Pedestrian Bridge Collapse Over SW 8th Street HWY18MH009
Vložit
- čas přidán 21. 10. 2019
- This animation depicts the sequence of events leading to the collapse of the reinforced concrete pedestrian bridge over SW 8th Street just north of Florida International University in Miami, Florida at March 15, 2018.
The animation begins with an overall area view showing the location of the pedestrian bridge relative to the center of the city of Miami, Florida. A satellite picture shows where the pedestrian bridge was to be located on the west side of the intersection of SW 8th Street and 109th Avenue. The bridge was intended to connect Florida International University with the City of Sweetwater by extending over SW 8th Street and the parallel running Tamiami Canal. The first section of the bridge that was built was the section over SW 8th Street, and that is the section that collapsed.
Security video shows the construction site where the bridge section was built on the ground adjacent to the roadway. The bridge section was moved from the construction location onto its support piers using two self-propelled modular transporters.
An artist’s rendition of the overall conceptual design, and a photo of the constructed bridge section as placed on the piers are used to display elements of the bridge structure, including the deck, the single row of non-redundant truss elements, and the canopy. Truss elements were numbered 1 through 12 beginning from the south. The 174-foot length and 950-ton weight of the bridge section over SW 8th Street are indicated.
A three-dimensional computer model of the bridge section is used to describe the pouring of the concrete in three stages: first the deck, then the truss members, and finally the canopy. The model is also used to show the locations of cold joints between elements, and to show the steel reinforcing bars and larger diameter steel post-tensioning rods within the concrete. The model is also used to explain that truss members 2 and 11 were post-tensioned to counteract the tensile forces developed while the ends of the bridge hung over the transporters when the span was moved. Truss members 2 and 11 were de-tensioned after the bridge section was placed on the piers.
A series of photographs show growing cracks in the structure at and adjacent to the cold joint between the deck and the bottom ends of truss members 11 and 12 (the north end of the bridge section). The photographs show increasing damage accumulating over the five days the bridge was in place, from March 10, 2018 through March 15, 2018.A photograph from March 15, 2018 shows workers on top of the bridge to re-tension member 11 in an effort to stop the cracking. The collapse of the bridge is shown in a video captured by a dashboard-mounted camera from a truck driving on SW 8th Street.
The animation ends with a picture of the collapsed bridge, with inset photographs showing closer views of truss members 11 and 12, the canopy, and the north or pylon pier where the collapse initiated. - Věda a technologie
I’ve worked on a lot of bridges
Our number one rule was
“No traffic can be around us when we are working”
It seems to me that I spent more time stopping and
Diverting traffic than I did actual bridge work.
I got cussed out by the traveling public more times
Than I can count. No one died in any of our bridge work.
Before watching this video I thought my boss was normal.
Now I think he is a genius.
That canopy looks 100x over weight.
:) No doubt i'm one of the ones who's cursed you for the delay at some time in your career. Guess I should apologize. Sorry dude.
jrregan LoL.
I kinda enjoyed it.
Helps break up the day.
Gives me something to talk about.
Like I use to tell my guys
As long as u know u are doing the
Right thing, you can do just about anything you want.
One time I shut down a freeway during a slow veterans motorcade back from Iraq parade thingie. My co workers were in shock. LoL. Good times
Actually the canopy is a structural element - it forms an I-beam shape, with the "webbing" itself actually being a truss.
But I agree, deficient design. A product of diversity hiring.
Benjamin Esposti I figured that was the case, but I couldn’t say it as good as u. I just think it was way too much
Fashion over form.
Titanium poles holding clothe canopy
Could’ve sufficed and been changed out annually and been about a million pounds lighter. Hindsight is 20/20
“They are 100% responsible. FIGG already had an issue on building bridges. On 2012 they got sue in Virginia for a 90 ton segment of the bridge that fell onto railroad tracks . They settle the lawsuit on their own to keep it on the low, so no one would here about it. Now look what happened in Florida. They are 110% responsible.....”
