Modeling with infrmDBPH element type

04-Unexpected behaviour/errors
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Koloubos
Posts: 19
Joined: 23 Dec 2019, 13:43

Modeling with infrmDBPH element type

Post by Koloubos »

Hello, I am trying to model a frame with the infrmDBPH element type in order to conduct a static pushover analysis but my analysis keeps collapsing at really low displacement such as 8mm, displacements that are not logical at all. I have checked the geometry, defined the materials correctly, I subdivided my members in six parts, I defined the incremental load and target displacement with care. My frame is also a simple, just one bay. What is a possible problem that I am missing? Thank you in advance.
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seismosoft
Posts: 930
Joined: 06 Jul 2007, 04:55

Re: Modeling with infrmDBPH element type

Post by seismosoft »

When using the infrmDBPH frame element type, there is no need to subdivide the member to more than one elements. In fact this will probably lead to numerical problems and divergence.
As mentioned in the manual the subdivision of the members to 4-5 elements should be done with the infrmDB model, but not with the infrmFB, infrmFBPH and infrmDBPH element types.
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Koloubos
Posts: 19
Joined: 23 Dec 2019, 13:43

Re: Modeling with infrmDBPH element type

Post by Koloubos »

Thank you for your response. I didn't subdivide my members this time, but now the analysis doesn't even run, it stops at step 0. What could be the cause of that, having in mind all that's stated above?
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seismosoft
Posts: 930
Joined: 06 Jul 2007, 04:55

Re: Modeling with infrmDBPH element type

Post by seismosoft »

Try to run an eigenvalue analysis to see what happens, e.g. if all the members are well connected. Although carry out a search in the forum for convergence problems, there are numerous posts with suggestions on what to do.
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Koloubos
Posts: 19
Joined: 23 Dec 2019, 13:43

Re: Modeling with infrmDBPH element type

Post by Koloubos »

Thank you for your suggestion, I watched and implemented all the suggestion of the convergence criteria video posted but to no avail. Is there any chance I could sent you my model, to check what the problem maybe is? I modeled the same frame with infrmFB and infrmFBPH and there was no problem. That's why it is strange to me. I am insisting on the infrmDBPH element because I need to make a comparison between the different element types so while the other two are working just fine, the latter is quite problematic.
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seismosoft
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Joined: 06 Jul 2007, 04:55

Re: Modeling with infrmDBPH element type

Post by seismosoft »

Yes, send the model to support@seismosoft.com. But first please make sure that you are using the latest version of the program (v2020 Release-2).
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Koloubos
Posts: 19
Joined: 23 Dec 2019, 13:43

Re: Modeling with infrmDBPH element type

Post by Koloubos »

I have the 2018 v3 of the program with an academic license. How can I upgrade it to the 2020 version?
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seismosoft
Posts: 930
Joined: 06 Jul 2007, 04:55

Re: Modeling with infrmDBPH element type

Post by seismosoft »

You can download the program from our website and request an academic license in the same way that you asked for a v2018 license.
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