gtl-s01-introduction to plaxis program

PLAXIS Standard Course Universiti Teknologi Malaysia - Johor May 14-16, 2007

Presented by GOUW Tjie Liong [email protected] 1

PLAXIS FINITE ELEMENT CODE FOR SOIL AND ROCK ANALYSES

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Introduction to Plaxis

presented by:

GOUW Tjie-Liong, Ir., M.Eng, ChFCSenior Geotechnical ConsultantEmail: [email protected]

Source of Lecture Notes:PLAXIS BV


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General Modelling Aspects

Defining a project:Define geometryGenerate meshDefine initial conditionsDefine calculation phasesCalculate Inspect results




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The geometry is the representation of the physical problem

Consists of points, lines and clusters Definition of soil layers, structural elements

and loads



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PointsStart and end of lines. Positioning of anchorsPoint forces, Point fixities Local refinements of the finite

element mesh.




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Lines Define the physical boundaries of the

geometry Define discontinuities in the geometry:

Sheet pile walls, distributed loads Separations of distinct soil layers or

construction stages. A line can have several functions or

properties


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ClustersAutomatically generated enclosed areasHomogeneous soil properties.




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(a) 6-noded triangle (b) 15-noded triangle

stress points

nodes


Mesh 6-noded or 15-noded triangular elements Displacements calculated in nodes Stresses calculated in Gaussian integration points


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Input Program




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INPUT

Composing a geometry model Creating and assigning data sets Generating a finite element mesh Generating initial conditions


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Composing a Geometry Model

Graphical input of geometry contour, soil- layers, construction stages, plates, geogrids, interfaces, anchors

Designer for circular or non-circular tunnels

Input of loads and boundary conditions




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Geometry lines (between soil layers, etc.)

Plates (Walls, Plates & Shells)

Hinges (free rotation between beams)

Geogrids

Interface elements (soil-structure interaction)

Anchors (node-to-node, fixed end)


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Creating and Assigning Material Data Sets

Enter model parameters as data sets in a material data base

Assigning data sets to geometry components by means of drag and drop




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Generating a Finite Element Mesh

Fully automatic mesh generation based on geometry model

Global and local refinement options


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Generating Initial Conditions

Generating initial pore pressures by means of phreatic line or groundwater flow calculation

Flip switch - gives: Initial stresses and geometry mode

Setting initial geometry configuration Generating initial stresses (K0 procedure)




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Calculation Program


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Defining Calculation Phases

Plastic calculation, Consolidation, Phi/c reduction and Dynamic analysis.

Updated mesh. Loading input: Multipliers or Staged Construction. Changing water conditions Multiple calculation phases can be pre-defined and

executed at once.




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Output Program


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View Results

Graphical and tabulated output of displacements, stresses and structural forces

Output in cross sections Multiple output windows can be opened

simultaneously (comparison of results)




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First Exercise

Resume of input steps


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Input Geometry

Draw Geometry




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Input Boundary Conditions

Default fixities


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Input Loads

Point force A & B




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Input Material Properties

General properties, model parameters


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Mesh Generation

Full automatic mesh generator




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Initial Conditions

Water pressures, Initial stresses


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See course manual

gtl-s01-introduction to plaxis program

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