How can I get the bending moment of the first floor?

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chenghung
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Joined: Tue Feb 08, 2022 9:01 am

How can I get the bending moment of the first floor?

Post by chenghung » Sun Jul 02, 2023 10:27 am

Dear STKO Team,
I want to get the right bending moment at the node of the first floor (only 2e-05 N), but I can only get the base bending moment( about 400000 N), how can I solve it? Thank you!
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STKO Team
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Joined: Tue Oct 29, 2019 8:45 am

Re: How can I get the bending moment of the first floor?

Post by STKO Team » Tue Jul 04, 2023 8:03 am

It's because you are extracting it as a reaction force. Of course the reaction will be non-zero only at fixed nodes. At the floor level you could try to export (from gauss points) the section.force result (pay attention: it's in local coordinates)

chenghung
Posts: 3
Joined: Tue Feb 08, 2022 9:01 am

Re: How can I get the bending moment of the first floor?

Post by chenghung » Tue Jul 11, 2023 6:50 am

Thanks for the response, but is there any way to obtain the moment at nodes? The moment from Gauss points are still a little bit different from column moments in ETABS. Thanks a lot. (Moments and Rotations at Gauss points have already correspond with hinges in ETABS. )
Hung

STKO Team
Posts: 2301
Joined: Tue Oct 29, 2019 8:45 am

Re: How can I get the bending moment of the first floor?

Post by STKO Team » Mon Jul 17, 2023 10:20 am

If you are using Lobatto integration in columns, then the last gauss points are located exactly at the end-nodes, so it should be the same.
Are you sure the models (OpenSees and ETABS) are actually equal?

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