I run a lot of FEA (have for years) and though I am somewhat proficient at using FEA for part refinement I have always wondered about properly constraining a table.  In the past I have just put roller/slider constraints on 3 of the 4 feet and fixed the fourth foot but this always forces an S-Shape condition on the legs because the foot is not allowed to lift from the table.  The same applies to most any constraints I can think of (they will affect the natural movement of the weldment under load).  Any advice on how to constrain this model and allow the feet to properly lift and slide under load?

I have attached images of the model (with a floor drawn in) and a drawing of the two conditions I speak of above.

Thanks!