Hernando de Soto Bridge (I-40 Mephis)
Hernando de Soto Bridge (I-40 Mephis)
(OP)
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Hernando de Soto Bridge (I-40 Mephis)
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Hernando de Soto Bridge (I-40 Mephis)Hernando de Soto Bridge (I-40 Mephis)(OP)
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RE: Hernando de Soto Bridge (I-40 Mephis)
On I-40 no less.
Statements above are the result of works performed solely by my AI providers.
I take no responsibility for any damages or injuries of any kind that may result.
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.eng-tips.com/viewthread.cfm?qid=483070
John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Hernando de Soto Bridge (I-40 Mephis)
Statements above are the result of works performed solely by my AI providers.
I take no responsibility for any damages or injuries of any kind that may result.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Is that what a progressive fatigue fracture looks like on a tension member?
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Statements above are the result of works performed solely by my AI providers.
I take no responsibility for any damages or injuries of any kind that may result.
RE: Hernando de Soto Bridge (I-40 Mephis)
There are other longitudinal members than the one that fractured. The structure along the sides seems to be intended to distribute any uneven loads to multiple cables and to stiffen the overall bridge deck to prevent unwanted deformations. The bottom chord is not the only one resisting the thrust load from the arch.
RE: Hernando de Soto Bridge (I-40 Mephis)
Do you have some drawings of the bridge? By the limited photos we have seen, I fail to understand what other tie members you mean.
RE: Hernando de Soto Bridge (I-40 Mephis)
It seems that the 'beam' in question is a strut in the lateral restraint system.
I don't think that area is tension I believe it would be compression from hogging about the supporting tie.Did the tie fracture? I didn't hear or see about this detail.
From what I can see the truss failed at a spot that is likely under compression due to the hogging close to the tie support. Load was likely redistributed to other sections of the truss and more tension on the deck.
Cause of failure likely corrosion/fatigue but certainly outside my area of expertise.
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
"The US Coast Guard also put a waterway restriction in place on the river below, and there were at least 44 vessels with more than 700 barges waiting to travel the river in either direction Thursday morning, according to Lt. Mark Pipkin of Coast Guard Sector Lower Mississippi River."
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Bigger image: Link
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.usatoday.com/story/news/nation/2021/05...
Maybe that helps people here hypothesize about the failure mechanism.
RE: Hernando de Soto Bridge (I-40 Mephis)
That is the arch tie, and is also a chord of the lateral truss. The force is not there anymore, so the gravity load is being carried by the arch/truss, I suspect mostly by bending of the two span truss, but still partially by overall compression of the arch. As noted before, this structure has exhibited excellent redundancy, as total separation of one vital member has resulted in only minor movement. But it needs at least temporary restoration of the tie before it can be placed back into service.
RE: Hernando de Soto Bridge (I-40 Mephis)
I agree with all you've said. And yes, the redundancy of this structure clearly saved lives this week (or whenever the fracture actually occurred).
I was referring that when the tie fractured and the arch thrust was no longer contained by that member, something had to have taken its place. Maybe the foundations simply 'handled' it. Maybe it went through the deck / lateral bracing system. I do agree there is now no forces in that tie. I get the feeling we're saying the same thing just differently.
My question for the board is HOW do you restore an arch tie? Seems like you'd need to post tension a tie to try and reclaim some of that dead load thrust back into the tie.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
How did they tighten those bolts. Someone had to hold the nut from the inside. I wonder if there is a hand hole anywhere near.
Could there be some torsion in the main tie beam. The main transverse floor beam is suspended by a single rod and pin. When a truck is on the bridge, the floor beam deflects down, which causes the end to rotate. This rotation imparts a torsion into the tie beam.
RE: Hernando de Soto Bridge (I-40 Mephis)
Although, I'm guessing it wasn't designed that way. I assume the arch action was considered and the overall behavior of the arch truss was that of a single compression arch member with these tension ties at the deck level resisting the thrust. I'd very curious to know how that was analyzed at the time of design 50 years ago.
RE: Hernando de Soto Bridge (I-40 Mephis)
I'd be curious to know how a bridge like this was analyzed back in the day too. I'd also settle for a set of As-Builts that are scanned in a little crisper than the one sheet the DOT released.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
It is a two span tied arch bridge, and the trusses forming the arch are integrated at the center support. However, the thrust at the end where the tie is broken is still there. Continuity in the trusses means that the thrust is less than would be the case if these were two simple spans, and that is part of the fortunate redundancy here.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.tntech.edu/engineering/pdf/cee/Alexand...
STRUCTURAL HEALTH MONITORING OF THE HERNANDO DESOTO BRIDGE
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
(Though I won't bet all my credibility on it as I already feel slightly abashed by not recognising earlier in this thread that this was an tie for the arch.)
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.commercialappeal.com/story/news/2021/0...
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.youtube.com/watch?v=MTb7UQrHofQ
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
This is a serious engineering forum.
That was hilarious. [bigsmile]
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.commercialappeal.com/story/news/2021/0...
Update: more details from TDOT:
https://www.tn.gov/tdot/news/2021/5/14/update-on-t...
RE: Hernando de Soto Bridge (I-40 Mephis)
And it looks like the tension ties had strain gages on them. Assuming they were still collecting data, it's hard to imagine that this crack propagation was not immediately noticed.
RE: Hernando de Soto Bridge (I-40 Mephis)
Link
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Hernando de Soto Bridge (I-40 Mephis)
More photos in here.
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
http://julianh72.blogspot.com
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
While this beam acts as an arch tie, it was installed after the arches were complete. Here is a picture from the March_1972_issue_of_Memphis_Press, showing the arch prior to the arch sections being joined. Note that construction support towers were used at this stage of the construction to balance the structure.
RE: Hernando de Soto Bridge (I-40 Mephis)
I hope he got out OK...
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
The original equipment QC documents should be accessed and reviewed to confirm that initial material specs and fabrication details were not compromised. The metallurgical analysis might give a clue to possible fabrication issues- there have been other material issues with metals supplied from overseas ( aka PRC) steel mills with false shipping documents. It could also open up a host of other issues, disqualifying other sections.
It also happens that some truckdrivers know how to bypass the weigh scales and there may have been higher than design axle loads ; it is not clear how to review past load history.Tennessee does have some industries that ship XX heavy loads.
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
I was involved with a major project in Winnipeg several years back where the 8" and 10" pipes failed at 1/10 their rated capatity. The mill test certs were identical with the exception of the test number... also from your overseas location.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
I assume this is the same location, so it appears that the cracking started at the bottom, outer corner. (the current photos show that the bottom plate is not yet fractured).
I can't believe they would leave a crack at least 80% of the web height, without even trying to drill out the crack tip to prevent it from progressing.
RE: Hernando de Soto Bridge (I-40 Mephis)
Bridge inspector also fired this morning.
https://www.youtube.com/watch?v=qmbeDO53TK8
RE: Hernando de Soto Bridge (I-40 Mephis)
During that time period, some CS components fabricated in Spain had metallurgical issues, so it might be useful to review the QC documents , at least regarding the source of the steel.
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Statements above are the result of works performed solely by my AI providers.
I take no responsibility for any damages or injuries of any kind that may result.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Statements above are the result of works performed solely by my AI providers.
I take no responsibility for any damages or injuries of any kind that may result.
RE: Hernando de Soto Bridge (I-40 Mephis)
Ie there are lorry's full always going in one direction and then empty going in the other direction?
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Also in the new image is the bolted cover for the access hole. They likely has some very small workers on the crew to use an access hole in this location. I would think stress would be higher at the access hole, then the crack location.
RE: Hernando de Soto Bridge (I-40 Mephis)
That pole sparweb pointed to isn't structural, it's a drain pipe from the roadway, but has been hit by something.
Were the vertical cross spars added later?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
And that inspection drone video is hard to watch. I know we're all looking for the crack while the inspector is looking at the hangar... but wow. Its such a large crack even then. How do you miss that?
RE: Hernando de Soto Bridge (I-40 Mephis)
As said we don't know if they looked at it ever again on a big screen or just that little 9 inch hand held thing in the bright day light.
This time the crack was visible to the naked eye looking down from the deck so a lot more visible.
But there do appear to be more visible cracks in the tie so I wonder if they are now doing a rather more thorough inspection while the bridge is closed...
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Hernando de Soto Bridge (I-40 Mephis)
Statements above are the result of works performed solely by my AI providers.
I take no responsibility for any damages or injuries of any kind that may result.
