Thanks for the article. The existence and practical effects and consequences of metal fatigue's been known and understood since the 30s and that was definitely so post WWII. This bridge was built in '67. They're still passing the BS about how they didn't know.
It's interesting, how in the same article, the folks that know and are responsible for spending the money, say that there was plenty to spend on fixing dangerous faults. The others say flat out in the face of that, that there was none. The fact is that the engineers didn't appreciate and know what they had in front of them and froze. IOWs, it was over their heads. MNDOT designed and built the bridge in the first place. Now they're doing a song and dance over the poor results.
I can't see a politician, rep, or rat that would turn down $s after a warning that their bridge is a jalopy that's threatening to fall in the water. The reason's are obvious. Regardless of credentials, they're inept bureaucrats frozen in the state of ignorance, confusion and indecision. I doubt many will be entertained by their song and dance. They may be taken in by it. The Gov is probably fuming and the rats are certainly over joyed that this occurred in a rep admin.
> “The existence and practical effects and consequences of metal fatigue’s been known and understood since the 30s and that was definitely so post WWII. This bridge was built in ‘67. They’re still passing the BS about how they didn’t know.”
Yes and No. Fatigue was not really known until metal airplanes. It was not well known in the aviation industry until after WWII — after several fatigue failures. It was not used elsewhere because it was expensive to design for that (mostly, it could not be designed for — parts were made and tested to failure) and most things were heavier than airplanes and did not need to worry about fatigue.
The information on fatigue was filtering down to the highway industry in the mid to late 1960’s. I had some of the early articles written on it at the start of my engineering career. A lot of it was VooDoo. I saw a newer article on it a while back that is much more usable. Over-the-road highway trailers were just starting to get light enough back then that fatigue started to be a problem — particularly in gasoline tankers (they went from a tank on a frame to a monocoque structure with the shell actually carrying the load and they also became totally welded at about that time).
Fatique information had not made it to the bridge industry even then. They had a bridge at Sioux City over the Missouri river that was built sometime in the 1970’s or so that started fatigue cracking within a year of its completion. It had to be replaced in just a few years.
Back then, the engineers thought that bridges would never see enough cycles to cause fatigue cracking (at least, that is what they are teaching in bridge inspection courses). Obviously, they were wrong. A combination of using calculators and computers to pare down the weight to the absolute minimum and the increased use of welding was the major causes (note that riveting and bolting structures, which is rarely used now, means fatigue cracks are less likely to start and will end at the next joint instead of cracking completely through the structure).
As far as you statement that politicians would NEVER fail to correct a problem — you have obviously never dealt with politicians. Unless you can give them and EXACT date and time when it will fail, they are not interested. Sometime soon is not good enough. Read my “All About” page here if you want to read about my experiences on that.
I see that there is a navigable canal and lock near the end of the bridge that seemd to drop first - wonder if there were any collisions over the year - a dent in the steel tube could drastically reduce its compressive strength - the lower chord is in compression, right?
Another article with a few more details: