Could you please help me

[mbopen]

Dear Dr fmk
Hi
I modeled a brace frame with "selfcentering" behavior. In fact for only tension behavior, I omitted negative part of this material and add a new material with dll file. I verify my new material with a result test and it works correct.
Now in my more analysis with earthquake, when I draw result of axial force of each brace versus drift, there are some horizontal line in first range of force and in the opposite direction of performance of brace. Could you please help me?

How can I send a picture of my result for you to show this problem?

[fmk]

did you get material stress and strain signs correct .. + is tension, - is compression .. put an elastic material in instead of your material for 1 analysis step and confirm your signs and it are the same in the output.

[mbopen]

Dear Dr fmk
thanks for reply.
I tried it again as you said but I get the same output.

[fmk]

still sound like something is wrong with your material.