A skyscraper that could have toppled over in the wind (1995)

I'm not sure about the initial mistake either. But then again, this was a lesson in one of my structural classes, so you don't forget about that sort of issue.

Basically, I'm surprised that no one did the basic worst case sigma=MY/I for the side and quartering loads. The old grizzled supervising engineer generally will run through a bunch of ballpark estimates to see if the designer has actually checked all the worst case combinations.

I don't really buy the article's factor of safety discussion -- the factor of safety is for uncertainty, not blunders. I _might_ save you from a blunder, but that's not what it's for. It's for variation in material dimension, quality, and loading variation.

As for the bolts vs welding, There's definitely scope for changes at the shop drawing stage. When an engineering firm designs a building, they'll generally design a set of typical connections, but when the shop goes to build them, they have to take this column:floor beam connection and actually turn it into "cut this cope, drill here, ..." and they'll generally do the simplest, cheapest thing they can.

The engineers have to review the shop drawings, and if they don't have a good set of calcs for what the loads are in that particular bit, then they aren't going to necessarily see that this substitution of bolts won't work. (Note -- bolts can be just as good, and potentially better than welds, depending on what you're doing, how you're erecting, and the space you have available. Full Penetration welds are a pain, but they're the easiest way to specify a full strength join. But doing them on site, in the air, when you're putting the thing together is not something that you'd generally want to spec.)

There have been a significant number of historical disasters connected to shop drawing changes that the engineers didn't pick up. (e.g., the Hyatt Regency walkway collapse).

Also remember, this was done in the 70's, so they wouldn't have had Finite element models of the building where it's super easy to just run a couple more loads. Everything there would have been indeterminate elastic analysis, so it's not quick to run an accurate calculation if you're trying to find beam sizes.

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Honestly, one of my favorite pieces I've read in 30+ years of reading that magazine.

LeMessurier gave a talk on this at my school when I was studying architecture and structural engineering. The narrative very much follows the lines of this story, but also appreciate the added detail in the article. His voiceover definitely emphasized the complex ethical considerations of engineering more than the technical: Balancing the interests of insurance, client brand, public sentiment and trust, government relations, and his own professional and firm. Don't get me wrong, the technical details and Delta P effect were super interesting. But the professional practice aspects were what he wanted students to take away from it.