Problem with imposing displacement

[redwood]

Hi,

I have a 2D model consisting of truss elements. I need to impose displacements on some of the nodes and run a static analysis. When I run the code, it gives error. But when I replace truss elements with 2D beam elements, it works. In the following, I copied the code for a simply supported truss element. Please help me find where the problem is.

Thanks,

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wipe;
model BasicBuilder -ndm 2 -ndf 2;

node 1 0 0;
node 2 1.0 0;

fix 1 1 1;
fix 2 0 1;

uniaxialMaterial Elastic 1 1000.0
element truss 2 1 2 1.0 1

recorder Node -file DBase.out -time -node 1 2 -dof 1 2 disp;
recorder Node -file RBase.out -time -node 1 2 -dof 1 2 reaction;

set SupportNode 2;
set GMdirection 1;

set DispSeries "Series -dt 1.0 -values {0.0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01}"

pattern MultipleSupport 1 {
groundMotion 1 Plain -disp $DispSeries
imposedMotion $SupportNode $GMdirection 1
};

system BandSPD
constraints Transformation
numberer RCM
test EnergyIncr 1.e-5 6 0;
algorithm Newton;
integrator LoadControl 0.9
analysis Static

analyze 10

[fmk]

the problem is you have zero unknowns. break the truss into two elements. otherwise build a bigger model as i doubt this is the model you need this type of results for.

[redwood]

thanks Frank