Brick u-p Element: Difference between revisions

From OpenSeesWiki
Jump to navigation Jump to search
No edit summary
No edit summary
Line 1: Line 1:
This command is used to construct an BrickUP element object.  A BrickUP element is an 8-node hexahedral linear isoparametric element. Each node has 4 degrees-of-freedom (DOF): DOFs 1 to 3 for solid displacement (u) and DOF 4 for fluid pressure (p). This element is implemented for simulating dynamic response of solid-fluid fully coupled material, based on Biot's theory of porous medium.  
{{CommandManualMenu}}
 
'''BrickUP''' is an 8-node hexahedral linear isoparametric element.  
Each node has 4 degrees-of-freedom (DOF): DOFs 1 to 3 for solid displacement (u) and DOF 4 for fluid pressure (p).  
This element is implemented for simulating dynamic response of solid-fluid fully coupled material, based on Biot's theory of porous medium.
 
'''Please''' [[Examples|click here]] '''for examples.'''
 
 
OUTPUT INTERFACE:
 
Pore pressure can be recorded at an element node using OpenSees Node Recorder:
 
 
'''recorder Node <-file $fileName> <-time> <-node ($nod1 $nod2 …)> -dof 3 vel'''
 
 
See OpenSees command manual (McKenna and Fenves 2001) for nodal displacement, velocity, or acceleration recorders. 
 
 
The valid queries to a BrickUP element when creating an ElementRecorder are 'force', 'stiffness', or 'material matNum matArg1 matArg2 ...', where matNum represents the material object at the corresponding integration point.


The arguments for the construction of this element are:


{|  
{|  
| style="background:yellow; color:black; width:800px" | '''element brickUP $eleTag $Node1 $Node2 $Node3 $Node4 $Node5 $Node6 $Node7 $Node8 $matTag $bulk $fmass $PermX $PermY $PermZ <$bX=0 $bY=0 $bZ=0>'''
| style="background:yellow; color:black; width:900px; font-size: 120%;" | '''element brickUP $eleTag $Node1 $Node2 $Node3 $Node4 $Node5 $Node6 $Node7 $Node8 $matTag $bulk $fmass $PermX $PermY $PermZ <$bX=0 $bY=0 $bZ=0>'''
|}
|}




----


{|
[[image:Brick.png]]
| style="width:150px" | '''$eleTag''' || unique element object tag
 
{|style="border-collapse: collapse; border-width: 2px; border-style: solid; border-color: silver; width:900px;"
|style="border-style: solid; border-color: silver; border-width: 1px;"|'''$eleTag'''
|style="border-style: solid; border-color: silver; border-width: 1px"|A positive integer uniquely identifying the element among all elements
|-
|-
|'''$Node1 .. $Node 8''' || Eight element node (previously defined) numbered as shown in figure below.
|style="border-style: solid; border-color: silver; border-width: 1px"|'''$Node1,… $Node8'''
|style="border-style: solid; border-color: silver; border-width: 1px"|Eight element node (previously defined) numbers (see figure above for order of numbering).
|-
|-
| '''$matTag''' || Tag of an NDMaterial object (previously defined) of which the element is composed
|style="border-style: solid; border-color: silver; border-width: 1px"|'''$matTag'''
|style="border-style: solid; border-color: silver; border-width: 1px"|Tag of an NDMaterial object (previously defined) of which the element is composed
|-
|-
| '''$bulk''' || Combined undrained bulk modulus Bc relating changes in pore pressure and volumetric strain, may be approximated by: where Bf is the bulk modulus of fluid phase (2.2x106 kPa for water), and n the initial porosity.
|style="border-style: solid; border-color: silver; border-width: 1px"|'''$bulk'''
|style="border-style: solid; border-color: silver; border-width: 1px"|Combined undrained bulk modulus B<sub>c</sub> relating changes in pore pressure and volumetric strain, may be approximated by:
 
B<sub>c</sub> &asymp; B<sub>f</sub>/n
 
where B<sub>f</sub> is the bulk modulus of fluid phase (2.2x10<sup>6</sup> kPa (or 3.191x10<sup>5</sup> psi) for water), and n the initial porosity.
 
