Incompatibility in Moment rotation diagram

[[email protected]]

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 (5.59 KiB) Viewed 2681 times

Mr resul vigas.PNG (6.25 KiB) Viewed 2681 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]

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

[STKO Team]

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 (59.68 KiB) Viewed 2660 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 (64.22 KiB) Viewed 2660 times

Finally this is the correct form:

MR_3.png (65.82 KiB) Viewed 2660 times