The inuence of self-induced and restraint stresseson crack development in a reinforced concrete wallsubjected to early-age...
IntroductionNumerical modelAnalysis of RC wallConclusionsThermalmoisture eectsThermalshrinkage crackingIntroductionconcret...
IntroductionNumerical modelAnalysis of RC wallConclusionsThermalmoisture eectsThermalshrinkage crackingIntroductionthermal...
IntroductionNumerical modelAnalysis of RC wallConclusionsThermalmoisture eectsThermalshrinkage crackingCrack development i...
IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analy...
IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analy...
IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analy...
IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analy...
IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analy...
IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisMaterial, techno...
IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisThermalmoisture ...
IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisTemperature and ...
IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisStress mapsFigur...
IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisTotal stresses1....
IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisSelf-induced str...
IntroductionNumerical modelAnalysis of RC wallConclusionsConclusions1 Thermalshrinkage cracking of massive cocnrete struct...
Juniorstav 2012Brno, Czech Republic, 26 Jan 2012
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Juniorstav 2012 Presentation on "The in uence of self-induced and restraint stresses on crack development in a reinforced concrete wall subjected to early-age thermal-shrinkage effects"

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Juniorstav 2012 Presentation on "The in uence of self-induced and restraint stresses on crack development in a reinforced concrete wall subjected to early-age thermal-shrinkage effects"

