Cheonan Cheongsoo Footbridge
In general, the foot bridges are built with lighter and less sturdier materials, which results in very flexible structure. The serviceability of the bridge may become an issue with heavy traffic of pedestrians. Also, if typical frequency from 1.5 ~ 2.3 Hz of the vibration from the pedestrians' walks are repeated, the structural may be liable to damages from them.
The Cheonan Cheongsoo Footbridge has 31m of main span, and has similar structure to that of cable stayed bridge. The primary natural frequency of the bridge has been suspected to be 2.2 Hz, which would match well with the vibration caused by the pedestrians. When the primary natural frequency matches with the frequency of the vibration caused by the pedestrians, the vibration is bound to become greater. In order to control the vibration, 0.75 ton vertical TMD was installed on the 2/3 area of the bridge, where the highest level of vibration was anticipated to occur.
Vibration Control Device Specifications:
▣ Type: TMD (1 set)
▣ Control direction: Vertical dir.
- Moving mass: 0.75ton(1 set)
- Stroke : ±13mm
- Optimal damping ratio: 6.7%
▣ Conceptual & Detailed Design / Manufacture / Installation
/ Performance test /