Control of Vibrations of Common Pedestrian Bridges in Jordan Using Tuned Mass Dampers

摘要

Due to their inherent slenderness and lightness, pedestrian bridges are typically subtle to human induced vibrations. This study was conducted to investigate the effect of human induced vibrations on common simply supported steel footbridges in Jordan, especially those with natural frequencies between 2 to 4 Hz. Such fundamental frequency is close to human movement frequency of walking, jumping and running. The ETABS software was utilized to develop a finite element model (FEM) in order to identify the footbridge dynamic properties including frequency, natural period, stiffness and the critical length at which the induced-vibrations become of great effect. The bridge was excited with multiple human walking and running loading scenarios. The response of the footbridge was evaluated and compared with and without integrating tuned mass dampers (TMD) tuned with the fundamental natural frequency of the footbridge in order to optimize appropriate mass, stiffness and damping coefficient. It was observed that after attaching the TMD, the fundamental vibration frequency decreased to stable value less than human excitation frequencies. Also, acceleration, velocity, and displacement responses were decreased significantly to be within acceptable limits. Finally, a recommendation and guidelines are given for considering the induced-vibrations in the design of common footbridges in Jordan.