Convergence problems in PDelta transformation

[Prayag Sayani]

Hello,

I am doing pushover analysis of a 3 story 4 bay 2D frame using
(a). Uniaxialsection (Section aggregator) and (b) UniaxialFiberSection.

When I use Linear Transformation, both the cases works just fine.

But when I use P-Delta transformation, I am getting convergence problems. I am using 100 load steps in both Linear and PDelta transformation.
I am getting following error.

WARNING: CTestNormDispIncr::test() - failed to converge
after: 10 iterations
NewtnRaphson::solveCurrentStep() -the ConvergenceTest object failed in test()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 19 with domain at
load factor 1
OpenSees > analyze failed, returned: -3 error flag
DispControl Analysis FAILED
Do you wish to continue y/n ?


When I use only 10 load steps (instead of 100) in PDelta transformation case, it works just fine.
I want to know what’s going on inside? Why is it giving me error when I use higher load steps.

Thanks,

[silvia]

find out what is happening at that time step.