ANALYSIS OF VIBRATION SERVICEABILITY OF FOOTBRIDGE WITH PEDESTRIAN FORCES

Many footbridges may suffer from the intensive vibration induced by human activities, vibration serviceability have been more highlighted since more modern, slender footbridges are constructed in cities. In this paper, footbridge vibration evaluation criteria are suggested based on some of the design procedures. Field measurement is widely used to access the vibration serviceability of footbridge. A typical footbridge is taken as a real example to investigate the human-induced vibration through field measurement. And the vibration characteristic of the footbridge is verified by finite-element analysis. The dynamic responses of the footbridge under ambient excitations are collected through field measurement to identify the natural frequencies and mode shape of the footbridge by using Natural Excitation Technique (NexT) and Eigen system Realization Algorithm (ERA). The vibration serviceability of the footbridge is checked based on dynamic responses made from field measurement and simulated result in line with the suggested footbridge vibration comforts. It is seen that the first vertical natural frequency of the footbridge is in the sensitive frequency of human step frequency. And the measured responses of the bridge are smaller than the permitted values in codes. The analytical results in this study can be taken as the references for the assessment of the pedestrian-induced vibration and dynamic serviceability of footbridges.