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No. I meant using the pinching parameters in the hysteretic material

you should use the pinching parameters in x and y axes. The link below shows pinching parameters of 0.2 and 0.6.

https://ibb.co/hBYTjhn

Hi all
in dynamic analysis, I am getting Jagging behavior in hinge moment-rotation curve when the stiffness changes to negative as shown in the pic in the link below
I am using ModIMKPeakOriented material for the plastic hinges. I got the same jagging using the Hestritic material.
under cyclic static loading, the moment-rotation curve was smooth.
Can you please give a reason for this jagging?
https://ibb.co/qp4VkWB

I am not an expert, but I had the same issue.
The axial force in fiber elements is caused by restraining the elements from expansion. Concrete fiber elements expand when subjected to moment. that is because the axial displacement of the element is calculated by integrating the strains at midsection at each integration point. these strains are often in tension resulting in expansion. If you restrain that expansion, a considerable axial force develops in the beam and, more importantly, the yield moment increases.
The expansion of beams is real [1]. However, I think expansion would happen in bare beams not in beams with slabs. To solve the problem you may model the beam with part of the slab, or use plastic hinge model for the beams.

1- Pantazopoulou, S.J., and X. Qi (1991). “Response of RC Frame under Lateral Loads,” Journal of Structural Engineering, Vol. 117, No. 4, pp. 1167–1188.

Did you solve this problem?

Thank you all.

Hi all
Is it possible in Opensees to apply DisplacementControl on two points (or more) at the same time?

"sidesawy collapse of deteriorating structural systems under seismic excitations" by Lignos and Krawinkler, Blume earthquake engineering center. Report number 177.

Thanks for your reply.

Hi
I am using Ibarra- Medina-Krawinkler Hysteretic model for concrete columns. The parameters for concrete columns can be obtained from (PEER 2007/03) by Haselton et al.
The parameters for steel members can be obtained from Blume report (TR 177) By Lingnos and Karawinkler. Both reports are accessible to anyone.
Note that lambda values are different depending on the model you are using ( the original model or the modified model) More information is provided in TR 177 page 30.

Hi
I noticed when a lateral load is applied to a reinforced concrete fiber element (column element), the element undergoes upwards displacement. This happens with or without axial load. Furthermore, when the same element is assigned linear elastic (or steel) properties there will be no upwards displacement.
The difference between reinforced concrete section and other sections is the strain profile of the section, in case of reinforced concrete sections, the neutral axis is far from the section center, toward the compassion zone, with most of the section appears to be in tension. Whereas in the other sections the neutral axis is located near the section center.
I think the issue of upwards deflection comes from the strain profile of the sections.
I know how the lateral displacement is calculated from section curvatures. But how the axial displacement is calculated from curvatures?. Would you please recommend a reference?

Thanks for your reply.

Hi all

The link provided to browse the source code is not working.

http://opensees.berkeley.edu/WebSVN/lis ... runk%2FSRC

is it not working or a permit is required?
I accessed the link months ago and it was working.

Regards