Meso Multiphase Model Of Concrete With Heterogeneous Interfacial Transition Zone

Concrete is a complex heterogeneous composite material. Many problems in concrete's process of failure destruction are difficult to explain from a macroscopic point of view, but from a lower scale-microscopic point of view to study these problems will be solved easily. This is because the nature of the microstructure properties of the concrete will influence the microstructure properties of the concrete. Therefore, Analyzing the macroscopic properties of concrete by microscopic methods is of great significance.On the meso level, the surface of coarse aggregate concrete was wrapped in an area-interfacial transition zone (referred ITZ), which is different from the mortar. Its macroscopic characteristics of concrete had a great impact. A new mechanical model of interfacial transition zone was established. The model considered the heterogeneous nature of the interface transition zone, reflected the gradient nature of the interface transition zone and laid the foundation for the study of the overall characteristics of the concrete. The main results are as follows:A numerical model of hydration of cement paste considering random holes was established. The model was subjected to uniaxial tension simulation, and the load displacement curve and the whole process of cracking were analized. Through a large number of numerical analysis, how the porosity and pore diameter distribution influence the property of hydrated cement was gotten. The qualitative analysis of the above-described laid the foundation for the study of the mechanical properties of ITZ.Interfacial transition zone of concrete were stratified. On the basis of this, a concrete meso multiphase model considering heterogeneous interfacial transition zone was established. Compared with the traditional model, this model is closer to the actual situation of the interfacial transition zone. The numerical model's results were compared with the experimental results, and the accuracy and stability of the model was validated. The influence of stratified of ITZ for the calculation accuracy of the numerical model was studied.On the basis of PYTHON, Secondary Development of ABAQUS was carried on. A set of procedures were prepared including modeling, calculation and post-processing, and saved much time. Through the program, a lot of modeling and debugging time was saved, and the problem of the separate of modeling and calculation could also be solved.On the basis of the model in this paper, the effects of the changes of meso material parameters on the macro -mechanical behavior of concrete were studied. Three-point bending beam's load-displacement curve and the whole process of cracking were studied. It can be found through simulation that meso multiphase model of concrete reflected the effect of changes in the meso structure on the macro characteristics greatly, highlighting the role of the interfacial transition zone on the failure process of concrete, and reflected the connections between the microstructure and the macro properties of concrete.