Footbridge Pedestrian Vibration

The UK Highways Agency has commissioned two companion studies for the review of the dynamic sensitivity of footbridges. The aim of the research in this part of the project is to provide information on the dynamic properties of footbridges to enable designers to identify potential vibration susceptibility at the design stage. This will allow them to take appropriate action such as modify the design, or make provision for vibration absorbers. The work is being carried out by TRL Limited and Flint & Neill Partnership and involves a review of the main parameters affecting dynamic performance, the collation of data obtained from the vibration testing of footbridges, and the development of a design strategy. A separate project has also been commissioned by the Highways Agency to investigate the susceptibility of pedestrians to footbridge vibrations with a view to developing appropriate acceptance criteria. The results of this study form the basis for a new approach to the assessment of the dynamic responses of footbridges. It provides a much more searching analysis than the existing simplified approach, however it achieves this using methods that are not much more complicated to apply than the existing method.

The paper presents an outline of the design strategy that has been developed, as a result of this project, for the prediction of vertical responses. It is anticipated that a procedure similar to that described in this paper will be developed for future inclusion in the Highways Agency's Design Manual for Roads and Bridges.