PM4Sand Material

Command_Manual
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  - uniaxialMaterial
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  - frictionModel
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    - fix
    - fixX
    - fixY
    - fixZ
  - mp commands
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  - pattern
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  - block commands
    - block2D
    - block3D
  - region
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- Analysis Commands
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  - recorder
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- Misc Commands
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  - Template:DataBaseCommandsMenu

This command is used to construct a 2-dimensional PM4Sand material.

nDmaterial PM4Sand $matTag $Dr $G0 $hpo $Den <$patm $h0 $emax $emin $nb $nd $Ado $zmax $cz $ce $phic $nu $cgd $cdr $ckaf $Q $R $m $Fsed_min $p_sedo>

$matTag	integer tag identifying material
Primary:
$Dr	Relative density, in fraction
$G0	Shear modulus constant
$hpo	Contraction rate parameter
$Den	Mass density of the material
Secondary:
$P_atm	Optional, Atmospheric pressure
$h0	Optional, Variable that adjusts the ratio of plastic modulus to elastic modulus
$emax and $emin	Optional, Maximum and minimum void ratios
$nb	Optional, Bounding surface parameter, $nb ≥ 0
$nd	Optional, Dilatancy surface parameter $nd ≥ 0
$Ado	Optional, Dilatancy parameter, will be computed at the time of initialization if input value is negative
$z_max	Optional, Fabric-dilatancy tensor parameter
$cz	Optional, Fabric-dilatancy tensor parameter
$ce	Optional, Variable that adjusts the rate of strain accumulation in cyclic loading
$phic	Optional, Critical state effective friction angle
$nu	Optional, Poisson's ratio
$cgd	Optional, Variable that adjusts degradation of elastic modulus with accumulation of fabric
$cdr	Optional, Variable that controls the rotated dilatancy surface
$ckaf	Optional, Variable that controls the effect that sustained static shear stresses have on plastic modulus
$Q	Optional, Critical state line parameter
$R	Optional, Critical state line parameter
$m	Optional, Yield surface constant (radius of yield surface in stress ratio space)
$Fsed_min	Optional, Variable that controls the minimum value the reduction factor of the elastic moduli can get during reconsolidation
$p_sedo	Optional, Mean effective stress up to which reconsolidation strains are enhanced

The material formulation for the PM4Sand object is "PlaneStrain"

Code Developed by: Long Chen, Pedro Arduino, U Washington

Notes

Valid Element Recorder queries are
- stress, strain
- alpha (or backstressratio) for <math>\mathbf{\alpha}</math>
- fabric for <math>\mathbf{z}</math>
- alpha_in (or alphain) for <math>\mathbf{\alpha_{in}}</math>

e.g.
 recorder Element -eleRange 1 $numElem -time -file stress.out  stress

Elastic or Elastoplastic response could be enforced by

Elastic:	updateMaterialStage -material $matTag -stage 0
Elastoplastic:	updateMaterialStage -material $matTag -stage 1

If default values are used for secondary parameters, the model must be initialized after elastic gravity stage by

setParameter -value 0 -ele $elementTag FirstCall $matTag

Post-shake reconsolidation can be activated by

setParameter -value 0 -ele $elementTag Postshake $matTag

Example

This example, provides an undrained confined direct simple shear test using one 4-node SSPQuadUP element and PM4Sand material model.

# HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH #
# 2D Undrained Direct Simple Shear Test Using One Element #
# University of Washington, Department of Civil and Environmental Eng   #
# Geotechnical Eng Group, L. Chen, P. Arduino - Jan 2018               #
# Basic Units are m, kN and s unless otherwise specified				#
# HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH #

wipe

# ------------------------ #
# Test Specific parameters #
# ------------------------ #
# Initial Vertical Stress
set sigvo -101.3
set K0 0.5
# set Poisson's ratio to match user specified K0
set nu [expr $K0 / (1+$K0)]
# Deviatoric strain (Cyclic)
set devDisp 0.10
# Permeablity
set perm 1.0e-9
# Initial void ratio
# relative density
set Dr 0.35   
# max and min void ratio  
set emax 0.8
set emin 0.5
set eInit [expr $emax - ($emax - $emin)*$Dr ]
# other primary parameters
set G0 476.0
set hpo 0.53
set rho 1.42

# Rayleigh damping parameter
set damp   0.02
set omega1 0.2
set omega2 20.0
set a1 [expr 2.0*$damp/($omega1+$omega2)]
set a0 [expr $a1*$omega1*$omega2]

# HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
# HHHHHHHHHHHHHHHHHHHHHHHHHHHCreate ModelHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
# HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

# Create a 2D model with 3 Degrees of Freedom
model BasicBuilder -ndm 2 -ndf 3

# Create nodes
node 1	0.0	0.0
node 2	1.0	0.0
node 3 	1.0	1.0	
node 4	0.0	1.0

# Create Fixities
fix 1 	1 1 1
fix 2 	1 1 1
fix 3	0 0 1
fix 4 	0 0 1
 
equalDOF 3 4 1 2

# Create material
#          PM4Sand  tag    Dr   G0   hpo   den  Patm  h0     emax   emin  nb   nd  Ado   zmax    cz    ce     phicv  nu 
nDMaterial PM4Sand   1    $Dr  $G0  $hpo  $rho 101.3 -1.00   $emax  $emin 0.5  0.1  -1.0  -1.0  250.0  -1.00  33.0  $nu
										 
# Create element
element SSPquadUP   1     1 2 3 4    1  1.0   2.2e6 1.0 $perm $perm $eInit  1.0e-5

# Create recorders
recorder Node  -nodeRange 1 4  -time -file Cycdisp.out  -dof 1 2 disp
recorder Node  -nodeRange 1 4  -time -file Cycpress.out -dof 3 vel
recorder Element -ele 1 -time -file Cycstress.out stress
recorder Element -ele 1 -time -file Cycstrain.out strain

# Create analysis
constraints Transformation
test        NormDispIncr 1.0e-5 35 1
algorithm   Newton
numberer    RCM
system      BandGeneral
integrator  Newmark [expr 5.0 / 6.0] [expr  4.0 / 9.0]
rayleigh    $a0 $a1 0.0 0.0
analysis    Transient

# Apply consolidation pressure
set pNode [expr $sigvo / 2.0]
pattern Plain 1 {Series -time {0 100 1e10} -values {0 1 1} -factor 1} {
	load 3  0.0  $pNode 0.0
	load 4  0.0  $pNode 0.0
}
updateMaterialStage -material 1 -stage 0

analyze 100 1
set vDisp [nodeDisp 3 2]
set ts1 "{Series -time {100 80000 1.0e10} -values {1.0 1.0 1.0} -factor 1}"
eval "pattern Plain 2 $ts1 {
	sp 3 2 $vDisp
	sp 4 2 $vDisp
}"

# Close drainage valves
for {set x 1} {$x< 5} {incr x} {
   remove sp $x 3
}

analyze 25 1
puts "Removed drainage fixities."

updateMaterialStage -material 1 -stage 1
setParameter -value 0 -ele 1 FirstCall 1
analyze 25 1

puts "finished update fixties"

set ts2 "{Series -time {150 5150 1.0e10} -values {0.0 1.0 1.0} -factor 1}"

eval "pattern Plain 3 $ts2 {
	sp 3 1 $devDisp
}"
# update Poisson's ratio for analysis
setParameter -value 0.3 -ele 1 poissonRatio 1
analyze 5000 1

wipe

References

R.W.Boulanger, K.Ziotopoulou. "PM4Sand(Version 3.1): A Sand Plasticity Model for Earthquake Engineering Applications". Report No. UCD/CGM-17/01 2017

PM4Sand Material

Notes

Example

References

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