Lattice discrete particle modeling (LDPM) of flexural size effect in over reinforced concrete beams

Abstract

At the macroscopic scale, concrete can be approximated as statistically homogeneous. Nevertheless, its macroscopic behavior shows quasi-brittleness, strain softening, and size effects evidencing a strong influence of material heterogeneity. A model naturally accounting for material heterogeneity is the Lattice Discrete Particle Model (LDPM). LDPM replaces the actual concrete mesostructure by an assemblage of discrete particles interacting through nonlinear and fracturing lattice struts. Each particle represents one coarse aggregate piece. Since the initial development, LDPM has shown superior material modeling capabilities. In this research, LDPM is used to simulate the flexural failure of three groups of over reinforced concrete beams. The groups represent 1D, 2D and 3D geometric similarities. Geometry is generated based on concrete mix design. Then calibration was only guided by the experimentally provided compressive strength. In order to reduce the redundancy of the calibration process, the fracture properties of concrete were estimated using relevant literature. Finally, the rebar assembly was connected to the LDPM mesh using penalty type constraints and the rebars were modeled using 1D beam elements. Numerical results show excellent agreement with experimental data and clear capability of capturing size effects.