Numerical modeling of recycled fibre reinforced concrete beams and comparison with experimental findings

Abstract

The presented work has the main focus on fibre reinforced concrete (FRC). FRC is examined in ATENA, and the numerical results are compared to the experimental.

The first part of this report treats the concept of nonlinear finite element method to get a better understanding of the analysis. A literature study based on previous research and published material of fibres and fibre reinforced concrete is also given within this report. Important mechanical properties of FRC are presented, such as tensile strength and fracture behavior.

The procedure of testing FRC at the laboratory is included within this report.

Modeling and analysis is performed with the FEM-software ATENA-GiD interface. The beams are modeled with respect to recreate a four-point bending situation. By advantage of symmetry, half the beam is constructed and analysed in ATENA. Computed load-displacement diagrams are compared to experimental results, and the behaviour is compared. Crack pattern and crack widths are studied with the use of a full-field measuring technique, using Digital Image Correlation (DIC) system to monitor the cracking on the beam surfaces.

In total, five beams were tested at the laboratory and recreated in ATENA. One of the beams served as a reference beam containing plain concrete and conventional steel bars, while the other beams additionally contained steel fibres of different type and amount.

This thesis shows through nonlinear FEM-analysis that it is possible to make somewhat good approximations to experimental fibre reinforced concrete. However, further research must be provided to determine the tensile and fracture behaviour of FRC.