RE: Hernando de Soto Bridge (I-40 Mephis)
Possibly the "gorilla" problem? While fixated on one topic, the brain ignores others. But I would have thought an inspector would be proactively looking at every detail, certainly I often find faults while looking for something unrelated. I would be at least tempted to fly the drone in for a closer look, if not break out the climbing gear. I guess their employer felt the same.
RE: Hernando de Soto Bridge (I-40 Mephis)
Yeah.
To be fair, according to ARDOT, that drone video came from the contractor (Michael Baker) who was only hired to inspect the arch and cables, and that snippet was apparently part of a 5 hour long video that included a similar video of every other cable. I certainly wouldn't expect the operator staring at a tiny screen in broad daylight to find features like that, I assume it's all meant to be reviewed later.
I'm not at all familiar with how these inspections work, but perhaps the drone video is 'backup material' used when you have some question about a more primary type of inspection? Drones being a 'new technology', I could well imagine it is not considered a primary source for such processes.
ARDOT themselves inspected the bridge 6 and 18 months later, supposedly focusing only on these fracture critical elements, and didn't see it. So two different teams, on three separate occasions, all missed it. Lots of 'opportunity' for process improvement, it would seem.
This is all in the press conference video:
https://www.youtube.com/watch?v=rAtuWNDttvk
RE: Hernando de Soto Bridge (I-40 Mephis)
If that drone is a team that specifically looking at the hangar / arch system. Sure I can see not getting that. But the fracture critical member of the structure would have been looked at closely. My experience in working with bridge inspectors doesn't cover a structure like this but I would assume a snooper truck being used to check under the bridge and get the inspector about arms length away from this.
I do agree that there is a lot of room for improvement here. And knowing the inspector was let go, its likely a person that didn't follow the inspection process. Its just a scary thought to think this crack was present for over 2yrs.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Replace the whole beam or just strap patch it
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
- Stabilize the crack
- Design permanent repair
- Install jig to allow installation of replacement beam
- Install replacement Beam
If more cracks are found - repeat as many time as necessary.Reopen for traffic
Design of the permanent repair should take into account understanding the cause of the crack, to prevent a repeat.
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.tn.gov/tdot/projects/region-4/i-40-her...
Sounds like the patch is pretty substantial:
RE: Hernando de Soto Bridge (I-40 Mephis)
Snooper truck definitely sounds like a plausible source of some of those dents and dings...
RE: Hernando de Soto Bridge (I-40 Mephis)
Link
RE: Hernando de Soto Bridge (I-40 Mephis)
The source is more likely the weld that formed the box. By the 1970's, they should have been smart enough to not have stitch weld connecting members on a cyclically loaded structure. There is a close up photo above, it looks like the thinner top plate runs over the vertical plate about half way, and it's connected by a fillet weld. That shouldn't be a too bad fatigue category.
RE: Hernando de Soto Bridge (I-40 Mephis)
No body seems to be curious about why it broke, it would appear.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
Traffic is always braking going in one direction and accelerating going in the other.
I know the King George V bridge in Glasgow Scotland has problems due to this effect.
RE: Hernando de Soto Bridge (I-40 Mephis)
The original Severn bridge had that issue when the queue for the toll booth backed onto the bridge on a regular basis on one side. They worked out that in strong winds the thing could fail. They partly solved it by making the tolls one way, hence the issue that you paid to get into Wales, but it was free to escape. tolls all gone now.
But uneven loading probably wasn't thought about in 1970...
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Hernando de Soto Bridge (I-40 Mephis)
Severn this bridge and KGV all built in the same period.
RE: Hernando de Soto Bridge (I-40 Mephis)
The Patroon Island Bridge (Interstate 90 over the Hudson River in NY) opened in 1968. It has interchange ramps just west of the main span. It's also downhill approaching the ramps.
Cracking in the floor beams was attributed to trucks braking for the westbound offramp. IIRC, braking forces were twisting them.
My glass has a v/c ratio of 0.5
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
Anyone an idea of what this could be?
It seem too regular to be the result of the fracture.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Hernando de Soto Bridge (I-40 Mephis)
My thought is that since the tie is also the chord member for the lateral system, the design didn't account for lateral forces in fatigue stresses. AASHTO Bridge Design Spec really only evaluates truck loads in fatigue. But with this being a long span and susceptible to large wind loads - there is a stress range there as well. That's where my guess is without having ANY knowledge about bridge design standards in the 60s.
