Modelling damage processes of concrete at high temperature with thermodynamics of multi-phase porous media

• Autorzy: Gawin D. , Pesavento F. , Schrefler B. A.

Warianty tytułu

PL

Modelowanie procesów zniszczenia betonu w wysokich temperaturach za pomocą termodynamiki ośrodków porowatych

• Języki publikacji: EN

Abstrakty

EN

In this paper, the authors present a mathematical description of a multi-phase model of concrete based on the second law of thermodynamics. Exploitation of this law allowed researchers to obtain definitions and constitutive relationships for several important physical quantities, like capillary pressure, disjoining pressure, effective stress, considering also the effect of thin films of water. A mathematical model of hygro-thermo-chemo-mechanical phenomena in heated concrete, treated as a multi-phase porous material, has been formulated. Shrinkage strains were determined using thermodynamic relationships via capillary pressure and area fraction coefficients, while thermo-chemical strains were related to thermo-chemical damage. In the model, a classical thermal creep formulation has been modified and introduced into the model. Results of numerical simulations based on experimental tests carried out at NIST laboratories for two types of concrete confirmed the usefulness of the model in the prediction of the time range, during which the effect of concrete spalling may occur.

PL

Autorzy pracy prezentują równania modelu wielofazowego betonu wyprowadzone na podstawie II zasady termodynamiki. Zastosowanie tej zasady pozwoliło badaczom na sformułowanie definicji i związków konstytutywnych dla kilku ważnych wielkości fizycznych, takich jak: ciśnienie kapilarne, ciśnienie rozklinowywujące, naprężenie efektywne oraz na uwzględnienie efektu wywołanego przez cienkie warstwy wody obecnej w betonie. Przedstawiono model matematyczny higro-termo-chemo-mechanicznych zjawisk zachodzących w podgrzewanym betonie traktowanym jako ośrodek porowaty. Skurcz betonu określono za pomocą równań termodynamiki opisujących ciśnienie kapilarne i współczynniki udziału powierzchniowego, podczas gdy odkształcenia termochemiczne skorelowano z parametrem zniszczenia chemicznego. Do rozważań wprowadzono zmodyfikowaną teorię pełzania opartą na sformułowaniu klasycznym. Wyniki przeprowadzonych symulacji numerycznych, bazujących na badaniach doświadczalnych zrealizowanych w laboratoriach NIST na dwóch typach betonu, potwierdziły użyteczność zaprezentowanego modelu w przewidywaniu przedziału czasu, w którym może dojść do termicznego odpryskiwania betonu.

Słowa kluczowe

EN

concrete; multiphase; damage; thermal creep

PL

termodynamika; beton

• Wydawca: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
• Czasopismo: Journal of Theoretical and Applied Mechanics
• Rocznik: 2006
• Tom: Vol. 44 nr 3
• Strony: 505--532
• Opis fizyczny: Bibliogr. 36 poz., rys.

Twórcy

autor

Gawin D.

autor

Pesavento F.

autor

Schrefler B. A.

• Department of Building Physics and Building Materials, Technical University of Łódź, Poland,

