Ambient vibration testing in the rehabilitation of centenary steel bridges

1501 ABSTRACT: The use of modal testing through ambient vibration to assess the changes in rehabilitated structures and to enable the evaluation of the actual effectiveness of different rehabilitation strategies emerge as an extremely important topic, since the current knowledge in this field is short and therefore demands an improvement in order to achieve more cost-effective designs without lowering the required safety levels. This paper presents the ambient vibration tests conducted on centenary steel bridges before and after their rehabilitation, with the purpose of evaluating the changes in their dynamic properties as a result of the adopted strengthening strategies. The implemented testing programs, experimental setups, data processing and modal identification techniques are described. Field data validated numerical models for the analysis of the structural changes produced by the strengthening process are presented. Significant conclusions were drawn by comparing the experimental and numerical results between the pre and post-rehabilitation conditions, namely in what concerns the vibration levels experienced by the structures, their stiffness variation and suitability of the adopted modeling methodologies.

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