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Ring girder stress analysis 
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#1
Jul1014, 10:57 AM

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I could use some guidance as to how I would analyse the stresses in a ring girder similar to the one shown in the attached picture. I have found the stress in the columns that support the ring but I do not know how to find the maximum stress in the ring. The best I have been able to come up with is that the stress = reaction force from column / crosssectional area of the ring, (σ=F/A) However I am sure that there is more to it than this.
Another thing that I want to consider is the transverse force from the friction at the slide bearing / rocker. I believe this will cause a moment where the columns are welded to the ring. Thank you 


#2
Jul1014, 11:44 AM

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It's not clear what loads are imposed on the ring girder.
Is the ring girder some sort of support, like for a pipeline perhaps? In any event, curved girders require a slightly different analysis technique than that used for straight beams. http://courses.washington.edu/me354a/Curved%20Beams.pdf Google 'curved beams' to find similar pages. 


#3
Jul1014, 12:17 PM

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Thank you for the link.
The ring girder is holding up a large pipeline filled with water. The most significant loading on the ring girder will be from the weight of the contents of the pipe and a possible moment caused by the friction resisting the columns tendency to slide laterally. (as the pipeline expands and contracts due to temp. change and Poisson's effect) I found these equations in the link that was provided. They seem to be what I'm looking for however I cannot find what should be used for the bending moment 'M' in the equations. σ=(Mc_i)/(Aer_i) and σ=(Mc_o)/(Aer_o) 


#4
Jul1014, 01:11 PM

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Ring girder stress analysis
I think M is a pure bending moment and is as shown on p.2 of the linked document. Most of these curved beam problems use a load suspended from a hook as an example, where the pull of the load is trying to open up the eye of the hook.
This link: http://nptel.ac.in/courses/105106049.../mainch10.html shows a little more development on applying a pure moment and an end load to a curved beam. I haven't found a similar set of notes about a distributed loading, however. 


#5
Jul1014, 01:20 PM

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This article gives a treatment of the stresses imposed on a closed ring by a force applied across the diameter of the ring.
http://elearning.vtu.ac.in/12/enotes...2/Unit1RK.pdf See p. 58 and below for the discussion of the analysis of closed ring girders. 


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