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Some pretty serious looking issues here.
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Hernando de Soto Bridge (I-40 Mephis) 19
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LionelHutz
Electrical
Except you can't expect the bolts on the ends of the damaged tie are not holding anything.
Retiredat46
Member
They probably felt it's best to do the least invasive thing rather than risk anything that might make the situation worse. I can see a lot of justification for that approach.
A pic from 2016 .. Its been there for awhile.
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Craig Neth
Computer
TDOT put up a photo gallery on Facebook with some more pictures:
This one is interesting, it shows the hole they made to pass the 'inner' mending plate through:
This one is interesting, it shows the hole they made to pass the 'inner' mending plate through:
This one shows exactly how the mending plate is offset from original plates. The crack is to the left, just off the edge of the image. Not clear that you have to log in to see the photos
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JohnRBaker
Mechanical
My first thoughts were the same ;-)
John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
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John R. Baker, P.E. (ret)
EX-'Product Evangelist'
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1- The mending plates prevent access to the gusset/splice plate bolts so the repairs cannot involve any work to that area.
2- The long unsupported length of the mending plates should only be adequate to resist tension forces.
3- After the repair is complete, the hundreds of holes drilled in the member for connection of the mending plates will remain, or be welded shut, I think. I wonder how this affects the strength of the box member.
Brad Waybright
The more you know, the more you know you don't know.
2- The long unsupported length of the mending plates should only be adequate to resist tension forces.
3- After the repair is complete, the hundreds of holes drilled in the member for connection of the mending plates will remain, or be welded shut, I think. I wonder how this affects the strength of the box member.
Brad Waybright
The more you know, the more you know you don't know.
Retiredat46
Member
The update from May 27 said something about "...removing a smaller section of the fractured piece...". Why do they have to remove it, and how would they remove it with the repair plates in place?
I'm having a hard time imagining how they can make further repairs without an extended shutdown and without removing the repair plates there now.
I'm having a hard time imagining how they can make further repairs without an extended shutdown and without removing the repair plates there now.
LionelHutz
Electrical
It's not making a lot of sense right now. The don't have much access to the crack or the splice plates to work on it. It doesn't make sense to be leaving all those bolt holes after the repair and cutting that big hole in the deck support beam that has to be repaired later doesn't seem to be a great idea either. It will be interesting to see how this proceeds.
I think that in order to have a complete metallurgical examination , then they would need to remove a piece and send it to a metallurgical lab, while protecting the fracture surface from damage during the removal process. After the surface is examined, the elemental analysis may offer a clue as to whether the failure was due to stress or due to a foundry error which may have introduced "poisons" into the steel , out of spec. Of course one relies on the lab to be perfectly honest in is presentation of results, but I am familiar with how some labs may shade their presentation of results to avoid implying liability onto a good client. One needs to read between the lines sometimes, or at least ask the correct questions.
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
Retiredat46
Member
How will several years of exposure and corrosion affect the metallurgical examination?
...in particular if the steel is not weldable... need coupons for that. Testing would have been the first thing that I would have looked at...
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Craig Neth
Computer
Today's update - they are doing Ultrasonic testing of all the other similar welds while they wait for the repair parts:
More here:
More here:
A wide spread NDE effort is an appropriate response to the current situation.
<Opinion>If UT was not part of the original construction QC process, indications will be found. Interpretation of significance of indications which might have existed from the original construction can be challenging. </Opinion>
<Opinion>If UT was not part of the original construction QC process, indications will be found. Interpretation of significance of indications which might have existed from the original construction can be challenging. </Opinion>
From ENR today (06/03/2021): Link
So I am assuming the PT is longitudinal (and temporary) over the 150 foot to apply preload, so that the 150ft long permanent steel plates can be installed, with 3,000 bolts.
8 each x 3" thick (I guess they mean dia?) rods - lets assume they are 3" dia @ 150 ksi PT bars, with 6.85 in[sup]2[/sup] of net area each rod x 8 rods, so at to achieve 3,000,000 lbf that equates to a prestress of 55 ksi - so about 36% of MUTS, seems low but ballpark.
Not sure what the 20,000 ton refers!
So I am assuming the PT is longitudinal (and temporary) over the 150 foot to apply preload, so that the 150ft long permanent steel plates can be installed, with 3,000 bolts.
8 each x 3" thick (I guess they mean dia?) rods - lets assume they are 3" dia @ 150 ksi PT bars, with 6.85 in[sup]2[/sup] of net area each rod x 8 rods, so at to achieve 3,000,000 lbf that equates to a prestress of 55 ksi - so about 36% of MUTS, seems low but ballpark.
Not sure what the 20,000 ton refers!
Craig Neth
Computer
Here is TDOT's press release of what is to be done, maybe fills in some blanks in the ENR report:
LINK
LINK
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