Abstract
The paper presents the application of a new nonlinear damage detection method for fatigue cracks on the deck system of a steel bridge. The István Türr Danube bridge in Hungary is a truss girder-type steel mixed road/railway bridge having orthotropic deck system for highway traffic placed on the top of the main girders. Fatigue cracks have been observed on the bridge deck at the junction point of the longitudinal stiffeners and cross-girders on the stiffener welds. The fatigue cracks have been visually detected during the regular inspections. On the basis of an advanced fatigue analysis, reparation method to avoid the crack propagation and the appearance of new cracks have been designed and manufactured on the bridge. The current research has the aim to present the application possibility of an innovative measurement-based damage detection method to identify the cracks on the structure between the regular inspection periods, using the current bridge example. This method is characterized by comparing the difference in dynamic responses of two neighboring sensors. The dynamic responses are obtained by pairs of sensors at locations prone to fatigue cracks with vehicle loading. The pairs of sensors on both sides of fatigue cracks will appear to have significant differences due to the local dynamic disruption induced by the fatigue cracks. To identify the presence and severity of fatigue cracks, the correlations of the measured dynamic responses are compared in time (frequency/time-frequency) domain. The proposed method can be an efficient tool for fatigue crack detection in an early time, which can be implemented in monitoring systems operating on bridges. Session
