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Typical warning message from LUSAS Solver text output file (*.OUT):


Most common causes & links to solutions 

If this occurs in a nonlinear analysis, we would recommend that you test your model on a linear analysis before setting non-linear & transient parameters since this will make it simpler to identify causes for failed analyses. There is a basic checklist on the User Area which is applicable to linear static analyses. 

The warning gives element numbers and these can be located in the model using

TreeView > Layers tab > Labels > (check) Element name (check) Label selected features only


Edit > Advanced selection

The most common cause of such a message is that there are insufficient supports assigned to the model.  It is necessary to ensure that there exist supports that restrain the entire model from rigid body movements.  The model should not be free to translate or rotate freely.  More common causes on a page of related warnings

Continued difficulties? Try the pivot checklist

More on cause & theory links

More on negative pivots  

Use of the option in Solution Control "Continue solution if more than one negative pivot occurs" should be used with care, as it is likely to hide more fundamental analysis problems. It invokes the LUSAS option number 62. 

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Any modelling, design and analysis capabilities described are dependent upon the LUSAS software product, version and option in use.