Help me please with this error

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Jean Domínguez
Posts: 22
Joined: Fri May 09, 2008 4:19 pm
Location: UCV

Help me please with this error

Post by Jean Domínguez »

I don´t post the model yet because is very big. it´s a 15 story 4 bay frame with nonlinear BeamColumn and BeamWithHinges elements. I´m trying to do a simple static analysis first but the model don´t run up.

OpenSees >source 15n82cpr.tcl
WARNING - ForceBeamColumn2d::update - failed to get compatible element forces &
deformations for element: 2(dW: << 1.20524e-011)
Domain::update - domain failed in update
LoadControl::update - model failed to update for new dU
WARNING NewtonRaphson::solveCurrentStep() -the Integrator failed in update()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 0 with domain at
load factor 0.1
OpenSees > analyze failed, returned: -3 error flag
OpenSees >
Venezuelan Foundation For Seismological Research
Earthquake Engineering Department
fmk
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Location: UC Berkeley
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Post by fmk »

element 2 is having problems .. usually means the sections are trashed and the flexibility based element just cannot figure out forces that agree with end deformations .. it is close to converging .. you can do 1 of a bunch o things:
1) try the -iter option on the element
2) tweak the section properties
3) reduce number of integration points.
4) use a different element type, if this is a column the beamWithHinges element should really be used.
5) consider that the element has failed and remove this element from the analysis at this point (you may need to look at ele end forces to see if element is carrying any load here .. if it goes away there will be unbalanced forces which other ele meeting at node are going to have to deal with at next step.)
Jean Domínguez
Posts: 22
Joined: Fri May 09, 2008 4:19 pm
Location: UCV

Post by Jean Domínguez »

Thanks FMK, the problem was in a sign error in the Clough material parameters. Now the model run, at least the static analysis.
Venezuelan Foundation For Seismological Research
Earthquake Engineering Department
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