RSA 2025 Cable not converging (and node instability)

[dndllc]

I have a netting support design for a backstop in a baseball stadium.  The cable analysis doesn't want to converge.  I've made sure it has DL on all members.  I've tried elongation in cables at -0.01 and also putting in a tension.  What am I missing?

Node stability at 20, 27, and 14 seem to be okay now.

[Simau]

Hi @dndllc 

Hard to say without the model.

Zip and share it

[dndllc]

didn't like the *rtd file.  posted a zipped file instead.  Thx for catching that.

[Romanich · Accepted solution]

Hi @dndllc,

You have to define load combinations and mark simple cases as auxiliary.

[dndllc]

@Romanich , I added the load cases and changed the simple loading to Auxiliary,  but it is still not converging 😞  Some were much better though.

I read somewhere that I should mark the P-Delta and Large Displacement as well, so I modify that as well.

If the diameter of the cable is not sufficient, will that cause it to not diverge?

Thanks

[Romanich]

@dndllc 

Are you sure that vertical elements also cables:

[dndllc]

In the real world design, it will be there to attach the net to.  The net/panel is a two-way panel.  It also seems to keep the node above stable.

I just read something that if a cable gets put in compression then it could lead to non-convergence.  Would a rod as a tension-only member work better here?

[Simau]

Hi @dndllc 

As @Romanich  said, if you replace the vertical cables with bars, the model converges.

Would a rod as a tension-only member work better here?

No, you need a bar fixed at its bottom.

[dndllc · Accepted solution]

@Simau , @Romanich Thank you for your help.  It was a combination of missed things on my part.  Between your suggestions, what I found online, and Krzysztof Wasik from Autodesk, I was able to get it

to converge. here is what was missing:

1. Create Auxiliary load cases. (Romanich)
2. where cables come together, create a support to prevent rotation in all directions. (I can keep the vertical cables).  (online)
3. Mark loads with P-Delta and Large Displacements.
4. Adjust the Non-linear Analysis Parameters. (Wasik)

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  Thanks again, David