## About the plastic rotation of the dispBeamColumn

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caosasa
Posts: 26
Joined: Sat Aug 07, 2010 5:31 am
Location: tongji

### About the plastic rotation of the dispBeamColumn

Dear all,
i am computing the plastic rotation of piers of bridge with OpenSees.
The pier is about 20 meters in elevation.
Fiber section and dispBeamColumn are used for all the elements.
Each element is 2 meters in length.
The number of the element is from bottom to top of the pier.
The element at the foot of the pier is number 1.
The plastic rotation of element 1 is -0.0033242, 0.00331776 for node 1, 2.
The plastic rotation of element 2 is -0.00160693, 0.00159828for node 2, 3.
i have two questions:
1. why the plastic rotations up and down node 2 are different? shouldn't they be identical?
2. can the plastic rotation of element 1 be computed as lp*(0.0033242+0.00331776)/2?
Thanks!

caosasa
Posts: 26
Joined: Sat Aug 07, 2010 5:31 am
Location: tongji

### Re: About the plastic rotation of the dispBeamColumn

Dear vesna, would you please consider my question? Thank you very much.

vesna
Posts: 3033
Joined: Tue May 23, 2006 11:23 am
Location: UC Berkeley

### Re: About the plastic rotation of the dispBeamColumn

I would avoid using plastic rotation recorder for nonlinear elements. I would rather use curvature and plastic hinge length to calculate plastic rotation.

caosasa
Posts: 26
Joined: Sat Aug 07, 2010 5:31 am
Location: tongji

### Re: About the plastic rotation of the dispBeamColumn

vesna wrote:
> To get plastic rotation of plastic hinges for element 1 here is the
> command:
>
> recorder Element -file Element1.out -time -ele 1 plasticDeformation
>
> The file will contain 4 columns. The 1st is time, the 2nd is axial plastic
> deformation, the 3rd is plastic rotation at node i, and the 4rt is plastic
> rotation at node j.

I saw your answer in the "how record the rotate in Hinges in steel frames" post to get
plastic rotation of plastic hinges. i am confused now:
1. why can't i use plastic rotation recorder in this situaion? is plastic rotation recorder
fit for beamwithhinges element, but not nonlinear elements?
2. how can i use curvature and plastic hinge length to calculate plastic rotation? would
you show me an example please? i have record the curvatures at integration points.
subtract the yielding curvature from it. calculate the plastic rotation with the integration
rule. isn't it?

vesna
Posts: 3033
Joined: Tue May 23, 2006 11:23 am
Location: UC Berkeley

### Re: About the plastic rotation of the dispBeamColumn

From the time I posted the answer on how to record the plastic rotation I had many users complaining about results that would not make sense. That is why I suggested not to use the recorder but to calculate it indirectly.

caosasa
Posts: 26
Joined: Sat Aug 07, 2010 5:31 am
Location: tongji

### Re: About the plastic rotation of the dispBeamColumn

I saw other users are also confused about how to compute the plastic rotation.
Would you please consider the question 2:
how can i use curvature and plastic hinge length to calculate plastic rotation? would
you show me an example please? i have record the curvatures at integration points.
subtract the yielding curvature from it. calculate the plastic rotation with the integration
rule. isn't it?

vesna
Posts: 3033
Joined: Tue May 23, 2006 11:23 am
Location: UC Berkeley

### Re: About the plastic rotation of the dispBeamColumn

if you search the message board you will find answer to your question.

paperairplane
Posts: 12
Joined: Mon Oct 29, 2012 11:49 pm

### Re: About the plastic rotation of the dispBeamColumn

Dear caosasa ,i still cannot understand why the ratation of node 2 are different?

caosasa
Posts: 26
Joined: Sat Aug 07, 2010 5:31 am
Location: tongji

### Re: About the plastic rotation of the dispBeamColumn

paperairplane wrote:
> Dear caosasa ,i still cannot understand why the ratation of node 2 are
> different?
i will send you a PDF about it.

paperairplane
Posts: 12
Joined: Mon Oct 29, 2012 11:49 pm

### Re: About the plastic rotation of the dispBeamColumn

caosasa wrote:
> paperairplane wrote:
> > Dear caosasa ,i still cannot understand why the ratation of node 2 are
> > different?
> i will send you a PDF about it.
shaohaiyipiao@gmail.com
thank you!

amir70007
Posts: 57
Joined: Sat Sep 20, 2008 11:13 pm
Location: Tehran-Amir Kabir University of Technology (Tehran Polytechnic)
Contact:

### Re: About the plastic rotation of the dispBeamColumn

Dear caosasa
Would you please send the PDF for me?
amir70007-@-yahoo.com
thank you

saijbz
Posts: 3
Joined: Sun Nov 18, 2012 7:00 pm

### Re: About the plastic rotation of the dispBeamColumn

Dear caosasa
Would you please send me the PDF too?
saijbz@126.com
thank you

linzhidan
Posts: 18
Joined: Sun Jan 16, 2011 9:40 pm
Location: Lanzhou University of Technology

### Re: About the plastic rotation of the dispBeamColumn

dear caosasa
would you plase send the pdf to me ?
zhidanlin@sina.com
thanks
and do you find the ways to calculate plastic rotation form curvature and plastic hinge length?

sabir
Posts: 12
Joined: Sat Mar 30, 2013 11:57 pm
Location: iau

### Re: About the plastic rotation of the dispBeamColumn

dear caosasa
would you plase send the pdf to me ?
sabir_lotfi@yahoo.com
thanks
"""and do you find the ways to calculate plastic rotation form curvature and plastic hinge length?""""""

please told me do you find the answer of question 2 (how can i use curvature and plastic hinge length to calculate plastic rotation)
Regards