fiber section recorders do not record stress/strain

[arashs]

Hi all;

I'm modelling a prestressed pile and I'm using InitStrainMaterial to introduce prestressing strains to my material. here is my material model for strands:

uniaxialMaterial ElasticPPGap 1 200e9 1700e6 0.0001 0.018
uniaxialMaterial InitStrainMaterial 2 1 0.006

So basically I'm introducing an initial 0.006 strain to my ElasticPPGap material model. and for the concrete model I've defined these materials:


uniaxialMaterial Concrete01 3 -27.6 -0.002 0 -0.005
uniaxialMaterial InitStrainMaterial 4 3 -0.000831

Then I assign my material model to my column section. I've already tested my column section with rebars(steel 01) and plain concrete materials and it works perfect, but when I replace these materials with prestressed ones that's when the problem begins. I have two questions here:

1) why section recorders do not record stress/strain when I introduce the initial strains??
2) does anyone know of any better way to define materials for prestressd piles??

Thanks you in advance!

[fmk]

does the analysis work with the InitStrain material? beacuase the material should respond as a normal material. a reason for the no response is that the analysis failed and hence the question.

[arashs]

Thanks for the reply. The analysis works fine and so the node reaction recorders , only the recorders for prestrained materials do not work, so if I only Initstrain my steel and leave concrete unstrained initially, then recorders for steel would not work while for concrete work just fine. Is there any better way to model prestress columns?