|-
|-
| '''$fmass''' || Fluid mass density
|style="border-style: solid; border-color: silver; border-width: 1px"|'''$fmass'''
|style="border-style: solid; border-color: silver; border-width: 1px"|Fluid mass density
|-
|-
| '''$PermX''' || Permeability coefficient in X direction
|style="border-style: solid; border-color: silver; border-width: 1px"|'''$permX, $permY, $permZ'''
|style="border-style: solid; border-color: silver; border-width: 1px"|Permeability coefficients in x, y, and z directions respectively.
|-
|-
| '''$PermY''' || Permeability coefficient in Y direction
|style="border-style: solid; border-color: silver; border-width: 1px"|'''$bX, $bY, $bZ'''
|-
|style="border-style: solid; border-color: silver; border-width: 1px"|Optional gravity acceleration components in x, y, and z directions directions respectively (defaults are 0.0)
| '''$PermZ''' || Permeability coefficient in Z direction
|-
| '''$bX, $bX $bZ''' ||Optional gravity acceleration components in X, Y and Z directions respectively (defaults are 0.0)
|}
|}




[[image:Brick.png]]
----


NOTE:
NOTE:

Revision as of 17:10, 7 August 2012



BrickUP is an 8-node hexahedral linear isoparametric element. Each node has 4 degrees-of-freedom (DOF): DOFs 1 to 3 for solid displacement (u) and DOF 4 for fluid pressure (p). This element is implemented for simulating dynamic response of solid-fluid fully coupled material, based on Biot's theory of porous medium.

Please click here for examples.


OUTPUT INTERFACE:

Pore pressure can be recorded at an element node using OpenSees Node Recorder:


recorder Node <-file $fileName> <-time> <-node ($nod1 $nod2 …)> -dof 3 vel


See OpenSees command manual (McKenna and Fenves 2001) for nodal displacement, velocity, or acceleration recorders.


The valid queries to a BrickUP element when creating an ElementRecorder are 'force', 'stiffness', or 'material matNum matArg1 matArg2 ...', where matNum represents the material object at the corresponding integration point.


element brickUP $eleTag $Node1 $Node2 $Node3 $Node4 $Node5 $Node6 $Node7 $Node8 $matTag $bulk $fmass $PermX $PermY $PermZ <$bX=0 $bY=0 $bZ=0>


$eleTag A positive integer uniquely identifying the element among all elements
$Node1,… $Node8 Eight element node (previously defined) numbers (see figure above for order of numbering).
$matTag Tag of an NDMaterial object (previously defined) of which the element is composed
$bulk Combined undrained bulk modulus Bc relating changes in pore pressure and volumetric strain, may be approximated by:

Bc ≈ Bf/n

where Bf is the bulk modulus of fluid phase (2.2x106 kPa (or 3.191x105 psi) for water), and n the initial porosity.

$fmass Fluid mass density
$permX, $permY, $permZ Permeability coefficients in x, y, and z directions respectively.
$bX, $bY, $bZ Optional gravity acceleration components in x, y, and z directions directions respectively (defaults are 0.0)


NOTE:

This element requires 4 degrees-of-freedom (ndf=4), the 4th degree-of-freedom being pore pressure. The Pore pressure can be recorded at an element node using OpenSees Node Recorder:

recorder Node <-file $fileName> <-time> <-node ($nod1 $nod2 …)> -dof 4 vel

The valid queries to a BrickUP element when creating an ElementRecorder are 'force', and 'material matNum matArg1 matArg2 ...', where matNum represents the material object at the corresponding integration point.

TYPICAL RANGE OF PERMEABILITY COEFFICIENT (cm/s)

Gravel Sand Silty Sand Silt Clay
>1.0x10-1 1.0x10-3 ~ 1.0x10-1 1.0x10-5 ~ 1.0x10-3 1.0x10-7 ~ 1.0x10-5 <1.0x10-7


EXAMPLE:

Please visit http://cyclic.ucsd.edu/opensees for examples.

REFERENCES:

Code Developed by: Zhaohui Yang, UC San Diego

Retrieved from "https://opensees.ist.berkeley.edu/wiki/index.php?title=Brick_u-p_Element&oldid=9623"