Armed Polite Society
Main Forums => The Roundtable => Topic started by: MillCreek on May 13, 2021, 08:59:22 AM
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https://www.npr.org/2021/05/12/996407481/cracked-memphis-bridge-remains-indefinitely-closed-disrupting-supply-chain?utm_medium=social&utm_campaign=npr&utm_term=nprnews&utm_source=facebook.com&fbclid=IwAR0pg0hHGOJ-mr6ewlMeYT-9S96hnkYqPZ7hKpluayQxsdk1kihmU8aY8qU
I don't have my civil engineering boards hanging on the wall, so how does one go about fixing a major crack in a major structural beam? Do you have to cut out and replace the beam, can you weld a patch over it, or what?
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Weld some paperclips over it. I think that's what they did with the bridge in Minneapolis some years ago.
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If one beam has a crack I suspect they will check all of them before starting repairs.
I also suspect they will revisit the blueprints and recheck everything to make sure this isn't the result of a design flaw.
No engineering background here either, but I did stay at a ... :laugh:
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This is exactly what happens when you let politicians steal the money destined for repairs and replacement of infrastructure. Of course those same politicians then decry the crises they created and if you don’t hurry up and vote for more taxes and funding you hate infrastructure.
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This is exactly what happens when you let politicians steal the money destined for repairs and replacement of infrastructure. Of course those same politicians then decry the crises they created and if you don’t hurry up and vote for more taxes and funding you hate infrastructure.
A day or two before Obama announced his grand trillion dollar infrastructure plan they found a crack and panic closed the I-64 bridge over the Ohio here in Louisville. Obama in his speech then used it as example of why we needed to pass his plan. Turned out the crack had been there since the bridge opened in the 50s. We did get two new 4 billion dollars bridges that they had been dragging their feet on out of the deal and it now cost $4 to cross our bridges except for one. Someone decided it would be racist if the local access one wasn't left free.
Edit: $4.31 one way
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The new bridge deal also cost us something like $300* million to dig a tunnel under the house of a friend of Yarmuth who refused to move. Before Yarmuth was elected they were going to force the guy out. After Y's election suddenly we had to dig a tunnel under the guy's "historic" house. After the tunnel was done the guy moved. Nothing suspicious about that at all.
* Hard to find an exact figure.
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Here in the Seattle area, they are looking at a multi-million dollar repair of the West Seattle bridge, a concrete high-rise bridge that is the main point of access to West Seattle. A routine inspection found a number of significant cracks in the concrete, and they have hired many concrete and engineering experts to try and find out what gives. The City of Seattle is now thinking about using car license tabs revenue to pay for the repairs.
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Bridge repair costs aren't covered by the last infrastructure bill?
When was the last time an infrastructure bill was passed? Obama?
Considering all the talk about infrastructure you would think we would have seen Federal funding pass.
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Bridge repair costs aren't covered by the last infrastructure bill?
When was the last time an infrastructure bill was passed? Obama?
Considering all the talk about infrastructure you would think we would have seen Federal funding pass.
States pass infrastructure funding every year. Or at least they tax people for infrastructure. Is is spent on infrastructure?
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How things happen in St. Louis.
A project goes up for bids. Preference is given to "small disadvantaged businesses" in most things. Usually minority friends of the administration. Someone will win the contract. They will then hire a firm which can actually complete the project, and maintain a trailer on the project site to "inspect." In reality, the same big construction companies do the work, and the graft happens.
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That's not a "crack" -- that's what we call a "break."
And that "crack" didn't happen overnight. That had to have been there for a long time, and it did start out as a crack. I'd like to know how many previous bridge inspections missed it.
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It'll buff right out.
Brad
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The fact that the bridge didn't collapse is testimony to the important of redundancy in the design of critical structures. As my first year structural engineering professor put it, "Stress goes where there's material there to resist it." Back in the early 1980s there was a bridge on I-95 in Connecticut that didn't have redundancy in its design. It collapsed into the river, killing a few people.
https://en.wikipedia.org/wiki/Mianus_River_Bridge
About three (or so) years ago, there was a break somewhat similar to this one in a bridge on the Northeast Extension of the Pennsylvania Turnpike, where it crosses from Pennsylvania into New Jersey. That one, too, was saved by a redundant design. One member failed, but the remaining structure had sufficient excess carrying capacity that the bridge didn't collapse.
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That's not a "crack" -- that's what we call a "break."
