Time-Frequency Analysis of Crowd Lateral Dynamic Forcing from Full-Scale Measurements on the Clifton Suspension Bridge

Abstract

Pedestrian-induced vibrations have caused significant issues on various footbridges, over the past few decades, as it can lead to an abrupt growth in the amplitude of structural oscillations, i.e. lateral dynamic instability.Measurements were taken during two separate crowd loading events on the Clifton Suspension Bridge, UK, to characterise the human-structure interactions observed. Two lateral modes of the bridge were studied, previously found susceptible to pedestrian-induced excitation. A comparative study is performed to identify the different interactions observed for the differing bridge deck amplitude responses through a novel procedure based on timefrequency analysis. This enables the identification of the fluctuations on the instantaneous modal amplitude and