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View Diary: Repairs on Bridge Were Delayed-Video Of Collapse Exists (150 comments)

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  •  Dead vs. Live Loads (12+ / 0-)

    For those unfamiliar with these terms, this has NOTHING to do with dead or living people.  Dead refers to permanent non-moving loads, like the weight of the bridge itself, while live refers to changing or variable loads due to use, like from the weight of the traffic.

    That said, an extra layer of asphalt would increase the dead load marginally, but this would probably contribute little towards the collapse of the bridge.  It is the variable live loads over the lifetime which contribute the fatigue cracking, which is probably one of the causes investigators are looking into at this moment.  Fatigue in a maritime environment, is even more potentially a problem.  

    Additionally, the report (linked above) makes reference to visual inspections.  Most often, fatigue cracking begins in weld roots.  This is typically the hidden, bottom part of the weld, that is non-visible.  By the time a crack of this type is visible, the cracking of the weld has become very severe.  The problem is that inspection of weld roots is much more expensive than the visible inspections carried out.

    These are just a few random and general thoughts.  I can't really comment more without knowing more details.  I'll be interesting in reading the final report of this catastrophic failure when it comes out.

    "You can ... waste your summer, praying in vain, for a savior to rise from these streets" - Springsteen

    by John in Norway on Thu Aug 02, 2007 at 12:33:24 AM PDT

    [ Parent ]

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