Computational modeling of ultra-high-performance steel fiber-reinforced concrete with discrete and explicit fiber representation

• Grant number: 25/22156-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2025
• End date: November 30, 2026
• Field of knowledge: Engineering - Civil Engineering - Structural Engineering
• Principal Investigator: Luís Antônio Guimarães Bitencourt Júnior
• Grantee: Letícia Gorgulho Gritti
• 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

Discontinuous steel fibers have been added to concrete as primary reinforcement to prevent sudden tensile failure, since this material exhibits low deformability. The role of the fibers becomes more relevant after the cracking of the cementitious matrix, as they act to resist crack propagation by transferring stresses across the crack surfaces and preventing abrupt failure of the composite. Despite their potential as a structural material, skepticism persists in the market regarding their use, which is directly related to the variability observed in laboratory experimental tests performed on structural elements and material characterization tests. Furthermore, it is known that the behavior of the composite can be influenced by several parameters, such as the structure of the concrete matrix; the material, shape, and geometry of the fibers; fiber content; fiber distribution; and the fiber/matrix interfacial structure.In this same context, and as an alternative for producing more slender structural elements, ultra-high-performance fiber-reinforced concrete (UHPFRC) has emerged. This material exhibits much higher strength than conventional concrete and typically contains at least 2% of steel fibers by volume. Despite its high cost, it holds promise for structural applications that require superior mechanical performance.Based on the above, this undergraduate research project aims to adapt a computational model with a discrete and explicit representation of steel fibers-developed by the proponent of this research and collaborators-to describe the formation and propagation of cracks in UHPFRC. The model will be adapted to account for typical fiber distributions at high volume fractions and for the interaction between high-strength matrix and fibers. Model calibration will be carried out using experimental results from material characterization tests being developed within the scope of the FAPESP Initial Research Grant Project (Grant #2022/03179-0).At the end of the study, it is expected to obtain a numerical model that provides a more realistic representation of the failure process of this type of composite.