Stochastic Fracture Behavior and Energy Dissipation of Aligned Steel Fiber–Reinforced Cementitious Composites

ABSTRACT The characteristics of the constitutive behavior of aligned (ASFRC) and ordinary (SFRC) steel fiber–reinforced cementitious composite exert a decisive influence on the fracture performance of the three‐point bending beam specimens. This study established a coupled analytical method by integrating the stochastic fiber bridging curve with the matrix constitutive relation, enabling quantitative characterization of the stochastic fracture behavior and energy dissipation mechanisms of both the matrix and fibers. Through stochastic modeling of the fiber embedment length distribution, the mean value and variance of bridging stress were derived. Subsequently, the effects of specimen size and the initial crack length‐to‐depth ratio ( a 0 / D ) on the fracture process zone (FPZ) and energy dissipation were systematically investigated. The simulation results showed good agreement with the experimental measurements. For ASFRC specimens, the proportion of energy dissipated by steel fiber pullout at peak load ( P max ) was significantly higher than that of SFRC. The energy dissipation U undergoes a transition from a matrix‐dominated mechanism to a fiber‐dominated mechanism. Additionally, the dispersion of energy dissipated by steel fiber pullout in ASFRC specimens was notably smaller than that in SFRC specimens, indicating that the performance fluctuations induced by the stochasticity of fiber orientation were partially mitigated in ASFRC specimens.