Experimental And Numerical Simulation Research On Concrete Fracture Model Based On Fracture And Damage Theory

Concrete is a kind of complex multi-phase composite material. Because of the different physical characteristics, cohesion surfaces of its various components, load conditions as well as the influence of environment, the failure mechanism of concrete is exceptionally complex, which makes the study of its fracture mechanism very difficult. In recent years, the researches on concrete cracking based on damage mechanics and fracture mechanics have draw more and more attentions and recognitions. However, the researches in this field are not mature enough although there are some achievements. Therefore, this paper carries out the relevant research as follows.Firstly, the advantages and disadvantages of damage constitutive models and fracture models of concrete are analyzed respectively. Then a improved consolidated concrete fracture model combining the damage model and fracture model is proposed in this paper.In this model, the meso-damage model is used to get the stress distribution of the fracture extension area and the impact of the fracture extension area on the fracture is considered. It combines the advantages of the two models above and can achieve the analytical solution.Secondly, the concrete fracture experiments are carried out to verify the new model above, using three concrete groups, whose initial seam height ratio of the concrete specimens are 0.1,0.2,0.3 respectively. The fracture behaviors of each group in eight different ages are reviewed. And the crack tip opening displacement and stress intensity factor are calculated using the theoretical model proposed in this paper.Then, the experiments on the fracture of concrete with mineral admixture are carried out. The fracture properties of the concrete mixed with fly ash and slag respectively are obtained and compared to the corresponding plain cement concrete. Then the influence of the fly ash and slag to the fracture properties of concrete are analyzed as well as their reasons.At last, the numerical simulation of the concrete cracking in the three-point bending beam is established with the finite element analysis software-ABAQUS. The finite element results and experimental results of the fracture properties of concrete with different ages and initial seam height ratios are compared.