# Unstable model in calculation

**URL:** <https://community.dlubal.com/t/instabiles-modell-bei-berechnung/1790>\
**Category:** Product Support\
**Tags:** addon-steel-design, rfem-6, stability-check\
**Created:** [September 1, 2025, 7:30am UTC](https://community.dlubal.com/t/instabiles-modell-bei-berechnung/1790 "2025-09-01T07:30:24Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Darek](https://community.dlubal.com/user_avatar/community.dlubal.com/darek/32/76_2.png) [@Darek](https://community.dlubal.com/u/Darek)\
**Post date:** [September 1, 2025, 7:30am UTC](https://community.dlubal.com/t/instabiles-modell-bei-berechnung/1790/1 "2025-09-01T07:30:24Z")

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Hello everyone,

I am trying to design a steel container, but my model is unstable. Can you tell me what might be causing this?

Best regards  
Darek

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**Author:** ![clemens.gutmann](https://community.dlubal.com/user_avatar/community.dlubal.com/clemens.gutmann/32/1585_2.png) [@clemens.gutmann](https://community.dlubal.com/u/clemens.gutmann)\
**Post date:** [September 1, 2025, 7:53am UTC](https://community.dlubal.com/t/instabiles-modell-bei-berechnung/1790/3 "2025-09-01T07:53:42Z")

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Hi Darek,

Thank you very much for your question.

Instabilities can have various causes. In the following FAQ, we have listed the most common causes. Have a look to see if any of the points are helpful for you:

[Finding and fixing instabilities in calculations: cause analysis and solutions](https://www.dlubal.com/de/support-und-schulungen/support/faq/005345)

Best regards  
Clemens Gutmann

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<div class="post-metadata">

**Author:** ![Darek](https://community.dlubal.com/user_avatar/community.dlubal.com/darek/32/76_2.png) [@Darek](https://community.dlubal.com/u/Darek)\
**Post date:** [September 1, 2025, 7:54am UTC](https://community.dlubal.com/t/instabiles-modell-bei-berechnung/1790/4 "2025-09-01T07:54:10Z")

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Hello Clemens,

it was a numerical problem. Due to the shortening of the supports, the bracing failed, so I assigned a minimal compressive force to the tension members. After that, the calculation ran through :)

Thanks for the link to your FAQ... that helped me a lot.

Best regards