Apparently some cracks appeared on the structure a few days ago after it was moved to the position it was in when the failure occurred.?ÿ I'm sure the nature of those cracks and whether they were cosmetic or an indication of?ÿsomething serious will be addressed by the NTSB.
From what I've read I get an uncomfortable feeling?ÿno one ever considered the possibility the span could collapse under its own weight.?ÿ?ÿTrust me, it did collapse under its?ÿown weight.?ÿ?ÿ I also get the feeling there were so many "cooks" on this pot of stew it will?ÿprobably be a nightmare attempting to determine what comedy of errors?ÿactually led?ÿup to the catastrophic failure.?ÿ The fact that about 90% of the construction funds were?ÿfederal in nature makes me think there might be a few folks wearing orange jump suits by the time it's all said and done.?ÿ
It's a sad day when the traveling public pays the ultimate price for something that might be found to have been 100% avoidable.?ÿ This is going to be one for the text books.
Just my opinion, The bottom slab that appears to be about 30 foot wide would have been in tension and possibly was post-tensioned.
The last diagonal on that end would have been in compression.
I don't picture in my mind how the compressed force in the 3ft. +/- wide diagonal would have been distributed evenly thru the post tensioned 30 ft +/- wide slab. It seems to me there would have been a lot of shear force at that point.
James
(disclaimer, it has been 40+ years since I was in a statics class)
It appears the vertical punched through the slab. I surmise that location is where the cracks were found.
Paul in PA, PE, PLS
More.....?ÿ?ÿ http://www.dailymail.co.uk/news/article-5511417/Commissioner-stunned-road-not-CLOSED-stress-tests-underway.html
thanks for the link, now I understand what and where the stays where going to be
this was the plan
enginerd
I like it
AvE /Boltr is one of my favorite YouTube channels.
?ÿ
I just realized the Title is wrong. The bridge?ÿis at Florida International University in Miami. Florida Atlantic University is in Boca Raton.
?ÿPaul in PA
This is a good zoomed in version of the dashcam. There's lots of offensive comments, but on the left it does look like they were working at exactly the place where it broke. And the worker on top does appear to have slipped out of his harness (that was connected to the crane).
I just realized the Title is wrong. The bridge?ÿis at Florida International University in Miami. Florida Atlantic University is in Boca Raton.
?ÿPaul in PA
Fixed.
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Wendell,
Thank you muchly.
Paul in PA
At 8 seconds into the zoomed collapse vid I noticed that it looks like the truss web comes through the bottom of the bridge deck.?ÿ Combine that with the enginerd vid which notices the tensioning rod breaks (you can see this rod come up and out to the left of the web), it instantly loads the web which punches through the bottom the the deck and then all integrity is gone which brings it down.
I'm not an engineer - nor did I stay in a Holiday Inn last night...why the hell would they install the bridge with all the well documented cracks??ÿ
N10,000, E7,000, Z100.00
PLS - IL, MO, AR, KS, MN, KY
Hopefully, a few someones go to prison for a few decades...might help with the courage to say "Stop!" for the next group of people.
I'm not an engineer - nor did I stay in a Holiday Inn last night...why the hell would they install the bridge with all the well documented cracks??ÿ
Or why wouldn't you close the road when the cracks are growing by the day?
When concrete cracks and fails, the steel in place is supposed to be sufficient to hold the structure in place.
That was an engineer's nightmare cone to light.
This bridge was incorrectly designed, design flaws and outright design omissions everywhere. The designers hired inexperienced engineers to check their design and they failed miserably. The design was intended to be built in a hurry and it also failed in a hurry. Minor cracks are to expected in concrete and one job of the steel is to hold the cracked pieces together, but a crack is typically invisible or hard to see. This bridge had 1/2" and larger gaps and the engineers were calling them cracks but they were in essence failed and yet stood for a while until corrective activity disturbed their peace. Most everyone that put their seal on the designs should lose their licenses and more than some should be in jail. You will find them at the design firm, at the university, at the design review firm and at Florida DOT who accepted the design and also accepted the selection of an unqualified review firm.
This was no ACCIDENT, it was a CRIME!
Paul in PA, PE, PLS
"No time to do it right, always time to do it over"...until lives are lost and no amount of rebuilding will fix the damage.
I suspect a more in-depth investigation would find cultural factors within the responsible organizations which led to the collapse, a la Morton Thiokol and the infamous o-ring. Failure on this level involves far too many individuals with direct knowledge of the problems for this to be a case of "somebody up high swept it under the rug".
I wonder how many fewer surveying screwups we would see if incompetence and corner-cutting in our professional sphere more often led to consequences like this.
I was told when you sell professional services the customer can have it 'fast, cheap, or accurate-- pick 2 of the 3'. Nobody picks accurate.
Until someone forces the customer to pay for competent work there's not much a professional can do.