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Thread: Minneapolis, Minnesota disaster

  1. #1
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    Minneapolis, Minnesota disaster

    Everyone keep our members in the Minneapolis area in your prayers. Major castrophe with the bridge collapse. I have a friend there that purchased one of our pups from the 1995 litter, and I can't get through to make sure he is ok. Tyler, and all the others there, hope you are all ok. Jim.
    Coolmeadow Setters...
    Exclusively Irish!
    Home of Irish Setter Rescue of North Texas
    When Irish Eyes are smiling, they're usually up to something!!
    At a minimum, I'm Pentatoxic...but most likely, I'm a Pentaholic. There seems to be no known cure. Pentatonix, winners of The Sing Off, season 3


  2. #2
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    Jim, this is certainly a catasrophe. don't worry too much about your friends. phone circuits in the Twin Cities are tied up pretty badly and likely will be most of the night.

    Hennepin County Medical Center reports 26 injuries. North Memorial, the other hospital that got a large quantity of injured haven't reported numbers yet. The mayor of Minneapolis reported 6 dead.
    Irony: The opposite of Wrinkly

  3. #3
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    Prayers and blessings from PA. to victims, family of the victims and
    rescue workers in this disaster.

    Strange seeing a bridge collapse in this way, have they ruled out
    terrorists?
    Donít have the best tools, don't use the best woods and projects donít always turnout perfeck.
    I just feel the need to work with wood!

  4. #4
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    Dunno what happened, but it was "Under Repair" when it broke, so the cause may be complex. Tagic to be sure, prayers go out to those in need.

    What a lousy way to die.
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  5. #5
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    Dave, as of last night they didn't think it was anything other than a structural failure.

    A reporter I heard on Minnesota Public Radio managed to dredge up an inspection report from, I think it was, 2001 which indicated that although there were no structural problems but there is a worrying lack of redundancy in the supporting structure.

    I also read a suggestion that a worker with a jack hammer might have been working and that the jack hammer set up a sympathetic osscillation at the right frequency to get the bridge moving.

    A design flaw perhaps. Maybe everything came just together at that moment.

    I expect the new bridge will be a lot different.
    Irony: The opposite of Wrinkly

  6. #6
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    They said on CNN that the repairs were being performed on the road surface, not structure. You make a good point Dave. We've all seen the video of the suspension bridge swaying violently form a wind that was not that strong. Once set in motion, it's hard to stop. And sympathetic vibration, and harmonics can do some weird things. It's for this reason that every 10 feet the Shuttle is made out of a different material/alloy so that this phenominon doesn't rip it apart on launch.
    Tried to get ahold of my friend up until bed time last night, but phone still busy. Not sure what part of town he lives and works in. Jim.
    Coolmeadow Setters...
    Exclusively Irish!
    Home of Irish Setter Rescue of North Texas
    When Irish Eyes are smiling, they're usually up to something!!
    At a minimum, I'm Pentatoxic...but most likely, I'm a Pentaholic. There seems to be no known cure. Pentatonix, winners of The Sing Off, season 3


  7. #7
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    All speculation of course but I heard someone else conjecture that a truck or a pair of them might have set the bridge in motion. Due to construction with lanes closed traffic speeds were much lower than normal. The number of vehicles on the bridge was also reduced due to the construction. I'm sure that plays a part in the relatively low death count.
    Irony: The opposite of Wrinkly

  8. #8
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    Another possibility, though, is that it was down to 2 lanes one direction, 1 lane the other direction, instead of 4 each way. Bumper to bumper traffic not moving much. It's possible that there were more cars in the 2 lanes standing still than there would have been with 4 lanes moving at normal speed, with several car lengths between each of them. The fact that the cars that fell weren't also doing 60+ mph did probably save some lives. Jim.
    Coolmeadow Setters...
    Exclusively Irish!
    Home of Irish Setter Rescue of North Texas
    When Irish Eyes are smiling, they're usually up to something!!
    At a minimum, I'm Pentatoxic...but most likely, I'm a Pentaholic. There seems to be no known cure. Pentatonix, winners of The Sing Off, season 3


  9. #9
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    Now they're saying there were structural problems....

    From CNN
    " A 2001 study conducted by the Minnesota Department of Transportation found "several fatigue problems" in the bridge's approach spans and "poor fatigue details" on the main truss.

    The study suggested that the design of bridge's main truss could cause a collapse if one of two support planes were to become cracked, although it allowed that a collapse might not occur in that event. But, the study concluded, "fatigue cracking of the deck truss is not likely" and "replacement of the bridge ... may be deferred."

    Two years ago, the U.S. Department of Transportation's National Bridge Inventory database said the bridge was "structurally deficient." "

    I'd imagine a harmonic failure would have been much more prolonged and spectacular, sounds to me like someone should have paid attention to that study.

  10. #10
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    I agree with John that harmonic failure is unlikely. Given the size of the bridge, the period would be very long - which would be experienced as a significant swaying of the bridge. From the press reports, the failure was quite rapid.

    It seems to me that either one of the support structures in the river was under scoured and collapased or some important structural element(s) failed (but I'm not a structural engineer).

    Think of all the other bridges in the US that are rated "structurally deficient". It's going to be interesting to see what's done to fix all of them and where the money is going to come from.

    Mike
    Ancora imparo
    Go into the world and do well. But more importantly, go into the world and do good.

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