Analysis of damage distribution in concrete specimens of varying sizes

This paper presents recent results obtained by the Lattice Discrete Particle Model (LDPM) for the simulation of concrete and fiber reinforced concrete behavior. LDPM is a meso-scale model which has been recently formulated at Rensselaer Polytechnic Institute and extensively validated against experimental data. LDPMcanaccuratelypredictseveralphenomenacharacterizingconcretebehavior,includingfailureunder uniaxial, biaxial, and triaxial compression; material compaction under hydrostatic compression; and tensile fracturing. 1 THELATTICEDISCRETEPARTICLEMODEL Since the mid-1980s, many meso-scale models for concrete have appeared in the literature. The main advantage of these models over classic constitutive models for concrete is their ability to simulate ma- terial heterogeneity and its effect on damage evo- lution and fracture. Noteworthy examples of meso- scale models are the ones published in Roelfstra et al. ˇ (1985), Wittmann et al. (1988), Bazant et al. (1990), Schlangen & Van Mier (1992), Carol et al. (2001), Lilliu & Van Mier (2003), Cusatis et al. (2003a), Cusatis et al. (2003b), Cusatis et al. (2006a), Cusatis &Cedolin(2006b), Yip et al. (2006). Thispaperpresentsanddiscussesrecentresultsob- tained at Rensselaer Polytechnic Institute by the Lat- tice Discrete Particle Model (LDPM). LDPM simu- Figure 1: a) Meso-structure tessellation. b) Three- lates concrete mesostructure by taking into account dimensional discrete particle. c) Definition of nodal de- only the coarse aggregate pieces, typically with char- grees of freedom and contact facets in two-dimension. acteristic size greater than 5 mm. Themesostructureis constructedthroughthefollowingsteps.1)Thecoarse stead of the facets themselves to ensure that the shear aggregate pieces, whose shapes are assumed to be interaction between adjacent particles does not de- spherical, are introduced into the concrete volume by pend on the shear orientation.