Hyperbolic Gap and Elastic PP Gap are not working

[gopaladhikari]

Hi there,

I was trying to use Hyperbolic Gap and Elastic PP Gap material in my analysis of a bridge abutment. It appears both models are not working with OpenSeesPy. I used both materials few years ago with tcl scripts. I am wondering whether I made any mistake in defining the material models. Below is examples of the material definition. The elastic PP model is however working fine. Any help is greatly appreciated.

Code: Select all

abutTag = 21
abutK = 200000.0
abutRf = 0.85
abutFu = -3730.0
abutGap = -0.01

ops.uniaxialMaterial('HyperbolicGapMaterial', abutTag, abutK, abutK, abutRf, abutFu, abutGap)
ops.uniaxialMaterial('ElasticPPGap', abutTag, abutK, abutFu, abutGap)

The error message is below.

WARNING: numeric analysis returns 1 -- Umfpackgenlinsolver::solve
DisplacementControl::newStep(void) - failed in solver
StaticAnalysis::analyze() - the Integrator failed at iteration: 0 with domain at load factor 0
OpenSees > analyze failed, returned: -2 error flag

[mhscott]

Can you make a similar model in Tcl to see if you get the same errors? You may want to put the materials in parallel with a very soft elastic material, it looks like zero stiffness is causing the analysis to fail in solving the equations.

[gopaladhikari]

Thanks Prof.

It is now working in parallel with a very soft elastic spring under monotonic loading. But the material models work fine under a cyclic loading though, without any need of a soft elastic spring.

cheers,
Gopal