On a large RC model with more than 230.000 FE which consist of Bars and Panels (Slabs and Walls) the design of RC elements according EC2 last 'forever' or more than 6 hours. I noticed that if I save a substructure from that model (e.g. bars only) the design finishes in less than 5 minutes.
When trying to save substructure with all panels only the Status bar displays Results: Out-of date although the results are available in the original model and in the substructure with bars only.
If I save sustructure with one panel thickness, then the Status bar displays Results: Available which is Ok. Then during the design almost half of the panels have errors: 'Incomplete results for panel no.xx' and 'Incorrect reinforcement direction for panel no.xx' Also, after the design finishes, the Status bar displays Results:none and no Reinforcement Maps can be presented.
When design is perfomed on the original model for the panels which were marked as with errors I do not obtain any problems.
Why this happens? Is there any way to speed up calculation of plates and shells?