Offshore-combin39 vs Splinter

© 2012 ANSYS, Inc. February 26, 2013 1

Using COMBIN39 for modeling piles

José Ramón Rodríguez

ANSYS Iberia


- There are a number of methods that can be used to analyze piled foundations in ANSYS Mechanical:

• SPLINTER (a standalone nonlinear solver that was originally developed as part of the ASAS suite)

• Matrix definition

• Spring definition (COMBIN39)

• Direct Definition of P-Y and T-Z curves

The Spring Definition method will be described in this lecture


COMBIN39

COMBIN39 is a unidirectional element with nonlinear generalized force-deflection capability that can be used in any analysis.

To use COMBIN39 with a Mechanical model, the process required on a jacket model is:

• Create soil properties file

• Change element formulation

• Define named selections for each Pile cap node named Pile1, Pile2 etc.

• Insert a command object to define the piles


COMBIN39 Notes

Important if running for the first time!

Copy P14.MAC and P12.MAC to either

C:\Program Files\ANSYS Inc\v140\ansys\apdl

or

C:\Program Files\ANSYS Inc\v145\ansys\apdl

dependant on whether you are using ANSYS v14 or v14.5


Soil Properties file creation • Create a file with the soil properties (P-Y and T-Z curves) similar to the

soil_properties.txt file attached

Note there are a number of assumptions made in these macros, primarily that the soil_properties.txt format file should have only 11 or 15 pairs of spring data, and that only the positive data is used. There should always be P-Y, T-Z and ENDB (endbearing) data available.

Example of definition of this file:

Pile diameter Path Start Path end

Soil Properties


• Expand Part [+] under Geometry branch. You will see all line bodies created.

• Ctrl-select all line bodies and from the Details View of “Multiple Selection” window change the Model Type to Pipe

• This action changes the element type from BEAM188/9 to PIPE288/9

Change the element formulation


• Click on Model(B4) and from the Menu Toolbar click on Named Selection icon

• A new Branch appears in the Outline Tree. Click on the highlighted cell in the Details of “Selection” window and then click on the vertex selection tool

• Create as many named selections as piles there are, one for each vertex (pile cap), and rename them to PILE1, PILE2, PILE3,…

Create named selections


Insert Pile Definition snippet

• Import Pile_definition.txt

Soil properties file location (change the path if needed)

Macro invoked for generating the spring elements. Sintax: • Pile Diameter (1.2 m) • Pile Thickness (0.03 m) • Pile Lenght (25 m) • Number of elements in pile (25) • Depth multiplier (1)


Case studies. Model 1

Elapsed Time: 204 s

Files size: 746 MB

Elapsed Time: 170 s

Files size: 340 MB

Offshore-combin39 vs Splinter

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Transcript of Offshore-combin39 vs Splinter