| This paper established a concrete-plastic constitutive model based on a classical theory of plastic mechanics, which can describe the mechanical behavior of concrete when the stress loading paths is along a single straight line or a complex two-segment line.At present,the stress loading path commonly used is a single straight line. In this paper, two-segment line stress loading path is divided into two phases,in the first phase is constant proportional loading to a setting value and in the second phase the stress-increment is constant. It is calledtwo-segment line stress loading path because the two-stage stress trajectory are two different lines. For constructing the constitutive model of concrete, firstly triaxial test data that our group had finished was analyzed. The focus of analysis is the test results of two-segment line stress loading path, and then compares their characteristics.This paper supposed there is only elastic deformation brought out before the Concrete reached the yielding state, and after that there is plastic deformation. This thesis constructs a constitutive model of concrete by choosing a reasonable equation of yield surface and plastic potential energy function, and compared the model with the experimental results. This thesis tries to modify the yield function that adopted in the model, which was put forwarded by Riqing Xu and others in the pear yield surface, in order to ensure the data to match with experimental results. The plastic potential energy function is modified from Druker-Prager yield function. There are eight loading paths of model in the simulation test, and three of them are single straight line stress loading path single straight line stress loading path, and five of them are two-segment line stress loading path. The model can simulate the relation of concrete stress and strain of the strengthen part, and also describe the transforming trend of concreter in the section of softening accurately. |
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