Closure to "Model for Lateral Excitation of Footbridges by Synchronous Walking" by Shun-ichi Nakamura

In this article, the original researcher replies to a comments on the pedestrian footbridge research study published in January 2004. The study demonstrated that on a pedestrian cable-stayed bridge that the girder vibrated laterally with a frequency of about 0.9 Hz, the natural frequency of the first lateral mode, when a large number of people crossed the bridge. Once the bridge started to vibrate, some of the pedestrians synchronized with the girder vibration, which further increased the girder response. However, when the vibration reached a certain level, pedestrians modified their walking and the girder response stayed at that level. The researcher proposed a dynamic model to evaluate the pedestrians' synchronized dynamic forces. The commentary author contended that the researcher's equation in the form of a nonlinear, second-order differential equation has no analytical solution; each individual case must be solved by numerical methods. The commentary author then offered a solution that falls within an "amplitude envelope." In this reply, Nakamura reviews the discusser's modifications and notes that although there is some difference in the girder responses calculated by the original and modified methods, both are acceptable.


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  • Accession Number: 01002512
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 28 2005 7:47AM