martybegan
Diamond Member
- Apr 5, 2010
- 85,263
- 35,715
- 2,300
Tensioner rod blew out while being tightened is what I heard....Broke near the crane where the workers were on top.While my degree is in chemical, not civil engineering I take enough cross-discipline continuing education to probably qualify more than you to have an opinion on this.
What i am trying to say is the lack of installation of the stays, if they were non-structural, has nothing to do with the collapse.
Edit:
From wikipedia:
Florida International University pedestrian bridge collapse - Wikipedia
Thanks for the info. That gives more detail than I had seen before. I was under the impression that the collapsed section was the entire bridge, and there was a support structure designed for midway of that span. 174 Ft is certainly long enough to require cable support, depending on the design. We can offer conjecture all we want, but as I said before, we will eventually know the whole story. It's important for them to determine the exact cause of the collapse, and to distribute that information as widely as possible to prevent future tragedies.
174 ft for a truss bridge is well within the structural loading capabilities, of steel. Here they used concrete in a novel way, and who know if this contributed to the problem.
One obvious fuck-up was allowing traffic to continue during a tensioning activity. This is something they should have done at night with the road closed,
I'm confident that the design was vetted to several times the expected maximum stress. They usually don't just throw up a structure and hope it will work. I'm guessing some questionable installation procedures. Of course, until the investigation is complete, anything you or I might think is just conjecture.
The Kansas City Hyatt collapse was caused by an improper installation, but THAT was caused by a designed installation that was nearly impossible to do.
The only real evidence we have so far is:
1. The span fell from one side, which dragged down the rest of structure
2. There were noticeable cracks in the area of the failure.
3. The installer was performing tensioning when the failure started
4. During the tensioning, traffic was not prevented from driving under the installed span.
What we don't know about the above is:
1. What type of cracks were they (surface or structural)
2. Where in the tensioning process they were
The question is was that enough to cause the collapse without other factors, i.e. bad design, bad materials, improper installation procedure, etc.
Most failures are not single point, they are cascade failures where multiple things have to go wrong to cause an given end result.