Both The Railway Simply Supported Steel Truss Bridge Remaining Fatigue Life Analysis

In this paper, based on the research achievements in the analysis, forecast and evaluation of the structural fatigue life at home and abroad, the fatigue features of riveting components which have a specificity are discussed. And the method of evaluating remaining life as well as the actual fatigue life in the simply supported beam of Nanjing Yangtze River Bridge are studied, which can be regarded as a theoretical foundation for the management and maintenance of the steel bridges. In details, the following aspects are investigated:1. Finite element model (FEM) of the simply supported beam, which is one part of Nanjing Yangtze River Bridge (NYRB), is established, and then the dynamic characteristics under the load of the train can be obtained. Furthermore, the 3D FEM is modified according to the data from field testing, and the finite element model aimed at evaluating the remaining life of the existing steel bridges, which is in accordance with the actual mechanic behavior, can be finally determined.2. The simulation and calculation method of the current bridge fatigue load spectrum and stress spectrum is summarized in this paper, and the load spectrum of this bridge at present is gotten according to the live load information gathered from the Nanjing Yangtze River Bridge Health Monitoring System. With ANSYS transient analysis, the time-history curves of stress in the main member bars are obtained, and the fatigue stress spectrum of the main member bars can be also gotten by compiling the program of rain-flow method.3. On the basis of the fatigue stress spectrum in the member bars which are located in the representative part of the bridge, the traditional fatigue analysis method is applied to evaluate the fatigue life of the main member bars in the simply supported beam of NYRB.4. The principle and method of calculating structural remaining fatigue life, which is derived from fracture mechanics, are demonstrated systemically. The finite element model of riveting components is established and the stress intensity factor of crack tip is calculated. In addition, the fatigue crack is simulated on the basis of linear elastic fracture mechanics, and the fatigue life of the main member bars, which are taken from the simply supported beam of NYRB, is also evaluated based on the damage tolerance analysis method.