Concrete meso-scale model with full set of 3D failure modes with random distribution of aggregate and cement phase. Part I: Formulation and numerical implementation

Abstract

Prediction of failure mechanisms in concrete is a fairly complex task due to heterogeneous concrete microstructure, localization process triggered by cracks, multiple crack interactions during their growth and coalescence, and different dissipative mechanisms in a fracture process zone prior to localized failure and in a localization zone during the failure. None of the currently used phenomenological models can represent the full set of 3D failure modes. This work presents an attempt to solve this with the 3D meso-scale model based on discrete lattice approach. In particular we show that we can capture such complexities at the meso-scale, which is able to represent microcracks in fracture process zone along with the localized failure represented in terms of embedded strong discontinuity and accompanied with softening constitutive law. The model can also successfully simulate salient features of concrete response, such as order of magnitude of reduction in strength in uniaxial tension versus compression, strength increase in biaxial loading or hydrostatic tension. Moreover, macro-scale representation of failure surfaces obtained with presented model for different loading programs confirms the need for failure concrete criterion of multi-surface kind. Part I of this work presents the proposed meso-scale based on extensive number of numerical simulations with multiple realizations of different concrete specimens, along as the optimal deterministic fit for several common concrete failure models. The ultimate interest of the work is to provide detailed data set for different failure modes which can be used for identification of probability distribution of material parameters for different criteria. Such task is carried in Part II of this work. c

Crack propagation in dynamics by embedded strong discontinuity approach: Enhanced solid versus discrete lattice model

“…The proposed discrete lattice model has been developed for quasi-static propagation of cracks in heterogeneous materials and already applied in progressive failure simulations of rocks [18,19], concrete [20] and saturated porous medium [21,22]. It relies on representing the cohesive links by spatial beam models, as a class of discrete lattice models where geometry is built using Delaunay triangulation.…”

“…We can write the displacement field as the sum of continuous displacement and a displacement jump as Thus, Eq. (2) can be rewritten by adding and subtracting a regular differentiable function from Heaviside function (see [20] for more details) and the resulting finite element interpolations for displacement field can be recast as…”

Three-Dimensional Finite-Discrete Element Framework for the Fracturing of Reinforced Concrete Structures

“…This conclusion applies under condition that approximately linear relationship of α and l cr /D exists, as it is valid for l cr /D ≤ 10 (see Eq. (26) and Fig. 9).…”

“…DEM was initially developed in granular material problems, but later it was applied in the fracture simulation of rocks [17,18] and concrete [19]. Discretisation of the structures is given in the form of particles, blocks or Delaunay/Voronoi tessellations, while the connections between the discrete elements were achieved with contact (joint, interface) elements [18], lattice elements [20][21][22][23][24][25][26] or rigid body springs [27,28]. Discrete elements are assumed as rigid or deformable bodies.…”

Hybrid Micro-Modeling Approach for the Analysis of the Cyclic Behavior of RC Frames

“…This approach leads to a significant simplification of the numerical problem. In micro-modeling approaches, the micro-mechanical interaction phenomena are explicitly modeled numerically (e.g., Karavelić et al, 2017;Sinaie et al, 2018) and generally high computational efforts are required. Therefore, when the target of the analysis is global behavior of RC structures, generally macro-models are preferred (e.g., Vamvatsikos and Fragiadakis, 2010;De Risi et al, 2017).…”