Plastic hinges

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javidsharifi
Posts: 66
Joined: Sat Oct 06, 2012 11:08 am
Location: shiraz university of technology

Plastic hinges

Post by 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
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Re: Plastic hinges

Post by 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
Posts: 66
Joined: Sat Oct 06, 2012 11:08 am
Location: shiraz university of technology

Re: Plastic hinges

Post by 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
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Re: Plastic hinges

Post by 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
Posts: 66
Joined: Sat Oct 06, 2012 11:08 am
Location: shiraz university of technology

Re: Plastic hinges

Post by 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
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Re: Plastic hinges

Post by fmk »

it depends on your model, so don't be asking me where the hinges are going to form.
javidsharifi
Posts: 66
Joined: Sat Oct 06, 2012 11:08 am
Location: shiraz university of technology

Re: Plastic hinges

Post by 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
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