gravity analysis fails

[vahidbarzegar]

hi,
I have modeled a shear wall with forceBeamColumn element.
Gravity analysis can't be performed even with zero loads; while the problem can be solved by increasing the amount of steel reinforcement.
what's the problem?

[fmk]

your model has issues .. start with elastic elements, then nonliner with elastic section, then nonlinear with fiber sections and elastic materials .. check the periods of each model to ensure almost exactly the same.

[vahidbarzegar]

I performed what you said and the periods are almost the same:
T(elastic element)=0.789 sec
T(fiber with elastic material)=0.784 sec
T(nonlinear fiber section)=0.777 sec
what should i do now?

[fmk]

and it still fails with 0 loads?? .. what is the error?

[vahidbarzegar]

I've just found out that there is a problem with leaning columns. The model works fine without leaning columns.
gravity analysis works fine with elastic wall element and fiber with elastic material with the leaning columns.
here is the leaning column script:

uniaxialMaterial Elastic $strutMatT $EStrut;
#leaning column nodes
node 301 42. 0 -mass 0.01 0.01 0.01
node 302 42. 4.500 -mass 0.01 0.01 0.01
node 303 42. 8.500 -mass 0.01 0.01 0.01
node 304 42. 12.500 -mass 0.01 0.01 0.01
node 305 42. 16.500 -mass 0.01 0.01 0.01
node 306 42. 20.500 -mass 0.01 0.01 0.01
node 307 42. 24.500 -mass 0.01 0.01 0.01
node 308 42. 28.500 -mass 0.01 0.01 0.01
node 309 42. 32.500 -mass 0.01 0.01 0.01

fix 301 1 1 1;

#leaning column elements
element elasticBeamColumn 5011 301 302 1.0 200000000.0 0.0 1
element elasticBeamColumn 5021 302 303 1.0 200000000.0 100.0 1
element elasticBeamColumn 5031 303 304 1.0 200000000.0 0.0 1
element elasticBeamColumn 5041 304 305 1.0 200000000.0 100.0 1
element elasticBeamColumn 5051 305 306 1.0 200000000.0 0.0 1
element elasticBeamColumn 5061 306 307 1.0 200000000.0 100.0 1
element elasticBeamColumn 5071 307 308 1.0 200000000.0 0.0 1
element elasticBeamColumn 5081 308 309 1.0 200000000.0 100.0 1

#leaning column connection to wall
element truss 5022 202052 302 1.0 599
element truss 5032 203052 303 1.0 599
element truss 5042 204052 304 1.0 599
element truss 5052 205052 305 1.0 599
element truss 5062 206052 306 1.0 599
element truss 5072 207052 307 1.0 599
element truss 5082 208052 308 1.0 599
element truss 5092 209052 309 1.0 599

the error is:
WARNING: CTestRelativeNormDispIncr::test() - failed to converge
after: 10 iterations
NewtnRaphson::solveCurrentStep() -the ConvergenceTest object failed in test()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 0 with domain at
load factor 0.1
OpenSees > analyze failed, returned: -3 error flag
***Gravity load application failed!!

[fmk]

just use a small I for I in cols as opposed to making ones big and small .. don't know what material 599 looks like, probably elastic and E is possibly too big or small.