Talk:Tacoma Narrows Bridge
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isn't this why many bridges now have upper and lower levels, because of the added strength? Slrubenstein
- I was under the impression that the new design doesn't twist in the wind because it is open and allows wind to flow through. Correct me if I'm wrong.
The original design was (relatively) smooth, like a sail, or an aeroplane wing. Refer to airfoils... The open truss means that passing air swirls turbulently preventing a smooth thrust - leading edge twisted up, force up on the smooth lower surface facing the wind, until the flex response forces the leading edge down, so a force down on the smooth upper surface; likewise on the back surface to the wind the airflow smoothly follows the surface, curving around the leading edge to do so and creating a low pressure that augments the high pressure on the wind-facing side in a nett force. With turbulent airflow, what would be the low pressure area is backfilled with turbulent air. Thus for example, sailors prefer to have no clutter near their sails, and sails with both sides smooth. NickyMcLean 20:58, 14 June 2006 (UTC)
- This I don't know. I only know that bridges are now built to avoid the "twisting" that set up the resonance in the TNB. -- April
- Resonance! Are we under the evil spells of entry-level physics textbooks? ;) TNB collapsed from simple aerodynamic instability, or at least I am writing a paper to support that argument. look at http://www.ketchum.org/ajp1.html ?
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[edit] Simple logic says it was resonance
By simple logic and Mill's Canons, it was resonance. Since the wind still blows across Tacoma Narrows and the re-designed bridge now stands, the original bridge design must have been susceptible to resonance, and the structure weakened by the oscillations caused by the resonance. Have you in fact seen the film of Galloping Gertie?
I hope to god that the entry above was made in sarcasm. Are you SURE the new design works because it's "resonance-proof" or because it fixes a different problem?
- The film clearly shows that the mode that destroyed the bridge was torsional, and was flutter. It also shows other modes, which were non-destructive and earned the bridge the Galloping Gertie nickname. That's why there's so much confusion out there. moink 04:57, 7 Dec 2003 (UTC)
[edit] blog comment
is the comment about the bridge being used in a blog logo really necessary? what purpose does it serve? --Rain 19:31, 20 May 2005 (UTC)
[edit] Picture?
What happened to the picture? Is someone working on replacing it? - Tεxτurε 21:17, 13 September 2005 (UTC)
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- I'm heading up to Seattle today. I'll stop by and take a photo on the way, hope the weather is nice. Cacophony 18:13, 21 January 2006 (UTC)
[edit] New Bridge
Why isn't there a picture of the bridge as it stands today? R'son-W 09:49, 7 November 2005 (UTC)
[edit] Vandalism
"GUANDI WAS A GREAT PRESIDENT"? Correct me if I'm wrong, but that has just about nothing to do with the Tacoma Narrows Bridge. And I don't think it's "280999990 ft/8543550 m" long. What the balls?!
[edit] Tubby the dog
Be Jesus.. does that mean Tubby was deliberately left in the car? Tubbyy!- max rspct leave a message 03:04, 29 April 2006 (UTC)
[edit] Picture of collapse mirrored
For some reason the photograph of the collapse is a mirror image. If you compare the still to this film: http://www.youtube.com/watch?v=uzdQer1gvsU , around second 53, you'll notice it clearly. Does someone want to flip it?
[edit] Length of bridges
All sources agree on the length of the main-span—2,800 ft—for all three bridges.
But for the total length we have the following (all from official sources):
- Bridge History – “…the [1950] bridge is 5,979 feet in length. That's 40 feet longer than its predecessor, Galloping Gertie.”
This would make the 1940 bridge 5,939 ft (5979–40)
- Bridge Connections: 1950 – Present – “Tacoma Narrows (1940) – Length of side spans: 1100 ft”
This would make the 1940 bridge 5,000 ft. (2800+1100+1100)
- SR 16 - New Tacoma Narrows Bridge – “New [2007] bridge deck is 5,400 feet in total length, 2,800 in the main span.”
The image on the last page also shows the 2007 deck longer than the 1950 deck. This makes me think that the full bridge deck lengths are 5,000 ft (1940), 5,040 ft (1950), 5,400 ft (2007), and that the 5,979 ft “length” for the 1950 bridge includes ramps etc. but I cannot find a definitive source. —MJBurrage • TALK • 16:18, 30 January 2007 (UTC)