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
dik - definitely could have stemmed from the box weld. I'm still thinking fatigue but we can both be right on this.
RE: Hernando de Soto Bridge (I-40 Mephis)
From the press conference, it appeared that the initial thoughts for the repair would be creating a collar and using tie bolts to pull the beam back together then welding the tie beam.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Also, in that bridge bearing study that someone linked to, they were seeing unexpected results during thermal expansion. They expected a build up of axial compression in the struts but weren't seeing it on one side of the bridge. They guessed it could be due to one of the piers tilting, but perhaps it had to do with this strut failing and redistributing the load into other members (that didn't have strain gauges).
RE: Hernando de Soto Bridge (I-40 Mephis)
Sorry I screwed up my bridge names It was the Kingston bridge that they have issues with. The M8 motorway goes over it everything blocks up at Anderson
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Link
The bridge was designed in the period prior to the increase in traffic weight. I also seem to recall that the bridge originally had fewer lanes. Is this another example of ever-creeping bridge use and load requirements leading to issues? Similar to some of the problems behind the Minneapolis I-35W Bridge Collapse (but the I-35W bridge also had an overlooked design flaw).
RE: Hernando de Soto Bridge (I-40 Mephis)
1. Are those strips backing strips for longitudinal welds?
2. Did those strips break or did they end there?
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Probably
2. Did those strips break or did they end there?
My opinion is that the weld crack propagated into the backer bar. The pieces of backer bar on the left are visible. The backer bar on the right id hidden by the camera position.
While welds are often made with backer bars, the design needs to consider these welds - just like all fillet welds have "crack like features" in the root of the weld. This sometimes drives a requirement to stress relieve beams when manufactured. If the situation can not tolerate weld root cracks, the backside gouging and welding is necessary, which probably can not be done in this case as the box is too small.
If the base metal is hot short it could also promote weld cracking. Hot short is possible even with a mill test report being to spec. Root cracks can also result from a welder having a bad day defect, and many other things.
WELD CRACKS, DEFINITIONS, CAUSES, PREVENTION & REPAIR
Members with a high proportion of alternating stress with respect to continuous stress are particularly prone to fatigue cracking. It is relatively easy to calculate the tension in the tie beams. It is significantly harder to quantify the variable load for fatigue calculations. Additionally in 1966 (a guess, based on the bridge opening in 1973) when the bridge was designed fatigue theory was not as well understood as it is now.
Here is a link to the Daily Update May 22, 2021.
RE: Hernando de Soto Bridge (I-40 Mephis)
From today's Daily update: https://www.tn.gov/content/dam/tn/tdot/region-4/i-...
Wonder how those bolts were installed, by someone crawling around inside?
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Through bolts on a box girder splice would be a poor joint design. The squeezing forces would wind up stressing the box beam corners - which already are cracked.
RE: Hernando de Soto Bridge (I-40 Mephis)
I'm impressed that guy with the mag-drill could punch that many holes that line-up well enough to match all those plate holes.
Hey! How did they get the bridge beam re-aligned so holes could be accurately drilled? (chicken and the egg issue)
Can anyone see the crack? I can't see it in the work pictures.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
Something like this:
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
https://twitter.com/TDOTCommish/status/13965904299...
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
What are they going to do? Cut out the old box beam and field weld in a new section?
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
I counted at least the same number of people leaning over the bridge rail as there are people doing something below.
Spot the ventilation tube going into the void space. Some pooor small and thin bastard is in there holding a spanner and fitting nuts to studs...
why not just cut out the damaged bit and weld in a new box section??
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.tn.gov/content/dam/tn/tdot/region-4/i-...
Pictures released today are very low contrast, but looks like the inside 'mending plate' is much smaller in height. Seems like you can just make out the crack section near the chain fall on right hand side of picture:
RE: Hernando de Soto Bridge (I-40 Mephis)
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.tn.gov/content/dam/tn/tdot/region-4/i-...
No mention of any damage to the inboard plate. I would think it would have to be deformed and require some kind of repair.
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
<Speculation> the repair will require replacing the beam - drilled per the original dimensions. To install, the existing beam will be removed, and the load transferred to some sort of jig. </Speculation>
No small design problem.
