Question about equalDOF command

[UniverstyToronto]

Hi everyone,

I am trying to use the equalDOF command to connect a column to a cantilever structure but the analysis fails prematurely (ConvergenceTest Object Failed). The reason I am using the equalDOF command is to avoid transferring rotation from the column to the cantilever structure. I noticed even if I constraint all the degrees of freedom (transnational and rotational) the analysis fails. But if I connect the column to the cantilever structure using the elasticBeamColumn elements, the analysis works fine. I provided my 2D model in the following. I would appreciate if you can help me to figure out the problem. If there is another method to connect the two structures without transferring rotation, please inform me.

Also, please note that I have to use SP command to apply the displacement loads because of other limitations and I can not change that part.

Thanks

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# units: kip, inch, sec
file mkdir output; # create data directory
model BasicBuilder -ndm 2 -ndf 3; # Define the model builder, ndm=#dimension, ndf=#dofs

# Cantilever nodes
node 1 0.0 0.0;
node 2 0.0 100.0;
node 3 0.0 200.0;
# Column nodes
node 4 0.0 100.0;
node 5 0.0 150.0;
node 6 0.0 200.0;

# Constraints
equalDOF 2 4 1 2; # or equalDOF 2 4 1 2 3;
equalDOF 3 6 1; # or equalDOF 3 6 1 2 3;

# Single point constraints -- Boundary Conditions
fix 1 1 1 1;

# MATERIAL parameters
set H 8;
set W 8;
set A [expr $H*$W];
set Iz [expr 1./12.*$W*pow($H,3)];
set Ec 3600; #kips/in2

# define geometric transformation:
set TransfTag 1;
geomTransf Linear $TransfTag;

#Cantilever Elements
element elasticBeamColumn 1 1 2 $A $Ec $Iz $TransfTag;
element elasticBeamColumn 2 2 3 $A $Ec $Iz $TransfTag;
#Column Elements
element elasticBeamColumn 3 4 5 $A $Ec $Iz $TransfTag;
element elasticBeamColumn 4 5 6 $A $Ec $Iz $TransfTag;

# create load pattern
pattern Plain 4 Linear {;
sp 5 1 1;
}

system BandGeneral;
constraints Penalty 1E20 1E20;
numberer RCM;
test NormDispIncr 1.0e-8 50 0
algorithm Newton;
integrator LoadControl 0.01;
analysis Static;
set ok [analyze 1000];
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[selimgunay]

Are you sure that your node coordinates are correct? It looks like you have two different elements between the same two points

[UniverstyToronto]

Hi Selimgunay,

Can you please specify which elements do you mean? I defined the column at exactly same coordinates of the cantilever structure. Even if I define the column at different nodal coordinates like the following, the model fails prematurely at the first load stage.
Nodes for column
node 4 -100.0 100.0;
node 5 -100.0 150.0;
node 6 -100.0 200.0;