A Study On A Useful Concrete Elastic-Plastic Constitutive Model And Its Application

Considering the popular of the application of computer numerical analysis, there are two manifest disadvantages about simulating the feature of concrete. First, the multi-linear constitutive model cannot describe the details about the behavior of yielded concrete, while those semi-empirical curves are not suitable for finite element analysis. Second, most of the numerical analysis tools are not capable enough to process non-linear relationship, since they are base on multi-linear method. In order to simulate the elastic-plastic behavior of concrete better, an effective curve fitting method is employed to find the constitutive function, and a new numerical analysis program using arch-length method to deal with nonlinear problem is designed in this article. There are 4 jobs had been done:1) Base on Legendre orthogonal polynomial and least square method,3 series of experimental data are fitted. Results show that the fitting effect would be satisfactory when the item number of orthogonal base is not less than 5. The most important consequence obtained in this article is that not only the fitting function, but also its derivative function and its definite integral are recursive.2) The fitting curve given by new method is applied in numerical analyzing. Cube and cylinder model are examined under uniaxial compressing with 3 different boundary conditions including unrestrained, semi-unrestrained and completely restricted. The results from semi-unrestrained and completely restricted modeling show convex deformation and the damage on oblique section clearly. Advanced virtual experiment illustrates the differences between loading with displacement and pressure, due to the phenomenon that pressing by force will cause deformation on top surface but displacing load wouldn't.3) The nonlinear constitutive model is employed to examine the shape of an arch dam. No tensile stress exists in the dam when water level is normal; while material yields when 1.4 times overloading is considered. It can be concluded that the dam is reliable and the safety margin is satisfactory.4) The progress of solving nonlinear function using arc-length method is discussed for designing new numerical analyzing tool, and the frame of programming base on nonlinear method is obtained.