Bibliografia

• 1. Bazant Z.P., Kaplan M.F., 1996, Concrete at High Temperatures: Material Properties and Mathematical Models, Longman, Harlow
• 2. Bazant Z.P., Thonguthai W., 1978, Pore pressure and drying of concrete at high temperature, J. Engng. Mech. ASCE, 104, 1059-1079
• 3. Brite Euram III BRPR-CT95-0065 HITECO, Understanding and industrial application of High Performance Concrete in High Temperature Environment - Final Report, 1999
• 4. Chaboche J.L., 1988, Continuum damage mechanics: Part I - General concepts, J. Applied Mech., 55, 59-64
• 5. England G.L., Khoylou N., 1995, Moisture ow in concrete under steady state non-uniform temperature states: experimental observations and theoretical modelling, Nucl. Eng. Des., 156, 83-107
• 6. Gawin D., 2000, Modelling of Coupled Hygro-Thermal Phenomena in Building Materials and Building Components, (in Polish), Publ. of Łódź Technical University, 853
• 7. Gawin D., Majorana C.E., Schrefler B.A., 1999, Numerical analysis of hygro-thermic behaviour and damage of concrete at high temperature, Mech. Cohes.-Frict. Mater., 4, 37-74
• 8. Gawin D., Pesavento F., Schrefler B.A., 2002a, Modelling of hygrothermal behaviour and damage of concrete at temperature above the critical point of water, Int. J. Numer. Anal. Meth. Geomech., 26, 537-562
• 9. Gawin D., Pesavento F., Schrefler B.A., 2002b, Simulation of damage - permeability coupling in hygro-thermo-mechanical analysis of concrete at high temperature, Commun. Numer. Meth. Eng., 18, 113-119
• 10. Gawin D., Pesavento F., Schrefler B.A., 2003, Modelling of hygrothermal behaviour of concrete at high temperature with thermo-chemical and mechanical material degradation, Comput. Methods Appl. Mech. Eng., 192, 1731-1771
• 11. Gawin D., Pesavento F., Schrefler B.A., 2004, Modelling of deformations of high strength concrete at elevated temperatures, Concrete Science and Engineering - Materials and Structures, 37, 268, 218-236
• 12. Gawin D., Pesavento F., Schrefler B.A., 2006, Towards prediction of the thermal spalling risk through a multi-phase porous media model of concrete, Comput. Methods Appl. Mech. Eng., DOI: 10.10.16/j.cma.2005.10.021
• 13. Gray W.G., Schrefler B.A., 2001, Thermodynamic approach to effective stress in partially saturated porous media, Eur. J. Mech., A/Solids, 20, 521-538
• 14. Gray W.G., Schrefler B.A., 2005, Analysis of the solid phase stress tensor in multiphase porous media, submitted
• 15. Hassanizadeh S.M., Gray W.G., 1979a, General conservation equations for multi-phase systems: 1. Averaging procedure, Adv. Water Resources, 2, 131-144
• 16. Hassanizadeh S.M., Gray W.G., 1979b, General conservation equations for multi-phase systems: 2. Mass, momenta, energy and entropy equations, Adv. Water Resources, 2, 191-203
• 17. Hassanizadeh S.M., Gray W.G., 1980, General conservation equations for multi-phase systems: 3. Constitutive theory for porous media ow, Adv. Water Resources, 3, 25-40
• 18. Kachanov M.D., 1958, Time of rupture process under creep conditions, Izvestia Akademii Nauk, 8, 26-31 (in Russian)
• 19. Khoury G.A., 1995, Strain components of nuclear-reactor-type concretes during first heating cycle, Nuclear Engineering and Design, 156, 313-321
• 20. Lewis R.W., Schrefler B.A., 1998, The Finite Element Method in the Static and Dynamic Deformation and Consolidation of Porous Media, Wiley and Sons, Chichester
• 21. Mazars J., 1984, Application de la mecanique de l'endommagement au comportament non lineaire et la rupture du beton de structure, These de Doctorat d'Etat, L.M.T., Universite de Paris, France
• 22. Mazars J., 1989, Description of the behaviour of composite concretes under complex loadings through continuum damage mechanics, Proc. 10th U.S. National Congress of Applied Mechanics, J.P. Lamb (edit.), ASME
• 23. Nechnech W., Reynouard J.M., Meftah F., 2001, On modelling of thermo-mechanical concrete for the finite element analysis of structures submitted to elevated temperatures, Proc. Fracture Mechanics of Concrete Structures, R. de Borst, J. Mazars, G. Pijaudier-Cabot, J.G.M. van Mier (edit.), 271-278, Swets and Zeitlinger, Lisse
• 24. Pearce C.J., Davie C.T., Nielsen C.V., Bicanic N., 2003, A transient creep model for the hygral-thermal-mechanical analysis of concrete, Proc. Int. Conf. on Computational Plasticity COMPLAS VII (on CD), Onate E., Owen D.R.J. (edit.), 1-19, CIMNE, Barcelona
• 25. Pesavento F., 2000, Non-Linear Modelling of Concrete as Multiphase Porous Material in High Temperature Conditions, Ph.D. Thesis, University of Padova
• 26. Phan L.T., 1996, Fire performance of high-strength concrete: a report of the state-of-the-art, Rep. NISTIR 5934, p. 105, National Institute of Standards and Technology, Gaitherburg
• 27. Phan L.T., Carino N.J., 2002, Effects of test conditions and mixture proportions on behavior of high-strength concrete exposed to high temperature, ACI Materials Journal, 99, 1, 54-66
• 28. Phan L.T., Carino N.J., Duthinh D., Garboczi E. (edit.), 1997, Proc. Int. Workshop on Fire Performance of High-Strength Concrete, Gaitherburg (MD), USA, NIST Special Publication 919
• 29. Phan L.T., Lawson J.R., Davis F.L., 2001, Effects of elevated temperature exposure on heating characteristics, spalling, and residual properties of high performance concrete, Materials and Structures, 34, 83-91
• 30. Pijaudier-Cabot J., 1995, Non local damage, In: Continuum Models for Materials with Microstructure, H.B. Muhlhaus (edit.), Chapt. 4, 105-143, Wiley and Sons, Chichester
• 31. Schrefler B.A., 2002, Mechanics and thermodynamics of saturatedunsaturated porous materials and quantitative solutions, Applied Mechanics Review, 55, 4, 351-388
• 32. Sullivan P.J.E., 2001, Deterioration and spalling of high strength concrete under fire, Offshore Technology Report 2001/074, p. 77, HSE Books, Sudbury
• 33. Thelandersson S., 1987, Modeling of combined thermal and mechanical action on concrete, J. Eng. Mech. ASCE, 113, 6, 893-906
• 34. Ulm F.-J., Acker P., Levy M., 1999a, The "Chunnel" fire. II. Analysis of concrete damage, J. Eng. Mech. ASCE, 125, 3, 283-289
• 35. Ulm F.-J., Coussy O., Bazant Z., 1999b, The "Chunnel" fire. I. Chemoplastic softening in rapidly heated concrete, J. Eng. Mech. ASCE, 125, 3, 272-282
• 36. Zienkiewicz O.C., Taylor R.L., 2000, The Finite Element Method, Vol. 1: The Basis, Butterworth-Heinemann, Oxford