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The use of a three-dimensional discrete element method ͑DEM͒ is proposed to study concrete structures submitted to dynamic loading. The aim of this paper is to validate the model first in the quasistatic domain, and second in dynamic compression, at the sample scale. A particular growing technique is used to set a densely packed assembly of arbitrarily sized spherical particles interacting together, representing concrete. An important difference from classical DEMs where only contact interactions are considered, is the use of an interaction range. First, the correct identification of parameters of the DEM model to simulate elastic and nonlinear deformation including damage and rupture is made through quasistatic uniaxial compression and tension tests. The influence of the packing is shown. The model produces a quantitative match of strength and deformation characteristics of concrete in terms of Young's modulus, Poisson's coefficient, and compressive and tensile strengths. Then, its validity is extended through dynamic tests. The simulations exhibit complex macroscopic behaviors of concrete, such as strain softening, fractures that arise from extensive microcracking throughout the assembly, and strain rate dependency.

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Purpose -YADE-OPEN DEM is an open source software based on the Discrete Element Method which uses object oriented programming techniques. The paper describes the software architecture. Design/methodology/approach -The DEM chosen uses position, orientation, velocity and angular velocity as independent variables of simulated particles which are subject to explicit leapfrog time-integration scheme (Lagrangian method). The three-dimensional dynamics equations based on the classical Newtonian approach for the second law of motion are used. The track of forces and moments acting on each particle is kept at every time-step. Contact forces depend on the particle geometry overlap and material properties. The normal, tangential and moment components of interaction force are included. Findings -An effort has been undertaken to extract the underlying object oriented abstractions in the Discrete Element Method. These abstractions were implemented in C++, conform to object oriented design principles and use design patterns. Based on that, a software framework was developed in which the abstractions provide the interface where the modelling methods can be plugged-in. Originality/value -The resulting YADE-OPEN DEM framework is designed in a generic way which provides great flexibility when adding new scientific simulation code. Some of the advantages are that numerous simulation methods can be coupled within the same framework while plug-ins can import data from other software. In addition, this promotes code improvement through open source development and allows feedback from the community. However implementing such models requires that one adheres to the framework design and the YADE framework is a new emerging software. To download the software see http://yade.wikia.com webpage.