Modal analysis of a footbridge under pedestrian traffic and additional shaker loading

This paper investigates the possibility of identifying the modal properties of footbridges while they are subjected to pedestrian traffic using the CSI algorithm. The analysis is based on vibration data collected from a footbridge under different pedestrian densities. The results show that the CSI algorithm provides consistent modal properties, but the identified damping ratio seems to be significantly influenced by pedestrians. This is likely due to the human-structure interaction. Identified apparent damping ratios appear plausible, but of course not representative of the bare structure. Overall, while the CSI algorithm helps alleviate the limitations of the authors’ previous approache to modal identification with a custom shaker, the practical usefulness of identifying modal properties of footbridges under pedestrian traffic is therefore limited.