And that "crack" didn't happen overnight. That had to have been there for a long time, and it did start out as a crack. I'd like to know how many previous bridge inspections missed it.
Agreed. A crack indicates the beam is not fully broken.
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There was a business here closed due to crack.
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That's not a "crack" -- that's what we call a "break."
And that "crack" didn't happen overnight. That had to have been there for a long time, and it did start out as a crack. I'd like to know how many previous bridge inspections missed it.
That was my first thought. Somebody who never had an engineering class could see that from a boat on the river and just know that was a problem. How did it get that far?
By the way, it may have happened before but this is the first time I've heard of the inspectors calling 911 to get the bridge shut down.
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Not an engineer but a steelworker and leftover airplane inspector. In my mind everything is suspect and a thorough inspection starts with the paperwork for all the steel in that heat when it got made and goes from there. All prior inspections, metallurgical analysis, and the whole bridge inspected. Cyclic fatigue isn’t fun so this isn’t just a weld a stiffening plate on it and move on fix.
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https://www.wdrb.com/news/national/mississippi-river-traffic-resumes-under-damaged-bridge/article_fe198301-edcf-5d3b-bb3b-0d60916d3cec.html
It is ok to go under, but not over.
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I wonder how many crackheads are circling under the bridge looking for fallout ...
Woody
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It was a stress-relief crack.
So now that the stress has been relieved, we can forget about it.
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An unidentified inspector who failed to discover a crack in the Hernando de Soto Bridge linking Arkansas and Tennessee that prompted the span’s closure was fired Monday morning and may face charges, according to reports.
Arkansas Department of Transportation Director Lorie Tudor said the inspector was fired after drone video showed the crack on the bridge spanning the Mississippi River in May 2019.
Tudor said all "fracture critical" bridges that had been inspected by the fired employee will be re-inspected.
Arkansas Department of Transportation Director Lorie Tudor said the inspector was fired after drone video showed the crack on the bridge spanning the Mississippi River in May 2019.
https://www.foxnews.com/us/hernando-de-soto-bridge-inspector-fired-for-not-flagging-crack-in-span
ARDOT says inspector who did 2019 & 2020 I-40 bridge inspection has been fired
https://www.youtube.com/watch?v=hpGDMQ0cvd4
Drone footage from 2019.
https://youtu.be/qmbeDO53TK8?t=19
Still from the drone footage. How could someone miss that? Yikes!
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If they have drone footage from 2019, why did it take until 2021 to close the bridge. Was the fired inspector the only one who viewed the footage?
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If they have drone footage from 2019, why did it take until 2021 to close the bridge. Was the fired inspector the only one who viewed the footage?
The drone footage is a tool to facilitate the inspection. The inspection product is the written condition report, and that's almost certainly what the superiors reviewed. The report didn't mention any cracks, so the supervisors assumed everything was okay.
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I already know the excuse. The bridge has been fine in the preceding years so there is no way a crack that big could just happen in such a short period of time. He assumed it was bird crap or some other biologic debris on the bridge. The arbitrator agrees, he is rehired, given back pay and allowances and a promotion where he no longer does the field work on bridge inspections. :O
bob
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It was undergoing a seismic retrofit. It is near the New Madrid Seismic Zone.
https://en.wikipedia.org/wiki/Hernando_de_Soto_Bridge#Seismic_retrofit_project
" It is of similar construction to the Sherman Minton Bridge between Louisville, Kentucky, and New Albany, Indiana."
I hope this generates a scrupulous review of all major engineering features throughout the country including bridges, tunnels, and dams for vulnerability as well as integrity.
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Due to the angle of the drone I am not certain, but did it progress from a crack in 2019 to the complete break in 2021?
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Due to the angle of the drone I am not certain, but did it progress from a crack in 2019 to the complete break in 2021?
I would say yes.
Also I wonder how far back the crack first started and was "missed"
(https://media.npr.org/assets/img/2021/05/12/ap21132687632291_wide-2747af6ce6d7e94270652e2f11e330b2d86861e5-s800-c85.webp)
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I'm wondering if since it was undergoing a Seismic retrofit anyway, it was one of those things that "everyone" knew was going to be taken care of during the retrofit, so why report it year after year. Yeah, somebody was fired, but I wonder about that, just a thought..
