Changing an element material after an analysis

[PabloEspinoza]

Dear DTKO team,

I was wondering whether it is possible to change an element's material after an static analysis.
This is because I'm trying to model a staged earth dam construction with the PM4SAND constitutive model and the stress state will change at every stage and so my calibrated soil model (stress dependent).

Thank you

[STKO Team]

Dear user,

OpenSees does not allow you to change material model during analysis.
However you can update certain material parameters during the analysis using the parameter and updateParameter analysis steps in STKO.
Of course you can change only those parameters provided by your specific material model.
For example, the PM4Sand allows you to update only these parameters:

• materialState: enforce elastic/elastoplastic response
• IntegrationScheme: change integration scheme (Explicit/Implicit)
• refShearModulus: change G0
• poissonRatio: change nu
• FirstCall: update first call, remove fabric
• voidRatio: change e_init
• PostShake: activate post shaking reconsolidation

To update material parameters for a certain group of geometries in your model:

1. create a selection set with all the geometries that should be affected by the material update
2. create a new AnalysisStep->Misc_commands->parameter. select the selection set previously defined, and write one of the aforementioned parameters in "Specific object arguments" attribute.
3. create a new AnalysisStep->Misc_commands->updateParameter. select the previously define parameter in the parameter attribute, and write the new value in newVal attribute

[PabloEspinoza]

Oh, too bad. I guess I'll have to stay with the single stage analysis.
Thank you for your reply STKO team