Posted on 08/01/2007 4:28:27 PM PDT by ButThreeLeftsDo
“A questions for the Civil Engineers & Designers out there. Is it possible that the combination of rush hour traffic (bumper to bumper maximizing the number of vehicles), lanes being closed (maximize the load to one side), years of potential neglect and the vibration of a passing freight train caused overstressing of a “weak point” that caused a cascading effect of popped rivets, etc. that would have led to catastrophic failure?”
All good questions. However, I can’t stress enough how much over design and redundancy goes into a major structural project. They would have taken into account the loads you mentioned and then increased it many times over to ensure safety. I’m not saying that it can’t happen, but people dedicate lives to thinking about those kinds of scenarios you mentioned. Also, it may not have been the steel, it could have just as easily been a change in soil conditions at the supports in the water (I think I saw midpoint supports).
I think it's a rigid structure from one end of the girder'ed section to the other, with the little pylons in the middle just to hold up the weight. The tangental support would be primarly at each end of the girder structure.
But, being a rigid structure, and being a bit aged and probably having a great deal of rusted fasteners, the structure was prime for a cascading failure as a result of a single failure.
My guess is that some important piece or brace broke - but it was something that wouldn't have caused a collapse back in 1967 when the bridge was new. However, considering that there are many old bolts or rivets, stress cracks, and other weaknesses, a simple failure and shifting load might have been all it took to cause the total collapse of the structure.
Homeland Security protesteth too much...and too soon...that this is not terrorist-related.
Which is why I don’t believe a word they say.
Better to call the Psychic Hotline on this one than to trust Chertoff’s gut.
Cell phones can be used to detonate explosives. It is possible that cell phone towers were turned off, or whatever they do, to make cell phones inoperative at this time. Or it could be that so many people are trying to use their phones, that the lines are jammed. That happened before Hurricane Katrina.
B4??
You spend a lot of time at MySpace, huh?
this looks like a corroding pin, as describe on Fox. It is rusty and in bad shape. HMMMMM
On December 15, 1973, the northbound lanes between Little West 12th Street and Gansevoort Street collapsed under the weight of a dump truck, which was carrying over 30 tons (27,000 kg) of asphalt for ongoing repairs of the highway. A four-door sedan followed the truck through the hole; neither driver was seriously injured.
Which would be the result of a "zippering" sequence of failures from overstress before the overall catastrophic collapse.
Up in the thread it said that the 4 lane bridge was down to 1 lane.
If true, where is the excess weight?
Here’s what the fellow on FOX is talking about:
http://en.wikipedia.org/wiki/Mianus_River_Bridge
The collapse was caused by the failure of two pin-and-hanger assemblies that held the deck in place on the outer side of the bridge. The hanger on the inside part of the expansion joint at the southeast corner was forced from the pin that was holding it, and the load was shifted to the only other pin in the joint. The problem was caused by rust formation within the bearing on the pin, exerting a tremendous force on the hanger. The extra load on the remaining pin started a fatigue crack at a sharp corner on the pin. It failed catastrophically and the deck was then supported at just three corners.
When two heavy trucks and a car entered the section, the remaining expansion joint failed and the deck crashed into the river below. The ensuing investigation cited corrosion from water buildup due to inadequate drainage as a cause. The highway drains had been deliberately blocked during roadmending some 10 years before, and water leaked down through the pin bearings, causing them to rust. The outer bearings were safety-critical and non-redundant, a design flaw of this particular type of structure. The bearings were difficult to inspect close-up, although traces of rust could be seen near the affected bearings
Fatima - I just saw your tagline. Congrats on Baby Ava. Better late than never I suppose.
http://www.cnn.com/2007/US/08/01/bridge.collapse/
updated 11 minutes ago
“3 dead as Mississippi River bridge falls amid rush hour in Minneapolis”
VIDEO
ARTICLE SNIPEPT: “(CNN) — At least three people were killed when an interstate bridge in Minneapolis, Minnesota, collapsed Wednesday evening, plunging cars and chunks of concrete into the Mississippi River below.”
Channel 4 is reporting that the Minnesota Twins have postponed tomorrow’s game as well as the ground-breaking for the new stadium.
Hey, that’s a really good point. Thanks again.
I was checking out beautiful Ava Rose also!
Good to see you, Colonel...
My sister worked at the U of M hospital for many years and still hears from some still there.
She’s pretty freaked, right now.
have you yet not ever sent a text message?
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