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

Chapter 1. IntroductionFigure 1.8: FE mesoscale discretization [Lopez et al., 2008a,b]: (a) 6 x 6 aggregate-arrangement,(b) matrix, (c) coarse aggregates and (d) interfaces.particle contact layers of the matrix particles [Jirasek and Bazant, 1994]. The pioneerproposals of particle simulation have been reported in the works of Cundall [1971], Rodriguez[1974] and Kawai [1980]. These works mainly modeled the behavior of granularsolids (such as sand) considering rigid particles that interact by friction. Furthermore,a particle model for brittle composite materials has been proposed by Zubelewicz andBazant [1987] and Bazant et al. [1990], for simulating cracking localization in concreteelements. Figure 1.7 outlines several particle schemes adopted by Bazant et al. [1990]for studying the size effect on the failure peak load for unnotched specimens in tension.Zero-thickness interface models: as an alternative to the continuous method, thediscrete approach based on interface elements has been followed by several authors.This approach is based on the use of zero-thickness joints which connect continuumsolid elements and possibly represent potential crack lines as outlined in Figure 1.8. Thematerial failure in crack processes is captured by means of those elements for discrete14