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What caused FIU’s bridge to fall? More clues come to light. This is the "to inform" and "to educate" thread on the subject.

By Feux Follets following x   2018 Mar 18, 7:32pm 1,958 views   34 comments   watch   sfw   quote     share    


Well written article on the failure, technical but not over the top for anyone.

If tightening support cables caused Florida International University’s signature new pedestrian bridge to collapse, as Sen. Marco Rubio has suggested in a tweet, the rubble spread across the Tamiami Trail could contain obvious clues, bridge experts say.

Adjusting tension cables, which ran like tendons through the 950-ton concrete span and the struts that connected a concrete canopy on the bridge to the walkway, can be a delicate operation. Over-tightening the cables, which are used to reinforce the concrete, can have devastating results, the experts say: It might cause torquing, or twisting, that would cause a specific cracking pattern in the concrete on impact with the road, something investigators would likely detect quickly.

National Transportation Safety Board investigators have confirmed that crews were tightening tensioning cables in a diagonal truss at the north end of the bridge on the day of the collapse. But they stressed they did not know whether that was the point at which the span failed.

Indepent experts have zeroed in on the tensioning work as one of a myriad possible causes for the failure of the unfinished bridge, which crumpled to the pavement on Thursday.

Independent experts focused in on work going on Thursday before the bridge fell. Late Thursday night, Rubio tweeted that he was told by workers at the site that cables connected to the bridge had loosened and engineers were instructed to tighten them.

One subcontractor that provides materials and services for concrete tensioning, Structural Technologies VSL, confirmed on Friday that it had a crew at work on the bridge and that one employee, Navaro Brown, had perished in the accident. Two others were hospitalized.

Company spokesman Michael Biesiada, wouldn’t say exactly what the crew was doing when the bridge collapsed, but he confirmed the workers were “providing installation support for our products.” Documents from FIU and consultant Bolton Perez & Associates, obtained by the Miami Herald, show that Structural Technologies, LLC (VSL) was paid $439,350 for “post-tensioning work.”

Whatever did in fact occur to weaken the bridge, one expert said, it could well be tied to work done Thursday. Engineers say that most bridge and building collapses that occur during construction are caused by work errors, not design flaws, though the latter can’t be ruled out this early.

Full Article: http://www.miamiherald.com/news/local/article205661039.html

#FIUBridge #NormalAccidents #Construction

1   Sniper   ignore (11)   2018 Mar 18, 7:43pm   ↑ like (5)   ↓ dislike (1)   quote        

It just has to be Trump's fault...

or, just blame it on a AR-15, yeah, that's the ticket!!
2   theoakman   ignore (0)   2018 Mar 18, 7:52pm   ↑ like (0)   ↓ dislike (0)   quote        

#NormalAccidents?
3   Feux Follets   ignore (0)   2018 Mar 19, 2:25am   ↑ like (0)   ↓ dislike (0)   quote        

theoakman says
#NormalAccidents?


Normal Accidents: Living with High-Risk Technologies is a 1984 book by Yale sociologist Charles Perrow, which provides a detailed analysis of complex systems conducted from a social sciences perspective.

It was the first to "propose a framework for characterizing complex technological systems such as air traffic, marine traffic, chemical plants, dams, and especially nuclear power plants according to their riskiness". Perrow says that multiple and unexpected failures are built into society's complex and tightly-coupled systems. Such accidents are unavoidable and cannot be designed around.[1]

Perrow's argument, based on human error, is that big accidents tend to escalate, and technology is not the problem, the organizations are. Each of these principles is still relevant today.

https://en.wikipedia.org/wiki/Normal_Accidents

The book shed light on a big problem when it was written and will be more timely with the rollback of regulations in safety etc.
4   Feux Follets   ignore (0)   2018 Mar 19, 4:58am   ↑ like (0)   ↓ dislike (0)   quote        

Another Update from "New Civil Engineer" Magazine/Website.

FDOT has released its own statement clarifying that it had, “at no time, from installation until the collapse of the bridge”, received a request to close the entire highway.

It also said that it was not made aware by FIU’s design and build team of any scheduled “stress testing” of the bridge following installation and has no knowledge or confirmation from FIU’s design build team of “stress testing” occurring since installation.

FDOT has said that had this been the case then the road should have been closed to traffic before any work was carried out.

“Per standard safety procedure, FDOT would issue a permit for partial or full road closure if deemed necessary and requested by the FIU design build team or FIU contracted construction inspector for structural testing,” it said.

