Numerical Analysis of Bending Toughness of Steel Fiber Reinforced Cement Based Materials

Abstract

Steel fibers have a significant toughening effect on cement-based materials. In order to address the issue of relying solely on experimental evaluation of their bending toughness, a numerical analysis method based on the steel fiber bridging theory has been proposed. By establishing a crack extension criterion for fiber-reinforced cement-based composite materials based on the balance between the stress intensity factor generated by external loads, steel fibers, and matrix cohesion at the crack tip and the fracture toughness of the composite material, the toughness of the composite material is evaluated. Through steel fiber-matrix pull-out tests, the bonding characteristics of four types of steel fibers, namely shear, milling, short hook, and long hook, with the matrix are analyzed. A program is then developed using Ansys software APDL language for numerical simulation of the bending and cracking process of the notched beam of the steel fiber-reinforced cement-based composite material. The obtained load-deflection curve and bending toughness index are compared with the results of the notched beam bending test, thereby validating the correctness of the numerical analysis method. The results show that the bending toughness of steel fiber-reinforced cement-based composite materials is closely related to the volume fraction of steel fibers and their bonding characteristics. The balance relationship of the stress intensity factor at the crack tip is the key factor determining crack propagation, and the proposed numerical analysis method can effectively assist in the analysis of the bending toughness of steel fiber-reinforced cement-based composite materials.