semester project – stress fields...2 kostic n., topologie des champs de contraintes pour le...

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Semester Project – Stress FieldsEPFL - IBETON

8th Semester

INTRODUCTION TO APPLETS iMESH – iCONC21 February 2018

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Kostic N., Topologie des champs de contraintes pour le dimensionnement des structures en béton armé, 2009

Muttoni, J. Schwarz et B. Thürlimann, Design of Concrete Structures with Stress Fields, 1997

Fernández Ruiz M., Muttoni A., On Development of Suitable Stress Fields for Structural Concrete, 2007

BIBLIOGRAPHY

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TractionCompressionAffaiblissement du béton

Element modelling with Elasto-Plastic Stress Fields theory

iCONC – CALCULATION PRINCIPLESC

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DOCUMENTS / TUTORIALS / LOGIN

iCONCRETE http://i-concrete.epfl.ch

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Objectives Understand available applets

Learn how to launch the applets

Use the on-line help/tutorials

Manage files

- Save a file

- Open an already saved file with Mydata or directly from the iMesh Applet

Management of display size

Solve any potential login problem

Open existing file

HelpSave model


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Exercise Introduction:-Open iMesh

-Create and save a file

-Open the file that has just been saved

Open file

HelpSave file


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From the applet: list of already saved personal files

Selection of the size of the window

Open

Opening from Mydata

Save a file

Saving window Opening a file


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Objectives Elements creation based on the active element type (nodes, polylines, areas,…)

Procedure for the elimination of an element:

-Activate the type of element you want to delete

-Select the element to be deleted (multiple selection with « Ctrl »)

-Use the command « Delete »

Elimination of a node/support/load by superposition with another node

- Drag the element to be deleted to another node

-Do not use for polylines/areas/bars!!

ELEMENT CREATION / ELIMINATION

Delete Nodes

Reinforcing bars

Areas

External loads

Supports

Polyline

Numbering

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ELEMENT CREATION / ELIMINATION

Exercise Phase00:-Understand the procedure for creating elements

-Use the different methods for deleting elements

Delete Nodes

Reinforcing bars

Areas

External loads

Supports

Polyline

Numbering

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Objectives Creation of Areas

From already existing nodes or simultaneous creation of areas and nodes

Creation of supports

Use the keys « Ctrl » and « Shift » for sliding supports

Creation of loads

Preliminary definition of direction and value

Creation of reinforcing bars

Use the key « Shift » to attach the bar to a surface

Mesh creation

Non-linear calculation with iConc / JAVA Console

GEOMETRY / MESHING / CALCULATION

Meshing

Calculation with iConc (non-linear)

Delete Nodes

Reinforcing bars

Areas

External loads

Supports

Polyline

Numbering

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Exercise Phase01:-Use the main commands for the creation of the structure

-Launch a first calculation with iConc and view the results

Meshing

Calculation with iConc (non-linear)

Delete Nodes

Reinforcing bars

Areas

External loads

Supports

Polyline

Numbering


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Iteration i

Error after the last iteration

Open the Java Console


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To increase the calculation memory allocated to iConc

Execution parameters:

-Xms512m -Xmx512m


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Scale Factor

Drag the mouse with the right button clicked

Deformed shape


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Scale Factor

Global: Drag the mouse with the right button clicked

Bars: Drag the mouse with the right button clicked and key « Shift »

Béton: Drag the mouse with the right button clicked and key « Ctrl »

Relative Stresses


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EVALUATION OF RESULTS

Failure at the location of the load introduction

modelling problem!

How do we solve this problem?

Introduction of a steel plate (infinitely elastic) and/or distribution of the load

among several nodes

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Yielding of reinforcement

Flexure in the figure below

Concrete crushing

Shear in the figure below

Divergence in the calculation!

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Pay attention to the quality of the mesh

Avoid highly detailed regions where they are not strictly necessary

Find a good balance between calculation time and quality of results

Represent adequately the size of the element that triggers the rupture (example: the compression strut)

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Objectives Definition of the geometry of areas (thickness)

Definition of materials

concrete, steel, elastic steel

Definition of the reinforcing bars geometry

equivalent bar diameter

Refinement of the mesh

Insert nodes in the refined region

Insert polylines

MeshingPolyline

Geometry and Materials


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Exercise Phase02:-Define the geometries (element thickness) and the materials

-Refine the meshing

-Check the model in iConc

MeshingPolyline

Geometry and Materials


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Check the materials Check the geometry


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CODE

Code

Materials

Geometry

Loads

Areas

Supports

Nodes

Bars

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CODE UTILISATION

Code

Exercise Phase03:-Analyse the code and understand its components

-Understand how it works

-Make further modifications to the element from the Code

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SHEAR WALL MODELLING

ExerciSe Phase04:-Creation of the wall

-Introduction of reinforcement calculated in exercises 5 and 6

-Non-linear analysis with iConc

-Comments/modifications/iterations

-…personal work!!!

result?

For each tie:

-1 bar with equivalent Ø for As,tot and fy = 435 Mpa

…if As,tot is not known:

-1 bar with any Ø et fy = elastic e = 0.4m

semester project – stress fields...2 kostic n., topologie des champs de contraintes pour le...

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