Modal participation factors

[berktaftali]

Does anyone has a script/code to calculate modal participation ratios in OpenSees?

[erol kalkan]

For MPF computation,

compute [story mass x eigen vector at the master joint] at each story and sum them up. It will be the modal participation factor.

I did some changes in the code to get directly the eigen vectors at certain node number, I wrote a command for that

[nodeEigen "nodenumber" "direction"] with that one to get the eigen vector at any node and at any time of the analysis is trivial. if you need I can send you the compiled opensees exe file or more info.

Hope this help,
E. Kalkan
ekalkan@ucdavis.edu

[berktaftali]

I'm also using a modified version of OpenSees, so the your executeable won't work with my models. The code underlying the

Code: Select all

nodeEigen

command and a script showing the MPF calculations will be very helpful, though...

Thanks in advance...

[silvia]

this is why scripts are more handy, as they are more transferrable.
Berk,
please let me know if you do write such a script.

[erol kalkan]

Hope that one helps, c++ code is as follows

The class added under Globals for nodeeigen comand is:

int
nodeEigen(ClientData clientData, Tcl_Interp *interp, int argc, TCL_Char **argv)
{

if (argc < 3) {
opserr << "WARNING want - nodeEigen nodeTag? dof?\n";
return TCL_ERROR;
}

int tag, dof;

if (Tcl_GetInt(interp, argv[1], &tag) != TCL_OK) {
opserr << "WARNING nodeEigen nodeTag? dof? - could not read nodeTag? \n";
return TCL_ERROR;
}
if (Tcl_GetInt(interp, argv[2], &dof) != TCL_OK) {
opserr << "WARNING nodeEigen nodeTag? dof? - could not read dof? \n";
return TCL_ERROR;
}

Node *theNode = theDomain.getNode(tag);
double value = 0.0;
if (theNode != 0) {
const Matrix dispe = theNode->getEigenvectors();
value = dispe(0,dof-1); // RETURNS only first 3 modes
}

sprintf(interp->result,"%35.20f",value);

return TCL_OK;
}

before using "nodeeigen" command call the [eigen] in opensees.

For the script to compute MPFs, I dont have any generic but case-specific.
I will try to put in a generic form and will post here.

[fmk]

it is also calculated in this example script.

http://opensees.berkeley.edu/community/ ... .php?t=426

[Ricsey]

Do you looking for this? I wrote a code which is model independant:
proc calculate_modalmass { modeNum dir } {
#################################################
#Calcuates modal masses in $modeNum at $dir with:
#
#(fi_transpose * M * fi)^2
#fi: eigenvector
#M: mass diagonal matrix
#################################################

# Calculate modal mass in actual direction
set NODES [getNodeTags]

set modalMassUP 0.0
set modalMassDOWN 0.0

set totalMass 0.0
foreach node $NODES {
set actualMass [nodeMass $node $dir]
set totalMass [expr $totalMass + $actualMass]
}

foreach node $NODES {
set m [nodeMass $node $dir]
set fi [nodeEigenvector $node $modeNum $dir]
set iota 1.0
set modalMassUP [expr $modalMassUP + $m*$fi*$iota]
for {set dof 1} {$dof < 7} {incr dof} {
set fi_dof [nodeEigenvector $node $modeNum $dof]
set m_dof [nodeMass $node $dof]
set modalMassDOWN [expr $modalMassDOWN + $fi_dof**2*$m_dof]
}
}

set modalMass [expr $modalMassUP**2 / $modalMassDOWN]

return [expr $modalMass/$totalMass]
}

#USAGE
set modeShapes 4
eigen $modeShapes
puts "X\tY\tZ"
for {set mode 1} {$mode < $modeShapes} {incr mode} {
puts "[calculate_modalmass $mode 1] [calculate_modalmass $mode 2] [calculate_modalmass $mode 3]"
}