torsion of Vessel Base ring

[Elise]

When erecting vessels with base rings, around 60-70 degrees from horizontal, the tailing lug load can be resolved into radial and Maximum longitudinal value components.
Taking the longitudinal component parallel to the vessel centreline, multipled by the distance from tailing lug hole to skirt outside diamenter, a moment is generate, which can be said to try to put the base ring in torsion

does anyone know how to analyze the torsion effect in the base ring

 

[ishvaaag]

A proper choice of the elements and geometrical representation of the structure will give information enough to design the structure. If you want to proportion some 1D element (member) for torsion between other things, use 1D elements for it, that way you will have the torsor moment explicit and so you will have design checks readily available for the members.

 

[Elise]

Imagine looking side on to a Channel section ring, angled at 60 degrees from horizontal.
On one is a concentrated moment.
I am after a method to determine if there would be local torsion in the ring at that point, or would the section modulus.rigidity provide overstiffness to overcome. as the ring is hanging from the point of load, so any anchor would be to the self weight.

I am considering writing a discussion paper, and some mathematical support to this situation would be nice to have.

 

[SAIL3]

Normally an open base ring section as shown in your sketch offers little resistence to torsion.
I would resolve that moment into two radial forces.
Check base ring for this conc radial load.
If the secondary ring is continous, also check that for the conc radial load.
If the secondary ring is not continous....just part of a bracket
then check this plate and a portion of the shell of the vessel for the conc. load.....would amount to checking a distributed conc load on the shell of a vessel.
There has been tons of tests done on various conc loads on shells of vessels resulting in mathematical approximations derived from the results....so do some research on this.
..a few that come to mind:
Useful information on the Design of plate structures, Vol2..AISI
Pressure vessel design manual....Dennis R. Moss
and many more