News Swaying bridge across the Volga

SiberianTiger

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Happened yesterday in my hometown:

[nomedia="http://www.youtube.com/watch?v=n1GOnDBgKmA"]YouTube- Аварийное состояние волгоградского моста - шатается![/nomedia]

It's strange that 70 years after collapsing the bridge in Tacoma, flutter is still a problem for bridge builders.
 
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SiberianTiger

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Urwumpe

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New German Autobahns are suffering from concrete degradation, because they had been build by the lowest bidder, who did decide to ignore the experience of GDR engineers, that the gravel in eastern Germany has a lot of silicic acid in it. This acid reacts with the concrete exothermally and makes it increase in volume, creating bumps and holes in the new road after a short time.

http://en.wikipedia.org/wiki/Alkali_Silica_Reaction

Those who don't learn from the past are forced to repeat it. In engineering this is true.
 
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Artlav

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Here is the full long version, with sound:
[nomedia="http://www.youtube.com/watch?v=uWP5d2t2JVE"]YouTube- Мост через Волгу шатается (полная версия)[/nomedia]

Looks both interesting and scary. I wonder what it would feel to stand on it.
 

Eagle

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It seems like they should park some tractor trailers or put up some big wind disruptor there to dampen that.
 

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i'm sure most of you know, thats a resonance effect, probably caused by wind. The tacoma narrows bridge in the 50's collapsed from a similar effect - if the windspeed is just right and so on. and theres a fairly spectacular vid [nomedia="http://www.youtube.com/watch?v=j-zczJXSxnw"]YouTube- Tacoma Narrows Bridge Collapse "Gallopin' Gertie"[/nomedia]

If you ever find yourself on a bridge thats doing that, fun though it might be, i'd recommend getting on solid ground ASAP.:thumbup: In recent years a footbridge in london had a similar effect caused by the rythmic pounding of peoples feet syncing up which caused a side to side motion. I think they put some dampers in to eliminate the effect in the end.

perhaps some cheap (cheaper than building a brand new bridge anyway) solution like that could be devised to fix this bridge before it collapses.
 

SiberianTiger

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My father was a road engineer in Volgograd. Right now he is in retirement, but he is still very anxious to know what caused the bridge to sway. He'll be in touch with the investigation group, when he is not busy with his garden, which probably would let me know the news first. At first glance, the stucture seems to be intact.

Some overly Orthodoxal people already advice a proper exorcism as a preventive measure against it happening again. :dry:

---------- Post added at 23:00 ---------- Previous post was at 22:44 ----------

i'm sure most of you know, thats a resonance effect, probably caused by wind. The tacoma narrows bridge in the 50's collapsed from a similar effect - if the windspeed is just right and so on. and theres a fairly spectacular vid YouTube- Tacoma Narrows Bridge Collapse "Gallopin' Gertie"

AFAIK, it was assumed that only suspension bridges were vulnerable to that wind-driven effect.
 

Coolhand

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yeah well maybe as you say they thought the more rigidly constructed bridges would be immune. i dont have a copy of the official report handy, but either way its the same thing, right? I hope they manage to find a sensible solution anyway, one that doesn't involve voodoo.
 

Urwumpe

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All very slim bridges are vulnerable to it, thicker bridges let more of the wind inside them for compensation.

slim bridges react to the wind like a sheet of paper, with the turbulence forming and detaching. You can tune such bridges to wind speeds that are either weak or impossible strong, but practically, you are better by making parts of the bridge deck react phase shifted to the wind and dampen such oscillations that way.
 

SiberianTiger

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http://www.themoscowtimes.com/news/article/medvedev-orders-review-of-wobbly-bridge/406550.html

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.


“I was driving to my country house when my car started bouncing like a ball,” a motorist wrote on a Volgograd Internet forum after being caught in the accident. “I thought something was wrong with the suspension.”

Deputy Transportation Minister Oleg Belozyorov, who arrived at the scene Friday as the head of a team of engineers, said the bridge most likely had reacted to strong winds that reached a speed of 18 meters per second Thursday.

Volgograd Deputy Governor Igor Pikalov suggested that the reason could have included an earthquake, but Belozyorov dismissed that theory.

“Experts agree that it is the dynamics of the air,” Belozyorov told reporters. “When wind gusts hit a certain resonance zone, they cause these kinds of consequences.”

Wind gusts were the most likely cause of the accident, said Vladimir Parshin, chief engineer at Transmost, a bridge construction company that was not involved in the Volgograd contract. He blamed the wind, despite recognizing that the beam bridge over the Volga River is more robust than suspension bridges that have been known to collapse in stormy weather.

“The spans in the Volgograd bridge are rather long, so theoretically it could be less wind-resistant than other similar structures,” he told The Moscow Times. “In any case, this sounds like a precedent for this type of bridge.”

The bridge — which cost 12.3 billion rubles, or $396 million, mostly in federal funds, to build — complied with all the industry standards, Pikalov said. The contractors collected “all the [necessary] signatures,” he said.

Belozyorov, the deputy transportation minister, said his engineering team would inspect the bridge in two stages, with the first one lasting several days, and would make a computer model of the bridge during the second stage to asses its wind resistance, a process that might take another 10 to 15 days.

The bridge will remain closed until the causes of the incident are revealed, Deputy Governor Pikalov said.

However, last Saturday the bridge was load tested by putting 15 KAMAZ trucks on it, totaling the weight to 300 tonnes and found safe for light traffic until the end of investigation. It's expected to be opened for passenger cars today. The possibility of opening passage under the bridge for shipping is still under scrutiny.
 

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Cool video. I have never seen a girder supported bridge swaying so much just from wind. Must have felt like being on boat.

Near my town is cable supported pedestrian bridge which can be made to oscillate with ~1,5 m amplitude by few people jumping in resonance frequency. Here is a video of a roughly similar pedestrian bridge resonating when people jump in right frequency.

[nomedia="http://www.youtube.com/watch?v=JWDuHekqt9c&NR=1"]YouTube- Fast moving bridge High jump![/nomedia]
 

SiberianTiger

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Finally, the evidence of the factor that lead to the bridge's wobbling, found!

[nomedia="http://www.youtube.com/watch?v=aLNQlCVsA9E&feature=player_embedded"]YouTube- СОБАКА РАСШАТЫВАЕТ МОСТ В ВОЛГОГРАДЕ![/nomedia]

:rofl:
 
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