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Swaying Russian bridge





Bondings
The bridge seems to go up and down, in the form of waves. They assume it was done by the wind. It's a new bridge in Volvograd.



Apparently there was no damage at all. I suppose they could make it a tourist attraction. Wink
Jinx
Reminiscent of "Galloping Gertie"



AKA the Tacoma Narrows Bridge : http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)

Wikipedia wrote:

Construction on the bridge began in September 1938. From the time the deck was built, it began to move vertically in windy conditions, which led to construction workers giving the bridge the nickname Galloping Gertie. The motion was observed even when the bridge opened to the public. Several measures aimed at stopping the motion were ineffective, and the bridge's main span finally collapsed under 40-mile-per-hour (64 km/h) wind conditions the morning of November 7, 1940.


Edit by Bondings, trying to fix the post, the () in the url are causing the post not to display.
Jinx
Sorry for the double post, but I can't figure out why my first post isn't showing up... I followed the directions for the youtube tag, but I've never tried using it before. All my tags are closed, as far as I can tell I followed the syntax for the tag, but my post just looks blank...

Brick wall Think

Here's what I wrote. Can anyone tell me where I went wrong?


Code:


Reminiscent of "Galloping Gertie"

[youtube]HxTZ446tbzE[/youtube]

AKA the Tacoma Narrows Bridge : [url]http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)[/url]

[quote="Wikipedia"]
Construction on the bridge began in September 1938. From the time the deck was built, it began to move vertically in windy conditions, which led to construction workers giving the bridge the nickname Galloping Gertie. The motion was observed even when the bridge opened to the public. Several measures aimed at stopping the motion were ineffective, and the bridge's main span finally collapsed under 40-mile-per-hour (64 km/h) wind conditions the morning of November 7, 1940.[/quote]


If they don't fix that one it will probably collapse eventually, also.
deanhills
I'm not an engineer, but how is it possible for the tar road not to crack up when it is going into waves? Sort of does not make sense to me. Is it built out of special construction materials that makes it flexible with the waves?

This has to be a test? Is the show for real? Confused
Jinx
I can't say on the concrete, but the tar - asphalt isn't solid, it's just a very, very viscous fluid, so it has a lot of stretch and give to it, which is what makes it such an excellent wear surface for roads.
deanhills
Looks as though the bridge is brand new, eight months old, and after the incident was immediately closed so that engineers can investigate what happened. Refer article in the Moscow Times of today. The bridge is a whopping 7 kilometres long:
Quote:
A new seven-kilometer bridge over the Volga River has staged a surreal dance, sending cars swirling and bouncing in gale-force winds in a puzzling accident that prompted President Dmitry Medvedev to order an investigation Friday.

The wobbling of the expensive bridge, which began operating in Volgograd eight months ago thanks to the government's much-touted road construction program, is raising questions about the quality of the work bought with the federal money.

No one was injured when the road turned into rolling waves of asphalt for about a half hour Thursday evening. The bridge itself remained intact, proving immune to the buckles that rose up to one meter high, officials said after examining it. Not even the paint cracked, they said.


There is also an interesting article on the history of the construction of the bridge, including a description of its design in the Bridge Design & Engineering Website.

Bikerman
The solid rock under your feet is actually flowing like a liquid in the right timescales (geological).
You cannot predict the behaviour of materials with only 'common sense' because it will bite you on the backside. 1 3ft length of 6 by 4 timber won't bend much before cracking. A 300 ft length would bend all over the place.

Suspension bridges are build to bend and give - otherwise they fail rather catastrophically like this one nearly did and the Tacoma Narrow bridge did. It is normally caused by resonance - any structure has a natural 'vibration frequency'. Vibrate the structure at just that frequency and the vibration is not damped, it builds and builds until something gives.
It is the wind, in most cases, setting up an oscillatory period which due to bad luck just happens to match the resonant frequency of the structure...it is then only a matter of time.
deanhills
Bikerman wrote:
The solid rock under your feet is actually flowing like a liquid in the right timescales (geological).
You cannot predict the behaviour of materials with only 'common sense' because it will bite you on the backside. 1 3ft length of 6 by 4 timber won't bend much before cracking. A 300 ft length would bend all over the place.

Suspension bridges are build to bend and give - otherwise they fail rather catastrophically like this one nearly did and the Tacoma Narrow bridge did. It is normally caused by resonance - any structure has a natural 'vibration frequency'. Vibrate the structure at just that frequency and the vibration is not damped, it builds and builds until something gives.
It is the wind, in most cases, setting up an oscillatory period which due to bad luck just happens to match the resonant frequency of the structure...it is then only a matter of time.
Right. This bridge is a good testimony to what you have said. It was built for maximum suspension, 7 kilometres in total, that is quite an enormous bridge and civil engineering construction undertaking. And it seemed to have made the grade, as apparently there was no damage after the "wobble" and the swaying of the bridge. According to the engineers, and even the paint was intact.

