Recording and writing to an text file when using adaptive time steps

miran
Posts: 37
Joined: Wed Apr 29, 2020 7:15 pm

Re: Recording and writing to an text file when using adaptive time steps

Post by miran » Mon Jun 07, 2021 9:06 am

Ok, thank you!
There is another, more performant way to do it, without the MPCO recorder. During your analysis, you can write text files with only the desired results. 1 file for each node/element. You can do it either using the Monitor (it will write .plt files, which are actually text files) or creating standard OpenSees recorders. Then you can post process them in the STKO post processor with python.
I initially used the "recorder" command in OpenSees, but there seems to be an important limitation. When using the "recorder" command in OpenSees in combination with you code for adaptive time steps, the recorder command yields strange results. I haven't really figured out exactly what gets recorded, but a large portion of the steps are missing, and the time step and displacement are not matching. See screenshot below. When using constant time steps however, it works great. Since my model is highly non-linear, the adaptive time step is a life-saver. This is why I wanted to do it through the mpco-files. I will try to use the Monitor.

recorder.JPG
recorder.JPG (168.23 KiB) Viewed 118 times
Regards,

Miran Cemalovic
PhD Candidate
Department of Structural Engineering
Norwegian University of Science and Technology (NTNU)
NO-7491 Trondheim, Norway
https://www.ntnu.edu/employees/mirancem

STKO Team
Posts: 708
Joined: Tue Oct 29, 2019 8:45 am

Re: Recording and writing to an text file when using adaptive time steps

Post by STKO Team » Mon Jun 07, 2021 1:05 pm

adaptive time steps, the recorder command yields strange results. I haven't really figured out exactly what gets recorded, but a large portion of the steps are missing, and the time step and displacement are not matching.
mmm... this si strange, because the recorders should record only when the current time step is converged... As the MPCO recorder does. I will look into it.
In the meantime you can use the monitor. For sure it writes to files if and only if the current time step is converged, so it should work for you

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