Meso-scale modelling of the size effect on the fracture process zone of concrete

TL;DR

This paper investigates how the size of concrete beams influences the fracture process zone using a meso-scale lattice model, aligning numerical results with experimental data to understand size effects and boundary condition impacts.

Contribution

It introduces a meso-scale lattice model to analyze the size effect on the fracture process zone in concrete beams, validated against experimental results.

Findings

Size and boundary conditions significantly affect the fracture process zone.

The model accurately reproduces experimental load-crack displacement curves.

Fracture process zone characteristics vary with specimen size.

Abstract

The size effect on the fracture process zone in notched and unnotched three point bending tests of concrete beams is analysed by a meso-scale approach. Concrete is modelled at the meso-scale as stiff aggregates embedded in a soft matrix separated by weak interfaces. The mechanical response of the three phases is modelled by a discrete lattice approach. The model parameters were chosen so that the global model response in the form of load-crack mouth opening displacement curves were in agreement with experimental results reported in the literature. The fracture process zone of concrete is determined numerically by evaluating the average of spatial distribution of dissipated energy densities of random meso-scale analyses. The influence of size and boundary conditions on the fracture process zone in concrete is investigated by comparing the results for beams of different sizes and boundary conditions.