Meso-numerical Simulation Of Concrete Based On Multi-scale Analysis

With the extensive use of reinforced concrete structures in infrastructure construction,the components are getting larger and larger,the forces are more complicated,and the bearing capacity requirements are getting higher and higher.As the main material of building structure,concrete has an important influence on the reinforced concrete structure.In this thesis,the multi-scale theory can be used to predict the mechanical properties of concrete members through the models at both the microscopic and macroscopic levels.At the meso level,concrete is a three-phase composite consisting of mortar,aggregate and transition zone between mortar and aggregate.Based on the gradation theory and Monte-Carlo method,the circular and polygonal random aggregate models are generated by using Matlab programming language.The geometric model of random aggregate is imported into the finite element software ABAQUS for meshing,and the corresponding material parameters are calibrated.The random aggregate model of concrete is analyzed under uniaxial tension,and the effect of meso-parameters on the macro-mechanical properties of concrete material is explored.Structural damage is usually caused by local first damage,and ultimately the whole structure damage.Meso-scale model simulates large-scale structure,and its calculation is too huge,which limits its practical application in concrete structure.With limited computing resources,the multi-scale model can achieve a better balance between the refinement of calculation and analysis and the calculation cost.Taking the classical four-point bending of concrete beams as an example,the application of multi-scale simulation in concrete members is realized,and the effect of aggregate meso-parameters on the mechanical properties of concrete members is analyzed.In order to realize the application of multi-scale numerical simulation in practical engineering,combined with the actual characteristics of the structure according to the test,based on the reinforced concrete meso-numerical analysis model,the homogeneous macro-element is used in the upper part,and the random aggregate method is used in the key damage area to simulate the concrete meso-structure.A multi-scale non-linear mechanical characteristic for the development of internal damage of reinforced concrete columns is proposed.Degree numerical model.The pseudo-static hysteretic behavior of the multi-scale model of the reinforced concretecolumn is simulated and compared with the experimental results.The results show that the macro-mechanical behavior and micro-damage characteristics of reinforced concrete columns simulated by the stochastic aggregate multi-scale model presented in this paper are in good agreement with the experimental results.The multi-scale model can effectively reduce the calculation cost and achieve the balance of calculation time and accuracy with limited computing resources.