DAMAGE EVOLUTION INVESTIGATION IN STEEL AND POLYPROPYLENE FIBER REINFORCED CONCRETE

Resumo

In fiber-reinforced concrete cement-based materials, the random dispersion of discrete fibers in the
cementitious matrix causes deviations in the global structural behavior. Bending tests are crucial to analyze the
mechanical performance of the composite for project and design at a structural level. Different numerical
approaches have been employed in the literature in order to analyze fracture propagation and damage evolution
in fiber reinforced concrete beams under bending. Traditionally, the association of probabilistic and numerical
approaches reproduces the variability regarding the fiber dispersion in the cement matrix and its influence in
the material mechanical behavior with less computational effort. In this sense, this paper proposes a damage
evolution investigation to perform a numerical fracture analysis using the Extended Finite Element Method
(XFEM). Mixed-mode fracture behavior is considered. Probability density functions are used to generate
random values of tensile strength, which are assigned to each finite element in the model. These numerical
methodologies are based on a constitutive damage model, adjusted to experimental results of failure
mechanisms in fiber-reinforced concrete. The numerical analyses reproduce experimental tests reported in the
literature by Monteiro et al. (2018), as the three-point bending tests, for steel and polypropylene fibers. The
results show that the probabilistic techniques can efficiently predict the load-displacement behavior at the
macroscale since the load capacity ranges present a good agreement with the experimental reference. Moreover,
it is possible to study and predict the fracture behavior of the beam in mixed mode based on numerical models
and Computational Damage Mechanics.