Fatigue damage analysis of long span steel bridge welded members using the finite element method and damage mechanics

The analysis method for analyzing the steel weld bridge member fatigue damage accumulation using the damage mechanics and finite element analysis has the obvious physical meaning. The finite element analysis method for the fully coupled fatigue damage evolution is proposed at first and then is implemented on the basis of the user interface of the finite element software ABAQUS. The proposed method can be utilized to analyze the fatigue damage accumulation in the practical engineering structure member. As a case for study, the fully coupled method using the damage mechanics and the finite element analysis is performed for the critical welded members fatigue damage accumulation assessment in the Tsing Ma Bridge. The calculated result shows that the fatigue damage accumulation in the critical welded members is accumulated in the region of welding toe. The value of fatigue life calculated by the fully coupled method is smaller than that by the uncoupled method, which suggests that there exists interaction between the fatigue damage evolution and the structural response. The widely used linear Miner's Law is conservative for the evaluation of fatigue life of bridge in service. And it is unfavorable for accurate assessment of fatigue damage accumulation in the online service structure. The above results provide the feasible method for accurate fatigue damage evaluation in steel bridge members based on the hot spot stress analysis and the damage mechanics theory.