Incompatibility in Moment rotation diagram

Hello! In this section we'll talk about the post processing module and the data visualization.
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a20145878@pucp.pe
Posts: 10
Joined: Thu Feb 06, 2020 4:33 am

Incompatibility in Moment rotation diagram

Post by a20145878@pucp.pe » Mon Jun 01, 2020 11:44 pm

Hi!
I write you in order to ask you why it is possible that a moment curvature diagram of a lumped plasticity model with zero
lenght using the command ModIMKPeakOriented shows a decreasing stretch after yielding even when I defined it as an
incresing after yielding for the beams as you can see in the attached photos in which the first is the input and the second
the output after several steps.
Mr vigas.PNG
Mr vigas.PNG (5.59 KiB) Viewed 255 times
Mr resul vigas.PNG
Mr resul vigas.PNG (6.25 KiB) Viewed 255 times
I think that the drawback could be in the definition of the analysis, though I am not sure where. Moreover,
it results some weird since the diagram has the same behaviour as I defined for the colummns. Hence, I look forward to you can help me.
Thanks in advance.

STKO Team
Posts: 168
Joined: Tue Oct 29, 2019 8:45 am

Re: Incompatibility in Moment rotation diagram

Post by STKO Team » Wed Jun 03, 2020 3:29 pm

Please send us your SCD file so we can have a look

STKO Team
Posts: 168
Joined: Tue Oct 29, 2019 8:45 am

Re: Incompatibility in Moment rotation diagram

Post by STKO Team » Thu Jun 04, 2020 9:07 am

Dear user,

The reason for your wrong response with negative rotations, is that you defined the hardening ratio for the negative part, as a negative value. But the hardening ratio is a ratio (and defines a slope) so if you put a negative value, you will have a negative slope (softening) rather then hardening:
MR_1.png
MR_1.png (59.68 KiB) Viewed 234 times

One more thing, all "Lambda" values should not be 0 (even if they say 0 is the default for no degradation, they meant 1, there is an error in the opensees doc...):
MR_2.png
MR_2.png (64.22 KiB) Viewed 234 times

Finally this is the correct form:
MR_3.png
MR_3.png (65.82 KiB) Viewed 234 times

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