"These cracks continued to grow over the next 5 days..." while cars and pedestrians continued to pass underneath. People need to be jailed over this.
And lawsuits served.
I agree
@General Bismarck The FIGG Engineer of Record is a male. He is not named in the NTSB report, but was widely reported as being W. Denney Pate. See: www.miamiherald.com/news/local/community/miami-dade/article236250848.html
Nothing is going to happen, if people make enough noise they'll throw some patsy in jail. That is as good as it gets.
@@alias19 before the bridge collapsed some woman named flores practically owned it. now, no mention of that name anywhere here. even her daughter was quoted as saying - I want to be an engineer like momy when I grow up.
Cracks appearing in the bridge for five days and the road below wasn't closed?
Furthermore, it wasn't closed when they were messing about with the tensioning?
Seriously?
Florence Gomer That requires acknowledging that there is a problem...
This is the dumbed down US education standards bearing the fruits of it's labor.
THE PONG LENIS indeed and pc culture.
They don’t give a beeep about people’s lives...
Yeah, I kinda think that passes beyond simple design failures into Criminally Negligent Homicide. The Bridge Collapse from poor design is abominable. But the lack of any basic safety sense or concerns once problems began developing is a depravity.
How can anyone justify not closing the road beneath something that weights 950 tons, when it is non redundant, and showing signs of failure?
by being the same person who approves the construction of a non-redundant design bridge in the first place?
Spiffcats - Thank you. I was scrolling through the comments and hoping for someone to ask exactly what you asked. My own answer would be that this is a prime example of many decision failures and non-competence all the way around.
I used to work for the Dept. of redundancy department.
David James - Really? Maybe we have seen each other around then. I use to work for the DDFNC. We must have crossed paths somewhere because I was always running into you guys. Small world. Had to let the job go though when they stopped serving Twinkies at lunch. One can only put up with so much.
why did they not just pick it up and put it back in the construction sight when they first saw the cracks ....alot of women need their kneecaps broken for this FUCKUP
So basically the design was gimped from the start purely so it would have the aesthetics of a cable stayed bridge? What kind of moron though that was a good idea. The fact the road was kept open to traffic for DAYS with those cracks is even worse, entire departments need to be fired and locked up for this one.
@@Groovy_Bruce
G'day,
Pennypinching Beancounters care much more about cutting their Production Costs than Product Durability.
Deciding to build a Bridge incorporating a "Perfect-Frame Girder" Design (which will fail totally if any one Loadpath is ever compromised)..., was the underlying reason why this Bridge fell down.
Building a "Redundant-Frame Girder" instead (one in which ANY one Loadbearing Member may be removed without compromising the overall Structural Integrity of the Bridge - because multiple Alternative Load-Paths will still be intact...) would have been heavier, & more expensive.
But the Bridge didn't have to Fly, so total Weight should not have been a factor ; whereas being located accross a major Highway made the Girder-Failure fatally catastrophic.
Deeply Professionally negligent devotion to the Profit Motive, or simply rank Incompetance, would appear to underlie this Bridge Collapse ; rather than whatever Fact-Free Misogynistic Fantasy might have motivated your comment, Pilgrim.
Just(ifiably ?) sayin'...
Take it easy,
;-p
Ciao !
@@Groovy_Bruce It was mostly men that designed the bridge.
@@yodaiam1000 Wrong. The original design, by a man, had a tower with cable support to handle such a heavy concrete structure.
The women changed it, and the project was pushed very hard as done by "female engineers".
@@Eighteenxray Please provide your sources. All evidence shows that EOR was Denny Pate. All NTSB documents and dockets indicate male designers and concept reviewers. There was only one female I know of for the PT fabrication design (which was not an issue) and one of the partners of Figg is the daughter of one founding member that appears to have nothing to do with the design other than marketing. I found no evidence for another design that was revised because of women.
