circular slab on springs

[jamalsid]

Hello

I have a problem with a model of a circular slab on spring supports. 

I have two questions related to this model that I cant seem to find any similar posts about so would appreciate some help.

dropbox link to model 

In the linked model above I have a large circular panel surrounded by smaller panels. It was split up this way to allow the outer panels to have a different thickness. 

1. My first question relates to the support conditions. I had originally specified supprts that where fixed in directions x and y with a spring in z. But my line manager upon reviewing the model suggested I should be modelling the springs as free in x and y with a spring in z. So i changed the supports accordingly but get instability errors that I cannot determine the cause of. I am assuming this must be related to the changes in the supports but do not understand the problem.

2. My second question is more of a general circular slab modelling issue. I would like to plot colour fields for the radial and circumferential moment plots (assuming question 1 can be fixed). The local axes of the outer panels are essentially radial but the large inner panel has local axes to match the global axes. How can be sure that the moment plots are for a polar coordinate system?

Any help would be appreciated.

[Rafacascudo · Accepted solution]

1- Yes , you got to have horizontal supports even if you have only vertical loads, otherwise instability warnings will pop up

2-On Results/maps click on Selection of direction and choose "Polar" , input the center of your circle  , and then the result maps for all your panels will be according to these "polar"  axes

XX will be radial and YY will be circunferencial moments/forces

[jamalsid]

Thankyou.

I figured as much but just wanted a little reassurance.