Comments on: The Fall of Galloping Gertie http://www.damninteresting.com/the-fall-of-galloping-gertie/ A collection of legitimately fascinating information culled from the past, present, and anticipated future. Tue, 22 May 2012 01:30:14 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: Daz a Zulu http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-26983 Daz a Zulu Mon, 09 Jan 2012 14:42:16 +0000 http://www.damninteresting.com/?p=759#comment-26983 i would think modern engineers would have learnt a big lesson from this, but here in the uk we have had similar experiences check out Londons Millenium bridge; http://www2.eng.cam.ac.uk/~den/ICSV9_06.htm i would think modern engineers would have learnt a big lesson from this, but here in the uk we have had similar experiences check out Londons Millenium bridge; http://www2.eng.cam.ac.uk/~den/ICSV9_06.htm

]]> By: zamaris http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-23088 zamaris Thu, 16 Oct 2008 23:00:34 +0000 http://www.damninteresting.com/?p=759#comment-23088 [quote]jaydawg53 said: ""After opening, the new bridge shortly came to be known as "Galloping Gertie," so named by white-knuckled motorists who braved the writhing bridge on windy days. Even in a light breeze, Gertie's undulations were known to produce waves up to ten feet tall. Sometimes these occurrences were brief, and other times they lasted for hours at a time." Ummm… you're joking, right? Who in their right mind would drive across a bridge that has a wave that reaches up to TEN feet tall, much less any feeling of movement at all? I mean, maybe it was just the perspective of the time, but I can't believe that the bridge, although supposedly safe, wasn't immediately closed until they could figure out what was wrong. I just can't understand how ten foot-tall bridge waves would be considered OK. Does the Golden Gate or any other large bridge noticeably move so much that the motorists can actually feel it?"[/quote] I have also felt movement on the Lion's Gate Bridge up here in Vancouver. I was stuck in traffic in the middle once, and I got quite motion sick. For someone who's terrified of heights, it was definitely a white knuckle experience!!! [quote]jaydawg53 said: “”After opening, the new bridge shortly came to be known as “Galloping Gertie,” so named by white-knuckled motorists who braved the writhing bridge on windy days. Even in a light breeze, Gertie’s undulations were known to produce waves up to ten feet tall. Sometimes these occurrences were brief, and other times they lasted for hours at a time.”

Ummm… you’re joking, right? Who in their right mind would drive across a bridge that has a wave that reaches up to TEN feet tall, much less any feeling of movement at all? I mean, maybe it was just the perspective of the time, but I can’t believe that the bridge, although supposedly safe, wasn’t immediately closed until they could figure out what was wrong. I just can’t understand how ten foot-tall bridge waves would be considered OK. Does the Golden Gate or any other large bridge noticeably move so much that the motorists can actually feel it?”[/quote]

I have also felt movement on the Lion’s Gate Bridge up here in Vancouver. I was stuck in traffic in the middle once, and I got quite motion sick. For someone who’s terrified of heights, it was definitely a white knuckle experience!!!

]]> By: Dropbear http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-22663 Dropbear Wed, 03 Sep 2008 11:27:32 +0000 http://www.damninteresting.com/?p=759#comment-22663 "...a triumph of man's ingenuity..." Gotta love that phrase. Goes so well with so many other structures. Titanic, Gertie, Love Canal, that random hotel in North Korea...... “…a triumph of man’s ingenuity…”
Gotta love that phrase. Goes so well with so many other structures. Titanic, Gertie, Love Canal, that random hotel in North Korea……

]]> By: Usernamee http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-17425 Usernamee Thu, 27 Sep 2007 14:11:17 +0000 http://www.damninteresting.com/?p=759#comment-17425 OMG!!!!!!!!!!! AHHH!!!!!!!!!!! WE'RE ALL GONNA DIIIIIEEEEEEEEEEEEEEEEEEEEEEE!!!!!!!!!!!!!!!!!! OMG OMFG OMG OMFG!!!!!!!!!!! HOLY SHET!!!!!!!!!!!!!!! AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH XD OMG!!!!!!!!!!! AHHH!!!!!!!!!!! WE’RE ALL GONNA DIIIIIEEEEEEEEEEEEEEEEEEEEEEE!!!!!!!!!!!!!!!!!! OMG OMFG OMG OMFG!!!!!!!!!!! HOLY SHET!!!!!!!!!!!!!!! AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

