Parameter command for loads

[lorcancon]

Mike,

I've been trying to use the parameter command for element loads and I get the following error when I run a FORM analysis:

SearchWithStepSizeAndStepDirection::gradientStandardNormal() -
the norm of the gradient is zero.

The commands I'm using are as follows:

parameter $Paramtag randomVariable $RVtag loadPattern $LPtag elementLoad $eltag wy
parameter $Paramtag randomVariable $RVtag loadPattern $LPtag elementLoad $eltag P

I do not get any error when assigning a parameter to a nodal load. Do you know what the probem could be? Is it possible that these commands only work for certain types of elements?

Thanks,
Lorcan.

[lorcancon]

Apologies, the first error is as follows:

Parameter::Parameter 80 -- error encountered while attempting to identify parameter

Regards,
Lorcan.

[lorcancon]

Mike,

In relation to the parameter command for an element point load, I notice that in one of your past lectures you specified that the last argument can be Px, Py or xOverL. Surely you need to specify all of these variables for an element line load?

Thanks,
Lorcan.

[lorcancon]

Mike,

It seems I can get the linear element load working for 2D but not for 3D. I am using elastic elements in 3D. Should it be possible use the parameter command for these elements?

I still cannot make sense of the parameter command for element point loads.

Regards,
Lorcan.

[henryluo]

Hi, I also encounter the same problem when applying the command "addToparameter". The existing random variables can not be assigned to the materials in the fiber section and even the element load. "addComponent x --no objects were able to identify parameter” occurs on the window. I have tried many types of expressions, e.g. :
addToParameter 1 element $i section 1001 fibersection 1 material 1 fc
addToParameter 2 element $i section 1001 fibersection 1 material 2 fy
(1001 is the section tag for section aggregator and concrete 01 and steel 01 materials are used)
addToParameter 3 loadPattern 2 elementLoad $j wy

Have you found some information about this issue? Thanks in advance.
henry