Mesoscale computational modeling of the mechanical behavior of cement composite materials

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This paper proposes a new numerical model for simulating cement composite materials' mechanical behavior in tensile and bending in a mesoscale approach. A new finite element is developed in which the fiber is embedded in the cementitious matrix element, taking into account fiber orientation, stiffness, and strength. The novel formulation consists of the coupling of uniaxial fiber finite elements with continuum cementitious elements through cinematic constraint equations. The fiber degrees of freedom are eliminated at the element level. One of the significant advantages of this methodology is that mesh generation does not depend on fiber dispersion. Furthermore, the implementation allows multiple fibers crossing an element and can be applied for any fiber type. A new cohesive interface element completes the description of fiber-reinforced concrete (FRC) behavior. In addition to describing the cementitious matrix's degradation and fracture, the interface element includes the effect of the cross fracture fiber reinforcement. Finally, direct tensile and bending tests presented in the literature are simulated. Fibers are distributed randomly in the model according to the volumetric fiber fractions of the experiments. The numerical results show close agreement with the experiments and illustrate the proposed model's efficiency and robustness.