Nonlinear behavior of 'rack' element class

[nuttaphon.B]

I already create open section in 'rack' element class. Then I want to assign nonlinear behavior to my open-section column (PMM Interaction). How to assign? Is rack element class has a fiber section like RC element?

Ps. I also found a 'rackH' element class but I don't under stand how can I assign PMM interaction to the end hinge

[z.gronti]

Dear nuttaphon.B,

Rack element has no fiber section.
In rackH element you may define moment rotation curves at the ends, but there is no interaction between the bending moments at the two local axes.

[nuttaphon.B]

Dear z.gronti,

Many thanks for your help, then, How can I release moment on my pin-brace element that is 'rack' element type?

[z.gronti]

Dear nuttaphon.B,

You may use the rackH element type and assign a very low stiffness value to the pinned end.