UK bridge experts who have spoken to New Civil Engineer have suggested compression failure caued by poor concrete in the top flange could be a cause. The Guardian newspaper has obtained and posted CCTV footage that captures the moment of the collapse which appears to shows the failure beginning in the top flange, close to the central pier.

Full Article: https://www.newcivilengineer.com/world-view/florida-update-engineers-dismissed-crack-in-bridge-hours-before-collapse/10029229.article?blocktitle=Breaking-news&contentID=2163
5   jvolstad   ignore (0)   2018 Mar 19, 9:36am   ↑ like (3)   ↓ dislike (1)   quote        

Were any of the workers part-time Realtor's?
6   bob2356   ignore (1)   2018 Mar 19, 10:20am   ↑ like (2)   ↓ dislike (0)   quote        

There are bridges built by the romans still in use every day and their engineers didn't have cad/cam. Just saying.
7   justme   ignore (0)   2018 Mar 19, 10:32am   ↑ like (1)   ↓ dislike (0)   quote        

FF, thanks for doing your part to Make Patnet Great Aagin (MPGA). If you are a new name for an old user, you probably know that I am big on trying to achieve the dissemination of CORRECT information, and this post is an example of how to try and foster such a culture.
8   Tenpoundbass   ignore (11)   2018 Mar 19, 10:37am   ↑ like (0)   ↓ dislike (0)   quote        

Don't sugar coat it, I don't care if it's the best stable design ever created. To precariously perch that structure over a 6 lanes of traffic, two full pedestrian sidewalks and a car wide median, without the center support. It was just gross incompetence on everyones part that even stood there and watched without saying a word.
The design if the sum of all of the parts, not just the photogenic features. How dare they to pull such cheap politics and how dare anyone that abides.

Some people are going to get fired and a few companies will be sued. This might be the end of FIU.
Florida Immigrant University.
9   justme   ignore (0)   2018 Mar 19, 10:41am   ↑ like (1)   ↓ dislike (0)   quote        

The bridge model photo looks like one of those "signature bridges" that are spreading like a plague across the municipalities (cities, etc) of the US. That does not necessarily mean that the design is bad, but an argument may be made that this bridge design and construction requires a high degree of expertise to be safe.

Signature bridges are vanity projects of vain people that sit on city councils and their vain voters. Cupertino has an expensive vanity bridge across I-280. Palo Alto City Council has been arguing for years about constructing a vanity bridge across I-101 to replace the older and less impressive-looking steel bridge. These two bridges are both pedestrian bridges. Their main purpose is vanity and branding (as in marketing), neither of which will be of any economic value when everybody has such a bridge. Spend the money more carefully and get more value.
10   Fivelbsbrowntrout   ignore (2)   2018 Mar 19, 12:02pm   ↑ like (1)   ↓ dislike (0)   quote        

justme says
FF, thanks for doing your part to Make Patnet Great Aagin (MPGA). If you are a new name for an old user, you probably know that I am big on trying to achieve the dissemination of CORRECT information, and this post is an example of how to try and foster such a culture.


I agree, going to miss you. Hopefully you will experience reincarnation again.
11   HEYYOU   ignore (13)   2018 Mar 19, 6:37pm   ↑ like (1)   ↓ dislike (0)   quote        

Tenpoundbass says
To precariously perch that structure over a 6 lanes of traffic, two full pedestrian sidewalks and a car wide median, without the center support. It was just gross incompetence on everyones part that even stood there and watched without saying a word.


I was wondering about the reason for not having a center support.
Traffic engineers already had plans for the center lane"
What is the purpose of the arrows in the lane?
....

We will not have any more of this informing & educating.
Where do you people think you are?
12   MoneySheep   ignore (0)   2018 Mar 19, 7:32pm   ↑ like (2)   ↓ dislike (0)   quote        

No matter what kind of bridges, I don't think the use tension cable to hold the "floor" span is a good idea. Cable will oxidize and corrode, the floor span will fail very soon.

When I drive under a bridge without arch, for example like these, I pray quickly before proceeding.
13   marcus   ignore (1)   2018 Mar 19, 8:07pm   ↑ like (1)   ↓ dislike (0)   quote        

Feux Follets says
This is the" to inform" and "to educate" thread on the subject.


Be honest though, if there was a lead engineer involved that both female and a minority, can't we have some good old fashioned right wing meme fun with it ? That is without any knowledge at all of whether engineers are even to blame ?

Where's the fun for right wingers if theres all that damn truth, logic, facts and stuff involved ?

