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Cracks in Sherman Minton Bridge 1
- Thread starter swall
- Start date
I live in Louisville and am familiar with *some* of the particulars. I can tell you that the people who have the good information generally cannot discuss it publicly.
If you have any direct questions, I can see if I can turn up some answers.
If you have any direct questions, I can see if I can turn up some answers.
Why a big secret?? I would think they would want people to know, so they would press to get it fixed, replaced, etc.
Obama is coming to Cincinnati to fight for the jobs bill in front of the Brent Spence Bridge. If that ever were to close, it would be major headache to everyone.
Obama is coming to Cincinnati to fight for the jobs bill in front of the Brent Spence Bridge. If that ever were to close, it would be major headache to everyone.
The big secret is related to the blame game. I am sure that there will be politic-ing come election time as to which party allowed this to happen.
Additionally, I think they are trying to avoid people panicing since you know how well the media reports on technical topics (sarcasm).
Finally, you're talking about a city (Louisville) that has been trying to build another bridge for the better part of 40 years. Bridges are a hot button issue and this situation is like throwing gas (petrol) on a fire.
Additionally, I think they are trying to avoid people panicing since you know how well the media reports on technical topics (sarcasm).
Finally, you're talking about a city (Louisville) that has been trying to build another bridge for the better part of 40 years. Bridges are a hot button issue and this situation is like throwing gas (petrol) on a fire.
It is not an issue of "secret". Any type of investigation of this type requires careful analysis and study. That study involves hiring engineers to do the study and in any competent contractual relationship you have a duty to your client to provide them with your results only after they have been checked and verified.
Taking results public before they have been checked, peer reviewed, etc. is simply stupid. With this being a public bridge, I'm sure the results will eventually be made public but engineering takes time does it not?
Taking results public before they have been checked, peer reviewed, etc. is simply stupid. With this being a public bridge, I'm sure the results will eventually be made public but engineering takes time does it not?
msquared48
Structural
I-64 bridges seem to have been a problem in recent years...
Mike McCann
MMC Engineering
Mike McCann
MMC Engineering
Forensic74
Structural
Skip to 10:13 for anything structurally interesting.
Wow, weld fatigue, how surprising. I would have thought the 2nd street bridge would have been the one to have problems.
I took a grad course in steel fatigue, very frightening. Nobody realizes that cracks are common. There are so many bridges out there that were never designed per good fatigue provisions....and even the ones that are still have issues.
TXStructural
Structural
ACI is having its fall convention in Cincinnati next month. I just thought I should point that out.
They caught this before a serious mishap occurred, and as ASCE has been saying, it is time to spend money on our infrastructure.
They caught this before a serious mishap occurred, and as ASCE has been saying, it is time to spend money on our infrastructure.
TXStructural,
ASCE is correct in their call that we need to be focusing our energy on maintaining these infrastructure items since it is much cheaper to maintain them than to replace them. You are correct that this was caught before something very bad happened. I would have thought that inspectors would have been covered up with work for years after the I-35W bridge in Minneapolis, but I guess it's not that important to all governments.
ASCE is correct in their call that we need to be focusing our energy on maintaining these infrastructure items since it is much cheaper to maintain them than to replace them. You are correct that this was caught before something very bad happened. I would have thought that inspectors would have been covered up with work for years after the I-35W bridge in Minneapolis, but I guess it's not that important to all governments.
It is also that in the mind of the common people buildings and infrastructure is something that should last forever ... at no expenses, preferably, of course.
The long life of buildings and structures instils them such thought; and insecure as every form of life in earth, they usually love the sense of permanence imparted by long-standing structures, through which the species lives a dream of long-lasting life. I once read an article "Architecture vs. Death" along these lines.
So to descend to maintain such big structures is to insult their inmortality, for the gods must never be molested; and if they fall, they do in fight with other gods. There is a lot of primeval thought in the public perception of monumental construction, or overall shape of the city. Those reforming are seen as blasphemous transgressors of divine order, and rarely loved for that.
The long life of buildings and structures instils them such thought; and insecure as every form of life in earth, they usually love the sense of permanence imparted by long-standing structures, through which the species lives a dream of long-lasting life. I once read an article "Architecture vs. Death" along these lines.
So to descend to maintain such big structures is to insult their inmortality, for the gods must never be molested; and if they fall, they do in fight with other gods. There is a lot of primeval thought in the public perception of monumental construction, or overall shape of the city. Those reforming are seen as blasphemous transgressors of divine order, and rarely loved for that.
- Thread starter
- #11
So, it sounds like the initial (2-1/2") crack found was in a gusset. I wonder if it was found due to enhanced inspections since I-35 or if it was found by happenstance. Years ago, a crack in a CTA bridge in Chicago was found just because a structural engineer happened to see it on his morning commute.
ishvaaag, the only thing you left out were the demi-gods at the state DOT's. Their reason for existance is to assure that any repairs to the monumen . . . bridges must be accompanied by many worshipful committee meetings consisting of many demi-god . . . DOT engineers. Then they must insure that there is at least $200,000 spent on this sacri . . . repair. "And the state of [insert your state here] just doesn't have that money available during these hard times"
It's just a fatigue crack. Big deal. Close the bridge -- no more 'Live Load'; jack and crib up the affected area -- no more 'Dead Load'. Air-arc out the crack, MT to verify removal, weld up area, MT to verify good weld. Remove cribbing & reopen the bridge. Inspect, using MT, annually for cracking in the similar areas of the bridge. After one or 2 more occurances, develope a 'fix' that will strengthen those sections without making them unduly stiff. Install the 'fix' to all similar areas.
