hysteretic material (damage1)

[kcorproro]

Hi, please I need help to understand the term damage1 due to ductility in hysteretic material , model by Filippou and Scott, the code in opensees is:


TloadIndicator = 1;
if (Cstress <= 0.0) {
TrotNu = Cstrain - Cstress/(Eun*kn);
double energy = CenergyD - 0.5*Cstress/(Eun*kn)*Cstress;

double damfc = 0.0;

if (CrotMin < rot1n) {

damfc = damfc2*energy/energyA;

damfc += damfc1*(CrotMin-rot1n)/rot1n;

}

TrotMax = CrotMax*(1.0+damfc);

}
}
REF: http://opensees.berkeley.edu/WebSVN/bla ... pp&peg=785

what is "CrotMax"? max strain in each ciclic due displacement history (input)? fmk could me explain briefly , how the model reduced strength in each cyclic?
Thanks you.

[skamalzare]

When materials change volume (almost always beyond their elastic limit), they undergo damage in their structure. This damage affects their response in subsequent cycles of loading, basically making them softer. Damage1 parameter is trying to include this effect. Have a look at the parametric study in Wiki:

http://opensees.berkeley.edu/OpenSees/m ... l/4052.htm

Check the last three studies, especially results from run 10. You can see that when, damage1 = 0.02, the material has experienced extreme softening (in Run 10), while when this parameter is zero, no softening happens.

Bests,
Soheil

[kcorproro]

thank for your answer skamalzare,but I need the rule this parameter, the damage due ductility is according displacement history.