Reversed Cyclic Displacement Control

Forum for OpenSees users to post questions, comments, etc. on the use of the OpenSees interpreter, OpenSees.exe

Moderators: silvia, selimgunay, Moderators

Post Reply
dapkraken
Posts: 15
Joined: Thu Aug 23, 2007 5:22 pm

Reversed Cyclic Displacement Control

Post by dapkraken »

Hello

I am trying to run apply a displacement history (varying amplitudes) I obtained from a test to a model. I am using the code below but I don't get my analysis to do a cycle and instead it keeps loading monotonically.
I have also tried changing the integrator to LoadControl but the analysis quits as soon as nonlinearities appear in the material. I have reviewed also example 4 for the implementation of reversed cyclic loading but it does not work either on my model.

Please if you can offer some advice I will appreciate it. Thank you

# Load Pattern Definition #
set filename OSBeamModel1200GFC16_DispHistory.dat
set NumSteps 10000
set ControlNode 2
set dofControlNode 2
set DxPattern 1; # Pattern Tag
pattern Plain $DxPattern "Series -dt 1.0 -filePath $filename -factor 1.0" {
sp $ControlNode $dofControlNode 1.0
}
# --------------------------------------------------------------------------------#
# Analysis Definition #
constraints Penalty 1e15 1e15
numberer RCM
system FullGeneral
test EnergyIncr 1.0e-8 50 0
algorithm Newton
set Dmax -2.5966;
set Dinc -0.00025966;
integrator DisplacementControl $ControlNode $dofControlNode $Dinc;
analysis Static
set ok [analyze $NumSteps];
fmk
Site Admin
Posts: 5884
Joined: Fri Jun 11, 2004 2:33 pm
Location: UC Berkeley
Contact:

Re: Reversed Cyclic Displacement Control

Post by fmk »

you either want displacement control or load control.
1) if you specify displacement control you are looking to determine load factor to apply to get change in displacement you want. for your case, you would place loads inside the load pattern and change the displacement increment at each step to reflect the change in displacements from the displacement history file of uours.
2) if load control, you impose the displacements as you are doing. you may experience problems in convergence due to the size of the Penalty factors. DispNorm is a better choice when using Penalty as the penalty factors in the form of applied forces do not appear in the test check.
dapkraken
Posts: 15
Joined: Thu Aug 23, 2007 5:22 pm

Re: Reversed Cyclic Displacement Control

Post by dapkraken »

Frank I forgot to thank you for your reply. It solved the problem.
Post Reply