This blog begins a series of articles relating to famous structural failures. Included will be articles on the Tacoma-Narrows bridge, New Orleans levees, Comet aircraft, etc.
The Millennium Bridge over the Thames River in London is a steel suspension bridge for pedestrian use only. It was opened on June 10, 2000 and closed only two days later due to excessive vertical and lateral motions. It was found that the motion was caused by the pedestrians exciting the bridge’s lateral natural frequency of vibration (approx. 1 Hz). This phenomenon is known as synchronous lateral excitation, which is caused by the slight sideways sway of pedestrians when walking.
The problem was fixed by adding 37 fluid viscous dampers to control horizontal movement, and 52 tuned mass dampers to control vertical movement. The bridge cost $30 million to build, and $7 million to repair.
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