Dynamic response under pedestrian loading of the footbridge “La Belle Liégeoise”

The particularly slender type of the footbridge "La Belle Liégeoise" is very sensitive to the pedestrian actions. A few days after the opening of the bridge, at the end of a huge spectacle organized in the Boverie park, some thousands of people took, in one way, the footbridge to reach the city. At this time, a lateral pitching of the suspended part of the structure started, making the crossing uncomfortable for users although this vibration frequency is outside the critical window defined by the SETRA guide.The purpose of this paper is to detail the sizing of the seven tuned mass dampers equipping the structure to meet the code’s requirements and to explain studies carried out by Greisch to analyse causes of these large vibrations and propose solutions to solve the problem, or even to anticipate it for future works.