  1. 1. The inuence of self-induced and restraint stresseson crack development in a reinforced concrete wallsubjected to early-age thermalshrinkage eectsMSc. Eng. Agnieszka KNOPPIK-WRÓBELSilesian University of TechnologyFaculty of Civil EngineeringBrno, Czech Republic, 26 Jan 2012
  2. 2. IntroductionNumerical modelAnalysis of RC wallConclusionsThermalmoisture eectsThermalshrinkage crackingIntroductionconcrete curingcement hydration processdissipation of heat and migration of moisturetemperature and moisture gradientsstressesself-induced restraint stresses in structureAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  3. 3. IntroductionNumerical modelAnalysis of RC wallConclusionsThermalmoisture eectsThermalshrinkage crackingIntroductionthermalmoisture eectsmassive structuresblock foundations,gravity damsmedium-thick restrained structuresRC walls of tanks,nuclear containments,abutmentsAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  4. 4. IntroductionNumerical modelAnalysis of RC wallConclusionsThermalmoisture eectsThermalshrinkage crackingCrack development in RC wallsCracks in RC wallshigh L/H - external restraintmainly restraint stressesFigure 1: Real cracks observed in RC wallAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  5. 5. IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analysisImplementationGeneral assumptions1 phenomenological modeldecoupling of thermalmoisture and mechanical eldsfull coupling of thermalmoisture elds2 stress state determined under the assumption thatthermalmoisture strains have distort character3 viscoelastoviscoplastic material model of concreteAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  6. 6. IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analysisImplementationThermal and moisture analysisCoupled thermalmoisture equations˙T = div(αTT gradT + αTW gradc) +1cbρqv˙c = div(αWW gradc + αWT gradT) − KqvAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  7. 7. IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analysisImplementationThermalshrinkage strainsImposed thermalshrinkage strains εn:volumetric strainsdεn = dεnx dεny dεnz 0 0 0calculated based on predetermined temperature and humiditydεnx = dεny = dεnz = αT dT + αW dWAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  8. 8. IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analysisImplementationStress analysisviscoelastic area˙σ = Dve( ˙ε − ˙εn − ˙εc)viscoelastoviscoplastic area˙σ = Dve ( ˙ε − ˙εn − ˙εc − ˙εvp)Figure 2: Failure surfacepossibility of crack occurrencesl =τoctτfoctFigure 3: Damage intensity factorAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  9. 9. IntroductionNumerical modelAnalysis of RC wallConclusionsThermal and moisture analysisThermalshrinkage strainsStress analysisImplementationImplementationA set of programs:TEMWILthermalmoisture eldsMAFEMstress analysisAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  10. 10. IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisMaterial, technological and geometrical dataconcrete fcm = 35 MPa, fctm = 3 MPa and Ecm = 32 GPa;steel class RB400;cement type CEM I 42.5R, 375 kg/m3;temp.: ambient Tz = 25◦C, initial of concrete Tp = 25◦C;wooden formwork of 1.8 cm plywood - removed after 28 days,no insulation, protection of top surface with foil.20.0 m0.7m4.0m4.0 m0.7 mZYX0.4 mFigure 4: Geometry and nite element mesh of analysed wallsAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  11. 11. IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisThermalmoisture eldsFigure 5: Temperature distribution in the wall [◦C] after 1.2 daysFigure 6: Moisture distribution in the wall (x100) after 1.2 daysAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  12. 12. IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisTemperature and moisture distribution in section25283134374043temperature [°C] with formwork for 28 dayswith formwork for 3 days70 cm15182124273033temperature [°C]with formwork for 28 dayswith formwork for 3 days40 cmFigure 7: Temperature distribution at the thickness the wall [◦C] after 3.5 days12.012.513.013.514.014.515.0moisture content(x100), m3/m3with formwork for 28 dayswith formwork for 3 days70 cm12.012.513.013.514.014.515.0moisture content(x100), m3/m3with formwork for 28 dayswith formwork for 3 days40 cmFigure 8: Moisture content distribution at the thickness the wall [◦C] after 3.5 daysAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  13. 13. IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisStress mapsFigure 9: Development of temperaturesand resulting stressesFigure 10: Stress distribution anddeformation of the wallAgnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  14. 14. IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisTotal stresses1.01.52.0a70‐cm thick wall‐2.0‐1.5‐1.0‐0.50.00.50 2 4 6 8 10 12 14 16 18 20Stress, MPaTime, daysinteriorsurface1.01.52.0a40‐cm thick wall‐2.0‐1.5‐1.0‐0.50.00.50 2 4 6 8 10 12 14 16 18 20Stress, MPTime, daysinteriorsurfaceFigure 11: Total stress development in timeHeatingphaseinteriorsurface70‐cm thick wallCoolingphase4.0 m‐2.0 ‐1.0 0.0 1.0 2.0Stress, MPaphase‐2.0 ‐1.0 0.0 1.0 2.0Stress, MPaphase0.7 mHeatingphaseinteriorsurface40‐cm thick wallCoolingphase4.0 m‐2.0 ‐1.0 0.0 1.0 2.0Stress, MPaphase‐2.0 ‐1.0 0.0 1.0 2.0Stress, MPaphase0.7 mFigure 12: Total stress distribution at the height of the wall (XY = 0)Agnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  15. 15. IntroductionNumerical modelAnalysis of RC wallConclusionsInput dataThermalmoisture analysisStress analysisSelf-induced stresses1.01.52.0a70‐cm thick wall‐2.0‐1.5‐1.0‐0.50.00.50 2 4 6 8 10 12 14 16 18 20Stress, MPTime, daysinteriorsurface1.01.52.0a40‐cm thick wall‐2.0‐1.5‐1.0‐0.50.00.50 2 4 6 8 10 12 14 16 18 20Stress, MPTime, daysinteriorsurfaceFigure 13: Self-induced stress development in time (EF 0)70‐cm thick wallHeatingphaseinteriorsurfaceCoolingphase4.0 m‐2.0 ‐1.0 0.0 1.0 2.0Stress, MPaphase‐2.0 ‐1.0 0.0 1.0 2.0Stress, MPaphase0.7 m40‐cm thick wallHeatingphaseinteriorsurfaceCoolingphase4.0 m‐2.0 ‐1.0 0.0 1.0 2.0Stress, MPaphase‐2.0 ‐1.0 0.0 1.0 2.0Stress, MPaphase0.7 mFigure 14: Self-induced stress distribution at the height of the wall (XY = 0)Agnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  16. 16. IntroductionNumerical modelAnalysis of RC wallConclusionsConclusions1 Thermalshrinkage cracking of massive cocnrete structures is awell-known problem.2 Thermalshrinkage cracking aects medium-thick elements ifexternally-restrained.3 Restraint stresses play the main role.4 Self-induced stresses share depends directly on the thickness ofthe element.Agnieszka Knoppik-Wróbel Self-induced vs. restraint stresses in early-age RC wall
  17. 17. Juniorstav 2012Brno, Czech Republic, 26 Jan 2012

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