View source for PM4Silt Material (Beta)

{{CommandManualMenu}}

This command is used to construct a 2-dimensional PM4Silt material.

{| 
| style="background:yellow; color:black; width:800px" | '''nDMaterial PM4Silt $matTag $S_u $Su_Rat $G_o $h_po $Den <$Su_factor $Patm $nu $nG $h0 $eInit $lambda $phicv $nb_wet $nb_dry $nd $Ado $ru_max $zmax $cz $ce $Cgd $ckaf $m_m $CG_consol>'''
|}  

{|
|  style="width:150px" | '''$matTag ''' || integer tag identifying material
|-
| style="padding-left: 2em;" |'''Primary''':
|-
|  '''$S_u''' || Undrained shear strength
|-
|  '''$Su_Rat''' || Undrained shear strength ratio. If both S_u and Su_Rat values are specified, the value of S_u is used.
|-
|  '''$G_o''' || Shear modulus constant
|-
|  '''$h_po''' || Contraction rate parameter
|-
|  '''$Den''' || Mass density of the material
|-
|  '''$Su_factor''' || ''Optional'', Undrained shear strength reduction factor
|-
|  '''$P_atm''' || ''Optional'', Atmospheric pressure
|-
| style="padding-left: 2em;"|  '''Secondary''':
|-
|  '''$nu ''' || ''Optional'', Poisson's ratio. Default value is 0.3.
|-
|  '''$nG''' || ''Optional'', Shear modulus exponent. Default value is 0.75.
|-
|  '''$h0 ''' || ''Optional'', Variable that adjusts the ratio of plastic modulus to elastic modulus. Default value is 0.5.
|-
|  '''$eInit ''' || ''Optional'', Initial void ratios. Default value is 0.90.
|-
|  '''$lambda''' || ''Optional'', The slope of critical state line in e-ln(p) space. Default value is 0.060.
|-
|  '''$phicv''' || ''Optional'', Critical state effective friction angle. Default value is 32 degrees.
|-
|  '''$nb_wet ''' || ''Optional'', Bounding surface parameter for loose of critical state conditions, 1.0 &ge; $nb_wet &ge; 0.01. Default value is 0.8.
|-
|  '''$nb_dry ''' || ''Optional'', Bounding surface parameter for dense of critical state conditions, $nb_dry &ge; 0. Default value is 0.5.
|-
|  '''$nd ''' || ''Optional'', Dilatancy surface parameter $nd &ge; 0.  Default value is 0.3.
|-
|  '''$Ado ''' || ''Optional'', Dilatancy parameter. Default value is 0.8.
|-
|  '''$ru_max ''' || ''Optional'', Maximum pore pressure ratio based on p'. 
|-
|  '''$z_max ''' || ''Optional'', Fabric-dilatancy tensor parameter 
|-
|  '''$cz ''' || ''Optional'', Fabric-dilatancy tensor parameter. Default value is 100.0.
|-
|  '''$ce ''' || ''Optional'', Variable that adjusts the rate of strain accumulation in cyclic loading
|-
|  '''$cgd ''' || ''Optional'', Variable that adjusts degradation of elastic modulus with accumulation of fabric. Default value is 3.0.
|-
|  '''$ckaf ''' || ''Optional'', Variable that controls the effect that sustained static shear stresses have on plastic modulus. Default value is 4.0.
|-
|  '''$m_m ''' || ''Optional'', Yield surface constant (radius of yield surface in stress ratio space). Default value is 0.01.
|-
|  '''$CG_consol''' || ''Optional'', Reduction factor of elastic modulus for reconsolidation. $CG_consol &ge; 1. Default value is 2.0.
|}

The material formulation for the PM4Silt object is "PlaneStrain"

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Code Developed by: <span style="color:blue">Long Chen, [https://www.ce.washington.edu/people/faculty/arduinop  Pedro Arduino, U Washington]</span>

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==Notes== 
* '''This page has been moved to the new [https://opensees.github.io/OpenSeesDocumentation/user/manual/material/ndMaterials/PM4Silt.html OpenSees documentation site]'''

* 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 1 -ele $elementTag Postshake $matTag

==Example==

<table border=1 width=600>
  <tr>
    <td width=90>[[PM4Silt-Example 1|Example 1]] </td>

    <td>2D undrained monotonic direct simple shear test using one element</td>
  </tr>
  <tr>
    <td>[[PM4Silt-Example 2|Example 2]]</td>
    <td>2D undrained cyclic direct simple shear test using one element</td>
  </tr>

</table>

==References==

R.W.Boulanger, K.Ziotopoulou. "PM4Silt(Version 1): A Silt Plasticity Model for Earthquake Engineering Applications". Report No. UCD/CGM-18/01 2018