The Instrumentation and monitoring of the Vårby Bridge

Numerous cracks have been discovered in the Vårby Bridge near Stockholm, Sweden. All cracks are found at the junctions between cross girders and the main girders, more specifically, at the welds connecting the vertical web stiffeners to the top flanges of the main girders. In order to identify the reason for the observed cracks, an ongoing investigation under the commision of the bridge owner was started in the spring of 2009. One conclusions so far is that the observed cracks are to 100 % certainty a result of fatigue.FEM-modeling is currently going on as a part of a master thesis. As the fatigue process is distortional the propagation phase of the observed cracks might slow down or even stop. One task will thus be to determine the stress intensity factor versus crack length relationship in order to model a growing crack. Suggestions of possible of methods of refurbishment, based upon the results, will then be presented to the bridge owner.Godkänd; 2010; 20120916 (mattni