Posted on 03/15/2018 2:07:05 PM PDT by Morgana
FULL TITLE: 'Up to 10' people crushed to death as 950-ton pedestrian bridge collapses on top of cars and pedestrians on Florida college campus - just five days after it was installed
Up to 10 people have been killed when a newly installed pedestrian bridge spanning several lanes of traffic collapsed at Florida International University on Thursday.
US Senator Bill Nelson of Florida told local TV station CBS Miami that between six to 10 people died.
The 174-foot 'instant bridge' hailed as a feat of engineering and safety, was installed Saturday morning but was not due to open to the public until 2019.
At least six injured people were taken away from the scene and eight vehicles were trapped in the bridge wreckage, Miami-Dade County Mayor Carlos Gimenez said in an interview with CBS Miami.
One person was suffering from cardiac arrest, Gimenez said.
Television images captured from helicopter show numerous cars crushed by the weight of the bridge.
Images also show a number of emergency rescue workers crawling along the rubble in an attempt to spot survivors.
(Excerpt) Read more at dailymail.co.uk ...
Lots of repercussions for the private company (as it should be) but no repercussions for .gov failures at the FLA high school.
Lol
“torsional”
That’s exactly the conclusion I came to http://www.freerepublic.com/focus/news/3639940/posts?page=408#408
You don’t have to be a structural engineer (and I’m not) to see that any sort of torque (twist) failure and that thing liquifies.
I am willing to believe that the Y-axis is adequately braced against compressive (downward) forces, by the zig-zag [concrete central] girders. But that is exactly and only at a perfect 90 degrees from horizontal. On a perfect vertical chord.
Any twisting starts an immediate progressive crumbling failure. That design is utter horses**t, modeled on a 2-D computer screen by someone with zero real world experience.
[or, as some have posited, construction supports were yanked before some sort of superstructure or suspension was installed; which would be galaxies beyond stupid and negligent]
The suspension cables and tower are utterly absent from that debris. Someone wanted the bridge opened quickly, and early, purely for PR value. They assumed that placing the span was just like placing a log over a creek. The supports were removed to allow traffic to flow sooner (and the Miami Herald wrote an article bragging about the speed of construction). Whoever made those decisions needs to go to prison.
From the photos looking like the installation was only the walkway structure ....the numerous support cables from the tower were missing.
I found them particularly interesting because a semicircular arch bridge has to be half as high as the arch is wide, and therefore requires steep ramps on both ends.
Oh man ! I look forward to your posts.
I have since seen a drawing of what was supposed to be the finished bridge. There was supposed to be a tall vertical tower in the center island with multiple tension braces going down from the tower to the top flange of the bridge.
I do not see a center support or a tall center tower. That means the compression dead load just before it failed was many times higher than what it would have been when completed. I now have no doubt that the engineers did not check if the partially completed top flange was strong enough to take the compression before buckling. If they did, they made a mistake (fairly easy to do with buckling as a failure mode).
It is impossible to tell how much more compression was actually in the top flange compared to what it would have had when completed, but I believe it was a lot. At the VERY LEAST, they should have had the center pier (from the island to the bottom flange) in place. That would have cut the load by a factor of 4 from what it had when it failed. This looks like an engineering failure to me.
I’d like to know how the construction company and engineering firm got the contract. Both we’re recently involved in prior project failures, including bridge collapses, according to the article - http://www.miaminewtimes.com/news/fiu-bridge-collapse-construction-firms-accused-of-unsafe-practices-10176596 . Additionally, the construction company is described as a local mom and pop business.
I smell political chicanery I.e. kickbacks, patronage, set asides, etc. hopefully they will investigate this.
Oh yeah, you know it is coming. Someone got cheap to help themselves to some easy cash.
I wonder why someone would put this thing up without the planned center structure?
That was not a bridge. That was the equivalent of the 1X6 board I pushed across the stream at age 7 when I was hoping to not get my feet wet. (all of me got wet).
That bridge was obviously not designed and built by a Nat Taggart, (or by Dagny Taggart and Hank Rearden).
Looks more like something Jim Taggart and Wesley Mouch would design with the primary intent of ripping off the taxpayers.
Ayn Rand predicted all this 60 years ago.
I think you’re right, except I wouldn’t call it an engineering failure, I’d call it a construction mgmt failure. As drawn (and I probably saw the same dwgs you did) the design is proven and there is a fine 12x over budget example spanning the SF Bay about 35 miles away from me. There are plenty of examples of this sort of quasi suspension bridge design in place (where there is a single central support tower; instead of dual tower designs like the Golden Gate or GWB) and those are fine.
Someone in management must have given the OK to yank the center temporary construction support without any part of the central tower or as you said, even the stanchion in the middle, from the ground to the lower flange in place. That’s simply unimaginable. Had the tower and stanchion been in place, there’s no reason to think the bridge wouldn’t have held just fine.
Darn, you can just look at the bridge and tell it is too long and thin to hold up its own weight. Somebody wanted a headline and didn’t bother to put up the suspension part.
Think about the weight that would have been walking across the bridge, and assume that 200 Moochelles at 250 lbs each would have been on it at one time, or 50,000 pounds of people. Whereas the bridge was 950 x 2000 lbs or 1,900,000 lbs. Which means the people weight would have been negligible, at 50,000/1,950,000 or about 2.5% of the weight.
That means the suspension’s big job was holding up the bridge, not the people and other stuff that may have been on it.
I don’t get it. Why would they build a $14,000,000 Bridge to Nowhere?
Are the College Students afraid to use the Crosswalks or something? Are there too many Assault Vehicles on that Street?
I understand all the Pedestrian Bridges in Vegas (which were not built using Federal Tax Dollars as far as I know), but this?
Would have served a good purpose but was probably poor construction, corrupt contracting, skimpy concrete, kickbacks, etc etc. I’m thinking...
Cf. the Viaduc de Millau, completed in 2017, which uses this type of “cable stayed” support. You can “drive” across it and around it in Google Street View, and it’s guaranteed to knock your socks off.
This needless tragedy makes a sorry comparison.
Did the Florida school pressure the firm to hurry up and take short cuts? If yes, the firm should have resisted, citing public safety. This is specifically called out in the Engineering Code of Ethics, having force of law in all states through respective licensing boards.
Yes. I’d be interested in where the cable was made.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.