A linearized toughness model for fiber reinforced concrete using multiscale approach

Reinforced concrete structures such as offshore supporting structures, bridge decks, road surfaces, machine foundations, etc. are subjected to fatigue loading throughout their service life.Understanding the fatigue behavior of these structures is crucial for ensuring their durability and safety.Fiber-reinforced concrete contains fibrous materials as reinforcement, improving the mechanical properties.Due to the heterogeneity of concrete and variable characteristics of fatigue loading, a multiscale approach is best suited to predict the fatigue life of reinforced concrete.In this study, a linear elastic fracture mechanics (LEFM) based method is attempted to predict the fatigue life of fiber-reinforced concrete using a multiscale approach by modifying the definition of Stress intensity factor (SIF).The nonlinear behavior of the fracture process zone is captured by considering the various toughening mechanisms such as aggregate bridging, fiber bridging and microcracking occuring at meso and micro length scales.The SIF is modified by relating the crack opening displacement at the macroscale and the microscale.This modified SIF based on LEFM approach includes the contributions from bridging stress which occurs due to the bridging of aggregate and fiber at the mesoscale and microcracking occurring at microscale.The modified SIF is validated by computing the fracture energy using available experimental data from literature.Finally, a parametric study is conducted to determine the influence of various parameters on the modified SIF.