Presentation for the paper on AMCM 2011 Conference, Cracow, Poland. Full text available: https://www.researchgate.net/publication/236171560_Numerical_analysis_of_early-age_thermal_and_moisture_effects_in_RC_wall?ev=prf_pub

1. Numerical analysis of early-age
thermal and moisture eects in RC wall
DSc. Eng. Barbara KLEMCZAK
MSc. Eng. Agnieszka KNOPPIKWRÓBEL
Silesian University of Technology
Faculty of Civil Engineering
Cracow, 14 June 2011

2. Introduction
Numerical model
Analysis of RC wall
Conclusions
Introduction
concrete curing
cement hydration process
dissipation of heat and migration of moisture
temperature and moisture gradients
stresses
self-induced, restraint stresses in structure
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

3. Introduction
Numerical model
Analysis of RC wall
Conclusions
Introduction
thermalmoisture inuences
massive structures
foundations
gravity dams
medium-thick restrained structures
RC walls of tanks, abutments, cast
against old foundation
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

4. Introduction
Numerical model
Analysis of RC wall
Conclusions
Thermal and moisture analysis
Thermalshrinkage strains
Stress analysis
Implementation
General assumptions
1 phenomenological model
decoupling of thermalmoisture and mechanical elds
full coupling of thermalmoisture elds
2 stress state determined under the assumption that
thermalmoisture strains have distort character
3 viscoelastoviscoplastic material model of concrete
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

5. Introduction
Numerical model
Analysis of RC wall
Conclusions
Thermal and moisture analysis
Thermalshrinkage strains
Stress analysis
Implementation
Thermal and moisture analysis
Coupled thermalmoisture equations
˙T = div(αTT gradT + αTW gradc) +
1
cbρ
qv
˙c = div(αWW gradc + αWT gradT) − Kqv
Initial conditions
T(xi, t = 0) = Tp(xi, 0)
c(xi, t = 0) = cp(xi, 0)
Boundary conditions
nT(αTT gradT + αTW gradc) + ˜q = 0
nT(αWW gradc + αWT gradT) + ˜η = 0
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

6. Introduction
Numerical model
Analysis of RC wall
Conclusions
Thermal and moisture analysis
Thermalshrinkage strains
Stress analysis
Implementation
Thermalshrinkage strains
Imposed thermalshrinkage strains εn:
volumetric strains
dεn = dεn
x dεn
y dεn
z 0 0 0
calculated based on predetermined temperature and humidity
dεn
x = dεn
y = dεn
z = αT dT + αW dW
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

7. Introduction
Numerical model
Analysis of RC wall
Conclusions
Thermal and moisture analysis
Thermalshrinkage strains
Stress analysis
Implementation
Stress analysis
viscoelastic area
˙σ = Dve( ˙ε − ˙εn − ˙εc)
viscoelastoviscoplastic area
˙σ = Dve ( ˙ε − ˙εn − ˙εc − ˙εvp)
Figure 1: Failure surface
possibility of crack occurrence
sl =
τoct
τf
oct
Figure 2: Eort level
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

8. Introduction
Numerical model
Analysis of RC wall
Conclusions
Thermal and moisture analysis
Thermalshrinkage strains
Stress analysis
Implementation
Implementation
A set of programs:
TEMWIL
thermalmoisture elds
MAFEM
stress analysis
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

9. Introduction
Numerical model
Analysis of RC wall
Conclusions
General case
Parametric study
Input data
concrete class C25/30, steel class RB400
cement type CEM I 32.5R, 450 kg/m3,
temp.: ambient Tz = 25◦C, initial of concrete Tp = 25◦C,
wooden formwork of 1.8 mm plywood, no insulation, no
protection of top surface; removed in 3 days (72h).
Figure 3: Geometry and nite element mesh of analysed wall
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

10. Introduction
Numerical model
Analysis of RC wall
Conclusions
General case
Parametric study
Thermal and moisture analysis
Figure 4: Temperature distribution in the wall [◦C] after 16 hours
Figure 5: Moisture distribution in the wall (x100) after 16 hours
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

11. Introduction
Numerical model
Analysis of RC wall
Conclusions
General case
Parametric study
Stress analysis
1.2
1.8
2.4
stress[MPa]
-1.2
-0.6
0
0.6
0 2 4 6 8 10 12 14 16 18 20
stress[MPa]
time [days]
Figure 6: Stress σx in time for cracked (surface) element
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

12. Introduction
Numerical model
Analysis of RC wall
Conclusions
General case
Parametric study
Stress analysis
(a) at expansion (16 hours) (c) at contraction (4.5 days)
Figure 7: Stress distribution
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

13. Introduction
Numerical model
Analysis of RC wall
Conclusions
General case
Parametric study
Parametric study of thermalmoisture cracking
(a)XZ=0m (b)YZ=3.5m
(c)XZ=0.35m (d)YZ=10m
Figure 8: Cracking patternbasic case
Analysed parameters:
1 Tp and Tz
2 time of formwork
removal
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

14. Introduction
Numerical model
Analysis of RC wall
Conclusions
General case
Parametric study
Inuence of placing and adjoining concrete temp. di.
(a) XZ=0m (b) YZ=3.5m
(c) XZ=0.35m (d) YZ=10m
Figure 9: CrackingTp = Tz = 15◦C
(a) XZ=0m (b) YZ=3.5m
(c) XZ=0.35m (d) YZ=10m
Figure 10: CrackingTp = 15◦C, Tz = 25◦C
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

15. Introduction
Numerical model
Analysis of RC wall
Conclusions
General case
Parametric study
Inuence of time of formwork removal
(a) XZ=0m (b) YZ=3.5m
(c) XZ=0.35m (d) YZ=10m
Figure 11: Crackingremoval after 7 days
(a) XZ=0m (b) YZ=3.5m
(c) XZ=0.35m (d) YZ=10m
Figure 12: Crackingremoval after 25 days
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

16. Introduction
Numerical model
Analysis of RC wall
Conclusions
Conclusions
Importance
need to ensure desired service life and function of the structure
on-going examination of early-age cracking problem
Numerical model
qualitatively and quantitatively proper results
conformation with present knowledge and experience
Contribution
multi-parameter numerical model of thermalmoisture eects in
early-age concrete and its implementation
Barbara Klemczak, Agnieszka Knoppik Early-age thermalmoisture eects in RC wall

17. AMCM 2011
Cracow, 14 June 2011