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

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

Objective

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

ICON Suite

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

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

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

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

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

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

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

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

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

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

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

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

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

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

External load effect on curling (Preliminary)

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

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

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

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

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

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

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)

Wrap-up Schedule

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

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