PM4Sand
- This page has been moved to the new OpenSees documentation site
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
- This page has been moved to the new OpenSees documentation site
-
Valid Element Recorder queries are
- stress, strain
- alpha (or backstressratio) for <math></math>
- fabric for \(\mathbf{z}\)
- alpha_in (or alphain) for <math></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
<table border=1 width=600> <tr> <td width=90>Example 1 </td>
<td>2D undrained monotonic direct simple shear test using one element</td> </tr> <tr> <td>Example 2</td> <td>2D undrained cyclic direct simple shear test using one element</td> </tr>
</table>
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