Research On Damage Constitutive Relationship For Concrete Based On Nondisturbance State

To study elastoplastic damage constitutive relations for concrete based on nondisturbance state, the paper make use of ANSYS software to simulate the mechanical behavior of concrete, combined with MATLAB software to plot the results of the finite element simulation. It has a significant influence on the deep understanding of constitutive relations, the improvement of material properties, the guidance of material enhanced design, the development of new material and energy saving.The paper elaborate the concept of Duality Disturbance and material changes, duality disturbance equation of many materials and a comprehensive detailed explanation of the disturbance.The stress-strain relationship is formulated and consists of strengthened stage and softened stage by by observing the stress-strain curve that use the uniaxial tension and compression test data for concrete. The outstanding feature of curve is the presence of softening phase inflection. The five parameters criteria for concrete includes derivation, the characteristic of deviatoric plane and hydrostatic plane, the parameters of determination and elastoplastic damage constitutive theory for concrete comprises the stress tensor decomposition theory, concrete constitutive relationship and damage criteria based on plastic strain. Proposed three representative nondisturbance stress-strain curve and analysed the relationship between plastic strain and disturbance, the relationship is fitted to Weibull curve.Through the results analysis of finite element simulation, rationality of the three kinds of nondisturbance stress-strain curves are proved. Nondisturbance stress-strain formulation is put forward. Taking advantage of simple five parameters criteria, the finite element model to simulate the uniaxial tension and uniaxial compression of concrete is established. Using elastoplastic damage constitutive theory for concrete to analyze the simulation results, analysis data is in good agreement with stress-strain curves of concrete, thus applicability of the theory for one-dimensional mechanical behavior of concrete is validated.Using the general five parameters criteria and establishing T-beam concrete model, finite element model is applied to the analysis of the mechanical behavior of concretthe and downward distributed load is applied at the right end section. The stress state of the concrete is multi-directional. Viewing the stress-strain diagram of finite element simulation and drawing principal stress distribution diagram of dangerous section by MATLAB, conclusion is defined that the dangerous node is on the upper section and on the lower section. Selected a dangerous node, analyzed the stress, strain and plastic strain, the stress tensor is decomposed of plus and minus parts throhgh the stress tensor decomposition theory. In addition, the decomposition results consistent with the elastoplastic analysis, thus applicability of elastoplastic damage constitutive relations for general mechanical behavior of concrete is confirmed.Through five parameters criteria and finite element analysis of one-dimensional and multi-dimensional mechanical behavior for concrete, rationality and applicability of damage constitutive relationship for concrete based on nondisturbance State is verified.