混凝土断裂过程的细观力学有限元模拟研究

Abstract

Concrete material has widely been used in construction engineering and bridge engineering. With the development of building structure and building technology, the demand for control of concrete material damage is getting higher and higher. Therefore, the study of concrete fracture mechanism is of great significance. Most studies are based on the phenomenological constitutive representation for the inelastic material response to investigate the micro-mechanical ductile failure. It is somewhat in lack of considerations of the .micro-deformation and failure mechanism of concrete. Based on the three-phase (different constitutive model for every single phase) micro-mechanical model, the present work systematically study the influence of mechanical properties of each single phase on the concrete properties.

According to the Fuller gradation curve and Monte Carlo stochastic principle, the present work built a 2D stochastic circular aggregate represtentative volume element (RVE) micro-mechanical model by considering the interaction of the interface, mortar and matrix to analyze the multi-scale deformation and failure behavior of concrete. the micro-mechanical behavior of concrete was further studied by using the real size model, and the results were compared with the two-dimensional simulation results. Cohesive Element constitutive was used to describe the mechanism between the aggregate and the cement mortar. The constitutive of matrix was represented by the concrete damage plasticity and elastic constitutive and concrete damage plasticity was used to capture the behavior of the aggregate. The micro-mechanical model was cablirated by comparing simulation results with experimental data.

This paper used the homogenization method to analyze the fracture behavior of concrete, and established the relationship of the macroscopic tensile strength with tensile strength of the mortar and the interface, the relationship between the macroscopic softening coefficient and the softening coefficient of mortar, and he relationship of the macroscopic compress strength with compress strength and tensile strength of the mortar. In addition, Based on the calibrated model, the present work analysis the relationship between the process of crack initiation and evolution and the

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property of every part, and find out the split line differentiating whether the aggregate is damaged. And the relationship between the macroscopic tensile strength and cracking of concrete under biaxial tension was studied.

Keywords: Micro-mechanical model, RVE, Damage plasticity, Cohesive element, Multiscale

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