Health monitoring and fatigue damage assessment of bridge-deck sections

Based on the real-time monitoring data, a fatigue damage model using continuous damage mechanics and a methodology and strategy for evaluating fatigue damage and possible critical locations of local fatigue on bridge-deck sections are developed. The proposed local damage model to evaluate the fatigue damage of bridge-deck sections allows fatigue damage to be considered at a continuum scale as a deteriorating process with its physical mechanism such as fatigue crack initiation and growth. Therefore the fatigue damage variable associates not only cycles of stress range on the accumulating process of fatigue, but also directly associates the state of deterioration and the mechanics behavior. The effective stress range for the variable-amplitude stress spectrum due to traffic load is used to evaluate the fatigue strength of the bridge-deck section at different locations, by which possible location of critical fatigue failure can be primarily determined. As a typical case to use the method and strategy proposed in this paper, fatigue damage assessment and the detection of possible critical location of fatigue in a deck section of the Tsing Ma Bridge are carried out by using strain-time history acquired by the bridge structural health monitoring system.