The Application Of Visco-elastic-plastic Unified Constitutive Theory For Concrete Material

In the numerical analysis of reinforced concrete, the strain-stress model of concrete is very important. Because of the complexity of concrete,by now there are not one perfect model which can describe the strain-stress connection.There are some model, for example nonlinear elastic theory and elastic-plastic theory, which have been put forward for many years and many practical formula. They have been applied broadly in the inlinear finite element analysis of reinforced concrete. But all these models don't think of the influence of rate effect, that is the correlation between concrete distortion and time. Actually the rate effect exists and have notablely effect on distortion of concrete.In this article author summarize these model and compare them, describe their virtue and disadvantage. Finally apply the visco-elastic-plastic unified constitutive theory to the concrete material so that we can analysis the reinforced concrete structure in nonlinear finite element method. Contrasting the result which the visco-elastic-plastic unified constitutive theory simulate with the result which educed from examination, we can find that the new model is practical.In this acticle the author make a program in VC++ language. The program simulate the whole process of reinforced concrete nonlinear finite element analysis. In this program the author adopt the visco-elastic-plastic unified constitutive theory, at the same time adopting the Kupfer-Gerstle destroy rule and mixed crack model. As far as the nonlinear function, the author make solution in mixed method. When making the program, the author adopt the idea of OOP(Object Oriented Programming) and compartmentalize the program into several module, so that it can be expanded and consummated easily. The beforehand module can compartmentalize the finite element reseau automatically, then it can economize the works markedly. The calculation module can simulate the whole process of the nonlinear finite element analysis for reinforced concrete structure, from distortion to crack. In this process we can choose different strain-stress model and destroy rule. Aiming at the randomicity of concrete crack, the author adopt the randomicity finite element model and Monte-Carlomethod to simulate the randomicity of material character and crack distribution. In the afterward module , the calculation result can be output in figure , include of the steel stress, element nodes displacement and crack distribution.At last the author validate the program through the examples and testify that the new visco-elastic-plastic unified constitutive theory can be used in the numerical analysis of reinforced concrete.