To import pile load. To import pile mass. To execute a pile run.

To select a set of pile elements. To import pile stiffness.

To set up pile cap displacement.

To carry out soil-pile analysis and import results to Mechanical APDL.

To automatically generate pile data.

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16.3. Performing a Soil-Pile Interaction Analysis

You can use Mechanical APDL commands to perform a soil-pile interaction analysis from an ANSYS Mechanical analysis. The commands can be placed in a Mechanical APDL input file, or they can be entered as a command snippet in a Command tree object under a Structural analysis system in Workbench.

16.3.1.Overview of Mechanical APDL Commands Used for Soil-Pile Interaction Analysis

There are two sets of commands. The first set invokes an automatic pile analysis procedure while the other is a set of fundamental commands that allow more user control for the pile analysis settings.

For automatic pile analysis, the commands available are:

PILEGEN

PILECALC

For general pile analysis, the commands available are:

PILEDISPSET

PILELOAD

PILEMASS

PILERUN

PILESEL

PILESTIF

16.3.2. Mechanical APDL Component System Example

This example shows the Mechanical APDL input file used for a single pile analysis.

/PREP7

/units,bft

!KEYOPT(3)=4, INPUT DATA AS 12 X 12 STIFFNESS MATRIX ET,1,MATRIX27,,,4,1

!TABLE 1 REAL CONSTANTS FOR MATRIX27 STIFFNESS MATRIX R,1

N,1	! Pile cap
N,2,0,0,-123.3	! Pile tip
E,1,2	! STIFFNESS MATRIX ELEMENT
OUTPR,ALL,1	! PRINT ALL ITEMS
! Pile material data
MP,EX,1,4.32E6
MP,DENS,1,1.52E-2
MP,PRXY,,0.3

! Pile section data
SECTYPE,11,pipe,,pipe11
SECDATA,3.0,0.17
ACEL,0.0,0.0,32.2	!	Body force required
PILEGEN,,1,11,1	!	Generate pile

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Performing a Soil-Pile Interaction Analysis

FINISH

/SOLU

! AXIAL 0 to 600. LATERAL 25. SELF WEIGHT IN 6 STEPS tinc=0.5

t1=tinc

t2=3.0

*DO,tim,t1,t2,tinc

time,tim

fxt=25 fzt=-200*tim FDELE,ALL F,1,FX,fxt F,1,FZ,fzt PILECALC SOLVE

*ENDDO

Command PILECALC above can be replaced by the following data:

PILEDISPSET,1	! Set		pile	cap displacements
PILERUN,1	! Run		pile	analysis
PILESTIF,1	!	Import pile stiffness to element 1
PILELOAD,1	!	Import pile load to cap enode 1

16.3.3. Static Structural Component System Example

To use soil-pile interaction with a Static Structural system in Workbench, a command snippet object must be added to the tree under the Static Structural branch. The command usage follows the same method as in the Mechanical APDL component system (in this example, it only shows it being solved

for the first iteration; multiple iterations should be used to enable convergence of the soil-pile interaction equations).

/PREP7

*get,ar10,etyp,,num,max

!KEYOPT(3)=4, INPUT DATA AS 12 X 12 STIFFNESS MATRIX ET,ar10+1,MATRIX27,,,4,1

!Set the type that the generated elements are going to use type,ar10+1

!Set the material that the generated elements are going to use mat,ar10+1

!Pile material data (steel, in Metric Units) MP,EX,ar10+1,2.1e11

MP,DENS,ar10+1,7850

MP,PRXY,ar10+1,0.3

! Pile section data SECTYPE,ar10+1,pipe,,PileSec1

SECDATA,arg2,arg3 !Arg2 is the diameter, Arg3 is the thickness

*DO,PileNo,1,arg1,1 !Arg1 is the number of piles R,ar10+PileNo

real,ar10+PileNo

nsel,s,node,,Pile%PileNo%

ar2%PileNo%=ndnext(0) !Arg4 is the pile length

N,,NX(ar2%PileNo%),NY(ar2%PileNo%),NZ(ar2%PileNo%)-arg4 *get,ar3%PileNo%,node,,num,maxd E,ar2%PileNo%,ar3%PileNo%

*ENDDO

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!IF RAKED PILES OR MORE CONTROL IS REQUIRED, REPLACE THE ABOVE DO

!LOOP WITH THE FOLLOWING FOR EACH PILE

!Create table of real constant for MATRIX27 stiffness matrix !R,ar10+1

!Set the real constant number for the element

!real,ar10+1

!This is the named selection that contains the pile node. !nsel,s,node,,Pile1

!Get the next node number

!ar20=ndnext(0)

!Add pile tip node, here is where you'd change your bottom node

!position,

!relative to the node above.

!N,,NX(ar20),NY(ar20),NZ(ar20)

!Get the next element number !*get,ar50,node,,num,maxd

!Add stiffness matrix element !E,ar20,ar50

alls
!OUTPR,ALL,1	! Print all items, uncomment if required
PILEGEN,,ar10+1,ar10+1,1	! Generate piles
FINISH
/SOLU
PILECALC

Using the appropriate geometry, create a named selection that contains a single vertex locating the pile cap; name the selection PileX, where X is the pile number (starting at 1).

Apply Forces and Standard Earth Gravity as required.

In the commands object, set input arguments as indicated below: the diameter, thickness, and length. Length is the distance to the pile tip and will be applied to all piles; the length is vertically downwards (Z direction) from the pile cap.

ARG1 – Number of Piles (max 9 without Command Snippet customization)

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372	of ANSYS, Inc. and its subsidiaries and affiliates.