Material fail in gravity load

[majidzar]

Hi,
I have RC frame with two bay and one story with Gravity loading and cycling loading
when I put Gravity loads on the beams(on the bay between columns) an error occur in opensees "Uniaxial material::setTrial<> material fail in setTrialStrian<> Large Trial compressive strain"
This error repeat many time and at the end this error appear: DisplacementControl::update_model fail to update for new dU
WARNING AcceleratedNewton::solveCurrentStep<>_the Integration failed in update
StaticAnalysis::analyze<>-the Algorithm Failed at iteration:0 with domain at load factor 1.79421
analyze failed returned :-3 error flag

But when I put gravity loads exactly on the columns( on the joints ) the error disappear and i get good result and also if I cancel cycling loading and puts just gravity load on beams it is OK. I mean gravity loading on beam with cycling load dose not work but gravity load on the columns with cycling load work well. why?

my model is fiber and all of elements on the frame is dispBeamColumn element.
I divided the beams to 4 element and put the load on the nodes of the beams and also my model have to cantilever beams and I want to put gravity loads on them.

please help me to put the gravity loads on beams.

pattern Plain 1 "Constant" {
load 14 0 -$Py 0 0 0 0
load 16 0 -$Py 0 0 0 0
load 18 0 -$Py 0 0 0 0
load 20 0 -$Py 0 0 0 0
load 22 0 -$Py 0 0 0 0
load 24 0 -$Py 0 0 0 0
}

set GravSteps 10;
integrator LoadControl [expr 1./$GravSteps];
system BandGeneral
test NormDispIncr 1.0e-4 2000 0
constraints Plain
numberer Plain
algorithm KrylovNewton
analysis Static
analyze $GravSteps
loadConst -time 0.0 # keep gravity load and restart time lead to lateral-load analysis
wipeAnalysis


set Px [expr $Weight/8];; # Reference lateral load

#Set lateral load pattern with a Linear TimeSeries
pattern Plain 2 "Linear" {
load 17 $Px 0 0 0 0 0
load 21 $Px 0 0 0 0 0
}

# Define analysis parameters

system BandGeneral
test NormDispIncr 1.0e-4 2000
numberer Plain
constraints Plain
algorithm KrylovNewton
analysis Static


set dU1 0.1
set dU2 -0.1

# Perform the analysis
integrator DisplacementControl 19 1 $dU1
analyze 20
integrator DisplacementControl 19 1 $dU2
analyze 39
integrator DisplacementControl 19 1 $dU1
analyze 39
integrator DisplacementControl 19 1 $dU2
analyze 39
integrator DisplacementControl 19 1 $dU1
analyze 39
integrator DisplacementControl 19 1 $dU2
analyze 39
integrator DisplacementControl 19 1 $dU1
analyze 19
###############################################

Thanks

[fmk]

i would suggest either your materials are defined incorrectly, your section is too small or the loads are too great!

[majidzar]

if materials are defined incorrectly or section is too small or the loads are too great why the model work well without cycling loading? I mean my RC frame stable just with gravity loading. but gravity loading with cycling load appear this error.
why?

[majidzar]

I have found the answer Thanks fmk I correct the section
I reduce the fiber in the beam section and the problem disappear