Parameter command for loads

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lorcancon
Posts: 25
Joined: Thu May 22, 2014 5:22 am
Location: Roughan & O Donovan

Parameter command for loads

Post by 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
Posts: 25
Joined: Thu May 22, 2014 5:22 am
Location: Roughan & O Donovan

Re: Parameter command for loads

Post by lorcancon »

Apologies, the first error is as follows:

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

Regards,
Lorcan.
lorcancon
Posts: 25
Joined: Thu May 22, 2014 5:22 am
Location: Roughan & O Donovan

Re: Parameter command for loads

Post by 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
Posts: 25
Joined: Thu May 22, 2014 5:22 am
Location: Roughan & O Donovan

Re: Parameter command for loads

Post by 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
Posts: 3
Joined: Thu Mar 14, 2019 8:41 pm
Location: HKUST

Re: Parameter command for loads

Post by 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
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