Abstract
A three-dimensional (3D) finite element method (FEM) based on an inserted cohesive element numerical analysis procedure was developed for concrete mesoscale systems on the ABAQUS platform with python scripts. Aggregates were generated based on dividing the existing geometrical element algorithms to randomize arbitrary spheres. Simultaneously, randomizations of the maximum aggregate size and uniform distributions of aggregate particles were also considered. An FEM for the mortar phase in concrete mesoscale systems was generated along with the interfacial transition zone (ITZ) by inserting a cohesive element. Numerical parameter analyses were performed for nine different concrete systems by varying the coarse aggregate volume fraction (α) and the ITZ tension strength (ITZ-S). The mechanical performance of concrete systems with the coupling effects of α and ITZ-S was evaluated for simulated tensile loading. The results of the numerical simulations for mechanical properties, such as the simulated tensile strengths and tension damage behaviour of concrete systems, were verified with experimental results. The proposed aggregate and ITZ generation approach and numerical simulation procedure can be used by researchers to better understand how aggregate volume fraction and ITZ strength affect the tensile behaviour of concrete mesoscale systems.
Highlights
At mesoscale, concrete is composed of three or four phases, namely, mortar with cementation, aggregate with a skeleton or filling effect, interfacial transition zone (ITZ) connecting mortar and aggregate, and random defects [1]. e ITZ forms a honeycomb wall between aggregate and mortar
A parametric analysis of the effects of the aggregate volume fraction and the ITZ strength behavior on the elastic and tensile strength of concrete was conducted to verify the reliability of the finite element method (FEM) based on an inserted cohesive element numerical analysis
Based on mesoscale numerical simulations, the tensile strength-strain relationships of concrete systems under uniaxial tensile load are shown in Figure 9 for different volume fractions and ITZ strength. e tensile stress-strain relationships of concrete systems showed a linear material behavior up to the peak response; thereafter, they experienced a slight parabolic softening phase and failed at the corresponding ultimate strain capacities, for which the aggregate volume fraction α < 0.6, and the ITZ tensile strength is within the normal range
Summary
Concrete is composed of three or four phases, namely, mortar with cementation, aggregate with a skeleton or filling effect, interfacial transition zone (ITZ) connecting mortar and aggregate, and random defects [1]. e ITZ forms a honeycomb wall between aggregate and mortar. Kamali-Bernard [4] used connecting elements to simulate the ITZ, the elements still need to be equal to the mortar in size, which results in the model analysis being unable to fully consider the role of the aggregate To address this issue, the present study first used the Ran_gen_agg_3D_ABAQUS program developed using python in an ABAQUS 3D 100 mm × 100 mm × 100 mm characteristic FEM model, according to the Fuller grading curve randomly picked aggregate. E traction-separation cracking criterion was applied to the cohesive element so that the three-phase interaction between the aggregate, mortar, and the ITZ in concrete could be expressed scientifically and reasonably in a multiscale form On this basis, a parametric analysis of the effects of the aggregate volume fraction and the ITZ strength behavior on the elastic and tensile strength of concrete was conducted to verify the reliability of the FEM based on an inserted cohesive element numerical analysis
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