Slack cables

04-Unexpected behaviour/errors
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rezasheikhi
Posts: 10
Joined: 17 Sep 2017, 20:46

Slack cables

Post by rezasheikhi »

Hi
I have to model a series of slack cables. Therefore I am trying to set a link with a gap_hk between two coincident nodes at the middle of each cable-element and assign 3K stiffness for each element class so the total stiffness of the slack cable brace will be K. Unfortunately, I’m not sure the way I model the link is correct and while I run the analysis, it gives the error "Unable to apply the entire phase load"
Could you please give me a clue about my problem?
Regards.
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seismosoft
Posts: 1184
Joined: 06 Jul 2007, 04:55

Re: Slack cables

Post by seismosoft »

If you carry out a search on "Unable to apply the entire phase load" you will find plenty of resources on the forum. Have you tried to run eigenvalue analysis with the model? It will give you a very good insight of the connectivity of your members.

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rezasheikhi
Posts: 10
Joined: 17 Sep 2017, 20:46

Re: Slack cables

Post by rezasheikhi »

I can’t find resources how to model slack cables in your website. Unfortunately, I’m not sure the way I model the link is correct. Could you please take a look at my project?
Thank you for the help
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seismosoft
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Joined: 06 Jul 2007, 04:55

Re: Slack cables

Post by seismosoft »

Why do you use the gap_hk curve. The lin_asm curve with zero stiffness in compression seems a better option.
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rezasheikhi
Posts: 10
Joined: 17 Sep 2017, 20:46

Re: Slack cables

Post by rezasheikhi »

So how can I model the slackness of the cable with lin_asm curve in tension?
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seismosoft
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Joined: 06 Jul 2007, 04:55

Re: Slack cables

Post by seismosoft »

You may use the lin_asm curve to cut off compression (zero stiffness),whereas in tension the stiffness may be positive with a large value, so that the stiffness of the cable is determined by the linear elements (frame or truss). Note that there are no specific models in SeismoStruct to model the cable slackness.

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rezasheikhi
Posts: 10
Joined: 17 Sep 2017, 20:46

Re: Slack cables

Post by rezasheikhi »

Would you like to take a look at my model? I'm working on my thesis and need your help
https://www.dropbox.com/s/1oa0onjjrvp3c ... d.spf?dl=0
Regards
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seismosoft
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Joined: 06 Jul 2007, 04:55

Re: Slack cables

Post by seismosoft »

It seems that the convergence problems start, when the gap-hook curve reaches the displacement limit in tension.
Maybe the diagonal struts (or most probably the frame elements close to them) cannot accommodate the additional forces created by the sudden increase in the link F1 force.

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rezasheikhi
Posts: 10
Joined: 17 Sep 2017, 20:46

Re: Slack cables

Post by rezasheikhi »

Thanks a lot
Would you recommend any solution for this convergence problems?
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seismosoft
Posts: 1184
Joined: 06 Jul 2007, 04:55

Re: Slack cables

Post by seismosoft »

Unfortunately, we cannot fully understand your model and how the gap-hook curve operates. If you carry our a search in the forum you will find plenty of resources on convergence difficulties and how to solve them. Also watch the video below from our Youtube channel:
https://www.youtube.com/watch?v=p6tAyoofDog
Regarding your structural model, you should probably discuss these issues with your supervisor, since the details of the model are out of the scope of the current forum.

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