I find it tremendously interesting, so hope we will get an update when the bridge is re-opened. Seems to be a strategic bridge for that area. What is quite interesting is that the President took interest in the safety of the bridge himself, closing it for thorough inspection. Also that the engineers and designers' Websites are very easy to read in English. I get a feeling that their expertise is of a high international standard, especially with the design details that have been posted in English.
thejessman86
deanhills wrote:
I'm not an engineer, but how is it possible for the tar road not to crack up when it is going into waves? Sort of does not make sense to me. Is it built out of special construction materials that makes it flexible with the waves?

This has to be a test? Is the show for real? Confused

That's what I was thinking. There's no way the asphalt would hold up...
deanhills
Looks as though the bridge was re-opened for service after a weekend of testing for safety:
Quote:
The Volgograd bridge that sent cars into the air as wind gusts shook the seven-kilometer construction last week has not been damaged and will be reopened Tuesday morning, Governor Anatoly Brovko said.

Vibrations on the bridge reached an amplitude of more than one meter on Thursday, throwing cars into the air and turning them around.

The bridge spanning the Volga River was tested over the weekend by a fleet of KamAZ trucks and ultrasonic devices as inspectors checked for signs of damage, Brovko told reporters Monday. The tests concluded that the bridge was "structurally sound," and it will reopen to passenger cars at 6 a.m. on Tuesday, he said.

Moscow Times
standready
deanhills wrote:
I'm not an engineer, but how is it possible for the tar road not to crack up when it is going into waves? Sort of does not make sense to me.

The asphalt (just like concrete) is sitting on top of deck plates which are mounted to the substructure. You can see the joints as the bridge moves. The bridge looks to me like each segment is "balanced" on a single pier hence the rocking. Bikerman is correct about natural 'vibration frequency'. All bridges are designed to flex under load.
ProwerBot
I knew that bridges usually sway a little so it doesn't collapse, but I don't think swaying like that would do much help.
missdixy
Holy crap, I feel bad for the people/cars (if any) that were on it when it started doing that! That would've just about given me a heart attack Sad
deanhills
standready wrote:
deanhills wrote:
I'm not an engineer, but how is it possible for the tar road not to crack up when it is going into waves? Sort of does not make sense to me.

The asphalt (just like concrete) is sitting on top of deck plates which are mounted to the substructure. You can see the joints as the bridge moves. The bridge looks to me like each segment is "balanced" on a single pier hence the rocking. Bikerman is correct about natural 'vibration frequency'. All bridges are designed to flex under load.
Thanks for the additional explanation. I did some research after the above quote and have a greater understanding. All of that makes sense, but then because of the added flexibility, and the very long length of the bridge over seven miles, it would make sense that the wobble through the different segments would become a magnified wobble. The bridge has enormous flexibility in it, more so than the vehicles on it, probably would have been better to attach the vehicles to rails when they travel over the bridge so that they can move with the flexibility instead of against it. I must say I'd rather drive a round trip of 16 kilometres to avoid this bridge. If the verdict of the inspection team after the "wobble" we've seen is that it is safe to use, I'd rather take my chances elsewhere.
SonLight
It's interesting that the bridge was designed between 1985 and 1987. It seems likely that most of the structure has been in place for several years, but I suppose it would not be pushed as much by the wind until the roadbed was installed.

@deanhills, I understand your skepticism about the safety of the bridge. The engineers might be able to certify that the bridge is not in danger of structural damage, but I wouldn't want to be on it when it's dancing up and down up to a meter. Perhaps they have adjusted tension in some of the cables or something which makes it less likely to do that.

Apparently there were gale-force winds when the bridge vibrated. It seems a reasonable compromise might be to close the bridge whenever winds close to that level occur or are expected. I would want to see a detailed engineering report published, including what changes have been made, before I would be willing to venture onto the bridge in high winds.
ocalhoun
SonLight wrote:

Apparently there were gale-force winds when the bridge vibrated. It seems a reasonable compromise might be to close the bridge whenever winds close to that level occur or are expected. I would want to see a detailed engineering report published, including what changes have been made, before I would be willing to venture onto the bridge in high winds.

Wind direction probably also has a large effect.
deanhills
SonLight wrote:
Apparently there were gale-force winds when the bridge vibrated. It seems a reasonable compromise might be to close the bridge whenever winds close to that level occur or are expected. I would want to see a detailed engineering report published, including what changes have been made, before I would be willing to venture onto the bridge in high winds.
Right. There is still an engineering report in the making. The safety report to allow the bridge to be re-opened, was a provisional report.

