The mad bridge

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.

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?

mr chris · 05-22-10, 05:30 AM

Quote:

Originally Posted by jimbuna

Who was that calmly walking the length of the bridge?

President Medvedev shouting " The is nothing to see here, Now go away"

Oberon · 05-22-10, 06:56 AM

Reminds me a bit of the Tacoma Narrows bridge:

Jimbuna · 05-22-10, 08:03 AM

Quote:

Originally Posted by mr chris

President Medvedev shouting " The is nothing to see here, Now go away"

LMAO

DarkFish · 05-22-10, 08:34 AM

Quote:

Originally Posted by XabbaRus

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

Quote:

Originally Posted by XabbaRus

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
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.

05-22-10, 01:27 AM	#1
Susexx Planesman Join Date: Aug 2007 Location: S.Peterburg, Russia Posts: 189 Downloads: 94 Uploads: 0	The mad bridge 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.

05-22-10, 02:55 AM	#2
XabbaRus Navy Seal Join Date: Sep 2001 Posts: 5,330 Downloads: 5 Uploads: 0	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. __________________

05-22-10, 05:18 AM	#4
Jimbuna Chief of the Boat Join Date: Feb 2006 Location: 250 metres below the surface Posts: 190,461 Downloads: 63 Uploads: 13	Who was that calmly walking the length of the bridge? __________________ Wise men speak because they have something to say; Fools because they have to say something. Oh my God, not again!!

05-22-10, 09:24 AM	#9
XabbaRus Navy Seal Join Date: Sep 2001 Posts: 5,330 Downloads: 5 Uploads: 0	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. __________________

05-22-10, 03:51 AM	#3
Susexx Planesman Join Date: Aug 2007 Location: S.Peterburg, Russia Posts: 189 Downloads: 94 Uploads: 0	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.

05-22-10, 06:56 AM	#6
Oberon Lucky Jack Join Date: Jul 2002 Posts: 25,976 Downloads: 61 Uploads: 20	Reminds me a bit of the Tacoma Narrows bridge: