Plastic hinges

[javidsharifi]

Dear all,
What is the fastest way to find out plastic hinges formed in the structure after a dynamic or pushover analysis?
Regards,
B. JavidSharifi

[fmk]

the fastest way to see if a plastic hinge formed is probably to look at eigenvalues.

a way to determine yielded hinges would be to create a list of element tags and possibly yield value (tangent or rotation) and when done loop over it and compare current value versus that in the list.

[javidsharifi]

Thank you very much. so I should first know the rotation corresponding to yield values, and then record the rotation after analysis and compare them with those values.
I want to check this for all beams and columns. Which element types are the most suitable for doing so? BeamWithHinges? Or nonlinearBeamColumn?

[fmk]

BeamWithHinges ad nonlinearBeamColumn are BOTH actually force beam column elements with different integration rules .. so there is no best as they are both the same .. the beamWithHinges (unless you are playing with the default) uses elastic section for all but end integration points so inelasticity will be concentrated there, the regular force beam column has nonlinear sections all along the length so there is the possibility if you have a girder that a hinge may form internally.

[javidsharifi]

Thank you. so the model I have prepared with nonlinearBeamColumn is probably suitably working. I shall check rotation at critical points manually chosen (middle and end points), is it right?

[fmk]

it depends on your model, so don't be asking me where the hinges are going to form.

[javidsharifi]

I meant OpenSees seemingly does not specify or give a hint about the probable location of plastic hinges and I'll need to figure it out manually. I was trying to ask for confirmation!
Also, I believe I have seen a command like plastic rotation somewhere in codes I have already inspected. But I cant find the command again. Does such a command exist? Or am I mixing it up?!
my kindest regards
Behtash - SUTech