A review on the damage behavior and constitutive model of fiber reinforced concrete at ambient temperature

Fiber reinforced concrete (FRC) has gained increasing interest in recent years due to its superior mechanical properties compared to plain concrete. The failure of it is a process in which the initial defects (e.g., micro voids and cracks, etc.) generate, propagate and connect under the action of external loads. A clear understanding of damage behavior and precise establishment of constitutive models of FRC are important basis for correctly evaluating the mechanical behavior and failure criterion, monitoring the damage development and controlling the failure process of FRC materials and structures. In this context, this paper presents a comprehensive review on the damage behavior and damage constitutive model of plain concrete and FRC at ambient temperature. The damage process, damage mechanism, damage evaluation and damage evolution are respectively discussed, especially for the findings measured by commonly used damage detecting methods of cyclic loading test and acoustic emission technique. Moreover, the effect of steel and polypropylene fibers on the damage evolution laws of FRC as well as the corresponding mechanisms are emphasized. In addition, the existing empirical and theoretical damage constitutive models for plain concrete and FRC are comprehensively concluded, respectively. The damage constitutive models of FRC at the mesoscopic scale using homogenization and mixing theories of composite materials are particularly expounded. By comparing and analyzing these models, the latest research progress of the damage constitutive models for FRC is understood, and a direction for the subsequent research of FRC is provided.