Updating of numerical models for enhanced dynamic assessment of existing structures - Analysing parameters for model updating of a riveted steel railway bridge, based on the sensitivity method
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Updating a numerical model of a real structure is an important tool to enhance an existing model, such that it represents the structure more accurately. To assess the current state of a structure, and predict the remaining service life of it, it is necessary to have a reliable and accurate numerical model of the structure. This is especially relevant for old structures, demolishing and rebuilding of which may be very costly, and structures that have to be preserved because of their high cultural and historical value.Starting with the theoretical background needed, this thesis leads the reader through the whole process of sensitivity-based model updating of a structure. It guides through a way of thinking when updating a model, aiming to optimize the process.To show model updating in practice, a complete study has been carried out, where two structures have been updated; a rig and a riveted steel railway bridge. The focus lies mainly on the importance and effects of different parameter choices on the updating. It includes a sensitivity analysis of parameters that are important, for the rig as well as the bridge. For the updating, a script has been made in Python, which is also attached as appendix A1-The script for the use and benefit of the interested readers.The rig is installed in the Materialteknisk laboratory at NTNU, and is a representation of a pedestrian bridge. The study is used as a simpler example to lead through the basic idea of model updating, and point out factors that are important to consider while updating a structure.The riveted railway bridge, Lerelva Bridge , is a truss bridge built in 1919, and is one of many old bridges that are part of The Norwegian railway system. The owner, Jernbaneverket , is interested in determining the remaining service life of this bridge, and therefore a reliable and accurate numerical model is needed. The study conducted, leads through a way of thinking when going forward while updating such a bridge model, showing examples of updating, and giving a more practical understanding of model updating.