what happens when you dont account for harmonic resonance when building bridges - Discussion Forum

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what happens when you dont account for harmonic resonance when building bridges

2012-09-16, 7:54 AM #1

Sarn_Cadrill

Mr. Know-Alot

Posts: 7,470

Pretty amazing video if you've never seen. Thought I'd share...

If you choose not to decide, you still have made a choice.

Lassev: I guess there was something captivating in savagery, because I liked it.

2012-09-16, 7:56 AM #2

Nikumubeki

NIKVMVS-REX-TODOA

Posts: 17,541

Poor dog.

Star Wars: TODOA | DXN - Deus Ex: Nihilum

2012-09-16, 11:32 AM #3

Baconfish

ALL GLORY TO THE CONTEST WINNER

Posts: 18,004

Hasn't everyone seen the Tacoma Narrows collapse or is it just because I'm an engineer?

nope.

2012-09-16, 11:43 AM #4

Jon`C

Admiral of Awesome

Posts: 18,626

also shown to CS students.

2012-09-16, 2:32 PM #5

Obi_Kwiet

It's Stuart, Martha Stuart

Posts: 7,943

Actually it's what happens when you know about the effects of unstable flow separation around cables, and therefore can't include them in your structural resonance analysis.

2012-09-16, 7:18 PM #6

Reverend Jones

Registered User

Posts: 9,096

Originally posted by Baconfish:

Hasn't everyone seen the Tacoma Narrows collapse or is it just because I'm an engineer?

yeah, engineers/physicists are usually told about this failure in class... BUT, can you recite from memory the name of the dog?

2012-09-16, 7:55 PM #7

Vin

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Fancy Pants

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Tubby

2012-09-16, 8:22 PM #8

gbk

Posts: 10,562

I never thought I'd see a resonance cascade, let alone create one.

And when the moment is right, I'm gonna fly a kite.

2012-09-17, 8:26 AM #9

Baconfish

ALL GLORY TO THE CONTEST WINNER

Posts: 18,004

Originally posted by Reverend Jones:

yeah, engineers/physicists are usually told about this failure in class... BUT, can you recite from memory the name of the dog?

Who cares? It bit the guy and fell into the river.

nope.

2012-09-17, 9:15 AM #10

Sarn_Cadrill

Mr. Know-Alot

Posts: 7,470

Anyway, I just drove over that bridge yesterday and it made me think of this.

But I don't know the story about the dog. Someone share?

If you choose not to decide, you still have made a choice.

Lassev: I guess there was something captivating in savagery, because I liked it.

2012-09-17, 10:12 AM #11

Jon`C

Admiral of Awesome

Posts: 18,626

Originally posted by Sarn_Cadrill:

Anyway, I just drove over that bridge yesterday and it made me think of this.

and you didn't stop hitler?

2012-09-17, 10:48 AM #12

Gebohq

ISB Kingpin

Posts: 8,352

Originally posted by gbk:

I never thought I'd see a resonance cascade, let alone create one.

GBK wins.

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2012-09-17, 2:01 PM #13

Reverend Jones

Registered User

Posts: 9,096

Originally posted by Sarn_Cadrill:

Anyway, I just drove over that bridge yesterday and it made me think of this.

But I don't know the story about the dog. Someone share?

It died (notable only for being the sole victim).

2012-09-17, 4:27 PM #14

Baconfish

ALL GLORY TO THE CONTEST WINNER

Posts: 18,004

Originally posted by Sarn_Cadrill:

Anyway, I just drove over that bridge yesterday and it made me think of this.

But I don't know the story about the dog. Someone share?

The bridge had a car on it with a dog trapped inside. Some professor dude went onto the bridge after it'd been cleared to try and rescue the dog but it was hysterical and attacked him. He left it and it died when the bridge fell into the river.

nope.

2012-09-26, 10:57 AM #15

UltimatePotato

Seniority Complex

Posts: 1,506

Sorry, don't know how to play this video :(
http://www.youtube.com/watch?v=6ai2QFxStxo&feature=share&list=ECED25F943F 8D6081C

It took a while for you to find me; I was hiding in the lime tree.

2012-09-26, 11:54 AM #16

Mentat

Human Computer

Posts: 2,844

I just watched the above video this morning via [url]www.unplugthetv.com[/url]. Tis a small world after all.

? :)

2012-09-27, 5:08 AM #17

DSettahr

to wound the autumnal city.

Posts: 5,313

As soon as I saw the title, I thought to myself, "Tacoma Narrows?" Then I opened the thread, and thought to myself "Yep, Tacoma Narrows."

2012-09-27, 8:45 AM #18

saberopus

Likes Kittens. Eats Fluffies

Posts: 12,306

Hey, nice video UP, now I can stop spouting off about harmonic resonance

2012-09-27, 10:41 AM #19

Reverend Jones

Registered User

Posts: 9,096

That video was actually much clearer than what I'd read about aeroelastic flutter on wikipedia.

2012-09-27, 3:40 PM #20

Jarl

Clean-Shaven and Baby-Smooth

Posts: 2,483

Originally posted by Jon`C:

and you didn't stop hitler?

It's actually still around today.

-Safer than the Alaskan Way Viaduct, at least.

2012-09-27, 4:07 PM #21

Cool Matty

Usuyami no Sekai

Posts: 15,246

So Sarn, what happens when you don't account for harmonic resonance when building bridges? I have to admit, I'm anxiously awaiting some examples!

2012-09-27, 11:07 PM #22

Reverend Jones

Registered User

Posts: 9,096

Originally posted by Cool Matty:

So Sarn, what happens when you don't account for harmonic resonance when building bridges? I have to admit, I'm anxiously awaiting some examples!

Well, Couch Potato's vid. reminds us that pushing a swing is done via harmonic resonance, so I'd imagine that you'd want to avoid building a swinging bridge. Otherwise people might swing it, like they did in Arkansas over the Little Red River in 1989, killing 5 people. (It collapsed.)

2012-09-27, 11:09 PM #23

Reverend Jones

Registered User

Posts: 9,096

I meant to say Ultimate Couch Potatoe.