Plot stress-strain curve

[marcoita]

Hi everyone,

I want to check the material I am using for an analysis so I want to display the backbone curve of the material before the analysis. Is there a way I can do it?
Moreover if at the end of the analysis (moment-curvature) I want to plot the Moment-curvature diagram, it appears just for a second and then it suddenly disappears. Does anyone know why?

Thank you!

Marco

[zvidrih]

Hi Marco,

simply create a .tcl with zerolength element (or whatever element) with your material, load the "free" node and record the force-displacement relationship. Later you can reuse this script for testing of any material (backbone or hysteresis)...

[marcoita]

Hi Zlatko,

thank you for your reply. I did what you said but my record is empty and I do not understand why (error in loading??). Here it is my .tcl file, I would really appreciate if you can test it and help me. Thank you.

Marco

model BasicBuilder -ndm 2 -ndf 3

file mkdir Data;

#---geometric parameters--------
set al 0.3; # section height
set la 0.3; # section lenght
set cf 0.042; # concrete cover
#-------------------------------

# ---material properties-----
set fy 391300.; # [kPa]
set fc 24900.; # [kPa]
#-------------------------

#----fiber-------------
set ncf 2; # n° fiber in cover
set nynuc 25; # n° fiber along al
set nznuc 25; # n° fiber along la
set ny [expr $nynuc+(2*$ncf)];
set nz [expr $nznuc+(2*$ncf)];
#--------------------------------

#---bars diameter----------------
set f_16 0.016; # 16 mm
set A_16 [expr 3.14159*(pow($f_16,2)/4)];
set nb_up 0; # n° of superior rebars
set nb_dw 0; # n° of inferior rebars
#-----------------------------------------------

#---bars diameter----------------
set f_18 0.018; # 18 mm
set A_18 [expr 3.14159*(pow($f_18,2)/4)];
set nb_up1 3; # n° of superior rebars
set nb_dw1 3; # n° of inferior rebars

#-----hoop------------------------------------------
set f_st 0.008; # 8 mm
set s 0.1; # hooop spacing 10 cm
set nbracciax 2;
set nbracciay 2;

#---material identification number---------
set CC 5; # confined concrete (Kent-Park)
set CP 7; # cover concrete (Kent-Park - Concrete01)
set Acc 3; # rebar steel
#----------------------------

set z1 [expr ($la/2)-$cf]
set z4 $z1

set z2 [expr -($z1)]
set z3 $z2

set z5 [expr ($la/2)]
set z8 $z5
set z9 $z5
set z12 $z5

set z6 [expr -($z5)]
set z7 $z6
set z10 $z6
set z11 $z6


set y1 [expr -($al/2)+$cf]
set y2 $y1
set y9 $y1
set y10 $y1

set y3 [expr -($y1)]
set y4 $y3
set y11 $y3
set y12 $y3

set y5 [expr -($al/2)]
set y6 $y5

set y7 [expr -($y5)]
set y8 $y7


#-------MATERIALS---------------

#----STEEL_01:BILINEAR---------------------------------------------------------------3
set Fy 391300.; [kPa]
set Ea 206000000.; [kPa]
set epsy [expr $Fy/$Ea];
set b 0.;
uniaxialMaterial Steel01 3 $Fy $Ea $b;
#--------------------------------------------------------------------------------------

#----CONCRETE_01:KENT-SCOTT-PARK-----------------------confined concrete--------------------------------
uniaxialMaterial Concrete01 5 18767.368 0.0022611 3753.47 0.020417;
#-----------------------------------------------------------------------------------------------------

#----CONCRETE_01:KENT-SCOTT-PARK---------------------unconfined concrete----------------------------------7
uniaxialMaterial Concrete01 7 16600. 0.002 3320. 0.00506;
#--------------------------------------------------------------------------------------------------------

set sezRett 3;

section fiberSec $sezRett {
patch quad $CC $nynuc $nznuc $y1 $z1 $y2 $z2 $y3 $z3 $y4 $z4
patch quad $CP $ny $ncf $y5 $z5 $y6 $z6 $y10 $z10 $y9 $z9
patch quad $CP $ny $ncf $y2 $z2 $y10 $z10 $y11 $z11 $y3 $z3
patch quad $CP $ncf $nznuc $y12 $z12 $y11 $z11 $y7 $z7 $y8 $z8
patch quad $CP $ncf $nznuc $y9 $z9 $y1 $z1 $y4 $z4 $y12 $z12

layer straight $Acc $nb_up $A_16 $y1 $z1 $y2 $z2
layer straight $Acc $nb_up1 $A_18 $y1 $z1 $y2 $z2
layer straight $Acc $nb_dw $A_16 $y4 $z4 $y3 $z3
layer straight $Acc $nb_dw1 $A_18 $y4 $z4 $y3 $z3
}


set axialLoad -400; # + Tension, - Compression


# Define two nodes at (0,0)
node 1001 0.0 0.0
node 1002 0.0 0.0

# Fix all degrees of freedom except axial and bending
fix 1001 1 1 1
fix 1002 0 1 0


# Define element
# tag ndI ndJ secTag
element zeroLengthSection 2001 1001 1002 $sezRett


# Define constant axial load
pattern Plain 3001 "Constant" {
load 1002 $axialLoad 0.0 0.0
}

# Define analysis parameters
integrator LoadControl 0 1 0 0
system SparseGeneral -piv; # Overkill, but may need the pivoting!
test EnergyIncr 1.0e-9 10
numberer Plain
constraints Plain
algorithm Newton
analysis Static

# Do one analysis for constant axial load
analyze 1

# Create recorder
recorder Element -file ele1sec1StressStrain.out –time -ele 2001 section 1 fiber 0.14 0 $CP stressStrain;
recorder Element -file Data/sez1Ele1StressStrainAcc.out -time -ele 2001 section fiber $y3 $z3 $Acc stressStrain;
recorder Element -file Data/sez1Ele1StressStrainCC.out -time -ele 2001 section fiber 0.08 0 $CC stressStrain;


puts OK

[gerber]

the recorder command should be before the analyze command !