@8w9hf89hw A women didn't design the bridge. It was a man who did a mostly good enough job. Obviously good enough isn't enough when it comes to structural design.
At 3:52, those aren't cracks,
*THOSE ARE FISSURES*
Funny. I called them canyons.....fissures works good too.
@@grumerguy
I seen on another CZcams channel (AVE?) where a construction worker said they were trying to tighten a tension rod bolt the day before, and it would never torque to the specification, so, they quit and continued with the other rods bolts...
@@grumerguy Chasms?
What type of fish is it?
Active fault lines
How do you not close off the road with cracks form? Let alone design a bridge with no redundancy?
Most long span bridges don't have redundancy. The lack of redundancy was only during the construction phase in this case. However, those cracks did demand that the bridge should have been shored up and the road closed.
@@SlocketSeven nice thinly-veiled way of trying to blame either women or immigrants (or both!) Occam's Razor applies here. Good ol' fashioned incompetence.
Florida.
@@SlocketSeven I generally agree with that statement. The cracks were much smaller at the time of the move. I am a structural engineer and I would have suspected the start of a shear friction failure if I saw those cracks. But if the engineers was having a bad day and didn't think so much, they may have not recognized the problem or gone back to check the calculations. We see cracks in concrete all the time and you can become complacent. You have to remind yourself to keep on thinking and evaluating. 99% of the time, the cracks are nothing important.
There was no excuse after the move when the cracks were much larger.
Bryce Nelson - A lot of bridges lack redundancy. You don’t necessarily get redundancy with multiple trusses, but you can compensate for lack of redundancy with conservative design and a generous margin of safety.
An example of how double trusses do not guarantee safety is a steel bridge on I-5 in Washington State which collapsed (in one section) in 2013 when an oversize load struck one element of the structure at the top. The bridge could easily support itself and its maximum load with a large safety margin, but could not tolerate breakage of the truss element.
Cracks!
That bridge did not have cracks. It was falling apart and going to fail from the get go.
Metal Mark, Indeed. At the time " cracks " were reported on the news, but seeing these photos! It looked like someone had taken a jackhammer to it. The bridge failed, but there were many failures all along the way. This should not have happened.
It started to come apart the very second they started to move it. I am surprise it stayed together long enough to be lifted into place.
Designed by wahmen & femnazis.
blessOTMA: According to the laws of physics yes it should have happened and did. This bridge wasn't all it was cracked up to be.
For real. Cracks are just that! Cracks. That fucker was coming apart
Crazy that with all that cracking nobody stopped the move
@Al Morrison Agreed. You get what you INspect, not what you EXpect. The cracks prior to lifting showed the structure could not support its own weight (let alone its anticipated live load) when sitting on blocks on the ground in the same positions as the piers. Thus, obviously things weren't going to get better once the bridge was lifted, without even considering possible exacerbating factors from the forces involved while lifting the bridge with the ends dangling. The bridge should never have been lifted.
The photos of the development of the cracks clearly show the symptoms of excessive compression forces in #11, which were present even before the bridge was lifted. Thus, the final decision to further increase compression by torquing up #11 only accelerated the process of failure. They might as well have planted a demolition charge there.
But this was only the last of a long list of bad decisions by multiple parties. Either the design, the construction, or both were bad. Regardless, both the design and construction processes have both in-house and 3rd-party review and inspection. So if either design or construction was faulty on its own, you have at least 3 culpable parties. If both were bad, you have at least 6. And that's just to get to the point of building the bridge on blocks and noticing #11 is already failing in compression. Then you add many more culpable parties for the decisions to lift the bridge anyway,, to let the situation further deteriorate without taking any corrective action for so long, to then apply the incorrect solution, and to keep the road below open throughout all this. And throughout, there are safety personnel with the power to stop work when they see unsafe conditions. Truly, the list of those who should be hanged is long.
