Moisture Curling and Corner Cracking of Concrete Slabs: Parametric Study Using ICON software

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Moisture Curling and Corner Cracking of Concrete
Slabs Parametric Study Using ICON software

• Jan. 30, 2007
• PI David A. Lange
• RA Chang Joon Lee, Yi-Shi Liu

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Outline

• Objective
• ICON Suite
• Role of geometry and base stiffness to the
  moisture curling of slab
• External load effect on curling (preliminary)
• Wrap-up Schedule

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Objective
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Objective

• To provide an effective prediction tool for the
  moisture curling of slab
• To study the role of geometry, base stiffness and
  external load to the moisture curling of slab
• To deliver software tool to FAA

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ICON Suite
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ICON Suite
Main analysis code
ICON
PATRAN interface code for ICON input output
ICONPCL
ICONPOST
Post processor for ICON result
ICONBATCH
Batch running code for multiple ICON models
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ICON

• 3D FEA code for Time dependent analysis of aging
  concrete structures
• Age dependent Material properties
• Time dependent excitations (RH and temperature)

• MATERIAL
• Linear Elastic for Instantaneous response
• Solidifying Material Model for Creep
• Hygrothermal Model for Drying Shrinkage
• Simple Linear Model for Thermal Expansion

• ELEMENTS
• 20-node solid element
• 8-node solid element
• 16-node surface interface element
• 8-node surface interface element

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Modeling analysis flow with ICON suite
Modeling FE geometry
MSC.PATRAN
ICONPCL
model.inp
Model input file
ICON
Main FE Analysis
model.rst
ICONPOST
Analysis results file
model.tcl
model.csv
ICONPCL
MSC.PATRAN
Graphical post-processing
TECPLOT
EXCEL
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ICONPCL

• MSC.PATRAN interface code for ICON Input output
• Written in PCL language
• Run on MSC.PATRAN

model.rst
ICONPCL
MSC.PATRAN
MSC.PATRAN with ICON result
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ICONPOST

• Postprocessor for ICON result
• Create TECPLOT tcl format file
• Create EXCEL csv format file

model.rst
ICONPOST
model.tcl
model.csv
TECPLOT
EXCEL
TECPLOT with ICON result
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ICONBATCH
Batch running code for multiple ICON models
Error control for ICON
model.inp
model.inp
model.inp

ICONBATCH
ICON
model.rst
model.rst
model.rst

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Role of geometry and base stiffness to the
moisture curling of slab
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FE model for NAPTF single slab curling
Solid element (Solidifying)

Interface element

Solid element (Elastic)
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Parameters

• Fixed
• Material properties
• Temperature RH
• Self-weight

• Variables
• L Slab size
• D Slab thickness
• Eb Base stiffness

Symm.
L/2
L/2
D
Eb
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Slab size (L) effect on curling
Eb 4.5e6 psi, D 11in, L 12.5 20ft
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Slab thickness (D) effect on curling
Eb 4.5e6 psi, L 15ft, D 913in
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Base stiffness (Eb) effect on curling
L 15ft, D 11in, Eb 4.5e3 4.5e6 psi
Deformations, Mag. Factor 1000
Eb4.5e3 psi
Eb4.5e4 psi
Lift-off Displacement at Corner (Time 14 days)
Eb4.5e5 psi
Eb4.5e6 psi
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Base stiffness (Eb) effect on curling
L 15ft, D 11in, Eb 4.5e3 4.5e6 psi
273 psi
205 psi
Eb4.5e3 psi
Eb4.5e4 psi
320 psi
336 psi
Highest Max. Principle Stress (Time 14 days)
Eb4.5e5 psi
Eb4.5e6 psi
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Base stiffness (Eb) effect on curling
Why is stress more sensitive than lift-off
displacement?
Deformations, Mag. Factor 1000
Eb4.5e3 psi
Eb4.5e6 psi
? More deformation on soft base ? More support
area under the slab
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External load effect on curling(Preliminary)
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FE model and loading area
200psi of external load was applied on the area
of 450 in2
Loading region
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Deformation map
The curled deformation was imposed ( not actual
curling simulation) and 200psi of external load
was applied on the loading region
Curling Only
Curling External loading
Base stiffness, Eb4.5e6
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Stress
Stresses are transferred from the central region
to the loading region of the slab.
smax 558 psi
smax 472 psi
Curling Only
Curling External loading
Base stiffness, Eb4.5e6 psi
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Stress in different base stiffness
Curling external loading
smax 856 psi
smax 1400 psi
Eb4.5e3 psi
Eb4.5e4 psi
smax 632 psi
smax 558 psi
Eb4.5e5 psi
Eb4.5e6 psi
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Stress for external loading only
External loading with NO curling
smax 77 psi
Eb4.5e6 psi
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Trend of stress development

• Stress as a function of base stiffness
• Stress was normalized by the value of Eb 4.5e6
  psi

WHY?
Normalized Stress
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Base deformation
Cantilever effect due to large deformation
under the loading region
Eb4.5e6 psi (Mag. Factor 200)
Eb4.5e3 psi (Mag. Factor 20)
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Wrap-up Schedule
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Contents of final document

• Material Model Description
• Numerical implementation and Development of ICON
• Experimental Program at UIUC and NAPTF
• Numerical simulations and Validation of the model
  (NAPTF single slab, Restrained RING test, UIUC
  Dogbone)
• Parametric Study for Slab Curling
• Users manual of ICON suite

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Final report

• Will be delivered by June, 2007