We're trying to have fun here, and push our agenda !! C'moooonnnnn please ! Can't I vent at least a little hate ?
14   Strategist   ignore (1)   2018 Mar 19, 9:09pm   ↑ like (2)   ↓ dislike (0)   quote        

Those responsible must be punished. The blame game will continue for a long time, and it will be years before someone actually gets punished. I have no doubt this is human error.
17   Strategist   ignore (1)   2018 Mar 20, 9:22am   ↑ like (1)   ↓ dislike (1)   quote        

zzyzzx says


The Romans used whips and slaves to build their structures, as did the ancient Egyptians. Those structures still stand.
I say we do the same. Sadly, you just don't get good slaves these days.
18   Tenpoundbass   ignore (11)   2018 Mar 20, 10:25am   ↑ like (0)   ↓ dislike (0)   quote        

Oh I get it now, that unfinished structure on the bottom right is the support. There's supposed to be 8 lanes of traffic under that side. That flag pole was meant to hold all of that weight without the counter weight of the other side being secured as well. That was no where near ready be set in place. That structure under it looks steel rebar support without the concrete being poured on it yet. The other side should have been hoisted into place the sometime the first side was and they both should have been secured with the cables in unison.

That pole is no where near as thick to scale as that model suggests.
19   anonymous   ignore (null)   2018 Mar 20, 10:28am   ↑ like (1)   ↓ dislike (0)   quote        

Tenpoundbass says
Oh I get it now, that unfinished structure on the bottom right is the support. There's supposed to be 8 lanes of traffic under that side. That flag pole was meant to hold all of that weight without the counter weight of the other side being secured as well. That was no where near ready be set in place. That structure under it looks steel rebar support without the concrete being poured on it yet. The other side should have been hoisted into place the sometime the first side was and they both should have been secured with the cables in unison.

That pole is no where near as thick to scale as that model suggests.


Yup, MAGA GOOGOO GAGA!

Lock her up!
20   Feux Follets   ignore (0)   2018 Mar 23, 6:00am   ↑ like (1)   ↓ dislike (0)   quote        

How do forensic engineers investigate bridge collapses, like the one in Miami?

Forensic engineers are taking center stage in the ongoing investigation to find out what happened and why – and, crucially, to learn how to prevent similar tragedies in the future.

I’m not actively involved in this investigation, but I’ve been a forensic engineer for nearly 20 years and am the 2018 president of the National Academy of Forensic Engineers. Similar to forensic scientists, we visit scenes of disasters and crimes to determine what role engineering practices played in what happened.

The first step in any forensic investigation, collecting evidence, often can’t begin until survivors are rescued and victims are recovered. Those operations displace material and can damage evidence, which means forensic engineers must study the emergency response as well, to be able to tell whether, for instance, a support column collapsed during the event or was destroyed to reach a victim in need of help. During the FIU recovery efforts rescuers used large equipment to break up massive blocks of concrete so that victims’ bodies could be recovered.

In Miami at the moment, forensic engineers and technicians from the National Transportation Safety Board are on the scene. Right now they’re collecting samples of materials from the bridge to test for their physical properties.

They’re reviewing drawings and plans, and examining both industry standards and site engineers’ calculations to understand what was supposed to be built – to compare with what was actually constructed.

They’ll look at photographs and videos of the collapse to identify the sequence of events and locations of key problems.

Of course, they’ll also talk to witnesses to find out what workers and passersby saw and heard around the time of its collapse.

Then they’ll combine and analyze all that data and information to identify as clearly as possible what went wrong, in what order.

Often there are many factors, each leading to or amplifying the next, that ultimately caused the disaster. Putting that puzzle together is a key part of the forensic engineer’s role.

More: http://theconversation.com/how-do-forensic-engineers-investigate-bridge-collapses-like-the-one-in-miami-93692
21   mmmarvel   ignore (0)   2018 Mar 23, 10:29am   ↑ like (3)   ↓ dislike (0)   quote        

Look, I've been working in construction for decades. I've seen and worked on hundreds of 'tension' bridges. What happens is the cables are embedded in the concrete as it was cast (poured). It's been determined by an engineer how many cables and where they need to be in the structure (or section of the bridge depending on the size of the bridge). RARELY does a bridge that is being placed fail (witness how few stories you've ever seen about something like this). What is more common is a cable fails/snaps as the cable is being tensioned (the cable embedded are pulled on each end of the structure to a tension (lbs) again determined by an engineer). I recently read that there was an issue noted prior to the tensioning (noticed two days before, when the bridge had been put in place and prior to the tensioning) about a crack. https://www.politico.com/states/florida/story/2018/03/16/engineer-of-fiu-bridge-reported-cracks-in-structure-to-fdot-days-before-collapse-318961

Some engineer is about to lose their license and possibly face jail time. Bottom line is that traffic should NOT have been allowed under the bridge until AFTER is was declared in place and good to go.
22   Heraclitusstudent   ignore (1)   2018 Mar 23, 11:50am   ↑ like (1)   ↓ dislike (1)   quote        

MoneySheep says
No matter what kind of bridges, I don't think the use tension cable to hold the "floor" span is a good idea. Cable will oxidize and corrode, the floor span will fail very soon.

