dispBeamColumn convergence problem

[Strep]

Dear all,

I'm trying to do a simple gravity (static) analysis of an RC 1 bay 1 floor frame.
For the column and beam i use fiber section and dispBeamColumn elements (4 elements for the column and 21 elements for the beam).
I use the eleLoad command for the gravity loads.

The analysis fails with the above message:

WARNING: CTestEnergyIncr::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
-3


I also tried the convergence script from the examples. I got some steps but then it failed again.

But when i use only 2 elements for the beam i get no error.

Is there any limitation about the number of dispBeamColumn elements i may use?

[fmk]

there is no limit on number of elements .. it all depends on the model .. sometimes if you have too many elements and the sections have a possible negative slope on moment-rotation curve all hell will break loose trying to converge to a solution if yielding starts to spread along elements .. (this can occu if you only use 1 force beam column element and see the message about convergence problems in the element ,, by using multiple dispBeamColumn elements you are having to deal with the problem at the scripting level)

why don't you put a 1 at the end of your test command to see what is happening to the norms .. you can also put a 4 if you want to see the actual dX and dR vectors.