It's just a fatigue crack. Big deal. Close the bridge -- no more 'Live Load'; jack and crib up the affected area -- no more 'Dead Load'. Air-arc out the crack, MT to verify removal, weld up area, MT to verify good weld. Remove cribbing & reopen the bridge. Inspect, using MT, annually for cracking in the similar areas of the bridge. After one or 2 more occurances, develope a 'fix' that will strengthen those sections without making them unduly stiff. Install the 'fix' to all similar areas.
Duwe6,
I agree, probably fatigue cracking. The problem is that they found, say 6 (made up number) cracks, but they had only completed, say 20% (made up number) of the bridge inspection.
Problem 1:
They are attempting to determine the extent of the damage. This has not been made available as of yet.
Problem 2:
The bridge was made from T-1 steel (NOT T1 tool steel) which is similar to A514. The use of this material in bridges was pretty innovative in the 60's. The gouge and weld method would work well if it were "normal" structural steel, but there are those who question the ability to make the repair and maintain the original strength.
Problem 3:
MT for the annual inspection would not detect the cracks that might form under the surface of the weld. RT would be my recommendation.
I do enjoy the discussion about this issue, since it is relevant to where I live.
I agree, probably fatigue cracking. The problem is that they found, say 6 (made up number) cracks, but they had only completed, say 20% (made up number) of the bridge inspection.
Problem 1:
They are attempting to determine the extent of the damage. This has not been made available as of yet.
Problem 2:
The bridge was made from T-1 steel (NOT T1 tool steel) which is similar to A514. The use of this material in bridges was pretty innovative in the 60's. The gouge and weld method would work well if it were "normal" structural steel, but there are those who question the ability to make the repair and maintain the original strength.
Problem 3:
MT for the annual inspection would not detect the cracks that might form under the surface of the weld. RT would be my recommendation.
I do enjoy the discussion about this issue, since it is relevant to where I live.
Gotta object to subsurface cracking -- doesn't seem to have a 'mechanism' to cause it, other than stress-concentrations due to major weld defects. Flexural cracking emanates from the surface. Thus a [relatively] fast MT using dry-powder will find bridge cracks. And the earlier they are found, the smaller and easier to fix they are.
Sometimes, I have found structural cracking early enough that the grinding for crack removal did not go below T-minimum for that area. We just blended out the excavation, buffed it to remove grinding scratches, put a little paint on it, and went home. DOT bridge engineers want to make everything a MAJOR problem. Most things aren't.
If it's rusting, needle-scale it and brush some zinc-rich primer on it. That approach would have saved the I-35 bridge. Minnesota DOT has records of the thickness loss due to rust of the gusset [side] plate that failed. Yes, it was too thin when it was installed, but watching it rust away, and doing nothing to stop it, was the proximate cause of that catastrophe.
Sometimes, I have found structural cracking early enough that the grinding for crack removal did not go below T-minimum for that area. We just blended out the excavation, buffed it to remove grinding scratches, put a little paint on it, and went home. DOT bridge engineers want to make everything a MAJOR problem. Most things aren't.
If it's rusting, needle-scale it and brush some zinc-rich primer on it. That approach would have saved the I-35 bridge. Minnesota DOT has records of the thickness loss due to rust of the gusset [side] plate that failed. Yes, it was too thin when it was installed, but watching it rust away, and doing nothing to stop it, was the proximate cause of that catastrophe.
- Thread starter
- #15
Fegenbush--that is interesting about the construction material being T-1. And it concerns me, since the repairs will most likely start at the outset of winter, which makes me think the pre-heat procedures more difficult to carry out at low ambient temperatures.
Forensic74
Structural
Wow, Duwe6, what a varied post. So you're one of those guys who paints DOT's as over conservative until the bridge comes down egh?
Second that wow. Most of the DOT engineers I know really want to keep bridges safe with a minimum of disruption to the public. Disruption to the public makes their lives miserable. It's hard to be in the position of having to decide whether a defect warrants bridge closure. Some erring on the conservative side seems a good idea when the bridge is non-redundant.
Do we really know where the cracks are? Out of plane bending at the floorbeam to tie connection can be an tough issue with this type of bridge. Simple welding of the crack might not be effective for this.
Do we really know where the cracks are? Out of plane bending at the floorbeam to tie connection can be an tough issue with this type of bridge. Simple welding of the crack might not be effective for this.
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- #19
bridgebuster
Active member
"ACI is having its fall convention in Cincinnati next month" - which will give them the opportunity to promote concrete bridges
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