This isn't just the failure of 1 bridge, it's a failure of the whole system we've set up to ensure such failures don't happen. To me, that's the most appalling part of this whole tragedy. All best practices in engineering and construction, and all safety regulations (which are largely based on those best practices) are written with the blood of the victims of previous failures. There's nothing worse than refilling the bloody inkwell and having nothing we didn't already know to write with it,
Lots of inspectors, reviewers and safety personnel all along the way let things slide here. Hopefully, their peers around the world will take this tragedy as an incentive to tighten up their work.
No one wanted to be accused of misogyny.
You nailed it.
Beyond crazy. Criminal.
Criminal negligence.
There should be felony charges.
@@2Truth4Liberty In one building collapse in South Korea. The builders and designer were criminally charge for the collapse.
Unbelievable that this design was even able to make it out of the drafting room, make it look strong with cable stays that were just decorations, and then under engineer it so it cannot hold its own weight.
3:47 -- Gross negligence.
3:58 -- Even greater negligence.
4:02 -- Wasn't anyone looking?
4:15 -- Unbelievable.
I love how at 3:47 you can see they tried to cover it up with a stupid banner. "Oh yea, nothing to see here. Don't worry, the bridge is safe." The one at 3:58 was after it collapsed, you can tell by all the steel rod covers that were pulled out of the concrete.
Just WoW, non-redundant concrete pillars 🤬... Never could imagine this is possible anywhere I the World
@@hrissan Only in woke Amerifat.
Aesthetic over function in civil construction. This is what happens.
But hey, steel truss bridges are "ugly". Was it worth it?
Frankly, I think THAT design was UGLY. I believe in the old adage, "form follows function". The HP Long Bridge outside of New Orleans is constructed from structural steel and it is BEAUTIFUL. And it has carried auto and train traffic for many, many decades. Form follows function! I mean, if they wanted the look of a cable stay bridge, WHY NOT MAKE IT A CABLE STAY BRIDGE????? Duhhh!
They should have used a pre-assembled concrete arch.
Which is ironic because steel beats concrete in the aesthetics department every time. There's nothing that makes you feel good when looking at concrete.
That’s what I was thinking too!
That's designed by structural engineers, not civil.
I hope the engineers of this project never see another job. This whole project had failure from the start, starting with the design.
All women/all minority engineering company = they already have more contracts.
@@seanwatts8342 czcams.com/video/Y5sceezeaY4/video.html
@@rcknross I don't have a problem with women in engineering. I'm in grad school working on an M.S. in engineering and female students can be great to work with *I DO HAVE A PROBLEM WITH INCOMPETENCE killing people* www.eurthisnthat.com/2018/03/19/all-women-engineering-team-gets-side-eye-for-collapsed-pedestrian-bridge-designed-by-them/ This was the SECOND bridge designed by the _now bankrupt_ Cuban immigrant owned, all woman design team from Munilla Construction Management (MCM) that failed.
A company that employs engineers based primarily on their genitals rather than their competence, qualifications & experience? What could possibly go wrong.
@Joe Kinchicken The lead engineer of the project was a white guy named Denney Pate.
Normally I would have just said was named Denney Pate but apparently we are making this about sex and race or something.
www.enr.com/articles/47108-bridge-designer-testifies-on-evidence-one-day-after-osha-slams-figg
What women think men want: girl in tight dress with makeup
What men actually want: more informative no-nonsense analytical videos like this giving closure on tragic events
AvE - czcams.com/video/KtiTm2dKLgU/video.html
I want the girl in a tight dress
Edward Saenz all things considered he was pretty much on the money even then, but I do wish he’d revisit the topic and watch this video, because it wasn’t one or two cracks the day before like he originally thought, it was endless cracks from day one.
I liked that video, but I was always curious to see what the official investigation would reveal.
How about the girl with the tight dress off? Regarding the official investigation and what it might reveal... probably that they were idiots.
rgtrooper13 nuur
100.00% criminal actions by designers, site supervisors and construction officials.
