About changed damping ratio for every one time step

[cicilixiaoran]

Hello! Everyone, If I regression the formulation of the η=a*pow(σ,b) , where , η is hysteresis damping coefficient, σ is the maximum stress of the section of column bottom , and δ=η/2 ,where δ is damping ratio, I want to extraction the section strain of every one time step, and multiplied by elastic modulus, then get η using η=a*pow(σ,b) ,and get δ using δ=η/2. I want to simulate the damping ratio which is changed for every one time step. How to do it? My code is as follows:
set mm 1;
set kN 1;
set s 1;
set xDamp 0.02;
set lambda [eigen 1];
set omega [expr pow($lambda,0.5)];
set alphaM 0.;
set betaKcurr 0.;
set betaKcomm [expr 2.*$xDamp/($omega)];
set betaKinit 0.;
rayleigh $alphaM $betaKcurr $betaKinit $betaKcomm;
set ok 0;
set controlTime [getTime];
while {$controlTime < $TmaxAnalysis && $ok == 0} {
set controlTime [getTime]
set ok [analyze 1 $DtAnalysis]
recorder Element -file $dataDir/DefoColSec1.out -time -ele 1 section 1 deformation;
set outFileID [open data/DefoColSec1.out r]
set bb [read $outFileID]
close $outFileID
set yibuslch [lindex $bb 1]
set yibusl [expr abs($yibuslch)];
set sigma [expr $yibusl*$Ec*1000.0];
set yita [expr a*pow($sigma,b)];
set lambda [eigen 1];
set omega [expr pow($lambda,0.5)];
set xDamp [expr $yita/2];
set outFileIDxDamp [open data/xDamp.out "a"]
puts $outFileIDxDamp $xDamp;
close $outFileIDxDamp
set alphaM 0.;
set betaKcurr 0.;
set betaKcomm [expr 2.*$ xDamp /($omega)];
set betaKinit 0.;
rayleigh $alphaM $betaKcurr $betaKinit $betaKcomm;
}
But when I open the xDamp.out, the file only record the changed damping ratio of forepart time series, and the damping ratio of the rest time series are constant. Why? How to simulate the changed damping ratio which is stress related for every one time step? Thank you!

[vesna]

You cannot use recorder to give you stress in the process of analysis since the output files are written after you finish the analysis and exit OpenSees.exe. However you can get the stress you need and use it inside of analysis loop by using eleResponse command: http://opensees.berkeley.edu/wiki/index ... se_Command

[cicilixiaoran]

Hello vesna, thank you very much for your reply,this problem is solved according to your suggestion.

Best regards.
cicilixiaoran