Large Diameter Tubular Conveyor Galleries - Reference?

[ARS97]

I'm about to start a engineering review of an existing 9' diameter tubular conveyor gallery that spans approximately 176'. Design references for such a structure are hard to come by. Here's what I have in my personal library:

1. "Tubular Steel Structures - Theory & Design", M.S. Troitsky (1982)
2. "Analysis of Circular Conveyor Galleries", H.M. Haydl (1980)
3. "Design Aspects of Large Diameter Tubular Conveyor Galleries", H.M. Haydl (1986)

Does anyone know of other references that may be available?

 

[BAretired]

Something 9' deep spans 176'? Doesn't sound right to me.

BA

 

[ARS97]

Yeah, I know. It's a tube that is 50-60 years old and spans over a major highway in WV. Something spanning that far I would expect to be in the 12' range. Info at the moment is a bit preliminary, but here's what I have:

1/4" shell (believed to be ASTM A36)
L5x3.5x3/8 stiffener rings on 9' centers
54" conveyor inside

There was a PE that reviewed it back in 2005 and said that everything was fine. I guess the state of WV requires periodic evaluations since it crosses a state highway. I looked at the report/calculations provided by the PE back in 2005.....let's just say that it looks a bit oversimplified.

 

[aggman]

I have designed a few of these. Their is some information in the structural engineering handbook by Gaylord. Troitsky is probably the best reference. He also references E.H. Baker "Structural Analysis of Shells". Baker has a pretty thorough review of the subject and I'm sure Timoshenko has information on it in his stability and strengths of materials books. I believe Troitsky also did some research on the subject himself published in Canadian Steel Industries Construction Council in the mid 70's. It's not to hard of a problem to work through if you have done any this shell structure design. The normal force checks still all apply and can control. Their is also a check for local shell buckling (critical buckling stress) that has several influences that need to be checked and the ring stiffeners.

 

[JStephen]

Is this just a big tube with stuff inside it?

If it was built 50 or 60 years ago, you can figure the analysis wasn't quite as sophisticated as what it could be now.
On the plus side, you may be able to use higher compressive stresses under current standards than back then.
Some of the pressure vessel/tank/penstock info may be applicable to it, if your quoted references don't cover it.

Two design issues are wind vibration and cold-weather fracture, and you can potentially rule them out based on the service life.

 

[ARS97]

aggman - thanks for the info.....I will see if I can dig some of those references up. I think the easy part would be the stress analysis on the shell. The local buckling issues and stiffener ring spacing is what seems to always throw a wrench into things.

JStephen - yeah, it's bascially a big tube with a conveyor and walkway through it. It's a common way of enclosing a conveyor and preventing spillage over highways or waterways. Expensive, but very effective. I've seen spans of 250' before.

I've looked at some of these tubes in the past, but I've always had some trouble "codifying" my procedure. Plus, the ones that I have done were relatively large diameter and shorter spans....the stresses were fairly low. In this case however, I'm guessing that the stresses will be at a level where they'll be pushing the limits. The stiffener spacing and design though has always been a bit vague.

In addition, past evaluations of this specific tube have shown some significant deterioration at various points within the shell. In fact, there are points where the shell is 1/8" thick...half of what the original thickness was. It might be possible that this tube is composed of COR-TEN steel, which may explain some of the deterioration issue.

I'll probably be evaluating this both manually and with a FEM in Staadpro. Staadpro will give me a better understanding of the P-delta effects along with a modal analysis for frequency calcs.