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.tn.gov/content/dam/tn/tdot/region-4/i-...
RE: Hernando de Soto Bridge (I-40 Mephis)
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
Extending the repair plates to the good tie beam didn't add anything. If the bolted joint at the end of the failed beam was good enough for the original build, it should be good enough for the repair. The spacer plates could have been much thinner since the nuts and bolts don't have to be cleared. It probably would have cut the added dead weight by more than half.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
"The fix will be as good as new."
"New wasn't that good. Can we try for better than new?"
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.mail.com/news/us/10803824-kayakers-pho...
Statements above are the result of works performed solely by my AI providers.
I take no responsibility for any damages or injuries of any kind that may result.
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.facebook.com/media/set/?vanity=myTDOT1...
This one is interesting, it shows the hole they made to pass the 'inner' mending plate through:
RE: Hernando de Soto Bridge (I-40 Mephis)
Some of us don't do facebook.
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Hernando de Soto Bridge (I-40 Mephis)
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.
RE: Hernando de Soto Bridge (I-40 Mephis)
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.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
...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...
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
More here:
https://www.tn.gov/content/dam/tn/tdot/region-4/i-...
RE: Hernando de Soto Bridge (I-40 Mephis)
<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>
RE: Hernando de Soto Bridge (I-40 Mephis)
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 in2 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!
RE: Hernando de Soto Bridge (I-40 Mephis)
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
LINK
RE: Hernando de Soto Bridge (I-40 Mephis)
20,000 lb makes more sense compared to 20,000 ton. Still, very 'beefy' PT brackets!!
RE: Hernando de Soto Bridge (I-40 Mephis)
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.aisc.org/globalassets/nsba/conference-...
https://docs.lib.purdue.edu/cgi/viewcontent.cgi?ar...
noted in FHWA Technical Advisory T5140.4 (1), “…the tied arch structure…is one of the most nonredundant structures, relying entirely on the capability of two tie girders to accommodate the total thrust imposed by the arch ribs.”
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.youtube.com/watch?v=9QprIzj45n4
Link
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
So it looks like they are adding extra steel plates in between all the existing bolted connections and then adding a further plate to bridge around the bolted sections.
Nothing about removing the damaged section or even sealing it.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
Some slight mods will probably be required to reinstall them.
RE: Hernando de Soto Bridge (I-40 Mephis)
Do the repair plates compensate for the weakened top/bottom sides of the original beam? I can see where the top outboard joint is rusting, near the break.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
They have me wondering about all of that too. I'd like to see the repair plan.
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
So a couple of those and some sort of yoke for all 8 PT rods at the same time?
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Based upon info of 4 Jun 21 posts above, the 8 x 3" dia PT bars shall provide 3,000,000 lbf of preload, so that is only 365 kips per PT bar (about 54 ksi service stress for an ultimate tensile capacity of 150 ksi). So a 200 ton capacity ram would 'theoretically' work.
Elongation over 150 feet will be approx 3.5"
For scale, the following photo is a 200-ton center hole ram over vertical rock anchors (PT rods of 2-1/4" diameter). Stroke is 8" and weights approx 320 lb. 4" dia center hole.
RE: Hernando de Soto Bridge (I-40 Mephis)
Thanks to Epoxybot for the original image.
There are other types but this illustrates the basic principle.
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
These are often used on slew ring bolts, and other similar bolted connections where it is desirable to avoid twisting the bolt when applying tension.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
From Link:
Here's the latest on materials/fabrication:
- 3,000 bolts for the post-tensioning (PT) arrived Wednesday. Crews are replacing old with the new one by one.
- The PT weldments/anchors, fabricated by G&G Steel out of Russellville, AL, will be delivered this weekend.
- The PT rods are being fabricated. The first shipment is expected Monday, 6/14.
- Steel strengthening plates and splice plates for the permanent repair are also being fabricated. No timeline yet for delivery.
Construction work expected through the weekend:RE: Hernando de Soto Bridge (I-40 Mephis)
More details: Here
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.youtube.com/watch?v=e8PodEM4Y8g
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Link
RE: Hernando de Soto Bridge (I-40 Mephis)
Here's a slightly bigger view of the fracture area picture, scraped from the Word doc. Does the fellow inside have to run the plasma cutter???
