Vibration serviceability assessment of ribbon-shaped large-span footbridge at high altitudes under wind-pedestrians coupling effects

Abstract

Large-span footbridges have low structural stiffness, light deadweight and small damping and thus are prone to significant vibration under the wind-pedestrian coupling effect. Fast and accurate calculation of structural dynamic response is the key to vibration serviceability assessment of footbridges. This study proposed a method of vibration serviceability assessment considering wind-pedestrian coupling for the ribbon-shaped large-span footbridge at high altitudes. The simulated crowd load and wind load were obtained through theoretical derivation and wind tunnel tests. A refined numerical model was developed to analyze the dynamic response of a large-span footbridge under wind-pedestrian coupling. The peak acceleration of the footbridge under different cases was statistically analyzed for an empirical formula, and the serviceability assessment of the footbridge was realized based on the fitting formula. The results revealed that the dynamic response of the footbridge under wind-pedestrian coupling was larger than that under one type of load alone. The dynamic response under the coupling effect was not equal to the linear superposition of the dynamic response in the case of one load. The closer the excitation frequency is to the natural frequency of the structure, the larger the dynamic response of the structure is, and the superposition of multiple modes occurs.