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It was undergoing a seismic retrofit. It is near the New Madrid Seismic Zone.
https://en.wikipedia.org/wiki/Hernando_de_Soto_Bridge#Seismic_retrofit_project
" It is of similar construction to the Sherman Minton Bridge between Louisville, Kentucky, and New Albany, Indiana."
I hope this generates a scrupulous review of all major engineering features throughout the country including bridges, tunnels, and dams for vulnerability as well as integrity.
The Sherman Minton bridge is being worked on right now, for what it matters.
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What I would like to know is: What's up with what appears to be a fairly new inspection port of some kind on the top of the corresponding beam immediately to the left of the upright? It's a slightly different color, so it must have been placed after the bridge was past painted. If I had to guess, my guess would be that someone wanted or needed to get a look at what was happening inside that connection, so they cut out an inspection port and then bolted on a cover rather than welding a plate over it -- which may suggest that they wanted to be able to come back and look at it again.
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Maybe access for the back side of those plates for the original construction?
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I would say yes.
Also I wonder how far back the crack first started and was "missed"
(https://media.npr.org/assets/img/2021/05/12/ap21132687632291_wide-2747af6ce6d7e94270652e2f11e330b2d86861e5-s800-c85.webp)
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Just, wow. :O
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Would meth be better or worse than crack for a bridge?
About five plus years ago we had a deck crack on a bridge south of me. Missouri came out and put a four lane wide piece of steel on it with. Bunch of bolts and a bump sign. My dad was visiting right after and asked when are they going to fix it? I said this is Missouri it is fixed. Last time he visited he said crap that is what they do around here.
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Lookin, at that crack/break, it appears to me that there wasn't enough tension on that clevis which means that the suspension cable went slack. At my age, I understand what it means to a clevis when my cable goes slack ... :rofl:
Woody
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What I would like to know is: What's up with what appears to be a fairly new inspection port of some kind on the top of the corresponding beam immediately to the left of the upright? It's a slightly different color, so it must have been placed after the bridge was past painted. If I had to guess, my guess would be that someone wanted or needed to get a look at what was happening inside that connection, so they cut out an inspection port and then bolted on a cover rather than welding a plate over it -- which may suggest that they wanted to be able to come back and look at it again.
I'm curious as to what dented that vertical drain pipe just there. It's also discolored which means it happened since the last paint job. Also oddly coincidental that it's close to the crack.
So we've got an added inspection cover, a strangely located dent, and a broken beam all in the same area. Clearly it's aliens.
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I'm curious as to what dented that vertical drain pipe just there. It's also discolored which means it happened since the last paint job. Also oddly coincidental that it's close to the crack.
So we've got an added inspection cover, a strangely located dent, and a broken beam all in the same area. Clearly it's aliens.
Could it all be the result of a bridge strike from a barge or some such?
Woody
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The articles refer to the cracked member as a "beam" but, in reality, I don't think it is a beam. The structure of that type of bridge relies primarily on the main arches to carry the weight -- of the bridge structure itself, of the roadway, and of the traffic. Think of it like at attic truss in a house. The lower, horizontal member that carries the ceiling isn't a "beam," it's the bottom chord of a truss. The nature of the members of a truss is that they are supposed to act mostly in tension or compression, and major loads are supposed to be applied only at intersections of multiple members.
You can see that in these photos. Look behind the riveted gusset plate and you can see several other parts converging in where the cracked "beam," the vertical member, and the other "beam" come together. That said, truss members do act to a lesser degree as beams for localized loads. Again using the house attic truss, the loads of the roof go along the top chord members until the loads get transferred into the truss verticals and diagonals. Likewise the weight of the ceiling -- each short section of bottom chord acts like a short, local beam to carry the weight of that section of ceiling to the points of intersection; at the points on intersection ("panel points") all loads are converted into either tension or compression in the truss members.
The cracked beam should have been subject almost entirely to tension or compression. That's not a tension crack -- that's a shear crack. For long beams, the type of stress away from the ends is bending, and the type of stress at the ends is shear. Joints in steel structures are often reinforced near joints to handle shear stresses. The fact that this member failed -- apparently in shear -- so close to the end of that gusset plate suggests to me that the entire design of the bridge may be flawed. I don't know what the two highway departments are doing but if I were the engineer hired to look at this thing, I would be re-running ALL the numbers for the design of the entire bridge. I would not be surprised if we read in a few weeks that those gusset plates are too small (too short) and that they all have to be replaced.
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A wider picture and maybe a level on th beam would by nice.