XD

]]> By: Aperio http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-17235 Aperio Tue, 11 Sep 2007 14:58:02 +0000 http://www.damninteresting.com/?p=759#comment-17235 There were so many factors involved here it was a 'perfect storm' of engineering and environmental forces interacting to the detriment of the whole. One of the seemingly innocuous details is that the railings along the sidewalks did not allow the wind to pass through them, which in turn encouraged the formation of vortexes over the roadway. If I remember correctly this was not in the original design. The roadway itself was essentially a long slender glider wing that flew when the wind exceeded just a few knots. Once the wind velocity climbed sufficiently to lift the roadway the suspender cables no longer supported its weight and became slack, which then allowed the roadway to twist, -and a vortex was shed. Lift was lost and the roadway would drop. With the span of the bridge and the variability of the wind pressures against it, given enough time it would settle into a resonance of lift, twist, shed, and drop. Had the side railings allowed the wind to pass through, the vortexes may not have developed sufficiently to have had the effect that they did, and while it is likely that the bridge deck would still have had considerable movement, it is quite possible it might have survived the 40-knot wind that ultimately brought it down. The new bridge is a pleasure to drive across. I'm hoping the Discovery Channel documented its construction. It's one thing to see it going up over the course of a couple of years, but something else to see it all condensed down into an hour or so. There were so many factors involved here it was a ‘perfect storm’ of engineering and environmental forces interacting to the detriment of the whole. One of the seemingly innocuous details is that the railings along the sidewalks did not allow the wind to pass through them, which in turn encouraged the formation of vortexes over the roadway. If I remember correctly this was not in the original design. The roadway itself was essentially a long slender glider wing that flew when the wind exceeded just a few knots. Once the wind velocity climbed sufficiently to lift the roadway the suspender cables no longer supported its weight and became slack, which then allowed the roadway to twist, -and a vortex was shed. Lift was lost and the roadway would drop. With the span of the bridge and the variability of the wind pressures against it, given enough time it would settle into a resonance of lift, twist, shed, and drop. Had the side railings allowed the wind to pass through, the vortexes may not have developed sufficiently to have had the effect that they did, and while it is likely that the bridge deck would still have had considerable movement, it is quite possible it might have survived the 40-knot wind that ultimately brought it down.

The new bridge is a pleasure to drive across. I’m hoping the Discovery Channel documented its construction. It’s one thing to see it going up over the course of a couple of years, but something else to see it all condensed down into an hour or so.

]]> By: piper http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-14822 piper Sun, 13 May 2007 06:10:28 +0000 http://www.damninteresting.com/?p=759#comment-14822 <p> <i>you would have never thought that steel and conrete could be "so flexible".</i></p><p>Nor would one necessarily think that 2" thick steel could be : <a href="http://pipingdesigncheckers.com/reference/burst_vessel.jpg" rel="nofollow">ripped apart like tinfoil.</a></p><p>DI is a great site (my new favourite), why haven't I heard of it before now? </p> you would have never thought that steel and conrete could be “so flexible”.

Nor would one necessarily think that 2″ thick steel could be :
ripped apart like tinfoil.

DI is a great site (my new favourite), why haven’t I heard of it before now?

]]> By: white_matter http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-12106 white_matter Fri, 26 Jan 2007 06:15:42 +0000 http://www.damninteresting.com/?p=759#comment-12106 <p>Isn't a 75 cent toll kind of steep for the 40's? Kind of steep nowadays now that I think about it.</p> Isn’t a 75 cent toll kind of steep for the 40′s? Kind of steep nowadays now that I think about it.

]]> By: FireDude http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-11831 FireDude Tue, 16 Jan 2007 20:18:08 +0000 http://www.damninteresting.com/?p=759#comment-11831 <p>It's really unfair to say the engineers and researchers at the time should have been able to predict this based on the longitudinal wave problem. When they gave the bridge a clean bill of health after the initial waves, there was no reason to expect torsional waves would ever arise. It's only when you consider the coupling between the aerodynamics of the system and the structure that problems arise. It was not some characteristic resonance in the structure itself that caused a problem but the interaction of different, complex phenomena. Most engineers don't learn this in the introductory classes where the talk about Galloping Gertie because they don't yet have the background to gain anything from a truly detailed discussion of the matter and then they never return to the matter in other classes. It actually contributed heavily to the creation of the field of aeroelasticity, "the science which studies the interaction among inertial, elastic, and aerodynamic forces," (wiki) a field which has some frickin' hard problems in it.</p><p><span class='quote'>senorstu said: "I recall a fluid dynamics class where this incident was used to illustrate an effect called vortex shedding. Basically, any blunt obstacle in an airflow will cause little eddies or vortices to peel off the trailing edge."</span></p><p>This is the reason that a flag waves in the wind - if you watch one carefully on a breezy (but not too windy) day you can clearly see a traveling wave move along the cloth. I think it looks cool. </p><p>Animation care of wiki:</p><p>http://en.wikipedia.org/wiki/Von_K%C3%A1rm%C3%A1n_vortex_street</p> It’s really unfair to say the engineers and researchers at the time should have been able to predict this based on the longitudinal wave problem. When they gave the bridge a clean bill of health after the initial waves, there was no reason to expect torsional waves would ever arise. It’s only when you consider the coupling between the aerodynamics of the system and the structure that problems arise. It was not some characteristic resonance in the structure itself that caused a problem but the interaction of different, complex phenomena. Most engineers don’t learn this in the introductory classes where the talk about Galloping Gertie because they don’t yet have the background to gain anything from a truly detailed discussion of the matter and then they never return to the matter in other classes. It actually contributed heavily to the creation of the field of aeroelasticity, “the science which studies the interaction among inertial, elastic, and aerodynamic forces,” (wiki) a field which has some frickin’ hard problems in it.

