Open the Geometry editor DesignModeler, assuming the disc is centered on the global origin, select the Tools > Symmetry > and set it to 2 planes and pick ZYPlane and XZPlane for the two planes and Generate.  If Symmetry Plane 2 remains yellow and doesn't accept the pick,change Model Type to Partial, then it will accept the input, and you can change it back to Full. This is a defect in the software. 

You will be left with a quarter of the circle. You may need to reattach the Convection BC in the Transient Thermal model (or not).

Refresh the project, then open the Model. The only BC you need in Static Structural is a Displacement on the table-touching face of Z = 0 leaving all others Free.

The part is now fully constrained by the two planes of symmetry and the one Displacement BC.