Fractional description of creep behavior for fiber reinforced concrete: Simulation and parameter study

•This study established a fractional creep model for fiber reinforced concrete, with a hierarchical single-surface (HISS) type yield function, isotropic hardening parameters and the fractional plastic flow rule.•The simulation based on testing results proves that the proposed model gave terrific description of long-term and short-term creep behaviors for concretes containing different fibers.•The analysis indicates the fractional order can not only govern the direction of the plastic flow, but also well control the magnitude and the rate of the creep deformation. Fiber reinforced concrete (FRC) exhibits enhanced strength and excellent durability, and the creep behaviors of FRC are major concerns for its application in structural analysis and design process. In this work, a novel fractional creep model for FRC is developed by introducing the fractional flow rule into the classical elastoplastic constitutive model. Specifically, a hierarchical single-surface (HISS) type yield function is adopted and an isotropic hardening function is introduced as hardening variables. Without using plastic potential, the proposed model exhibits higher accuracy than several conventional creep models with relatively simple form which is validated by comparing the numerical predictions with experimental results from short-term and long-term creep tests. Furthermore, a parameter study on the fractional order suggests that the order can adjust the magnitude and rate of the creep deformation, and the consistency between macroscopic deformation and the material formulation of FRC could be reflected by the tendency of the fractional order.