A variational micro-mechanical model is proposed to reproduce the complex response of fiber-reinforced concretes to tensile loadings. The composite is described as a mixture where two phases are combined: a brittle phase, corresponding to the cementitious matrix, and an elasto-plastic phase, describing the ductile contribution of fibers. The model is formulated in the simple one-dimensional setting of a tensile bar, and implemented in a finite element code. Simulations of tensile tests are performed, which capture the different stages of the evolution typically observed in experiments: the stress-hardening phase of microcracking, and the subsequent stage of stress-softening in which a macro-crack opens, leading to the sample failure. Simulations also reproduce the stiffness degradation and the occurrence of residual strains observed when samples are unloaded.
Variational modeling of micro-cracking and failure in fiber-reinforced concretes / Lancioni, G.; Alessi, R.; Baioni, E.. - (2020), pp. 1554-1565. (Intervento presentato al convegno 6th ECCOMAS European Conference on Computational Mechanics: Solids, Structures and Coupled Problems, ECCM 2018 and 7th ECCOMAS European Conference on Computational Fluid Dynamics, ECFD 2018 tenutosi a Scottish Events Campus, gbr nel 2018).