Long-Term Vibration Serviceability Assessment of a Steelplated Stress-Ribbon Footbridge
José M. Soria
Iván M. Díaz
Jaime H. García-Palacios
|Conference:||Footbridge 2017 Berlin - Tell A Story, 6-8.9.2017, Technische Universität Berlin (TU Berlin)|
|Published in:||Footbridge 2017 Berlin - Tell A Story|
The research group is working on vibration cancellation of pedestrian structures with time varying modal properties. As a previous step of the design and installation of a semi-active vibration control device (e.g. semi-active tuned mass damper), the Vibration Serviceability Assessment (VSA) of a real case of time-varying modal-parameter footbridge is studied throughout this paper. The structure is a steel-plated stress-ribbon footbridge sited in Valladolid (Spain). This structure is particularly lively in vertical direction exhibiting several closely-space vibration modes with similar natural frequencies that might be excited by human excitation.
A continuous vibration monitoring system that measures the acceleration and the environmental factors was installed and one-year measuring raw data is analysed here. From the modal analysis of the structure, the location of the control device is proposed. Then, the long-term VSA for this particular location is carefully analysed. Thus, predictors described in general standards for human exposure evaluation to whole-body vibration are used. Time histories and circular hourly distribution charts are derived from the whole-year data. The results show periods of time where the structure undergoes excessive accelerations, motivating thus the installation of a vibration absorber.
|Keywords:||dynamic behaviour, human-induced vibrations, vibration serviceability assessment, time-varying modal parameters|