I attached a really simple model for the purpose of checking the analytical results of hand calcs. I wanted to check the robot design of the footings against my hand calcs. That said, I can't even get the model to run. I get a type 3 instability warning. Any idea how to get this model to run? Maybe I'm modeling grade beams wrong.
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Elastic ground acts only in local Z direction so you need to apply restraints in UX UY direction - example - green rectangles below
Ground beams are rotated upside down so uplift in your case must me in the direction on -z
It may happen that some simple cases (with lateral loads) may not converge without vertical loads. Set thme as auxiliary cases and run calculations only for combinations containing these cases.
Corrected model attached.