Previsão da vida à fadiga em vigas de pontes de aço sob carregamento cíclico de amplitude variável

Abstract

Steel bridges are normally subjected to random loads with different traffic frequencies. In this way, steel bridges are structures of dynamic behavior and are subjected to fatigue failure process. Nucleation and growth of cracks maybe due to loading fluctuations. After to locate and to determine the amplitude of an existing flaw, it is important predicts crack propagation and the convenient time to repair. Therefore, fracture mechanics and fatigue concepts are essential to the right approach to the problem. At this work, the fatigue crack propagation on steel beam bridges, has been studied under different spectrum of variable-amplitude loading. To study the fatigue crack growth, it was developed a computational code, by using the root-mean-square and the cycle-by-cycle models. One observe the variable amplitude loading influence on the life structural prediction. Different loads histories and initial crack length were considered as input variables. Thus, it was evaluated the dispersion of results of the expected structural life choosing different initial parameters.