Localisation studies have been carried out for an unconstrained, elasto-plastic, strain-softening Cosserat continuum. Because of the presence of an internal length scale in this continuum model a perfect convergence is found upon mesh refinement. A finite, constant width of the localisation zone and a finite energy dissipation are computed under static as well as under transient loading conditions. Because of the existence of rotational degrees-of-freedom in a Cosserat continuum additional wave types arise and wave propagation becomes dispersive. This has been investigated analytically and numerically for an elastic Cosserat continuum and an excellent agreement has been found between both solutions.

Localisation in a Cosserat continuum under static and dynamic loading conditions

Pore space and brittle damage evolution in concrete

An experimental study on creep of welded tuff

In this paper, a novel adaptive multiscale model is proposed for accurately predicting the nonlinear mechanical response of periodic brick masonry due to crack initiation and propagation under general in-plane loading histories. Such a model relies on a two-level domain decomposition technique, used in conjunction with an adaptive strategy able to automatically zoom-in the zones incipiently affected by damage localization, with the aim of reducing the typically high computational effort associated with fully microscopic models. The proposed switching criterion is based on the numerical determination of microscopically informed first failure surfaces taking into account higher-order deformation effects. In order to assess the validity of the proposed strategy, a sensitivity analysis is carried out on a shear wall sample by varying the required input numerical parameters. An additional application of the proposed multiscale model is then presented for investigating the role of the fiber content in fiber-reinforced mortars (FRMs), recently introduced for masonry construction and rehabilitation, on the overall response of a deep beam sample.

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Multiscale failure analysis of periodic masonry structures with traditional and fiber-reinforced mortar joints

An adaptive multiscale strategy for the damage analysis of masonry modeled as a composite material

Mesoscopic modelling of masonry using weak and strong discontinuities

A novel constrained large time increment method for modelling quasi-brittle failure

In this paper, a combined experimental-computational study of a double-edge notched specimen subjected to tensile loading is presented. In the experimental part, the loaddeformation response and the displacement field around the crack tip are recorded. An Electronic Speckle Pattern Interferometer (ESPI) is used to obtain the local displacement field. The experimental results are used to validate a numerical model for the description of fracture using finite elements. The numerical model uses displacement discontinuities to model cracks. The discontinuities are able to pass through finite elements. At the discontinuity, a plasticity-based and a combined damage-plasticity cohesive zone model are used, while the continuum remains elastic. Both local and global results from the numerical simulations are compared with experimental data.

Combined experimental-computational study to discrete fracture of brittle materials

A mesoscopic masonry model is presented using the partition of unity finite element method. Joints are only explicitly introduced when a critical stress state is exceeded, resulting in a computationally more efficient procedure when compared to models in which all joints are a priori active. The performance of the presented model is demonstrated by several numerical examples.

/pdf/modelling-crack-initiation-and-propagation-in-masonry-using-2zemsop4w7.pdf

K. De Proft

Papers

Mesoscopic modelling of masonry using weak and strong discontinuities

A novel constrained large time increment method for modelling quasi-brittle failure

Combined experimental-computational study to discrete fracture of brittle materials

Modelling crack initiation and propagation in masonry using the partition of unity method

A discrete model for cyclic mode I loading