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

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. Outline. Objective ICON Suite Role of geometry and base stiffness to the moisture curling of slab

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

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

  7. σ CR SH T σ 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

  8. 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

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

  24. Stress in different base stiffness Curling + external loading σmax = 856 psi σmax = 1400 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=4.5e6 psi (Mag. Factor = 200) Eb=4.5e3 psi (Mag. Factor = 20)

  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. Final report Will be delivered by June, 2007

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