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windsrf
Joined: 01 May 1998
Posts: 464
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 Posted: Thu Oct 29, 2009 1:35 pm Post subject: |
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| The "cables" were actually two-inch solid steel rods, thus no strands to snap but instead the entire rod broke. Since it was 80 ft long and only 2 inches in diameter it looks like a loopy cable when collapsed. Amazing no one was killed. |
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kirk
Joined: 10 Apr 2000
Posts: 158
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| Posted: Thu Oct 29, 2009 2:55 pm Post subject: |
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| windsrf wrote: | | The "cables" were actually two-inch solid steel rods, thus no strands to snap but instead the entire rod broke. Since it was 80 ft long and only 2 inches in diameter it looks like a loopy cable when collapsed. Amazing no one was killed. |
Ah, that makes a lot more sense. I doubt you could see tiny fractures at the junction with binoculars (might need xrays) but one would think they had good enough models to know if the vibrations would stay within the elastic limits of the steel rods at the junction.
Oddly, the failure mechanism seems very similar now to how I used to break one or two Fibersnap booms every season before they switched to carbon front ends. With Aluminum and my weight and Coyote Chop, making the walls of the Al head tubes thicker would make the booms last longer, but they still eventually broke.
More from Prof Ibbs
and
http://www.wibw.com/nationalnews/headlines/67272752.html
"According to a 2009 American Society of Civil Engineers report, more than 26 percent of the nation's bridges are either structurally deficient or functionally obsolete. The American Association of State Highway and Transportation Officials estimated in 2008 that it would cost roughly $140 billion to repair every deficient bridge in the country."
Prof Ibbs on KCBS (been the big critic I've listened to)
http://multimedia.play.it/m/audio/27114255/what-went-wrong.htm
Suggests setting speed limit based on wind speed!
_________________
Best Regards
Kirk Out
http://bayareawindsurfing.blogspot.com/
http://kirklindstrom.blogspot.com/ |
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YippieYo
Joined: 16 Jul 2000
Posts: 108
Location: San Francisco
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| Posted: Thu Oct 29, 2009 3:12 pm Post subject: Re: Bay Bridge Damage Blamed on Wind |
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| kirk wrote: |
Solution THEY SAY now is to put some neoprene between the metal saddle and cables... at least that is what I heard this AM on the radio. |
I would recommend 4mm for this time of year. much safer for when the bridge collapses into the bay. let's tie a marine radio and a strobe to make everyone feel better. |
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