Multiscale Modeling of Concrete

Abstract

In this paper, a mesoscale model of concrete is presented, which considers particles, matrix material and the interfacial transition zone (ITZ) as separate constituents. Particles are represented as ellipsoides, generated according to a prescribed grading curve and placed randomly into the specimen. Algorithms are proposed to generate realistic particle configurations efficiently. The nonlinear behavior is simulated with a cohesive interface model for the ITZ. For the matrix material, different damage/plasticity models are investigated. The simulation of localization requires to regularize the solution, which is performed by using integral type nonlocal models with strain or displacement averaging. Due to the complexity of a mesoscale model for a realistic structure, a multiscale method to couple the homogeneous macroscale with the heterogeneous mesoscale model in a concurrent embedded approach is proposed. This allows an adaptive transition from a full macroscale model to a multiscale model, where only the relevant parts are resolved on a finer scale. Special emphasis is placed on the investigation of different coupling schemes between the different scales, such as the mortar method and the arlequin method, and a discussion of their advantages and disadvantages within the current context. The applicability of the proposed methodology is illustrated for a variety of examples in tension and compression.

Cohesive surface model for fracture based on a two-scale formulation: computational implementation aspects

“…The meso-scale model for concrete failure developed in this Section follows very closely the approximations reported in Carol et al [50] and Unger and Eckardt [51].…”

“…These data have been taken from Unger and Eckardt [51] with all the elastic moduli increased 10%. The parameters defined in [51], such as peak stresses and fracture energies of constituents, are considered a very rough estimation for simulating the concrete beam test in sub-Section 4.3 Note that the experimental work (Bocca et al [52]) taken for validating the numerical results in sub-Section 4.3, reports an overall Young's modulus: E = 27. [GP a] and an overall fracture energy G f = 100.[N/m].…”

Multiscale modeling of polycrystalline materials: A boundary element approach to material degradation and fracture

“…Multiscale models have been developed for the analysis of different classes of materials. Unger and Eckardt [34] developed a concurrent embedded multiscale method for studying the non-linear behavior of concrete structures, modelling explicitly the mortar matrix, the coarse aggregates and the interfacial transition zone at the material mesoscale and testing different methods (constraint equations, mortar method and arlequin method) for coupling the different length-scales. Few multiscale methods, in the sense specified here, have been developed for polycrystalline materials.…”

Scale selection in nonlinear fracture mechanics of heterogeneous materials

“…These methods make use of a domain decomposition framework whereby the zones where homogenisation fails are directly modelled at the microscale (e.g. [18][19][20][21][22][23]). In the context of fracture mechanics, concurrent multiscale methods take advantage of the fact that only a small portion of the total domain is affected by high strain concentrations [24,25].…”

“…Information is exchanged between the scales through the interfaces of the domain decomposition. In order to represent crack propagation, the microscale domain needs to be adaptively expanded into new critical regions [19,20,26]. In such a failure-oriented concurrent multiscale method, the main challenges are to…”