Update

[Jhno]

Hi,
is there a way to update particular values of material? Example, I use the Drucker-Prager material, the command is as follow :
nDMaterial DruckerPrager $matTag $k $G $sigmaY $rho $rhoBar $Kinf $Ko $delta1 $delta2 $H $theta $density
Then, during analysis, I want to change the value of k to.. say 2*k.
I guess I could remove element $eleTag with the assigned material ... then remake the element... then define a new material. This process is time consuming and frustrating especially when you have alot of elements! Is there a way around this? Thanks.

[selimgunay]

I don't think there is a shortcut to do this other than the way that you described. There are some hybrid simulation studies that update the materials and elements in OpenSees during the simulation, but I believe those are not implemented in the standard version. If interested, I can refer to a paper and you can contact the author

[rafal]

You can use 'parameter' and 'updateParameter' OpenSees commands. See the docs for the syntax. You can use this approach when the materials of interests have setParameter method in cpp source files.


From OpenSees/SRC/material/nD/UWmaterials/DruckerPrager.cpp
we have:

-----------------------------------------------------------------------------
....
int DruckerPrager::setParameter(const char **argv, int argc, Parameter &param)
{
if (strcmp(argv[0],"materialState") == 0) {
// switch elastic/plastic state
return param.addObject(5,this);
} else if (strcmp(argv[0],"frictionalStrength") == 0) {
// update rho parameter
return param.addObject(7,this);
} else if (strcmp(argv[0],"nonassociativeTerm") == 0) {
// update nonassociative rho_bar parameter
return param.addObject(8,this);
} else if (strcmp(argv[0],"cohesiveIntercept") == 0) {
// update zero confinement yield strength
return param.addObject(9,this);
} else if (strcmp(argv[0],"shearModulus") == 0) {
// update shear modulus
return param.addObject(10,this);
} else if (strcmp(argv[0],"bulkModulus") == 0) {
// update bulk modulus
return param.addObject(11,this);
} else if (strcmp(argv[0],"updateMaterialStage") == 0) {
return -1;
} else {
// invalid parameter type
opserr << "WARNING: invalid parameter command for DruckerPrager nDMaterial with tag: " << this->getTag() << endln;
return -1;
}
...
-------------------------------

It means you can set parameter and then update it. Look at the examples here:

http://opensees.berkeley.edu/wiki/index ... oil_Column

HTH

[Jhno]

Thanks for the info!