Isn't there any ways to set up parameters for pinching4?

[chris]

Hello
From a few months ago, I am trying to find way to decide parameters for pinching4 model. But I can't find any good ways... ^^

So in my research, I just assumed several values for pinching4.
But reviewers ask how realistic these values are.

Even though I sent email to researhers of UW, I can't get any reply.
Maybe they seems to be very busy...

Isn't there anyone have ideas ?

In this message board, I found several questions related with this topic.
But I can't find any good ways...

Give me some help...
Thanks...

[silvia]

the way i see it, they are all the paramters on the curve.
the material is meant to match some experimental curve you have. so there's nothing "realistic" about it, or maybe everything.
it's just a tool to define a pinched curve.
you might want to consider using the hysteretic material, wich is very similar, and very reliable.

so, you have to define the parameters to what fits your curve. it's not like concrete material or something, or maybe it is.
here is what I have, when i was trying to match my steel and hysteretic materials:

Code: Select all

# ----------------------------------------------------------------------------------- 
# LibMaterialsPinching4.tcl:  define this material
#			by Silvia Mazzoni, 2006


##########pinching4 Material
set ePf4 [expr  0.2 * $Fu];	 # force point on the positive response envelope
set ePd4 [expr 10*$epsU];	 # deformation point on the positive response envelope
set rDispP 0.8;	 # ratio of the deformation at which reloading occurs to the maximum historic deformation demand -- SM: match hysteretic
set rForceP 0.2;	 # ratio of the force at which reloading begins to force corresponding to the maximum historic deformation demand -- SM: match hysteretic
set uForceP 0.0;	 # ratio of strength developed upon unloading from negative load to the maximum strength developed under monotonic loading -- SM: match hysteretic
set gK1 1.0;	 # cyclic degradation model for unloading stiffness degradation -- SM: values taken from documentation example
set gK2 0.2;	 # cyclic degradation model for unloading stiffness degradation -- SM: values taken from documentation example
set gK3 0.3;	 # cyclic degradation model for unloading stiffness degradation -- SM: values taken from documentation example
set gK4 0.2;	 # cyclic degradation model for unloading stiffness degradation -- SM: values taken from documentation example
set gKLim 0.9;	 # cyclic degradation model for unloading stiffness degradation -- SM: values taken from documentation example
set gD1 0.5;	 # cyclic degradation model for reloading stiffness degradation -- SM: values taken from documentation example
set gD2 0.5;	 # cyclic degradation model for reloading stiffness degradation -- SM: values taken from documentation example
set gD3 2.0;	 # cyclic degradation model for reloading stiffness degradation -- SM: values taken from documentation example
set gD4 2.0;	 # cyclic degradation model for reloading stiffness degradation -- SM: values taken from documentation example
set gDLim 0.5;	 # cyclic degradation model for reloading stiffness degradation -- SM: values taken from documentation example
set gF1 1.0;	 # cyclic degradation model for strength degradation -- SM: values taken from documentation example
set gF2 0.0;	 # cyclic degradation model for strength degradation -- SM: values taken from documentation example
set gF3 1.0;	 # cyclic degradation model for strength degradation -- SM: values taken from documentation example
set gF4 1.0;	 # cyclic degradation model for strength degradation -- SM: values taken from documentation example
set gFLim 0.9;	 # cyclic degradation model for strength degradation -- SM: values taken from documentation example
set gE 10;	 # define maximum energy dissipation under cyclic loading. Total energy dissipation capacity is defined as this factor multiplied by the energy dissipated under monotonic loading. -- SM: values taken from documentation example
set dmgType "energy";	 # type of damage (option: "cycle", "energy") -- SM: values taken from documentation example
 
if {  [info exists imat ] != 1} {set imat 0};		# set value only if it has not been defined previously.
uniaxialMaterial Pinching4 	[set IDPinching4 [incr imat 1]] 	$Fy $epsY $Fy1 $epsY1 $Fu $epsU $ePf4 $ePd4 $rDispP $rForceP $uForceP $gK1 $gK2 $gK3 $gK4 $gKLim $gD1 $gD2 $gD3 $gD4 $gDLim $gF1 $gF2 $gF3 $gF4 $gFLim $gE $dmgType