The approaches for the bridge are continuous trusses. I read the story in my local paper over the weekend but the report didn't identify a location on the bridge. Assuming it's over a support, and given the age(notice the rivets) I'd guess brittle fracture.
Very interesting report. I wonder who the consulting engineer is, or if there are a couple involved for all the testing, design, inspection.
That's amazing that the paint contractor hears a loud pop, the bridge shakes, then proceeds on as if nothing happens and either doesn't notify the resident engineer or the engineer doesn't move quick on it.
These structures have more redundancy than we give them credit for. But who knows what element is paying the price to keep it up.
I have a hard time picturing it going to compression also but may make more sense if I saw the plans/details. I would think if it went to compression there would be more problems but maybe that's the strengthening the author discusses.
I'd like to think that I'd report a bang as loud as that -- but you hear a lot of sounds when working under an active bridge.
Especially if the final fracture area was only a small portion of the total section (hence the energy/sound was less) -- I might not have thought too much of it if it wasn't related to the work I was doing (e.g painting).
