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#91
08-02-2007, 12:12 AM
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Re: Bridge collapses in Minnesota
ummm... I hate to sound like a smartass in this... but I really feel like so called "civil engineering inspectors" ought to be fired right on the spot for this sort of thing. This is the 21st century, and engineering (bridge strength analysis) is at a fairly high enough level to be able to prevent this easily I would suspect.
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#92
08-02-2007, 12:13 AM
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Re: Bridge collapses in Minnesota
[ QUOTE ]
Joe - Re: these scheduled inspections, would it be state-employed engineers (MNDoT) doing the inspecting, or would they contract a firm to do it? [/ QUOTE ] There is definitely a state bridge inspection team, likely many, a team per district. They may contract the SCUBA inspection but many states have a full time dive team. I know for a fact that Massachusetts has 5 full time SCUBA bridge inspectors. I would imagine a state like Minnesota (the land of 10k lakes), has full time inspectors. You'd be surprised on how often these people are called upon. A lot goes on behind the scenes of large infrastructure. It can be as simple as a cop reporting a pot hole on a bridge to the state. The inspector goes out and finds a crack through the surface and a hint of a crack on the pier. He calls the dive team. They show up and find that the pier is scoured. They shut down the bridge and a full scale construction project ensues.
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#93
08-02-2007, 12:21 AM
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Re: Bridge collapses in Minnesota
[ QUOTE ]
Are you saying that the construction on the bridge is merely coincidental? Do bridges just collapse -- due to scour or otherwise -- without some kind of trigger? In the Schoharie County bridge collapse referenced in the article, it discussed a flood, for example. I understand that the surfacing work itself actually did not add meaningful additional weight to the bridge -- but it seems like an awful coincidence that there was a contractor working on the bridge around the time that this happened (and I don't mean that anything the contractor did that might have caused this happened today -- it could have happened weeks ago). [/ QUOTE ] What I'm trying to say is that the forces at play are greater than most people imagine. The bridge was over designed for the everyday load, even to today's standards. What happened was bound to happen unless a MAJOR change took place. In Minnesota, there is short window to do paving/surface work because of the weather. I'm sure there are 100 bridges or more being worked on in the state. [ QUOTE ] And I'd like more stories about banging strippers. Not necessarily in this order. [/ QUOTE ] I got married on Saturday. No, not a stripper. These stories never happened, I have no idea what you are talking about. [img]/images/graemlins/smirk.gif[/img]
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#94
08-02-2007, 12:23 AM
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Re: Bridge collapses in Minnesota
[ QUOTE ]
joe, can u define abutment failure for us? [/ QUOTE ] Pretty simple really, if you pull the rug out from underneath your feet, you are going to fall. This link on scour will help though. ADDED: MN Bridge Inspection Statute
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#95
08-02-2007, 12:24 AM
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Re: Bridge collapses in Minnesota
[ QUOTE ]
Not to be a nit or anything, but pounds per square inch is a unit of pressure, not density. Are you sure you don't mean 150 pounds per cubic foot? [/ QUOTE ] I meant per cubic foot, thanks. [img]/images/graemlins/smile.gif[/img]
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#96
08-02-2007, 12:36 AM
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Re: Bridge collapses in Minnesota
[ QUOTE ]
[ QUOTE ] Are you saying that the construction on the bridge is merely coincidental? Do bridges just collapse -- due to scour or otherwise -- without some kind of trigger? In the Schoharie County bridge collapse referenced in the article, it discussed a flood, for example. I understand that the surfacing work itself actually did not add meaningful additional weight to the bridge -- but it seems like an awful coincidence that there was a contractor working on the bridge around the time that this happened (and I don't mean that anything the contractor did that might have caused this happened today -- it could have happened weeks ago). [/ QUOTE ] What I'm trying to say is that the forces at play are greater than most people imagine. The bridge was over designed for the everyday load, even to today's standards. What happened was bound to happen unless a MAJOR change took place. In Minnesota, there is short window to do paving/surface work because of the weather. I'm sure there are 100 bridges or more being worked on in the state. [ QUOTE ] And I'd like more stories about banging strippers. Not necessarily in this order. [/ QUOTE ] I got married on Saturday. No, not a stripper. These stories never happened, I have no idea what you are talking about. [img]/images/graemlins/smirk.gif[/img] [/ QUOTE ] congratts on the marriage! also thanks for all the good info. i feel very fortunate to say my friends and family here in MN are all OK.
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#99
08-02-2007, 12:45 AM
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Re: Bridge collapses in Minnesota
[ QUOTE ]
[ QUOTE ] Not to be a nit or anything, but pounds per square inch is a unit of pressure, not density. Are you sure you don't mean 150 pounds per cubic foot? [/ QUOTE ] I meant per cubic foot, thanks. [img]/images/graemlins/smile.gif[/img] [/ QUOTE ] Square foot is fine if you're talking about how much weight was added to each square foot of the bridge for the purposes of multiplying it by the bridge area. Cubic foot means nothing here.
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#100
08-02-2007, 12:47 AM
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Re: Bridge collapses in Minnesota
[ QUOTE ]
[ QUOTE ] joe, can u define abutment failure for us? [/ QUOTE ] Pretty simple really, if you pull the rug out from underneath your feet, you are going to fall. This link on scour will help though. ADDED: MN Bridge Inspection Statute [/ QUOTE ] as previous posts pointed out, the bridge was built so no support was placed in the center of the river - it's a steel span bridge with it's support on both bank sides - don't see how scour is a possibility here rb
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