive to deflection (this will be confirmed once the final vendor is selected).

You are correct - it will be more or less a giant flute - I was going to base the wind loads on the tube itself on ASME stack wind loads. I don't think any vortex shedding issues will occur, but I am planning to run the numbers on it.

 

[dhengr]

Structural dood:
I’ve seen these stock piling columns before, and never particularly paid much attention the exact arrangement of the outlet holes. I suspect the 4’ dia. column tends to fill up a bit more (higher) than the lowest flowing hole/holes, and in this respect, could two or three spiraling holes all be putting out material mostly on one side of the column? And thus, be causing an unintended lateral loading on the center column. Would it be any better to have two opposing holes at a given level and then the next set of opposing holes be 90 degrees from the lower set? I would think that treating the column as a stack is reasonable, with some attention to localized stresses at the outlet holes. At the very least, cut the outlet holes and clean them up, so there are no stress raisers on the edges of the holes, and/or reinforce the openings like you would on a stack opening.