Research on Pedestrian-Induced Vibration Test and Damping Control of Long-Span Simple-Supported Steel Truss Girder Pedestrian Bridge

Abstract

Purposes This work has been done in order to study the dynamic response of long-span simply-supported steel truss pedestrian bridge under human-induced excitation and the damping effect of tuned mass damper (TMD). Methods The research object is a 123 m span simply supported steel truss girder pedestrian bridge——Xuanyue Bridge in Shanxi Province, and on site human-induced vibration tests and numerical simulation have been carried out. The influences of different excitation frequencies, number of pedestrians, and excitation mode on the vibration of the structure are studied. The damping effects of single frequency tuned mass damper (STMD) and multiple frequency tuned mass damper (MTMD) under the central frequency and frequency deviation are discussed. Findings And the optimized design proposal of structural damping considering frequency deviation is proposed. The results show that the low order mode plays a role in controlling the structural vibration. When the pedestrian excitation frequency is close to the first order vertical fundamental frequency of the structure, resonance occurs, and the peak acceleration is 0.13 m/s2; The running and jumping excitations of pedestrians have a great influence on the vibration comfort of the footbridge, and the peak accelerations are 194% and 166% of the walking excitations, respectively; The STMD damping frequency band is narrower at low total mass ratio (μ≤1.0), improving the total mass ratio of STMD μ can improve the damping effect and simultaneously improve the problem of its band narrowing, after the total mass ratio of pedestrian bridge STMD is increased from 0.6% to 3.0%, the allowed range of frequency modulation deviation β can be expanded from 0 to ±15%; At the same mass ratio and frequency modulation deviation, the damping effect and robustness of MTMD are better than those of STMD, and increase with the number of sub units.

Keywords

• long-span footbridge
• human-induced vibration
• vibration control
• tuned mass damper