Sounds like typical, "close the barn door, the horse has gotten out" thinking. How about the other 49 states? Are they going to wait until someone gets hurt or killed?
At my previous firm in Buffalo, NY we were hired on occasion to design steel girder erection plans for bridges, and we always did an analysis considering the lateral stability of the girders for their self weight. We considered the stresses when the girder was lifted by the crane, and when it was set in place.
As for adding additional bracing or doing other things that may add a small amount of money to the job, our primary responsibility as structural engineers is to design safe structures. Economy is definitley a consideration, but it has to take a back seat to safety. Too many owners (and architects)don't care about this as they apply the thumb screws to get designs from structural engineers quicker and for less money, with the resulting structure as cheap as possible. I am writing this at 7:10 a.m. on Saturday to try to get another job out to meet an aggressive schedule. Again.
This thread is pretty old, but I just came across it and did not see mention of a cause I heard on a TV news story. Bear in mind that reporters don't always get it, but the root cause as I heard it was that the beam had been set in place reversed which made the designed bracing impossible to fit and that the contractor had rigged some temporary braces which then failed. Had I designed it, I would have wanted to see it erected. A very sad situation, especially if the rush to make money on the job contributed.
Nope. There was never any intent to brace up one girder line. The plan was to erect two girder lines and their connecting crossframes, creating a stable cross-section.
The "beam" is actually two (or more) girders bolted together end to end. One of those components was lifted backwards, so they then had to take it back down, turn it around, lift it again. Then when they got it back up, they put in the wrong bolts, and had to waste more time taking those bolts out and putting the right ones in. The result was they only had time to get up the one girder line and not the second parallel one. That's why they had to rig something up.
Thanks HG for setting me straight. The last link worked and is very clear. I'd guess future erection plans call for removal of the first girder if the second can not be set in place right away.
I've wondered about that. My initial reaction was that when they reached a point in time that they knew they couldn't get the second girder line up, they should have taken the first one back down. But I'm guessing that would never, ever happen in the real world. No one would throw away a whole day's work, a whole road closure. Instead, they'd design a fix they considered in fairly good faith to be safe...and this is where we came in.
After Corn's comment about "wanting to see it erected", it got me to thinking about how few times I have witnessed erection of my designs (actually 0 in 28 years!!!). Do others have the same problem that they can never afford to get out of the office?
"Do others have the same problem that they can never afford to get out of the office?" Judging from the number of designs I see in the fab shops that came from the brain of someone who hasn't seen a whole lot of the real world, I'd say yes. (Not that I'm saying this applies to you, cage.)
This probably belongs in its own thread but...I think it should be mandatory for designers to spend a certain amount of time at construction sites and fabrication shops, even if it's not their own projects (which might be built too far away), in order to understand how those lines on paper translate into physical objects that real human beings and real pieces of equipment must somehow create under real conditions. (Number one: everything is always a LOT bigger than young designers expect it to be.)
("First, assume a perfectly spherical horse in a vacuum...")
A designer once joked with me that it's much better to work in design than in fabrication because "we can create designs on paper that you couldn't possibly achieve in a fabrication shop." He was kidding, but yet there's a certain amount of sad truth to that.
