From the linked news item:"Things can happen with temperature, and with construction, or a lot of other confounding factors," French said.
This was a 40-year-old truss bridge, and French did say that some early truss bridges don’t have as many structural redundancies — backups to carry the loads — as is now considered desirable.
Another engineer, Michael Ramerth, a principal at MBJ Consulting Structural Engineers in Minneapolis, said in the search for answers "I would start at the foundations." I’m hearing bad concrete job in that.
This sounds like a full-employment program for litigators.
Minneapolis-St. Paul was a lovely place when I went through there a few decades back. I remember driving around in the early morning hours, clearly lost. I pulled over to re-check a map and directions, and this regular guy pulled over behind me, gets out, and says to me, "I can see you’re lost, do you need some help with directions."
That was very nice. Some places are like that. Or used to be.
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Written By:
Martin McPhillips
URL:
http://mcphillips.blogspot.com/
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The bridge is next to the University of Minnesota, and I lived in the Twin Cities for ten years from 1985-95 (and was born there - though grew up in South Dakota) and have crossed that bridge hundreds of times. It’s amazing how despite being away from the Twin Cities for 12 years something like this makes me a Minneapolitan again. Minneapolis has been called the largest small town in America because so many people move there from rural Minnesota, bringing with them small town values of community and cooperation. "Minnesota nice" is real. The loved ones of victims will be taken care of, and the community will band together. Still it is stunning. |
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Written By:
Scott Erb
URL:
http://faculty.umf.maine.edu/~erb/blog.htm
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the channels to watch the Braves I didn’t see any major league baseball game.
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Written By:
ChrisB
URL:
http://
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The bridge is a 40-year-old arched steel truss structure. The only concrete/cement portions are the very bases of the bridge, and the bridge deck itself. The bridge deck was undergoing a resurfacing, which involved removing the existing concrete and rebar, and replacing it. Most of the structural engineers in my office don’t feel that the true answer to why it collapsed is going to be known for a long time.
The U.S. had given it a rating of "structurally deficient", but that’s nothing new for many bridges in this area. Recent analyses had been done (some involving measuring stresses on bridge components with strain gauges) which indicated that they researchers didn’t feel that the bridge was in imminent danger, but that several members of the structure needed to be monitored for fatigue cracks.
I grew up in Minneapolis, and have lived here on and off for almost 50 years. I watched this bridge being erected (back in 1966 and 1967), and remembered thinking even after it was completed how "spidery" it looked. One of the major drawbacks of this type of bridge design is that it lacks multiply-redundant load paths. If several critical members fail, then it all comes down. It appears that this is what happened. |
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Written By:
blackwing1
URL:
http://
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