Analysis Of Fracture Process Zone In Temperature Field By FEM

That a concrete structure with cracks continues to work under both the temperature load and general load is a common engineering phenomenon. But because the simulation of either the structure performance or the temperature field is a very complicated problem, little research has been done in this field. Concrete material has complex physical mechanics behavior, making the performance of the structure become more complicated. Before a crack becomes unstable and starts to expand, there exists a fracture process zone at the tip of it, in which strain-softening character takes place and cohesive force decreases with the increase of crack opening displacement. Generally, the stress transmission is not taken into account inside the concrete in the fracture process zone when researchers analyze concrete structure by FEM. In addition, they seldom dispose the cracks by means of fracture mechanics. In concrete structure, not only the quantity of its cracks is multitudinous, but also the location and direction of the cracks can not be known previously. Hence if researchers analyze concrete structure by fracture mechanics and FEM, it would be very complicated. At present, fracture mechanics mainly studies the development of a single crack. As for the disposal of series of cracks, the researchers still need to do a lot of work. In this thesis, introducing a concept of the fracture process zone, the concrete structure with a single crack under the action of a stable temperature field is analyzed by FEM, which mainly includes contents as follows:(1)Establish the concrete specimen model with a single crack, and convert the function of the temperature field into the solution of temperature distribution and thermal stresses. Based on the temperature gradient and material coefficient of thermal conductivity, temperature distribution is solved. Then, thermal stress can also be calculated.(2)Based on the FCM and Duan-Nakagawa Model, there are the cohesive stresses within the fracture process zone,which influences crack growth. According to the liner relationship of the stress and crack opening displacement, fictitious...