Phase‐Field Modeling for Failure Behavior of Polymer Fiber‐Reinforced High‐Performance Concrete Using the Schapery Viscoelastic Model

Source abstract

ABSTRACT Concretes and cement‐based materials are known to exhibit brittle failure, which limits their structural performance after cracking. To overcome this, fiber reinforcement is commonly used to enhance the post‐cracking properties of the material. In this regard, the polymer fibers have emerged as a more environmentally friendly alternative to steel fibers. However, the inherent viscoelastic behavior and its influence on the performance of fiber‐reinforced concrete require further research. This study investigates the impact of polymer fiber viscoelasticity on the failure behavior of fiber‐reinforced high–performance concrete (HPC), considering different strain rates and volume fractions of fibers. Thus, the three‐point bending test, considering a boundary value problem based on the EN14651 is conducted under two different loading rates to assess time‐dependent effects. For that purpose, a recently developed phenomenological material model for fiber‐reinforced HPC combined with the non‐linear viscoelastic Schapery model is implemented. The failure behavior of the HPC in tension and compression is governed by step‐wise linearly approximated degradation functions, and the fibers are aligned in the horizontal direction. Finally, the performance of the numerical model is discussed using load‐CMOD (crack mouth opening displacement) curves and the phase‐field parameter distribution. The proposed model is sensitive to increasing fiber content, effectively capturing the additional strength contribution of the added fibers. Moreover, it successfully extends the previously presented formulation as it effectively describes the influence of the viscous dissipation on structural performance, particularly under low loading rates, thereby highlighting the importance of viscoelastic effects in time‐dependent fracture behavior.