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FAQ 000221 | My model is stiffened by tension members. The calculation is terminated with the message about instability. How can I finish the calculation?
First Steps with RFEM
QuestionMy model is stiffened by tension members. The calculation is terminated with the message about instability. How can I finish the calculation?
The calculation can be terminated due to an unstable structural system for various reasons. There can be a 'real' instability due to overloading the system, but the instability effects may also be caused by failing members.
In the calulcation parameters, you can deactivate the nonlinearity 'Members due to member type' (see Figure 01). If the calculation is then possible without the error message, the problem is probably caused by failing members.
The complete failure of the tension members can be prevented using the option 'Failing Members to Be Removed Individually During Successive Iterations' in the dialog box Global Calculation Parameters (see Figure 02). This should help in most cases. The number of possible iterations should be specified sufficiently large.
An alternative method is to apply a prestress to the tension members to prevent the failure of them.
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