Analysis of human-induced vibration response and TLD vibration reduction of high fundamental frequency aluminum alloy footbridge

To investigate the variation laws of human-induced vibration responses coupled with high-frequency footbridges and explore the feasibility of Tuned Liquid Damper (TLD) for vibration reduction in high fundamental frequency footbridges. Field tests were carried out on an aluminum footbridge (with a vertical fundamental frequency of 7.42 Hz) to assess the impact of different walking patterns on human-structure interaction and to evaluate the applicability of various theoretical models for high-frequency aluminum footbridges. The effectiveness of a simple pure water TLD on the vibration control was tested, and the feasibility of using a high-viscosity fluid for vibration control was analyzed. Results indicate that an increase in both the number of pedestrians and walking frequency enhances structural response. The Distributed-Mass-Stiffness-Damping (D-MSD) model effectively captures the dynamic coupling characteristics between humans and the structure. The introduction of the TLD device lowers the system's fundamental frequency and increases the damping ratio, with optimal damping force observed when the TLD's fundamental frequency is close to the bridge's lateral fundamental frequency, achieving a maximum vibration reduction rate of 34 %. While using a high-viscosity fluid increases fluid damping force, the effectiveness of vibration control may still be debatable due to insignificant differences in stiffness calculated by the equivalent Nonlinear Stiffness and Damping (NSD) model. The findings provide relevant data for structural health monitoring and vibration control of high fundamental frequency footbridges with similar structural systems under human-induced vibration excitation.