Re: [Phys-l] Why soldiers break step on small bridges, and not so small.

[William Robertson <wrobert9@ix.netcom.com>]

 For what it's worth, the Mythbusters addressed this issue and made a  
fairly good case that it would be difficult for soldiers to get a  
regular bridge (not a flimsy footbridge) to execute normal modes of  
vibration by marching in step. The skyscraper story is definitely  
believable, as extensive measures are taken to prevent winds from  
making skyscrapers sway out of control. A brief article intended for  
the layperson on the subject:  http://www.nsta.org/publications/search_journals.aspx?keyword=skyscrapers&journal=SC

Bill



On Jul 26, 2011, at 12:23 AM, Bernard Cleyet wrote:

> Again, because Links were broken.
>
>
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> Scientist: Tae Bo workout sent skyscraper shaking – This Just In -  
> CNN.com Blogs
>
>
> bc
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> p.s. It is a "real" problem:
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> Angers Bridge - Wikipedia, the free encyclopedia
>
> p.p.s Anyone seen the film loop of a demonstration of the normal  
> modes of a foot bridge?
>
> This is all I could find -- is the one I remember.
>
>
> Resonant Bridge Video Clips
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>
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