tesi A. Caggiano.pdf - EleA@UniSA - Università degli Studi di Salerno

1.2. Theoretical proposals for concrete-like materialsa) b)Coarse aggregateMedium aggregateSmall aggregateITZMortar matrixMacroscaleL 10 -1 mMesoscale10 -1 m L > 10 -4 mc) d)Microscale10 -4 m L > 10 -6 mNanoscale10 -6 m L > 10 -9 mFigure 1.3: Concrete materials under different scales of observation: (a) macroscale continuum,(b) 2-D mesoscale concrete analysis [Kim and Al-Rub, 2011], (c) modeling the hydration of cementsat microscale [Bishnoi and Scrivener, 2009] and (d) simulations by means of electrophilicand nucleophilic attack at a nanoscale standpoint [Puertas et al., 2011].be found in the RILEM-TC162-TDF [2003] where different constitutive relationshipsfor structural applications and based on the stress equilibrium in the critical crackedsection have been presented.Macroscale modelsIn the field of the computational failure mechanics, intended as the set of mathematicaland computational tools aiming at identifying the failure mechanisms and predictingthe critical and post-critical behavior of structures, the “material failure” representsone of its main ingredients. Cement-based materials can be ideally considered ascontinuum media and modeled within the theoretical framework of the material failure.Such constitutive proposals are based on the classical continuum formulations (i.e.,strain localization [Cervera et al., 2010], smeared cracking [Einsfeld et al., 1997]) or theenriched continuum ones (e.g., Cosserat media [Jeong et al., 2011], gradient enrichment7