How can I solve this structure?
2

Question

How can I solve this structure?

JM_10 (Industrial)

(OP)

30 Nov 17 10:57

Hello all

My name is Javier, I am a worker for Helmholtz Institut Mainz. We are building some steel support for a lead ring, and we want to simplify the model to a linear beam so we can calculate the stress.

The beam must be rectangular with a little open so some elements can get through. Please take a look at the attached images. Blue is the steel beam. Lead ring will go inside (in total, 15.000 Kg)

ALBUM IMAGES: https://imgur.com/a/Lcb1r

First thought was to isolate inferior semicircle: create a linear beam with its length, and then apply two distributed loads:
Horizontal load, maximum at the sides, minimum at the center
Vertical load, minimum at center, maximum at sides

(note the symmetry)
That way we recreate the weight of the lead during this inferior semicircle (7,5 tons)

About the leg beams, they are drawn with the pertinent angle, recreating the circular model

Will this be a good approach?
Any ideas?

Help much appreciated

dik (Structural) · Answer 1 · 2017-11-30 14:52:55

Do you have lots of these to build? or is this a 'one off'?

Dik

JM_10 (Industrial) · Answer 2 · 2017-11-30 15:29:52

RE: How can I solve this structure?

JM_10 (Industrial)

(OP)

30 Nov 17 15:29

This is only one

dik (Structural) · Answer 3 · 2017-12-01 06:56:49

The structure looks pretty robust without doing any sums on the design. You might want to 'batter' the outside supports to improve the lateral resistance.

Dik

prex (Structural) · Answer 4 · 2017-12-01 08:42:20

Thi is a ring beam: Roark has formulae for this, or you can find them here and here.
Basically this would be treated as a uniformly distributed vertical load with support at the bottom plus two vertical loads (positioned in between the actual supports) again with support at the bottom. The superposition will eliminate the bottom support.
But of course you'll have also stability issues, particularly with the ring section, if it's particularly thin and as it is cut.

prex
http://www.xcalcs.com : Online engineering calculations
https://www.megamag.it : Magnetic brakes and launchers for fun rides
https://www.levitans.com : Air bearing pads

JM_10 (Industrial) · Answer 5 · 2017-12-01 08:55:20

Thank you for the help

Well, actually FEM simulations seems to be ok (70 Mpa Von Mises), so yes it looks robust.
https://imgur.com/a/9K8c6

Also, we will think about the outside supports

However, we also want to make the manual calculations. So prex, thank you, I will look at it carefully. Why the vertical loads are positioned in between supports?

prex (Structural) · Answer 6 · 2017-12-01 09:03:14

Quote:
Why the vertical loads are positioned in between supports?

Just to replace the four reaction supports with two. But you can also maintain the four supports and superpose three loading conditions: the two with support reactions will require the same vertical deflection at the bottom (and of course their sum will equal the total weight).

prex
http://www.xcalcs.com : Online engineering calculations
https://www.megamag.it : Magnetic brakes and launchers for fun rides
https://www.levitans.com : Air bearing pads

JM_10 (Industrial) · Answer 7 · 2017-12-01 09:20:57

Quote (prex)
Just to replace the four reaction supports with two. But you can also maintain the four supports and superpose three loading conditions: the two with support reactions will require the same vertical deflection at the bottom (and of course their sum will equal the total weight).

Ok then, I will be using the two vertical loads

So about the stability issues. Do you know how could I work on it?
Thank you

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