Like this one?

MoneySheep says
When I drive under a bridge without arch, for example like these, I pray quickly before proceeding


You think praying will help?
23   Feux Follets   ignore (0)   2018 Mar 24, 11:37am   ↑ like (0)   ↓ dislike (0)   quote        

A few articles from Public Works Magazine/website post collapse.

Florida's Collapsed Bridge Underwent Last-Minute Design Changes. http://www.pwmag.com/roadways/bridges-culverts/floridas-collapsed-bridge-underwent-last-minute-design-changes_c

What You Need to Know About the Tragic Bridge Collapse in Florida. Investigators try to solve the mystery of who's to blame for this construction failure.

http://www.pwmag.com/roadways/bridges-culverts/what-you-need-to-know-about-the-tragic-bridge-collapse-in-florida_s

There are more links covering construction etc. in the main website. Worth a look and maybe as keeper on a read list.

http://www.pwmag.com/
24   Feux Follets   ignore (0)   2018 Mar 25, 2:46am   ↑ like (0)   ↓ dislike (0)   quote        

@mmmarvel - this link may be of interest to you. You can select from the list below amongst a lot more on the site:

Building
Bridge Engineering
Concrete Engineering
Highway Engineering
Hydraulics
Marine Engineering
Piles Engineering
Prestress Engineering
Soil Engineering
Steelworks
Surveying
Timber Engineering

https://www.engineeringcivil.com/
25   Feux Follets   ignore (0)   2018 Mar 25, 2:48am   ↑ like (0)   ↓ dislike (0)   quote        

Experts cite explosive joint failure as cause of Florida bridge collapse.

The collapse of the bridge in Florida was probably caused by an explosive failure of a key joint in the bridge’s concrete truss, structural engineers have told New Civil Engineer.

The 862t concrete bridge over a highway at the Florida International University (FIU) in Miami collapsed last Thursday killing six people. Investigations are now underway to determine the exact cause.

But structural engineers who have spoken to New Civil Engineer have studied multiple photographs of the scene and believe the collapse was caused by an explosive failure of the north end, bottom joint – a critical connection in the bridge’s structure.

In its final state, the FIU bridge was supposed to be a two span, concrete truss and cable stayed bridge – the main span over an eight lane highway and the backspan over a narrower waterway. However, at the time of the collapse, it was in a temporary configuration having only been partially constructed. Only the main trussed span was in place, with the backspan, central mast and cable stays yet to be installed.

The 53m concrete truss had been installed six days before its collapse. It had been built off site, wheeled into place and then lifted onto its supporting piers. At the time, the bridge appeared stable.

More: https://www.newcivilengineer.com/tech-excellence/experts-cite-explosive-joint-failure-as-cause-of-florida-bridge-collapse/10029278.article
26   RafiMaas   ignore (0)   2018 Mar 25, 5:55am   ↑ like (0)   ↓ dislike (0)   quote        



This guy says that 1 of the he vehicals used to move the bridge into place was not in the right spot which damage one of the trusses.

So fuck all you people who jump to conclusions.
27   anonymous   ignore (null)   2018 Mar 25, 6:04am   ↑ like (1)   ↓ dislike (0)   quote        

This guy says that 1 of the he vehicals used to move the bridge into place was not in the right spot which damage one of the trusses.

If it was a white male its of no significance because white males are the majority

Lol WTF
28   RafiMaas   ignore (0)   2018 Mar 26, 12:23pm   ↑ like (1)   ↓ dislike (0)   quote        

http://ottawacitizen.com/news/canada/random-canadian-finds-the-smoking-gun-in-florida-bridge-collapse/wcm/c49afb54-e04f-4889-8d9a-5c1b47e34188

Here is further confirmation that one of the vehicles used to move the bridge into place was placed in the wrong spot.
30   RafiMaas   ignore (0)   2018 Mar 27, 6:47pm   ↑ like (0)   ↓ dislike (0)   quote        

Booger says


Didn't know this was an all female project. Is she the one who said it was ok to misplase the vehicles used to put the bridge in place? Or is she the one who didn't have traffic stopped when it was realised that there was damage to the bridge?
31   Feux Follets   ignore (0)   2018 Mar 27, 7:05pm   ↑ like (0)   ↓ dislike (0)   quote        

RafiMaas says
Didn't know this was an all female project


It wasn't.
32   Feux Follets   ignore (0)   2018 May 8, 1:49am   ↑ like (0)   ↓ dislike (0)   quote        

Cracks where FIU bridge buckled may have signaled 'imminent failure'

A key concrete support truss in the doomed Florida International University pedestrian bridge developed worrisome cracks 10 days before the structure was lifted into place over the Tamiami Trail, photographs and an internal email unintentionally released by the school show.

