This is the best NSFW explanation of the Florida bridge collapse

https://www.youtube.com/watch?v=ioC61QW7SHQ

If you like sweary Canadians with lots of knowledge about building materials and construction, Arduino versus Evil has the most interesting armchair analysis of what caused the Florida International University bridge collapse.

Bonus: his very amusing explainer on why paper and card decks explode in those kooky hydraulic press videos, starring his own press Lil Skrewy:

Simply Explained Bridge Collapse | Engineering and Construction (YouTube / AvE)