How to Determine whether Soil Pressure is pressure or tension

[JoeH78]

I have difficulties when deciding whether the obtained soil pressure values are compression or tension under the foundation, Definition of soil springs under the footing is compression only, bottom and inward defined, For quick check I test the values of soil pressure obtained for dead loads only and software reports possitive value for all, If I check only for the quake loading then only the small portion of foundation is receiving the negative values.

The structure is slightly eccentric canopy which is suppoerted only by columns on one side, and whole canopy is cantilevered. So I would expect the very negative soil values ( tension ) since it will be forced for overturning moments during sesimic loading. I 'd like to know the logic of sap2000 of for soil pressure, I couldn't find the comprehensive description in the manual.

 

[ENGIRL]

Sap2000 reports stress values on one face of the of the fondation, top or bottom. Did you check both?
One thing that helps me see if the The structure is experiencing tension or compression is by plotting deflection.