The Mesoscopic Numerical Simulation Of The Reinforced Concrete Failure

Concrete and Reinforced concrete are widely used as an important building material. people have carried out many researches on mechanical properties of concrete and reinforced concrete for a long time. The subject how to make the best use of their mechanical properties and make the engineering structure more economical, safer and more reasonable, is always very important in the field of the structure design.The description about the damage process of solid material is one of the difficult problems in mechanics, and at the same time it is a materials multi-scale analysis, interdisciplinary proposition in Mechanics and materials science for nearly a century.In this paper, from meso-scale level, the numerical simulations of uniaxial tension and uniaxial compression on concrete and reinforced concrete are performed by finite element program, and the calculated results are analyzed.And the relationship of load and displacement and the damage process of samples are given, The specific contents and conclusions are shown as follows(1) Based on the mesoscopic random aggregate model, the random size and random shape of aggregate, the algorithm is taken with concave and convex aggregate in the calculation(2) Three random aggregate mesoscopic numerical models of concrete sample with a dimension of150×150mm are build. The loading process of sample is controlled by displacement, and bottom nodes of sample are constrained in the normal direction. The numerical simulations are performed for uniaxial tension and uniaxial compression,and the relationship of strain and stress is given and the damage process is analyzed.(3) Three random aggregate mesoscopic numerical models of reinforced concrete sample with a dimension of150×150mm are build. The thickness of interface between bar and concrete is not defined as zero to approach the problem. The loading process of sample is controlled by displacement, and bottom nodes of sample are constrained in the normal direction. The numerical simulations are performed for uniaxial tension and uniaxial compression,at the same time the relationship of strain and stress is given and the damage process are analyzed.The resulting curve of tension and compression is in reasonable range, and this provides a method for future study on bond behavior of reinforced concrete. (4) Based on the three different section, the stress curve line of eight parts under the different iterative step, and some simple rules can be finded, we can conclude the preliminary assumption of relation of the affected area and reinforcement diameter under uniaxial tension of reinforced concrete.(5) The peak stress don’t increase under uniaxial tension and uniaxial compression when the macro size of concrete and reinforced concrete samples increases with150mm×150mm as a standard. For the size effect, the peak stress decreases on the whole when the macro size increases,and finally it tends to a stable value. Size effect of reinforced concrete samples has some influence on the steel bar.