It's not uncommon to occasionally see models with geometry issues such as entities that are very close to - but not quite - co-planar. Such small inconsistencies can cause issues with many operations, such as load decomposition and analysis, and should be avoided. Such issues rarely result from modeling directly in Tekla Structural Designer (TSD), but may more commonly occur for import of models with geometry issues from other applications, such as Revit. The new Planarize tool can assist you in resolving these inconsistencies by allowing you to move nodes of not-quite co-planar entities into the ‘correct’ target plane, as selected by you.
To run Planarize, you right-click on the target grid line (the one on which entities are correctly modeled) in any view and select Planarize FRM <grid ref>. This identifies the target plane into which nodes can be moved, and opens the Planarize properties. See the short video above for a demonstration of the Planarize tool helping to quickly alleviate common modeling errors.