Link
RE: Hernando de Soto Bridge (I-40 Mephis)
Based on the photos posted by IRstuff above on that weld seam split, and the photos of the rest of the crack, I'm thinking the tie never had its load significantly relieved. Methinks <15% was redistributed.
RE: Hernando de Soto Bridge (I-40 Mephis)
Could an issue with either the design or maintenance of that support led to the excess tension on the tie beam?
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
a pdf on the retrofit which shows some of the post-retrofit bearings:
https://cdn.trccompanies.com/legacy/images/121-Schamber.pdf
The original design would have had some form of rockers or sliders to accommodate the length variation. It would be interesting to see if the new bearings had a higher friction load as compared to the prior arrangement but I have not found details on the prior bearings to compare to.
RE: Hernando de Soto Bridge (I-40 Mephis)
So then is the 3000kip post-tension load on the rods meant to take just half the load off the damaged member? I suppose that is a possibility.
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
And some images:
Source
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
3 days ago
https://www.facebook.com/watch/?v=1732047853668574
RE: Hernando de Soto Bridge (I-40 Mephis)
Bigger picture of some of the interior 'mending plates':
Link
RE: Hernando de Soto Bridge (I-40 Mephis)
I have no doubt that the repair work will ensure that that beam never breaks again.
BUT
Did I miss the reason why it broke?
Why is this important?
What about the three remaining identical tie beams?
If we don't know why the first one broke..........
Sorry if I have missed the answer.
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
Source
RE: Hernando de Soto Bridge (I-40 Mephis)
Seems like the ND testing found quite a few failed welds that needed repairs.
TDOT also published a picture of the 'phase 2' repairs with a fresh coat of paint:
Source
RE: Hernando de Soto Bridge (I-40 Mephis)
"Plenty of blame to go around following Mississippi River Bridge closure". Link
According to him, the fault was not visible from the angle of the snooper truck because it could not go far enough outboard...
Definitely feels like a 'process' failure. I hope they are fixing the process rather than just making this fellow a scapegoat.
RE: Hernando de Soto Bridge (I-40 Mephis)
"According to him, the fault was not visible from the angle of the snooper truck because it could not go far enough outboard..."
The snooper bucket launches from the bridge deck and then articulates outboard on its way for inspectors to access structure under the deck. The bucket is absolutely outboard of the structure far enough to see the crack, even if there is some distance bridge length-wise.
The crack is very visible viewed from above, and from anywhere outboard. Not visible from directly below or inboard.
Heck, this crack was visible in photos taken by kayakers 100' below.
Something else must explain why it was missed... Repeatedly.
RE: Hernando de Soto Bridge (I-40 Mephis)
All snooper trucks may not be equal.
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
Two comments:
1. I had wondered why the beam had failed and if the failure was isolated to this member or could be more widespread.
I am glad to see that the consulting engineers had the same thought and tested and identified other problems.
2. Does this now look like an error in the original design? Are there any bridges of similar design and construction that should be rigorously inspected?
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
from https://www.bridgeriggers.com/on-road-equipment/a-...
RE: Hernando de Soto Bridge (I-40 Mephis)
Also, this:
Since it sounds like the procedure always had the same start points and number of stops, it seems like you could potentially end up with consistent 'blind spots'.
RE: Hernando de Soto Bridge (I-40 Mephis)
Sounds like possible inadequate training. Maybe a failure to properly use the axle locks.
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
And
RE: Hernando de Soto Bridge (I-40 Mephis)
However, looking at the pictures of the Aspen A-75, I can see why they might have to make stops pretty close together and do a backtrack/skip procedure to inspect all of the tie beam. If you divided the beam into sections A,B,C,D,E,F...., you'd park the truck at B to inspect A and C, then move to C to inspect B and D, then move to F to inspect E and G, etc. That's a bit confusing and time consuming, but doable. A good inspector would figure it out, and write a procedure to get the job done right.
RE: Hernando de Soto Bridge (I-40 Mephis)
Just kidding, sort of.
On a serious level, did anyone figure out what was going on on that beam to cause the fracture years ago, and then cause the fracture to deflect that much (a lot) and yet have the remaining part of the beam to NOT fail??
I've seen a lot of fractured steel (in machinery, mostly), but if loads are enough to break it half way through, you would think the remaining bit would fail soon after. Not be still hangin in there years later.
