rror when using zeroLengthSection and zeroLength elements for segment joint modeling

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jiayanghnu
Posts: 13
Joined: Wed Nov 29, 2023 9:56 am

rror when using zeroLengthSection and zeroLength elements for segment joint modeling

Post by jiayanghnu » Fri Sep 12, 2025 3:49 am

Dear STKO Support Team,
I built a numerical model of two tunnel segments using shell elements. To simulate the segment joints:
I used zeroLengthSection elements to represent the compression behavior of the joints.
I used zeroLength elements with uniaxialMaterial to represent the bolts in the joints, considering their tensile and shear behavior.
However, when I run the analysis, I encounter the following error:
MPCORecorder FATAL Error: trial_fiberdata.size() != trial_sec_id.size()
I strongly suspect the issue is related to my setup of the zeroLengthSection element and the zeroLength elements for the bolts, but I cannot identify the exact cause. Could you please help me check whether my modeling approach is correct, and why this error might occur?

Thank you very much for your support.

jiayanghnu
Posts: 13
Joined: Wed Nov 29, 2023 9:56 am

Re: rror when using zeroLengthSection and zeroLength elements for segment joint modeling

Post by jiayanghnu » Fri Sep 12, 2025 3:50 am

I have attached my original model file for your reference.
Attachments
Segment joint-9.10.rar
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STKO Team
Posts: 3066
Joined: Tue Oct 29, 2019 8:45 am

Re: rror when using zeroLengthSection and zeroLength elements for segment joint modeling

Post by STKO Team » Fri Sep 12, 2025 10:11 am

The zeroLengthSection does not give the correct output (for the MPCO recorder) when used with a fiber section. Unfortunately, we need to change the code in OpenSees to fix this.
Otherwise, you can simply avoid recording results in the zeroLength sections. To do so, you can create a selection set (and then a region) of all the geometries, excluding the interactions with zeroLength sections. The you can use this region in the mpco recorder to restrict the recording only to that selection

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