The Instrumentation and monitoring of the V?rby Bridge

摘要

Numerous cracks have been discovered in the V?rby Bridge near Stockholm, Sweden. All cracksrnare found at the junctions between the cross girders and the main girders, more specifically, at thernwelds connecting the vertical web stiffeners to the top flanges of the main girders. The cracks mightrnpossibly be causing serious problems if they are allowed to propagate through the entire length ofrnthe weld, thereby permitting out-of-plane bending of the main girder web. In order to identify thernreason for the observed cracks, an ongoing investigation under the commision of the bridge ownerrnwas started in the spring of 2009. One conclusion so far, is that the observed cracks conclusively arerna result of fatiguernAs a part of a master thesis, FEM-modelling is currently under way. As the fatigue process isrndistortional, the propagation phase of the observed cracks might slow down or even stop. One taskrnwill be to determine the stress intensity factor versus crack length relationship in order to model arngrowing crack. The final chosen method of refurbishment will be based upon the results of thernstudy and will be implemented in cooperation with the bridge owner.