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Abstract: This paper deals with the formulation, calibration, and validation of the Lattice Discrete Particle Model (LDPM) suitable for the simulation of the failure behavior of concrete. LDPM simulates concrete at the meso-scale considered to be the length scale of coarse aggregate pieces. LDPM is formulated in the framework of discrete models for which the unknown displacement field is not continuous but only defined at a finite number of points representing the center of aggregate particles. Size and distribution of the particles are obtained according to the actual aggregate size distribution of concrete. Discrete compatibility and equilibrium equations are used to formulate the governing equations of the LDPM computational framework. Particle contact behavior represents the mechanical interaction among adjacent aggregate particles through the embedding mortar. Such interaction is governed by meso-scale constitutive equations simulating meso-scale tensile fracturing with strain-softening, cohesive and frictional shearing, and nonlinear compressive behavior with strain-hardening. The present, Part I, of this two-part study deals with model formulation leaving model calibration and validation to the subsequent Part II. [Copyright &y& Elsevier]

Abstract: In this paper, the Lattice Discrete Particle Model for fiber reinforced concrete (LDPM-F) is calibrated and validated with reference to a new high-strength, ultra-high-performance concrete (UHPC) named CORTUF and applied to the simulation of projectile penetration. LDPM-F is a three-dimensional model that simulates concrete at the length scale of coarse aggregate pieces (meso-scale) through the adoption of a discrete modeling framework for both fiber reinforcement and embedding matrix heterogeneity. In this study, CORTUF parameter identification is performed using basic laboratory fiber pull-out experiments and experiments relevant to a CORTUF mix without fiber reinforcement. Extensive comparisons of the numerical predictions against experimental data that were not used during the calibration phase (relevant to both plain CORTUF and CORTUF with fiber reinforcement) are used to validate the calibrated model and to provide solid evidence of its predictive capabilities. Simulations are then carried out to investigate the behavior of protective CORTUF panels subjected to projectile penetration, and the numerical results are discussed with reference to available experimental data obtained at the Engineering Research and Development Center (ERDC). [Copyright &y& Elsevier]

Abstract: The Lattice Discrete Particle Model (LDPM) formulated in the preceding Part I of this study is calibrated and validated in the present Part II. Calibration and validation is performed by comparing the results of numerical simulations with experimental data gathered from the literature. Simulated experiments include uniaxial and multiaxial compression, tensile fracture, shear strength, and cycling compression tests. [Copyright &y& Elsevier]