The Fatigue Performance Of Concrete Thick-Walled Cylinder

With the continuous progress and development of modern civil engineering, most concrete structures, which include bridges, crane beams, oil production platforms, nuclear defense and so on, have withstood cyclic loading, leading to one of its main failure modes----fatigue failure. There has been much research at home and abroad on the fatigue properties of concrete structures under uniaxial repeated loading. However, the actual structure of concrete is constantly under complex stress, fatigue test data on which is relatively few.Based on the collection and summary of domestic data as well as the international ones, the first part of this paper above all introduces the current situation and relative theories of fatigue test of concrete, which is mainly divided into two categories----compression fatigue test and fatigue in tension test; and the relative theories can generally be boiled down to the mechanism of fatigue damage, fatigue damage accumulation and fatigue constitutive model. Then, the author set forth the basic theories as well as the concepts of the study on fatigue properties of concrete, focusing on the fatigue life distribution of concrete:subject to two-parameter Weibull distribution; the criteria of cumulative damage of concrete and guidelines for non-linear fatigue damage accumulation.The second part is a study on fatigue life of concrete, on the basis of Professor Lv Peiyin's data of fixed side pressure concrete biaxial fatigue test, the author uses linear regression and proves that the fatigue life of biaxial compression concrete under fixed side pressure summit to the two-parameter Weibull distribution. According to the analysis of linear regression of two-parameter Weibull distribution, the author has come to the regularities of distribution of the fatigue life of biaxial compression concrete under fixed side pressure and put forward the semi-logarithmic fatigue equation considering the different side of stress ratio and survival rate.In the third part, a finite element simulation against the background of the fatigue test on biaxial compression concrete under fixed side pressure has been conducted. In line with the failure mode of concrete given in the tests, the author has also analyzed the mechanism of concrete failure and risen the relative failure criteria and fatigue failure criteria. Combining the fatigue equation given in Chapter Three and applying the finite element software Ansys Workbench, the author also conducted a finite element simulation of the fatigue property of biaxial compression concrete under fixed side pressure and did a contract study of the simulated result and the experimental result.The finite element software MSC.Patran, Dytran has been applied in the fourth part to do an analog calculation of the stress distribution of concrete thick-wall cylinder and to reach a conclusion of the Stress-radius variation curves, the Stress-time variation curves of stress distribution of concrete thick-wall cylinder as well as the variation curves of speed, accelerated speed and displacement changed with time of the concrete medial node. Then the author has taken a fatigue test of concrete thick-wall cylinder by using the S-N fatigue function to forecast the fatigue life.