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Susexx
05-22-10, 01:27 AM
The wind and water stream has shaken the bridge in Volgograd (the former city of Stalingrad) through the river Volga. Such amplitude can be seen only in films about a doomsday.

http://www.youtube.com/watch?v=dM1rwdcFMG4&feature=related
XabbaRus
05-22-10, 02:55 AM
Bridges are designed to do that. As long as it doesn't hit the harmonic frequency of the structure and it has been engineered with decent materials than this is fine. If a bridge can't flex then it will more likely collapse.
Susexx
05-22-10, 03:51 AM
No, this bridge is now closed and the commission works, he should not so to "play", the wind was very weak. The idiotic Russian habit to steal all, the bridge was very expensive.
Jimbuna
05-22-10, 05:18 AM
Who was that calmly walking the length of the bridge? :o
mr chris
05-22-10, 05:30 AM
Who was that calmly walking the length of the bridge? :o

President Medvedev shouting " The is nothing to see here, Now go away" :haha:
Oberon
05-22-10, 06:56 AM
Reminds me a bit of the Tacoma Narrows bridge:

http://www.youtube.com/watch?v=3mclp9QmCGs
Platapus
05-22-10, 07:45 AM
Reminds me a bit of the Tacoma Narrows bridge:

http://www.youtube.com/watch?v=3mclp9QmCGs


That was some bridge. I think engineers learned a lot from Galloping Gertie.
Jimbuna
05-22-10, 08:03 AM
President Medvedev shouting " The is nothing to see here, Now go away" :haha:


LMAO :haha:
Platapus
05-22-10, 08:11 AM
In Russia, the bridge walks you.
DarkFish
05-22-10, 08:34 AM
Bridges are designed to do that. As long as it doesn't hit the harmonic frequency of the structure and it has been engineered with decent materials than this is fine. If a bridge can't flex then it will more likely collapse.it clearly does hit the resonance frequency of the bridge, otherwise it wouldn't move like that.
XabbaRus
05-22-10, 09:24 AM
It is hitting a certain frequency thus why it is swaying, however if that was its resonant frequency it would have torn itself apart.

BBC is saying that a vertical support had failed and thus the water was causing it to sway. Other reports are saying it is the wind.

I've seen the Forth Road Bridge Oscillate in high winds, though not like that though.
DarkFish
05-22-10, 10:33 AM
It is hitting a certain frequency thus why it is swaying, however if that was its resonant frequency it would have torn itself apart.Being on its resonance frequency doesn't necessarily mean the bridge tears itself apart. Any other frequency than (a multiple of) its resonance frequency wouldn't produce this result.

If there were no drag and stuff, a resonance frequency would make the bridge collapse. But the harder the bridge swings, the more drag appears. This makes there is a limit to how high the bridge can swing.

I'm studying electrical engineering, and though being a different field of engineering, it works the same. For a nice example, check this applet of an RCL circuit:
http://www.lon-capa.org/~mmp/kap23/RCL/app.htm (http://www.lon-capa.org/%7Emmp/kap23/RCL/app.htm)
The C and L can be seen as certain aspects of the bridge that determine its resonance frequency, the R is the "drag" of the bridge.
You'll see that the closer you put the drag (R) to zero, the higher the response at its resonance frequency will be.
But as soon as you put the drag up, the max output will decrease.