"I know that epoxy can be stronger than steel, so that wasn't necessarily the problem. Necessarily.
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It can, if it's properly catalyzed and mixed, and if the temperature range is right, and if the material it's holding together is dry, clean and without loose materials.
I can see the engineers now, working from a spec. book from the adhesive manufacturer. "OK, let's make the safety factor 150% on this crap." Not enough, apparently, to compensate for lazy workers trying to make a deadline, or for improperly-cleaned holes where the epoxy was to bond the concrete and the bolts, or the wet hole, or the rusty bolt.
I've used a lot of epoxy in boat work. A lot. It's great, as long as every factor is correct. If it's not, it doesn't work for crap. A friend of mine had a boatyard replace the transom on a fiberglas boat. I'm not sure what they did wrong, but the first time he took it out and slammed the throttle forward on the 225 hp outboard, the transom ripped right off the boat, sinking the outboard and the boat in about 150 ft. of water.
He was OK, but they couldn't recover the boat, so there was no way to figure out how the boatyard had screwed up this repair.
Epoxy's great, especially when tested in the lab.