My oldest brother has been an engineer for 45 years, and has built numerous projects, most more complicated than the bridge, but he has been involved designing more than one bridge, as well. We have actually had conversations , before, on numerous topics, (as he is my brother) , including, but not limited to, structural design of just about everything from bird feeders to high construction cranes. He's pretty sharp.
Information on structural design is freely available to all who can read. I have welded numerous engine lifts, and other load bearing devices, all of which work exceedingly well, the oldest cherry picker I built in 1983, that has pulled DT466 diesels weighing nearly a ton, while the hoist itself weighs less than 400 lbs., and is still working great.
I grasp how structural strength works, thank you.
Any student of architecture is aware of the strength of arch supports; many the Romans built are still standing, bearing weight.
One doesn't need a degree in engineering to see the weakness in the design illustrated above; one needs only to have built an erect, load-bearing structure.
Try READING about it; the engineers who authored this work AGREE WITH ME :
. . .
If the designers of the ill-fated Florida bridge had added cross-supports , underneath it, from the 1st or 2nd vertical supports , it would likely still be standing.
Or, if they had just built an arch bridge, it would likely still be standing. They JUST PUT IT UP, and it fell; that screams "design flaw". It's also likely that whatever the crane operators were doing, on the side that fell first, contributed to its fall.
It doesn't take a genius to see the inherent weakness in that design. Any kid that has ever successfully dammed a creek could likely see it...