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Cracks in Sherman Minton Bridge 1
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bridgebuster
Active member
but it's easier to fix a steel bridge
msquared48
Structural
You don't have to fix a steel bridge ever - they do not reproduce.
Mike McCann
MMC Engineering
Mike McCann
MMC Engineering
....and in most states, will get you a misconduct citation from the board...or more.JAE said:
As for a state DOT over-reacting...well, if they don't find and highlight issues, they get criticized for being unresponsive or negligent. Where life safety is an issue, it is better to use an abundance of caution. If it turns out to be a minor or non-issue, so be it. The only thing lost is a little face and maybe some time.
msquared48
Structural
You know, the subbject here has been mainly highway bridges. That's all well and good.
However, I have not seen one railroad local bridge that had more rust hilding it together than rivets. The most recent maintenance on them has been from the painting of the local taggers and that is pathetic in my opinion. I see a lot of maintenance on the rails and ties, but nothing on the bridges.
Mike McCann
MMC Engineering
However, I have not seen one railroad local bridge that had more rust hilding it together than rivets. The most recent maintenance on them has been from the painting of the local taggers and that is pathetic in my opinion. I see a lot of maintenance on the rails and ties, but nothing on the bridges.
Mike McCann
MMC Engineering
Forensic74
Structural
My theory would be that a railroad bridge is stouter to begin with and undergoes far less cycles than a bridge carrying vehicles/trucks.
bridgebuster
Active member
Railroad bridges tend to be more stiff(no pun intended but say it anyway Mike 
)than highway bridges, which would help with fatigue.
AASHTO (Standard Specs) considers a riveted connection to be a Category D detail (although LRFD lowers it to C) - I don't have AREMA handy to see what they prescribe.
I would agree that the stress cycles in a railroad bridge are lower. In NYC, there are a lot of riveted train trestles in use 24/7. The last elevated train line opened around 1915 and I don't ever recall hearing anything about fatigue cracks.
As an aside, 30 years ago I wrote to the Transit Authority about the deteriorated column rivets on a section of the elevated train I used to take. I never heard back from them; they never fixed anything; but the structure is still standing.
)than highway bridges, which would help with fatigue. AASHTO (Standard Specs) considers a riveted connection to be a Category D detail (although LRFD lowers it to C) - I don't have AREMA handy to see what they prescribe.
I would agree that the stress cycles in a railroad bridge are lower. In NYC, there are a lot of riveted train trestles in use 24/7. The last elevated train line opened around 1915 and I don't ever recall hearing anything about fatigue cracks.
As an aside, 30 years ago I wrote to the Transit Authority about the deteriorated column rivets on a section of the elevated train I used to take. I never heard back from them; they never fixed anything; but the structure is still standing.
msquared48
Structural
Perhaps, and I can understand the number of cycles issue. However there is another, in my opinion, and that is the live load to dead load issue. The engines alone are over 200 tons, and with four carriages with two wheels, puts 50,000 pounds on each axle. Admitedly the car axles see nowhere near this. In a train of 100 cars, there could be over 400 axles that would pass.
In highway bridges, I would contend that the live to dead load ration is much less than a railroad bridge, prompting greater deflections and the need for trusses to limit that.
I still think these bridges are just an failure waiting to happen, especially with little or no apparent maintenance.
Mike McCann
MMC Engineering
In highway bridges, I would contend that the live to dead load ration is much less than a railroad bridge, prompting greater deflections and the need for trusses to limit that.
I still think these bridges are just an failure waiting to happen, especially with little or no apparent maintenance.
Mike McCann
MMC Engineering
bridgebuster
Active member
I've inspected 100's of bridges and have also seen a lot of failures waiting to happen. Some bridges have more internal redundancy than we're aware of, maybe some others have guardian angels.
About 20 or so years a consultant did a study of the Williamsburg Bridge cables - suspension bridge over the East River in NYC - because an inspection indicated broken wires. One conclusion was that the broken wires were still able to contribute to the strength of the cable. Who knows?
About 20 or so years a consultant did a study of the Williamsburg Bridge cables - suspension bridge over the East River in NYC - because an inspection indicated broken wires. One conclusion was that the broken wires were still able to contribute to the strength of the cable. Who knows?
Forensic74
Structural
Mike, that's a common misconception. The magnitude of applied load is not what matters, it's the resulting stress in the member that matters....combined with the number of cycles. Fundamentals of fatigue design. Rail bridges are far stiffer, for much higher loads, hence lower cycle stresses.
Just an update for anyone interested. There was an estimate given on the repair time of 6 months. That would put the completion of the project near the end of March 2012.
What you guys may not be familiar with is the time limitation that they are under. The bridge will need to be open by (approx.) April 7. There is a very large fireworks show that closes on of the other bridges across the Ohio River about the 14th of April. It's a big deal around here every year, and they won't be able to close the other bridge if the Sherman Minton isn't open.
So, the drama continues...
What you guys may not be familiar with is the time limitation that they are under. The bridge will need to be open by (approx.) April 7. There is a very large fireworks show that closes on of the other bridges across the Ohio River about the 14th of April. It's a big deal around here every year, and they won't be able to close the other bridge if the Sherman Minton isn't open.
So, the drama continues...
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ImminentCollapse
Structural
Definitely no welding. That was part of the original problem, welding of the old T1 steel in a tension tie. Not revited either, bolted.
woodman88
Structural
- Oct 23, 2009
- 1,020
bridgebuster,
Your comment "As an aside, 30 years ago I wrote to the Transit Authority about the deteriorated column rivets on a section of the elevated train I used to take. I never heard back from them; they never fixed anything; but the structure is still standing."
Reminds me of traveling with an older engineer (30 years ago) under a railroad bridge that steel plates were buckled. I asked him why the bridge was still in use. He said that the old railroad bridges were built for big locomotives and the new locomotives were much lighter that the old ones. They just added additional locomotives as needed for the train load.
Does anybody think/know if this is true? Or was he just playing on my (than and now) inexperience about railroads.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
Your comment "As an aside, 30 years ago I wrote to the Transit Authority about the deteriorated column rivets on a section of the elevated train I used to take. I never heard back from them; they never fixed anything; but the structure is still standing."
Reminds me of traveling with an older engineer (30 years ago) under a railroad bridge that steel plates were buckled. I asked him why the bridge was still in use. He said that the old railroad bridges were built for big locomotives and the new locomotives were much lighter that the old ones. They just added additional locomotives as needed for the train load.
Does anybody think/know if this is true? Or was he just playing on my (than and now) inexperience about railroads.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
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