Heres my rough opinion only based on limited research. As the cable tie snapped, a small amount of torsional movement was created due to vortex shedding and wind eddies. The shedding frequency did not match that of the bridge so it was not the FINAL cause of collapse. However, it did allow some torsional movement. The cross-section of the bridge acted as an airfoil. As it tilted up on the windward side, the velocity of the wind was greater on the top (since a greater distance had to be covered in the same time) than the bottom. This created a greater pressure (P=F/A) on the bottom edge, thus creating a force perpendicular to the cross-section of the bridge. THis motion was repeated until the bridge finally collapsed. As the width to length ratio of the bridge was very small causing the bridge to be too flexable.
2007-11-03
20:26:48
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4 answers
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asked by
Anonymous
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Physics