Not a bridge engineer, but just looking at the number of bolts in the that box beam's web splice plates there looks to be better than a 1,000,000 pounds of bolt shear capacity. Assuming such significant tension? load I would have expected major/significant splice plates on the top and bottom also to better engage the entire box beam and smooth out the load transfer and associated stresses when load is transferred from the splice plates to the box beam section. Wonder if that splice detail gives rise to unforeseen stress concentrations then along with cycling/fatigue you have what you see. Of course this is assuming that entire box beam section is required design wise. Going to be interesting to see the final report on the root cause.
Structure was behaving unsymmetricaly back in 2017. If I'm interpreting structural monitoring report properly (from 3DDave above), span with fracture was showing reduced loading from temperature forces back in 2017, which resulted in new bearings not moving anywhere near the amount as the ones on the other end. This was interpreted as possibly the result of foundation movement. In light of this failure one could draw other conclusions.
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.
Not recent, and I don't think I could have cut that member that nicely; I cannot imagine how it failed so cleanly... as the doc noted... maybe the duct tape failed.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
https://www.ardot.gov/divisions/public-information/40-ms-river-bridge/[/URL]]"In May 2019, a video shows the evidence of the damage on the lower side of the bridge. ARDOT is now investigating to see if that damage was noted in a September 2019 inspection report and, if so, what actions were taken." ... The agency likely will release an image from the May 2019 inspection Monday, Parker added.
My understanding is that highway departments have long has a distrust of welded structures, and particularly field welds. The box section could be a weldment, built in a shop. The field connections are all bolted. The box looks big enough that a worker can get inside so handholes for access to tighten the nuts are not necessary
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.
Since the failed member is no longer carrying load, it would seem to be appropriate to removed the failed section and replace it with a another section, The failed section would need to be sent to a metallurgist for analysis, and the new section ( and others ) monitored with strain gauges attached to a data aquisition system and the real loading measured and analyzed after passing a significant load across the bridge. Nowadays, with the low cost of such monitoring, it might become normal for all bridges to have such as-built stresses monitored after initial construction.
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
To my eye, the second image I posted on 14 May 21 21:50, does not look like the member has completely separated. It also looks like a small crack is progressing from the opposite side, just to the right.
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?
If fatigue or metallurgical, I wonder what other parts of the structure are affected. I understand with fatigue, it is often difficult to determine the extent.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
![[lol]](/data/assets/smilies/lol.gif "[lol] [lol]")
