Modelling and System Identification of Pedestrian Bridges - Bårdshaug
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The main objective of this thesis has been to evaluate and compare different load models and comfort criteria given in guidelines for pedestrian loading, with respect to accuracy and usability. The guidelines taken into consideration are Eurocode, BS 5400, UK National Annex to Eurocode, Håndbok 185, SÉTRA, ISO 10137, JRC - Design of Footbridges for Human Induced Vibrations and HIVOSS. In addition, a desired outcome has been to obtain an approach to the modelling of a pedestrian bridge in order to achieve accurate dynamic behaviour for the model, and obtain realistic acceleration output when pedestrian loads are applied. A case study was done for Bårdshaug Bridge, a pedestrian bridge located in Orkanger, Norway. The different guidelines taken into consideration have vast variations in the approach to the simplification of the pedestrian load and how to obtain a comfort criterion; from including only mass and damping, like Eurocode, to also including length, number of pedestrians and natural frequencies, like UK-NA and SÉTRA. The load parameters are weighted differently depending on the guideline, such that a more comprehensive load model does not necessarily yield the most accurate result. The different approaches and simplifications cause large variation in the results, making it challenging to recommend a single guideline for obtaining the most realistic responses. It is shown that a guideline can obtain a good approximation for the acceleration values for one case, but poor approximations for other cases. It is found that a simplified FE-model is sufficient in order to obtain a good approximation to the dynamic behaviour of a pedestrian bridge under normal use. SÉTRA is found to be the guideline preferable to use when applying pedestrian loading to a structure.