senorstu said: “I recall a fluid dynamics class where this incident was used to illustrate an effect called vortex shedding. Basically, any blunt obstacle in an airflow will cause little eddies or vortices to peel off the trailing edge.”

This is the reason that a flag waves in the wind – if you watch one carefully on a breezy (but not too windy) day you can clearly see a traveling wave move along the cloth. I think it looks cool.

Animation care of wiki:

http://en.wikipedia.org/wiki/Von_K%C3%A1rm%C3%A1n_vortex_street

]]> By: Khate http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-11829 Khate Tue, 16 Jan 2007 18:12:25 +0000 http://www.damninteresting.com/?p=759#comment-11829 <p>As always, DI has just as much nifty info in the comments as the well-written feature. Thanks to all!</p><p>Once I started watching the footage, I realized I'd seen it before, but never knew the story. I'd always assumed it was shot during an earthquake or somesuch! Amazing that they didn't close it down as soon as the problems became apparent.</p> As always, DI has just as much nifty info in the comments as the well-written feature. Thanks to all!

Once I started watching the footage, I realized I’d seen it before, but never knew the story. I’d always assumed it was shot during an earthquake or somesuch! Amazing that they didn’t close it down as soon as the problems became apparent.

]]> By: nighthawk808 http://www.damninteresting.com/the-fall-of-galloping-gertie/#comment-11796 nighthawk808 Sun, 14 Jan 2007 09:40:24 +0000 http://www.damninteresting.com/?p=759#comment-11796 <p>Regarding the 10-foot wave: without more information, it is impossible to say whether this would be safe, barely perceptible, or worrisome. You would need to know more about the ratio of the wavelength to the amplitude and whether it is periodic. If two periodic, sinusoidal ten-foot waves are a mile apart, or if one ten-foot wave takes up the entire bridge, you may hardly notice the movement at all. If they are thirty feet apart, you would probably be thrown to the ground. One aperiodic ten-foot wave with a width of thirty feet may launch you into the air. Simply saying that the waves were ten feet high gives very little information at all.</p><p>Try this to get an idea of the difference: fill your bathtub halfway. Place a boat, rubber ducky, or other floatie near one end. Put your hand on the one side, then rather slowly move it about a foot toward the other side and stop. You will get one long wave. Let the tub return to normal. Do the same thing with the same speed, but repeat it. You will get several waves at a long wavelength. Let the tub return to normal. Move your hand faster, but not as far. You will get one wave with a greater height than the other one, but not as long. Finally, once the tub is normal once more, move your hand the way you did the last time, but repeat. You'll get several waves of the same, higher amplitude but shorter wavelength. Throughout, compare how the boat/duck/thingy reacts. Imagine a tiny person standing on top of that and what it would feel like to them and you should start to get a feel for the information that is missing in just saying "a three-inch wave".</p> Regarding the 10-foot wave: without more information, it is impossible to say whether this would be safe, barely perceptible, or worrisome. You would need to know more about the ratio of the wavelength to the amplitude and whether it is periodic. If two periodic, sinusoidal ten-foot waves are a mile apart, or if one ten-foot wave takes up the entire bridge, you may hardly notice the movement at all. If they are thirty feet apart, you would probably be thrown to the ground. One aperiodic ten-foot wave with a width of thirty feet may launch you into the air. Simply saying that the waves were ten feet high gives very little information at all.

Try this to get an idea of the difference: fill your bathtub halfway. Place a boat, rubber ducky, or other floatie near one end. Put your hand on the one side, then rather slowly move it about a foot toward the other side and stop. You will get one long wave. Let the tub return to normal. Do the same thing with the same speed, but repeat it. You will get several waves at a long wavelength. Let the tub return to normal. Move your hand faster, but not as far. You will get one wave with a greater height than the other one, but not as long. Finally, once the tub is normal once more, move your hand the way you did the last time, but repeat. You’ll get several waves of the same, higher amplitude but shorter wavelength. Throughout, compare how the boat/duck/thingy reacts. Imagine a tiny person standing on top of that and what it would feel like to them and you should start to get a feel for the information that is missing in just saying “a three-inch wave”.

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