Numerical modeling of FRC with an explicit representation of coarse aggregates and fibers

• Grant number: 25/01354-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Engineering - Civil Engineering - Structural Engineering
• Principal Investigator: Luís Antônio Guimarães Bitencourt Júnior
• Grantee: Mathew Kikuti Mancilio
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/03179-0 - Multiscale modeling of plain and steel fiber reinforced concrete and its application to predicting the behavior of structural members, AP.PNGP.PI

Abstract

Currently, it is well known that representing concrete at the aggregate scale is essential for understanding the process of crack formation and propagation. Thus, an adequate prediction of material failure should be based on a model that considers this observation scale. To achieve this goal, numerical models with an explicit representation of aggregates have been widely proposed in the literature. Recently, the proponent of this project and his collaborators developed a mesoscale model for concrete based on a finite element mesh fragmentation process.Discontinuous steel fibers have been added to the concrete as a primary reinforcement to prevent abrupt tensile failure, as this material has a low deformation capacity. The role of fibers becomes more significant after the cementitious matrix cracks, as they help resist crack propagation by transferring stresses between crack faces, maintaining a certain load-bearing capacity, and preventing sudden composite failure. The inclusion of fibers in the cementitious matrix requires that mesoscale models, previously focused only on the explicit representation of aggregates, incorporate a realistic fiber distribution, considering both orientation and dispersion. In this context, the proponent and his collaborators developed a model with a discrete and explicit representation of steel fibers to describe the failure behavior of this type of composite.The multiscale numerical models recently developed by the proponent of this research and his collaborators have shown great potential in describing the complex failure process of plain and steel fiber-reinforced concrete. However, one of the main challenges of this project is to improve these models by incorporating the definition of coarse aggregates from micro-CT and CT images and integrating the combined representation of coarse aggregates and steel fibers in a single model. The adopted numerical model will use the finite element mesh fragmentation technique to represent the crack formation and propagation process, along with coupling finite elements to describe fiber/matrix interaction.By the end of this research, a numerical model that more realistically represents the failure process of this type of composite is expected to be achieved.