Pro-Mechanica Constraints

Hello,
I'm using Pro-Mechanica at present for the modelling of water storage tanks, as part of our engineering department's work on low-cost
domestic rainwater harvesting.
Having made solid models of possible tank designs, I now want to apply suitable constraints for the FEA analysis. Ideally I would like to be able to constrain the base of the tank such that any displacement downwards would generate a resistive force that increased with displacement (probably linearly), but that any displacement upwards would not generate any resistive external force.
I seem to remember the old Pro-Engineer version of mechanica having a spring constraint option in the constraint dialogue box, but in Wildfire the options are now free, constrained, or specified displacement.
Does anyone have any advice?
Thanks,
Gwilym Gwilym
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Yes - I finally found the time to look this up... The spring is an element in independent Wildfire Mechanica (not a constraint) you give it a stiffness under Properties.
In integrated mode you go to Model/Idealizations/Spring and put it in. -D
Gwilym wrote:

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