ABSOLUTELY!!!
Designers failed by under-reinforcing for shear, but that should have been picked up way before construction. If the site engineers agreed to tensioning with those cracks present, especially without closing the road, it was criminal negligence. I doubt the contractor just decided to do it without a go-ahead. The video doesn't give enough detail on whose fault it was.
@@SuperAngryHippo Everyone who was on the site and saw the cracks is at fault for not saying anything. Down to the lowest employee. I would've called 911 if that's what it took to get the road shut down.
@@ffjsb That depends on the level of knowledge of the people on site. Like I said, there isn't enough information in the video to come to conclusions. Generally it's decision makers who are liable. I just wanted to point out that the designers were likely not at fault. I doubt you'd call emergy if you're a construction worker who's doing what he's told, without the engineering knowledge required to understand why the cracks were there in the first place. This kind of stuff isn't about emotions mate.
@@SuperAngryHippo It's about cracks, though. Seems rational to react to those.
Bridge: * cracking *
Engineer: This is fine.
I think the engineering was female
The Executioner so what? That has nothing to do with it, there are many cases of negligence from male engineers too.
@@dominicancheif117 Wrong, dumbass.
@@bilbobaggins4710 The FIGG Engineer of Record is a male. He is not named in the NTSB report, but was widely reported as being W. Denney Pate. See: www.miamiherald.com/news/local/community/miami-dade/article236250848.html
the cracking was only part of the art
I really hope the ones responsible for the decision to not close the road under the severely damaged bridge for DAYS is going to jail for lifetime for manslaughter.
Negligence. Murder is premeditated and proactive.
That level of negligence should be criminal.
@@TheSpacecraftX thanks for the correction
I hope you are in many traffic jams. Do you also think joggers should wear helmets?
@@NathansHVAC what's wrong with you? Do you really think that people should be crushed to death because that's better than to close the road and drive around it?🤦♂️
A bad concept, bad engineering and bad construction management; a deadly mix.
The design looks fine, its just poor execution. There was supposed to he cables to support the weight end there were none there. Should have built the tower first then the bidge
@@menthasis4798 The "cables" and tower are not load bearing structures, see 1:19
@@menthasis4798 as [SAW]Spitfire stated. The cables were entirely for aesthetics, not structural at all. If anything it would have fallen faster due to the higher load. people died because the dumbass architect wanted the bridge to LOOK like it was supported well.
Menthasis the support pillar was the equivalent of anime filler
Add into the mix the known political corruption in Dade County, and you have to wonder how many inspectors were paid off.
Why didnt they just actually make a cable stayed bridge instead of just having tbe aesthetics of one?
My thoughts exactly
probably cost.
@@AndrewFrink Too bad this bridge cost them many times more what multiple structurally sound bridges would have in the end.
They wanted some that look different. This was built more for looks than function
@@davidhenderson3400 well, from what happened, I would say looks more like it didn't function.
OMG they knew it was unstable & didn't shut down the road??????
I'm no engineer but everything about this sounds so dumb
I am an engineer (BSME) and this bridge and the construction process is a billboard-sized warning of what not to do.
Instead of Tacoma bridge they might start showing this too for structural design
FLORIDA ... yu can't say it w/out saying "Daaa"
Probably the only good thing here, is that it was *so* bad, it failed before construction was finished.
Imagine if it had made it into use by students actually trying to walk over the thing.
Welcome to Florida!
I might be a mechanical engineer by training, but even I can tell, by looking at those cracks, that that member had lost all of its structural integrity. At that point there was no saving the bridge. At that point they should have transported it back or demolished it. Tensioning the member onto the already damaged joints was absolute folly and no one should have even thought it. It looks like it started with a bad design and then was compounded by bad decision making on inspection of the damage.
