Output data

[kavir]

HI
I use element recorder for record ele force in following form:

recorder Element -file "$dataDIR/$subDIR3/element134force.txt" -ele 134 globalForce
and model is 2D
the output file consist of six columns.but in opensees wiki has been written "the output follows the order of the degrees of freedom

globalForce
2D, 3dof: FX FY MZ

one row of my results is: -1964.35 2295.11 -162.936 1964.35 -2295.11 86.5711
What are the last three numbers represent?
What is the last number?

[nskok]

There are six columns because the reactions at the two nodes of the element are being recorded.
Columns 1 and 4 are horizontal reactions; 2 and 5 are vertical reactions; 3 and 6 are end moments.

-Nick

[kavir]

Thank you so much, nskok

[kavir]

Hi
What is Basic Force and Basic Deformation? ( force beam column element)

[lorcancon]

I had another question in relation to this.

I have a 3D model and I want to assign a variable to a particular force output (e.g. set a variable "A" equal to the bending moment in a member). Is it possible to do this for elastic beamcolumn elements? I know I can set a variable equal to the entire response using the eleResponse command, but I would like to set variables for each individual response to load.

Thanks in advance,
Lorcan Connolly.

[nskok]

Kavir,

From this document, it looks like the basic forces are at the end nodes of the element and are used to compute the sectional and material reactions. So maybe the basicForce recorder just saves those end forces and not the forces computed from the finite approximation? I'm not sure. I suggest trying to the different recorders and comparing their results. http://opensees.berkeley.edu/wiki/image ... EvsDBE.pdf

Lorcan,

One way to accomplish your objective is using the "lindex" command in Tcl. The eleResponse command returns a list and the lindex command can be used to select values from it. The first value in the list has an index of 0. See http://www.tcl.tk/man/tcl8.4/TclCmd/lindex.htm

- Nick

Example:

# Store the moment at nodeI of an element
set eleNum 111
set momentI [lindex [eleResponse $eleNum forces] 2]
puts "Moment: $momentI"

[lorcancon]

Nick,

Thanks very much. This worked perfectly.

Lorcan.

[lorcancon]

Nick,

I had another question. Is it also possible to assign a variable to an element property (e.g. Area). I realize the same lindex command could be used. but in this case, It is not an element response but an element property that is required.

Thanks again,
Lorcan.

[nskok]

I'm glad it worked!

So do you want to use a command similar to "eleResponse" in order to get a property of an element? If so, I do not know a direct command to do this, and I guess I do not understand the motivation behind this. When I create elements, I usually assign all of their parameters to variables and then reference them with the element command. That way if I need to use them later on in the code I refer to them again.

- Nick

[lorcancon]

Nick,

I am working with a large model with a lot of elasticBeamColumn elements and I want to create a loop which will automatically apply self weight as a line load for all elements. Something like the following:

foreach elem [getEleTags] {
set area [lindex [eleResponse $elem] 4]; # Here we need to get the area of element with tag "$elem"
set unitW 7.85; # For example - Unit weight of material (steel)
set Wz [expr $area*9.81*unitW]
pattern Plain 1 Linear{
eleLoad $elem -type -beamUniform $Wz
}
}

However, the "eleResponse" command only gives information about responses to loads. We require a command here which gives a list of element properties (e.g. stiffness, inertia, Area etc). If there was such a command, we could obtain the area for each element tag. Maybe there's another way of applying self-weight to different elastic members?

Regards,
Lorcan

[nskok]

I think the easiest way to accomplish this is to create lists for all of properties of the elements and use those to assign all of the values. It's important that across all of the lists the list values correspond to the appropriate elements, otherwise you'll incorrectly assign properties to elements.

- Nick

# Example
set elem_list [list 111 121 131 141 151]
set area_list [list 10. 20. 20. 20. 10.]
set unitW 7.85

foreach elem $elem_list area $area_list {
set Wz [expr $area*9.81*$unitW]

pattern Plain 1 Linear {
eleLoad $elem -type -beamUniform $Wz
}
}

[lorcancon]

Nick,

Thanks again for your quick reply. I'll give this a go.

Lorcan.

[duyduan]

HI everyone,
I am modeling an 3D bridge structure. Please help me to explain the output of element forces of piers. The output table has 12 columns, so, how is meaning of each column?
Thank you very much.

[fmk]

it dpenends n the element and what you asked for in the recorder .. if beam elements and you asked for forces the results are 6 end forces at each end acting in the global direction, 3 translational (Fx,Fy,Fz) and 3 moment (Mx, My, Mz) .. the forces are listed for end1 first and then end2. Fx1 Fy1 Fz1 Mx1 My1 Mz1 Fx2 Fy2 Fz2 Mx2 My2 Mz2.

[duyduan]

Dear fmk,
Thank you very much for your answer.