Test cantilever column, error: could not invert flexibility

[kyen]

Hi guys,

I'm testing the built-in uniaxial material: "ElasticBilin", with a cantilever column. As I build up the simple structure without applying any force, an error occurred "could not invert flexibility".
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The following is my code:

wipe;
model basic -ndm 2 -ndf 3;

node 1001 0 0
node 1002 0 10

fix 1001 1 1 1

geomTransf Linear 10001

uniaxialMaterial ElasticBilin 2001 1000 0.1 0.8 1e-8 1e-8 1e-8;

section Uniaxial 3001 2001 P;

element nonlinearBeamColumn 4001 1001 1002 2 3001 10001;
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error message:
ForceBeamColumn2d::update() -- could not invert flexibility
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Thank you in advance.

kyen

[kyen]

To follow up:

I tried applying flexural material to the section, and then it worked. Is this because the flexibility matrix would contain '0' in the diagonal terms if I don't assign flexural material? And this is true in the case with only axial force?

Thanks,
kyen