PM4Sand Material: Difference between revisions

From OpenSeesWiki
Jump to navigation Jump to search
No edit summary
 
(7 intermediate revisions by the same user not shown)
Line 1: Line 1:
{{CommandManualMenu}}
{{CommandManualMenu}}
* '''This page has been moved to the new [https://opensees.github.io/OpenSeesDocumentation/user/manual/material/ndMaterials/PM4Sand.html OpenSees documentation site]'''


This command is used to construct a 2-dimensional PM4Sand material.
This command is used to construct a 2-dimensional PM4Sand material.
Line 11: Line 12:
|-
|-
|-
|-
|  '''Primary''':
| style="padding-left: 2em;"|  '''Primary''':
|-
|-
|  '''$Dr ''' || Relative density, in fraction
|  '''$Dr ''' || Relative density, in fraction
Line 21: Line 22:
|  '''$Den ''' || Mass density of the material
|  '''$Den ''' || Mass density of the material
|-
|-
| '''Secondary''':
| style="padding-left: 2em;"| '''Secondary''':
|-
|-
|  '''$P_atm ''' || ''Optional'', Atmospheric pressure
|  '''$P_atm ''' || ''Optional'', Atmospheric pressure
Line 66: Line 67:
----
----


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


----  
----  


==Notes==  
==Notes==  
* '''This page has been moved to the new [https://opensees.github.io/OpenSeesDocumentation/user/manual/material/ndMaterials/PM4Sand.html OpenSees documentation site]'''
* Valid Element Recorder queries are  
* Valid Element Recorder queries are  
** '''stress''', '''strain'''
** '''stress''', '''strain'''
Line 86: Line 89:
|}
|}


* If default values are used for secondary parameters, the model must be initialized after elastic gravity stage by
* The program will use the default value of a secondary parameter if a negative input is assigned to that parameter, e.g. Ado = -1. However, FirstCall is mandatory when switching from elastic to elastoplastic if negative inputs are assigned to stress-dependent secondary parameters, e.g. Ado and zmax. FirstCall can be set as, 
setParameter -value 0 -ele $elementTag FirstCall $matTag
setParameter -value 0 -ele $elementTag FirstCall $matTag


* Post-shake reconsolidation can be activated by
* Post-shake reconsolidation can be activated by
setParameter -value 0 -ele $elementTag Postshake $matTag
setParameter -value 1 -ele $elementTag Postshake $matTag


* The user should check that the results are not sensitive to time step size.


==Example==
==Example==


<table border=1 width=800>
<table border=1 width=600>
   <tr>
   <tr>
     <td width=90>[[PM4Sand-Example 1|Example 1]] </td>
     <td width=90>[[PM4Sand-Example 1|Example 1]] </td>

Latest revision as of 06:44, 9 February 2021



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
  • The program will use the default value of a secondary parameter if a negative input is assigned to that parameter, e.g. Ado = -1. However, FirstCall is mandatory when switching from elastic to elastoplastic if negative inputs are assigned to stress-dependent secondary parameters, e.g. Ado and zmax. FirstCall can be set as,

setParameter -value 0 -ele $elementTag FirstCall $matTag

  • Post-shake reconsolidation can be activated by

setParameter -value 1 -ele $elementTag Postshake $matTag

  • The user should check that the results are not sensitive to time step size.

Example

Example 1 2D undrained monotonic direct simple shear test using one element
Example 2 2D undrained cyclic direct simple shear test using one element

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

Retrieved from "https://opensees.ist.berkeley.edu/wiki/index.php?title=PM4Sand_Material&oldid=12798"