Field Testing on Natural Frequencies of a Cable-Stayed Footbridge Based on Ambient Excitation

Many footbridges may suffer from the intensive vibration induced by human activities. To be a direct and effective approach, field measurement is widely utilized to assess the vibration serviceability of footbridge. The field measurement and modal identification of a cable-stayed footbridge is conducted in this study. The dynamic responses of the example footbridge subjected to ambient excitations are collected through field measurement and utilized to identify the structural dynamic properties by using two approaches. The made observation indicate that the peak acceleration responses at different testing points are different to great extent but the spectrum properties of all the points are quite similar. The fundamental frequency for the vertical vibration of the concerned footbridge is close to the lower frequency of the pedestrian loading and a relatively large vibration and discomfort of pedestrians can be observed