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Dynamic behaviour of the Vindel River railway bridge: measurements and evaluation for eisplacements and eigenfrequencies
2006 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

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 detected? Modal shapes up to the ninth order could be extracted in a new type of statistical process including damping ratios, deflections and transverse displacements for different sets of train and different train speeds. Comparison with predicted response from 3D FEM calculation showed satisfactory agreement. To conclude much more information could be extracted than expected considering the relatively small number of measurement points along the bridge. Especially the second measurement in December, gave plenty of information to continue to work with. However, new measurement is planned for this summer that hopefully will reinforce the already attained result and give answers to some of the unresolved questions about the temperature dependency of the bridge dynamic properties.

Place, publisher, year, edition, pages
Keyword [en]
Technology, Dynamic properties, Finite element, Bridges, Concrete, Accelerometers, Eigenfrequencies, Natural, frequencies, Displacements, railway bridges
Keyword [sv]
URN: urn:nbn:se:ltu:diva-51690ISRN: LTU-EX--06/154--SELocal ID: 8e3c66f7-3470-4811-9730-d5d26e8df024OAI: diva2:1025054
Subject / course
Student thesis, at least 30 credits
Educational program
Civil Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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