Update Truss Material

[dschmuhl]

Hello all,

I would like to know if there is a way to update the material model used for a truss element during analysis, i.e.

#
element truss $eleTag $iNode $jNode $A $matTag
# do some things here
# update $matTag to $matTag1
# do some more things
#

I have tried parameterizing the material using:
parameter element $eleTag material $matTag
...but it will not let me do that. Any help is appreciated!

Dan

[fmk]

that is not an option available to a truss .. you can set a parameter in a material, but you cannot change the material .. if you need to do this you have to write some source code.

[dschmuhl]

Thanks for the reply!

Should the parameter command work for any material, or is it only a certain subset of materials? I'm using Steel02 for my truss element, but the parameter command does not seem to want to let me specify a parameter within the Steel02 material. For example, I cannot get this to work:

#
set matTag 6
uniaxialMaterial Steel02 $matTag [expr 60.0*$ksi] [expr 29000*$ksi] 0.01 20 0.85 0.15
#-------
element truss 1 1 2 0.1 $matTag
parameter 1 element 1 material $matTag Fy
#

The only thing I've been able to get "parameter" to work with so far is "A" (area) in a truss element (i.e. parameter 1 element 1 A). I've tried a few other things besides the above example with, but to no avail. Am I doing something wrong with syntax or is parameter just not supported for every material?

[fmk]

it depends on the material. it is not a well documented part of the code as people put it in for their research. i am afreaid the best source for what is available is to look at the source code.

you wan to look at what is implemented for the setParameter, updateParameter methods in the source code of the different materials and the truss element:
http://opensees.berkeley.edu/WebSVN/lis ... niaxial%2F

http://opensees.berkeley.edu/WebSVN/lis ... 2Ftruss%2F

[dschmuhl]

I suspected the situation surrounding the parameter and updateParameter commands was as you said as it seemed the documentation on them was fairly light. Thank you for the links to the source code though, I appreciate it! I will make the best of it and see what I come up with!