New wonder of the world

[Gr.Viper]

Bridge design 101: It shouldn't go all wavy in strong wind.

 

Happening now-ish on a new bridge in Volgograd aka Stalingrad.

[MigBuster]

ooopsy - back to the drawing board - unless of course the contract went to the lowest bidder.

 

 

Any idea how strong the winds are?

[Gr.Viper]

Reports say a thunderstorm with gusts of up to 30m/s set the thing in motion. No info on casualties but there was traffic on it when the bridge started to wave. They say the cars were jumping.

 

Construction took 12 years , the bridge itself is sightly over 1200m long. Opened autumn 2009.

Edited May 21, 2010 by Gr.Viper

[+76.IAP-Blackbird]

Why don`t they learn from history

[Fubar512]

Too little, too late. That doesn't even classify as "fun to drive across". Now, this on the other hand, applies advanced aerodynamic principles in assuring that one experiences an entertaining drive while crossing the span

 

[+Stary]

[+Dave]

Wow that just looks weird.

[+Gepard]

Tja, its not a new problem. Its simply a wrong design of the bridge. If the wind hits the swing frequence (hope this is the correct term, Schwingungsfrequenz is it called in german language), the bridge becomes shaking.

 

Kick the architect into the butt for not being able to do the job right!

Edited May 21, 2010 by Gepard

[Fubar512]

Tja, its not a new problem. Its simply a wrong design of the bridge. If the wind hits the swing frequence (hope this is the correct term, Schwingungsfrequenz is it called in german language), the bridge becomes shaking.

 

Kick the architect into the butt for not being able to do the job right!

 

I've forgotten the exact term that was used, but that was one of the factors in the Tacoma Narrows bridge collapse. The other was underestimating wind speeds at that point in the Tacoma Narrows area. I understand that hurricane-force gusts (over 130 kph), are common there.

[TX3RN0BILL]

The question that remains unanswered is if the dog managed to get out or not...

 

But definitely eerie music for such a video!!!

 

 

[Derk]

At least the men were wearing hats (that remained on their heads) .......

 

Hou doe,

 

Derk

[Fubar512]

The question that remains unanswered is if the dog managed to get out or not...

 

But definitely eerie music for such a video!!!

 

The dog was so terrified, that he would not leave the car...he was the only fatality

 

 

At least the men were wearing hats (that remained on their heads) .......

 

Hou doe,

 

Derk

 

The winds at that time were only 40 knots....if you re-read my post, you'll see that I said that "hurricane-force gusts (over 130 kph), are common there", I never said that was the wind speed at the time of the collapse.

 

Anyway, here's a link to the wiki page on the collapse: http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)

[+Gepard]

The swing frequence is the frequence on which an object starts to swing. For instance take a glass of water and move your finger over the dge of the glass. If you do it correct the glass will starts to "sing", it is the singn that you hit the swing frequence. At a bridge the swing frequence can be "found" by the wind. If the wind is blowing from the right direction and with the right speed the bridge will start to swing. To avoid this you must only "jam" the swing frequence with some attachments on the bridge. At one of the old vides you will see a car on the swinging bridge. This was the attempt to "jam" the swing frequence, but the car was to small for that big bridge. The jam factor was not strong enough.

By the way, a marching column is also able to bring a bridge to swing if the soldiers marching by step. Thatswhy it is forbitten to do this.

[+SkippyBing]

Gepard, the word in English is harmonic or harmonic frequency, essentially the vibrations are in harmony with the natural frequency of the object. I think the German actually makes more sense!

There was a similar thing with some power station cooling towers in the UK. The original set-up had been tested in my university's wind tunnel with four towers. They then added a fifth to the end of the row without doing anymore testing. At that point a relatively light wind running along the row demolished the end tower by getting it to vibrate at it it's harmonic frequency. How we laughed.

[Fubar512]

The swing frequence is the frequence on which an object starts to swing. For instance take a glass of water and move your finger over the dge of the glass. If you do it correct the glass will starts to "sing", it is the singn that you hit the swing frequence. At a bridge the swing frequence can be "found" by the wind. If the wind is blowing from the right direction and with the right speed the bridge will start to swing. To avoid this you must only "jam" the swing frequence with some attachments on the bridge. At one of the old vides you will see a car on the swinging bridge. This was the attempt to "jam" the swing frequence, but the car was to small for that big bridge. The jam factor was not strong enough.

By the way, a marching column is also able to bring a bridge to swing if the soldiers marching by step. Thatswhy it is forbitten to do this.

 

I've seen harmonic dampers under some long spans, and they've also used fiberglass fairings (that act like spoilers) on others.

 

EDIT: From the same wiki article I posted a link to, above.... "The Bronx Whitestone Bridge, which is of similar design to the 1940 Tacoma Narrows Bridge, was reinforced shortly after the collapse. 14-foot (4.3 m) high steel trusses were installed on both sides of the deck in 1943 to weigh down and stiffen the bridge in an effort to reduce oscillation. In 2003, the stiffening trusses were removed and aerodynamic fiberglass fairings were installed along both sides of the road deck."

Edited May 24, 2010 by Fubar512