Edit: And man did they go big with the sistering plates!! That is a lot of steel added. CYA is strong here!!
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
RE: Hernando de Soto Bridge (I-40 Mephis)
Source
RE: Hernando de Soto Bridge (I-40 Mephis)
Not sure if that is 53 tones each or 53 tons total, but we are looking at hundreds of tons of added weight.If that is the weight of each plate plus the weight of the bolts they may be adding almost 1.7 thousand tons.
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
Link
The posted a video on twitter of a truck driving across, apparently they are doing some load testing using the existing sensor network.
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.tn.gov/content/dam/tn/tdot/region-4/i-...
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
I saw it in one of the briefing documents here-Link
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
Steel weighs about 40 pounds for a 1 foot square an inch thick.
If we assume each steel plate is 4 feet high and one inch thick, then each plate weighs 24,000 pounds--12 tons.
If there is a plate on either side of a beam, and there are two beams, it is looking like the 53 tons is the total for all four pieces.
I will guess the nuts and bolts will add another 3 tons.
spsalso
RE: Hernando de Soto Bridge (I-40 Mephis)
June 25, 2021
"108,000 pounds of structural steel plating added to the tie girder"
So ya got 54 tons. Not "hundreds of tons". Not "1.7 thousand tons".
In reading those rather neat press releases, it looks like they might also have been removing some steel.
spsalso
RE: Hernando de Soto Bridge (I-40 Mephis)
https://www.enr.com/articles/52319-as-fracture-que...
RE: Hernando de Soto Bridge (I-40 Mephis)
"Lesson learned from the FIU pedestrian bridge collapse."
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
With respect to drones being used to inspect damage, the first time I saw this being mentioned to any degree was in 2014 after the 6.0 magnitude earthquake that hit Napa, California. The news spent a fair amount of time talking about and showing videos from drones that were used to inspect the damage to buildings, particularly masonry buildings, before building inspectors were allowed to physically enter these same buildings. At about that same time there were stories about how power companies were also starting to use drones to inspect high-tension power lines, a job that used to done my people suspended for helicopters.
Anyway, it was an interesting comment, I just wish they would have included more details about how the drones were used and what lessons they learned about their use and practicality.
John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Hernando de Soto Bridge (I-40 Mephis)
That is a very old weight limit, most semis are heavier than that today.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
Update
Link
RE: Hernando de Soto Bridge (I-40 Mephis)
"The fired inspector had missed the crack in 2016, 2017, 2019 and 2020. Another inspector who had missed the crack in 2018 had never inspected that portion of the bridge before, and the department said he has been “verbally counselled” and will receive additional training.
The department’s report said the agency’s failure to adequately respond to employees concerned with the fired inspector’s job performance “perpetuated a culture where team members did not feel they had the authority or support to question a lead inspector’s procedures or thoroughness.”"
RE: Hernando de Soto Bridge (I-40 Mephis)
Failure to deliver honest services?
I ain't impressed.
spsalso
RE: Hernando de Soto Bridge (I-40 Mephis)
Actually, if the report is to be accepted as to the numerous management shortcomings and subsequent changes to the bridge inspection program, the inspector may have a case for wrongful dismissal. Possibly not a strong case, but.....
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
RE: Hernando de Soto Bridge (I-40 Mephis)
I am sure he will sue at some point and retire early as a happy man. And all the MBA's will keep their bonuses as will he.
RE: Hernando de Soto Bridge (I-40 Mephis)
I work and live in Memphis, Tennessee. I work as a maintenance director for a nursing home.
I come here today to learn or try to find out, if the repairs they did to the Hernando-DeSoto Bridge are permanent and is good or as good as before?
Is it possible that the load that was intended to bear weight on the damaged beam was transferred somewhere else and possibly causing the integrity of that location to be impacted negatively?
Any idea the estimated remaining lifetime of the bridge, as-is right now?
Thanks in advance for any feedback.
RE: Hernando de Soto Bridge (I-40 Mephis)
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: Hernando de Soto Bridge (I-40 Mephis)
Additional information here Link
Brad Waybright
The more you know, the more you know you don't know.
RE: Hernando de Soto Bridge (I-40 Mephis)
Fracture-Investigation-I-40-MS-Rvr-Bridge.pdf
WJE 10/7/2021