The documents, released in response to public records requests from the Miami Herald, show that FIU's construction and engineering team discovered potentially problematic cracks in the bridge earlier than officials have previously acknowledged.

The cracks were found in late February at the base of a diagonal support member at the north end of the span. Independent engineers have identified that as the point where the structure shattered on March 15 while under construction, sending the 950-ton bridge crashing onto the roadway below and claiming six lives.

Three independent engineers who examined the photos, records and bridge blueprints at the Herald's request concurred the cracks were a red flag signaling potentially critical structural problems. Outside experts have zeroed in on that truss member, identified in plans as No. 11, as being "under-designed" — that is, not strong enough to withstand the pressure from the weight of the bridge it was supposed to hold up.



Because FIU and state transportation officials continue to withhold other critical records under instructions from the National Transportation Safety Board, it's hard to say what the FIU team's response to the cracks was.

NTSB, which is investigating the bridge collapse, has told FIU and the Florida Department of Transportation not to release records dated after Feb. 19, so there are no available public records to document any response from FIGG or other team members to Morales' memo. The Herald has sued to obtain subsequent records related to the bridge collapse. The bridge collapse is also the subject of a Miami-Dade police homicide investigation and families of some of the victims have filed lawsuits.

The Feb. 28 memo and the attached photos of cracking were released in error, an FIU attorney, Eric Isicoff, said Monday. After the Herald contacted FIU for comment on the cracks, Isicoff demanded reporters delete any copies of the documents from their computers.

"Any hard copies that have been made also should be destroyed," Isicoff wrote.

Full Story: http://www.miamiherald.com/news/local/community/miami-dade/article210449384.html
33   Feux Follets   ignore (0)   2018 Jun 14, 5:11pm   ↑ like (0)   ↓ dislike (0)   quote        

FIU had grand plans for 'signature' bridge. But the design had a key mistake, experts say

The design hid a fatal flaw that its designers and reviewers failed to recognize, according to experts who have examined plans and mathematical calculations for the project.

The unconventional placement of diagonal supports in an uneven zig-zag pattern along the bridge produced a complex structural web with a glaring weakness at a key connection point, apparently overlooked by designers at FIGG Bridge Group, say three independent structural engineers who reviewed nearly 2,000 pages of calculations for the bridge at the Miami Herald's request.

The weakness was likely a key factor in its fatal March 15 collapse, the independent engineers told the Herald.

The engineers believe FIGG significantly misjudged what would happen when a large amount of structural stress was placed on a single diagonal strut — a concrete brace that helped support the bridge — at the north end of the 174-foot span. That resulted in an undernourished strut and anchor that could not adequately bear the weight of the bridge and the substantial forces placed on them when the span was lifted into place over two support piers, the outside experts said. That joint is precisely where the bridge appears to have failed — and where potentially worrisome cracks began to appear even before the bridge was installed over the eight-lane road on March 10.

As a consequence of the apparent design error, the diagonal support at the span's north end was so overloaded that additional stress put on it by construction crews tightening internal support rods on March 15 likely caused it to separate from the walkway deck, instantly sending the entire 950-ton span crashing to the roadway in a chain reaction of structural failure, the engineers said. The accident killed one construction worker and five people sitting in cars at a stoplight below.

"The tensioning work could have pushed it over the edge," said Linwood Howell, an Austin-based engineer who is contracted to inspect bridges for the state of Texas.

More: about 5-8 minutes to read, somewhat technical: http://www.miamiherald.com/news/local/community/miami-dade/article212571434.html
34   Tenpoundbass   ignore (11)   2018 Jun 14, 6:16pm   ↑ like (0)   ↓ dislike (0)   quote        

RafiMaas says
. Is she the one who said it was ok to misplase the vehicles used to put the bridge in place? Or is she the one who didn't have traffic stopped when it was realised that there was damage to the bridge?


I think She's the one that said... "Say Cheese!" two weeks early before the support cables were ready.




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