| A General Framework for the Numerical Modeling of Concrete Structures Behavior Francesco Pesavento1; Dariusz Gawin2; Giuseppe Sciumè3; Marcin Koniorczyk2; 1UNIVERSITY OF PADOVA, Padova, Italy; 2LODZ UNIVERSITY OF TECHNOLOGY, Lodz, Poland; 3UNIVERSITé DE BORDEAUX, Bordeaux, France; PAPER: 222/Geomechanics/Keynote (Oral) SCHEDULED: 16:45/Fri. 25 Oct. 2019/Athena (105/Mezz. F) ABSTRACT: The prediction of the behavior of cementitious materials and concrete structures under severe conditions and/or for long time spans is of paramount importance in civil, environmental and nuclear engineering. Often, commercial tools do not provide a sufficiently accurate response, so it is necessary to use more sophisticated approaches. In this work, a general framework for the simulation of the non-linear behavior of concrete is shown and described. It is based on the mechanics of multiphase porous media. The mathematical model is developed by writing the relevant balance equations for the constituents at the pore scale, i.e. the local form of governing equations formulated at micro-scale, and by upscaling these equations to the macroscopic scale, taking into account thermodynamic constraints according to the so-called TCAT (Thermodynamics Constrained Averaging Theory) which assures that all the thermodynamics are properly up scaled from the micro to the macro level. Thanks to this approach, all the relevant quantities involved are thermodynamically correct, no unwanted dissipations are generated, and both the bulk phases and interfaces are taken into account. This procedure does not exclude, however, the use of a numerical multiscale approach in the formulation of the material properties. The numerical solution is obtained directly at the macro level by discretizing the governing equations in their final form. The resulting model can be usefully applied to several practical cases: evaluation of the concrete's performance at early stages of maturing massive structures [1-3], structural repair works [2,3], exposure of concrete to high temperatures, e.g. during fire [4,5], cementitious materials subject to freezing/thawing cycles [6], etc. In this work, the general model focuses on the specific situations described above and several examples are shown. References: [1] D. Gawin, F. Pesavento, B.A. Schrefler, Modelling creep and shrinkage of concrete by means of effective stress, Materials & Structures 40 (2007) 579-591. [2] G. Sciume, F. Benboudjema, C. De Sa, F. Pesavento, Y. Berthaud, B.A. Schrefler, A multiphysics model for concrete at early age applied to repairs problems, Engineering structures 57 (2013) 374-387. [3] F. Pesavento, B.A. Schrefler, G. Sciumè, Multiphase Flow in Deforming Porous Media: A Review. Archives of Computational Methods in Engineering 24 (2017) 423-448. [4] D. Gawin. F. Pesavento, B.A. Schrefler , Modelling of hygro-thermal behaviour of concrete at high temperature with thermo-chemical and mechanical material degradation, Comput. Methods Appl. Mech. Engrg. 192(13-14) (2003) 1731-1771. [5] D. Gawin, F. Pesavento, B.A. Schrefler, Towards prediction of the thermal spalling risk through a multi-phase porous media model of concrete, Computer Methods in Applied Mechanics and Engineering 195 (2006) 5707-5729. [6] D. Gawin, F. Pesavento, M. Koniorczykc, B.A. Schrefler, Non-equilibrium modeling hysteresis of water freezing - ice thawing in partially saturated porous building materials, Int. Journal of Building Physics, in print. |
