Home Forums NextFEM Designer support forum Plastic Hinge Monitoring

This topic contains 10 replies, has 4 voices, and was last updated by  fp 2 months ago.

Viewing 11 posts - 1 through 11 (of 11 total)
  • Author
    Posts
  • #2482

    IMAN MANSOURI
    Participant

    Hi

    How can we find the location of plastic hinges in OpenSees?

    Thanks!

    #2490

    Admin NextFEM
    Keymaster

    It depends on how the plastic hinges have been modelled. Please upload a simple file to let us check.

    #2491

    IMAN MANSOURI
    Participant

    Thank you so much for your attention.
    I have attached a 2-story frame under pushover analysis.

    Thanks :)

    Attachments:
    You must be logged in to view attached files.
    #2498

    Admin NextFEM
    Keymaster

    In the attached file, hinges are modelled inside the beam element (dispBeamColumn), so they cannot be displayed since they formed into the fiber element.

    #2499

    IMAN MANSOURI
    Participant

    Yes, so what is your suggestion?

    #2501

    Admin NextFEM
    Keymaster

    If you can switch solver, use the one included in Designer and keep working with hinges.
    If you like to maintain the use of Opensees, use separate elements for hinges.

    #2503

    IMAN MANSOURI
    Participant

    Thank you for the comments. Is there any video that shows how we can do a nonlinear analysis using your product?

    #2506

    Admin NextFEM
    Keymaster

    Not yet, we will add it soon.

    #2512

    Nadia Mirzai
    Participant

    Hi

    In my opinion, to monitor the formation of plastic hinges I found the most accurate way is to check the strain value in each section.
    As you know, in OpenSees we mesh the section to several fibers.
    Using the below command we can get the values of strain in each fiber for the integration points (usually number of integration points is 5; so we have 5 sections).

    ecorder Element -file $dataDir/StressStrain51_Sec1.out -ele 51 section 1 fiber $fiberCoordinateZ $fiberCoordinateY stressStrain

    ecorder Element -file $dataDir/StressStrain51_Sec5.out -ele 51 section 5 fiber $fiberCoordinateZ $fiberCoordinateY stressStrain

    We should extract the maximum strain among the fibers of each section. Then, we can compare it with the yield strain (e.g. the attached photo show this ration in 5 stations (integration points) for each element).

    This technique needs to generate many many output files (above command). But I do not know that is NextFEM able to do such post-processing or not?

    Attachments:
    You must be logged in to view attached files.
    #2514

    Nadia Mirzai
    Participant

    In the following of my comments, I would like to add that recently I made a Matlab code for generation of the mentioned “recorder” command. For a 2-bay and 2-story frame, 8000 commands were generated (total number of fibers = 8000).
    The volume of files was over 14 GB!

    I think if NextFEM is able to do such post-processing it would be great!

    #2515

    fp
    Moderator

    NextFem Designer at the moment supports the import of simple datasets containing a single integer value for each node or element for each step. That was supposed to work in conjunction with the procedure009.tcl file given with our program (look for the checkProc parameter to be passed to the functions). The current capability seems quite limiting with respect to the use you want to make of it. We cannot however exclude a wider support for additional datasets capabilities in the future.
    As a side note you may want to reduce the number of fibers monitored to those where yield is likely to occur, like the top and tips of the flanges or the midpoint of the web if shear also plays a big role.

Viewing 11 posts - 1 through 11 (of 11 total)

You must be logged in to reply to this topic.