1-story, 2-bay RC frame dynamic simulation

[michaelchen]

I am trying to simulate a 1-story, 2-bay RC frame experiment. I have built the model and when I try to do the dynamic EQ analysis, it can not run successfully.
I wrote some "Puts" between my code, so I figured out that "Rayleigh Damp" might be the problem. But I don't konw how to correct it.
Here is my code:

source LibAnalysisDynamicParameters.tcl; # constraintsHandler,DOFnumberer,system-ofequations,convergenceTest,solutionAlgorithm,integrator
puts "3"
# ------------ define & apply damping
# RAYLEIGH damping parameters, Where to put M/K-prop damping, switches (http://opensees.berkeley.edu/OpenSees/m ... l/1099.htm)
# D=$alphaM*M + $betaKcurr*Kcurrent + $betaKcomm*KlastCommit + $beatKinit*$Kinitial
set xDamp 0.037; # damping ratio
set MpropSwitch 1.0;
set KcurrSwitch 0.0;
set KcommSwitch 1.0;
set KinitSwitch 0.0;
puts "4"
set nEigenI 1; # mode 1
set nEigenJ 3; # mode 3
puts "5"
set lambdaN [eigen [expr $nEigenJ]]; # eigenvalue analysis for nEigenJ modes
set lambdaI [lindex $lambdaN [expr $nEigenI-1]]; # eigenvalue mode i
set lambdaJ [lindex $lambdaN [expr $nEigenJ-1]]; # eigenvalue mode j
puts "6"
set omegaI [expr pow($lambdaI,0.5)];
puts "7"
set omegaJ [expr pow($lambdaJ,0.5)];
puts "8"
set alphaM [expr $MpropSwitch*$xDamp*(2*$omegaI*$omegaJ)/($omegaI+$omegaJ)]; # M-prop. damping; D = alphaM*M
set betaKcurr [expr $KcurrSwitch*2.*$xDamp/($omegaI+$omegaJ)]; # current-K; +beatKcurr*KCurrent
set betaKcomm [expr $KcommSwitch*2.*$xDamp/($omegaI+$omegaJ)]; # last-committed K; +betaKcomm*KlastCommitt
set betaKinit [expr $KinitSwitch*2.*$xDamp/($omegaI+$omegaJ)]; # initial-K; +beatKinit*Kini
puts "9"
# define damping
rayleigh $alphaM $betaKcurr $betaKinit $betaKcomm; # RAYLEIGH damping

when I run my code, the model is built successfully, but it shows "domain error: argument not in valid range" just after "6" and the progress stopped. No warning or anything else.
would you please help me?

[mhscott]

You must have negative eigenvalues. Check your model's boundary conditions and element connectivity.

[michaelchen]

mhscott wrote:
> You must have negative eigenvalues. Check your model's boundary conditions
> and element connectivity.

Thanks for your reply!
I thought it may be this reason, but I do not know how to fix it.
Could you please tell me which command I should check?
I fix my three support nodes by "fix 1 1 1 1".
And where should I check about "element connectivity"?
Looking forward to your reply.

[michaelchen]

mhscott wrote:
> You must have negative eigenvalues. Check your model's boundary conditions
> and element connectivity.

Dear Professor mhscott,
I used "constraints Transformation" when I got the problem I mentioned above.
When I tried "constraints Lagrange", Opensees showed numbers of "Warning" and I can not even see them clearly. And the window shut down automatically.
Can you help me with that?
Please give me more information to improve my model.