If you are interested in the technical side of this, you may be interested in the history of the construction of the bridge that was published by Bridge Design and Engineering, the official website of Bridge design & engineering, a quarterly international bridge construction magazine aimed at structural engineers, architects, bridge owners, contractors and specialist manufacturers. At one point there was an enormous delay in the construction of the bridge due to funding issues, and then in 1998 construction was resumed again. By 2006, with the bridge still not finished, contractor Volgomost was charged to work with a new design company, BSK Company, with a brief to complete the bridge within three years. This was prompted by a federal programme intended to see completion of some of Russia's important bridges whose construction was running late. At the time when the history was written up by the engineering company, August 2008, the bridge was a year away from being completed. But it is obvious the long history of the design and construction of the bridge had not been uncomplicated, probably deserving of a James Michener type novel and an entertaining movie. Smile
Bikerman
It doesn't have to be gales that cause the problem. As I said, it depends on the resonant freqiency of the structure.
A persistent but light breeze can cause resonance, in fact it can do so more than a much stronger wind. Gales tend to be constantly shifting so they do not 'hit the sweetspot for very long. A continuous breeze could be just on that sweet-spot and then it builds and builds..

There are also examples of structures standing for years and then suddenly becoming badly hit by resonant effects. It could be another building that has been built or demolished and produced a change in the wind, or a change in the frequency.

It is pretty simple to rule out the major frequencies but then you can get caught out by the multiples/harmonics.
Everyone is familiar with resonance - running a damp finger around a wineglass to make it 'sing' is a classic example - as is shattering a glass with the voice (something which very very few people can do), and I know one of them Smile
In real life it is very complex - different parts of a structure have different resonant frequencies and an apparently insignificant change can totally alter the resonance response of an object.

This site shows how even just two people can 'resonate' a bridge:
http://home.messiah.edu/~barrett/mpg/mpg.html
deanhills
@Bikerman. That is fascinating. Similar to the photos of your example, do you think if there were a particular kind of traffic on both sides of the bridge, and they drove at a particular frequency being responsible for a combined resonance of the kind you described, that they could activate a wobble like the one that was reported?
Bikerman
deanhills wrote:
@Bikerman. That is fascinating. Similar to the photos of your example, do you think if there were a particular kind of traffic on both sides of the bridge, and they drove at a particular frequency being responsible for a combined resonance of the kind you described, that they could activate a wobble like the one that was reported?
Yes, it is certainly possible.
There are persistent reports of an army troop destroying a bridge by accident. They marched across and the footfalls were synchronised to the resonant frequency of the bridge - it shook apart.
This may be an urban myth, but the physics are correct.
Nicholai Tesla was into this in a big way - he built a small vibrating device which he called his 'earthquake machine' which was supposed to match the frequency of large objects and destroy them using resonance.
deanhills
Bikerman wrote:
deanhills wrote:
@Bikerman. That is fascinating. Similar to the photos of your example, do you think if there were a particular kind of traffic on both sides of the bridge, and they drove at a particular frequency being responsible for a combined resonance of the kind you described, that they could activate a wobble like the one that was reported?
Yes, it is certainly possible.
There are persistent reports of an army troop destroying a bridge by accident. They marched across and the footfalls were synchronised to the resonant frequency of the bridge - it shook apart.
This may be an urban myth, but the physics are correct.
Nicholai Tesla was into this in a big way - he built a small vibrating device which he called his 'earthquake machine' which was supposed to match the frequency of large objects and destroy them using resonance.
Right, so voice and music could then be powerful in different ways too? Smile
Bondings
deanhills wrote:
Quote:
There are persistent reports of an army troop destroying a bridge by accident. They marched across and the footfalls were synchronised to the resonant frequency of the bridge - it shook apart.
This may be an urban myth, but the physics are correct.
Nicholai Tesla was into this in a big way - he built a small vibrating device which he called his 'earthquake machine' which was supposed to match the frequency of large objects and destroy them using resonance.
Right, so voice and music could then be powerful in different ways too? Smile

You need one specific resonance/tone and that one needs to have enough energy. But one tone isn't music. Wink

But indeed you can break things with just your voice. At least some people can break a glass with just their voice. But you need lots of energy (100db) and find the right tone.



http://www.straightdope.com/columns/read/801/can-opera-singers-shatter-glass-with-their-high-notes (about breaking glass, but also contains parts about bridges)
Bikerman
Here's Mythbusters trying out the Tesla Earthquake machine
standready
A suspension bridge swaying in the wind like the Tacoma Narrows I understand. I am still fascinated that a pier supported bridge could rock and roll like the Russian bridge. As I said earlier, each bridge segment appears to be balanced on a pier, yet pictures in the "Bridge Design and Engineering" article shows segments being raised between two piers.
goutha
It's a very well known phenomena and happened about a dozen of times in the past.

Actually it's an engeneering error. Error in measures cause the bridge to move even with a low wind speed. I thought that it will never happen again, but I guess that the information did not arrived yet to Russia Smile
ankitdatashn
This appears somewhat unreal to me, I have known bridges moving but in earthquakes, this is appearing more or less edited! Surprised
Bikerman
ankitdatashn wrote:
This appears somewhat unreal to me, I have known bridges moving but in earthquakes, this is appearing more or less edited! Surprised

No, it is real. There are several examples on film.
Here's the tacoma narrows bridge:


Here's an Asian bridge in an earthquake
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