| Summary: | The mining, steel and oil industry is currently investing considerable amounts in extraction and refinement of natural resources in the northern part of Scandinavia. Also the cultural exchange between the countries in the Barents region is rapidly increasing, therefore the Swedish Railway administration have launched several projects aimed at increasing the accessibility of the railway lines to meet future demands. One of these lines connects the southern and northern part of Sweden and constitutes one of the major arteries for the transportation of heavy goods between the northern steel mills and the manufacturing industry located in the south of Sweden. Major investment are planned to upgrade the load bearing capacity, the axle load, of this railway line. This work is mainly focused on the larger structures and their dynamical properties. Today, these properties can be used to assess existing infrastructure and to evaluate the performance. Advantages are obvious since the existing structural integrity form the base for any investments in structural repair and upgrade of railway bridges. Especially one bridge has come into focus, the Vindel River Railway Bridge situated 55 kilometers northwest of Umeå, since large motion was discovered during train passages. So far, the behaviour of the bridge crossing the river of Vindeln has been measured two times, one in September and one in December 2005. Measurements of displacements and acceleration of the bridge during train passages has been conducted using accelerometers, LVDT’s and laser instruments. The first measurements was done to give more experience on the motion of the bridge and to try out new sensors. The second measurements in December gave much more information of the bridge motions, results that could be used to calibrate a 3D Finite Element Model (FEM) of the bridge in a study conducted by a visiting researcher from China, Professor Guojing He. Based on measurements, natural frequencies of the bridge (eigenfrequencies) in the range of 0 to 8 Hz could be ...
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