Human-induced vertical vibration of a glass suspension footbridge: experimental study and numerical analysis
Yunsheng Li, Xu Zhang, Can Wang, Yanling Zhang, Xinxin Wei
Abstract
Glass-bottomed suspension footbridges are increasingly constructed, especially in scenic regions, because of glass-bottomed and transparent decks to, e.g. attract tourists. This study investigated a newly built glass suspension bridge. The whole mass-spring-damper (MSD) model was selected as the appropriate model. Results showed the bridge had low vertical natural frequencies, many of which were within the human-induced excitation frequency ranges, resulting in (near-)resonance under walking and running tests. The structural responses were affected by the step frequency, number, and trajectory of the tested pedestrians. The study also reveals modal parameter features of the glass-bottomed footbridge are not the same as that of conventional ones. The glass deck only slightly changes the natural frequencies of the structure but leads to significantly higher damping ratios against conventional ones. Additionally, the footbridge can have around 20% lower modal masses than the concrete footbridge, and have slightly higher modal masses for lower modes but significantly higher modal masses for higher modes than the steel one. These distinctive features again reveal the importance of the investigation for the human-induced vibrations of the glass-bottomed footbridges. The paper may provide insights for understanding the dynamic behaviour of this new type of footbridges and support better design.