In addition to repairing the failed piece, determining the root cause is of equal importance, and if it is due to overstress due to passage of overweight vehicles, the state will need to pretend that they will do a better job at ensuring the max permitted axle load is nhot exceeded. Perhaps a review of past permits that had allowed overweight vehicles to pass and a review of bypass routes that truckers can use to avoid the weigh scales is also prudent.
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
This ended up in my mail this morning and I don't know why... [Added] I suspect I know why... just my interest... did not know the poster, but responded that I would put the info on Eng-Tips.
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?
The links which dik posted address lack of redundancy in tied arch bridges. But there is a distinction between the arch consisting of a single member vs. a truss. The bridge in this thread had substantial redundancy by truss action.
So the video posted by TDOT shows how the bridge will be temporarily supported to allow access for repairs. How the 'permanent strengthening repair plates' are to be employed remains a mystery.
Brad Waybright
The more you know, the more you know you don't know.
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.
Still not much detail there. If that animation is to scale (probably not) it looks like the first set of plates actually overlaps part of the bolted node connection next to the failure. Then, the second set of plates overlap each end of the first. That would leave a gap between the new repair plates and the original steel and connections. That would certainly not lend itself to assisting with ongoing maintenance operations. Also, not able to determine if this stuff is bolted in place or welded. I'm not a civil, bridge, or structural guy, but it really looks like a patch job to me. I hope there's more detail to come out soon to change my mind.
Brad Waybright
The more you know, the more you know you don't know.
Are the permanent repair plates on both sides of the beam or only on the outboard side, as it appears in the video?
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!
So, the nuts on the ends of the 3" diameter PT rods are going to be like 6" across, How are they going to tighten them to get the tension needed? Is it like a 10' long box wrench?
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
![[bigglasses]](/data/assets/smilies/bigglasses.gif "[bigglasses] [bigglasses]")
