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

2. 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

3. Objective

4. 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

5. ICON Suite

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

7. ICON MATERIAL: ELEMENTS:
3D FEA code for Time dependent analysis of aging concrete structures
Age dependent Material properties
Time dependent excitations (RH and temperature) σ CR SH T
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

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

9. 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

10. 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

11. 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

12. Role of geometry and base stiffness to the moisture curling of slab

13. FE model for NAPTF single slab curling
Solid element
(Solidifying) +
Interface element +
Solid element
(Elastic)

14. 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

15. Slab size (L) effect on curling
Eb = 4.5e6 psi, D = 11in, L = 12.5 ~ 20ft

16. Slab thickness (D) effect on curling
Eb = 4.5e6 psi, L = 15ft, D = 9~13in

17. Base stiffness (Eb) effect on curling
L = 15ft, D = 11in, Eb = 4.5e3 ~ 4.5e6 psi
Deformations, Mag. Factor = 1000
Eb=4.5e3 psi
Eb=4.5e4 psi
Lift-off Displacement at Corner (Time = 14 days)
Eb=4.5e5 psi
Eb=4.5e6 psi

18. Base stiffness (Eb) effect on curling
L = 15ft, D = 11in, Eb = 4.5e3 ~ 4.5e6 psi
273 psi
205 psi
Eb=4.5e3 psi
Eb=4.5e4 psi
320 psi
336 psi
Highest Max. Principle Stress (Time = 14 days)
Eb=4.5e5 psi
Eb=4.5e6 psi

19. Base stiffness (Eb) effect on curling
Why is stress more sensitive than lift-off displacement?
Deformations, Mag. Factor = 1000
Eb=4.5e3 psi
Eb=4.5e6 psi
 More deformation on soft base
 More support area under the slab

20. External load effect on curling (Preliminary)

21. FE model and loading area
200psi of external load was applied on the area of 450 in2
Loading region

22. 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, Eb=4.5e6

23. Curling + External loading
Stress
Stresses are transferred from the central region to the loading region of the slab.
σmax = 472 psi
σmax = 558 psi
Curling Only
Curling + External loading
Base stiffness, Eb=4.5e6 psi

24. Stress in different base stiffness
Curling + external loading
σmax = 1400 psi
σmax = 856 psi
Eb=4.5e3 psi
Eb=4.5e4 psi
σmax = 632 psi
σmax = 558 psi
Eb=4.5e5 psi
Eb=4.5e6 psi

25. Stress for external loading only
External loading with NO curling
σmax = 77 psi
Eb=4.5e6 psi

26. 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

27. Base deformation
“Cantilever effect” due to large deformation under the loading region
Eb=4.5e3 psi (Mag. Factor = 20)
Eb=4.5e6 psi (Mag. Factor = 200)

28. Wrap-up Schedule

29. 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
User’s manual of ICON suite

30. Will be delivered by June, 2007
Final report
Will be delivered by June, 2007