To follow in the spirit of your comment. I might be a network engineer by training, but even I know that when there is a problem with something heavy that is at a raised height, the first thing you do is clear the area below it and keep it clear while you work out a solution to the problem. :)
@@kencramer1697 And to follow from your comment, I might only be a historian by training, but even I could tell that when an experimental-design bridge develops cracks in the load-bearing joints that appear on day one and grow wider and longer every day, it's time to get everybody out of there.
@@deppexcavation5483 "structural integrity is GONE." I do not think it was ever there to start with.
@Graham Welby Oh, I could see the numbers being well over a hundred. A fully loaded bridge and a bus or two under it.
spacecadet35 Don’t forget the probable paid-off inspector. How could any inspector with integrity sign off on this?
A steel bridge for this job would have been the obvious choice, even to a moron. 950 tons of dead weight for a foot bridge that couldn't hold itself up.! alarm bells should have been ringing for the designers right from the off. Jail Please.!
The core problem with this an many other projects is the board or whatever is the decision making body is sold on the idea by the architects and engineers that their names are going on a plaque on an "iconic structure." Instead of handling it as a structure designed to maximize utility, keep the costs low and be completed as quickly as possible, they are sold on an art piece. A library was built in Baton Rouge which was sold as an iconic piece having part of the building cantilevered over a plaza. There were no restraints in fitting the building within its footprint. The cantilevering failed. I'm sure the cost per square foot was higher than something straightforward and the building was not in use in a timely manner.
I agree. Maybe they can brush up on their engineering at the prison library.
Florida has some weird obsession with concrete
The reason we use so much Concrete in Florida, is because when it comes to Hurricanes and other high wind events, Concrete wins every time.
Check out Miami-Dade Building Codes. Every new structure must be built to withstand 150+ MPH winds. My home was built to Miami-Dade Code. We were in Irma and saw winds of 135-145 MPH, the only damage we had was a screen got ripped.
This bridge was criminally designed, criminally installed, and was unable to support itself let alone withstand a CAT4 Hurricane.
@@juancreepo Yep, that does make sense. Though it's never good practice to apply the one thing to all the things.
Meanwhile in France, the ancient Roman aqueduct bridge "Pont du Gard", built c. 40-60 AD still stands to this day.
It is interesting that at about the same time this structure was being built, University of Miami nearby was also building a pedestrian bridge for the same reason. Theirs is a conventional steel truss design, however, but with design elements added to make it more attractive. A side-by-side comparison of these two structures would be instructive.
The University of Miami pedestrian bridge is a 125 foot span which weighs about 66 tons. Extrapolating to the length of the FIU bridge, we might expect it to weigh on the order of 100 tons for that length. That would make it about nine times more efficient by weight if the FIU design worked (which it didn’t). I wonder how the costs compare (not counting all the extraordinary post-collapse costs).
Static loads on bridges go up with square of the length not linearly. That said, a steel bridge would have been lighter.
@@allangibson8494
Square of absolute length, or longest unsupported length?
@@bcubed72 The unsupported length - but on this design the entire length was unsupported.
I'm no civil engineer, but who in the hell thought concrete was a good material for a truss bridge?
All structural engineers are civil engineers, but not every civil engineer is a structural engineer.
College leftist administrators chose an incompetent architecture firm based on diversity requirements instead of merit.
Hit nail right on the head there someguy.
The diversity hires.
The bending moment of that deck span being restrained by a few angled pillars tied into the roof beam, and the central pillars not adequately reinforced and not post tensioned. The serious cracking due to post tensioning of the abutment piers was a clear warning that the pillars could not contain the compressive force of the post tensioning. At the very least, several temporary piers were required to support the deck while all cable tensioning and grouting was competed. Surprised to hear the tower and cable stays were not structural. This a design of style over substance.
Not closing the road to traffic during construction was a 'feature' of this plan. It would have failed anyway, due to design errors.
Engineer and architect: it doesn’t need redundant trusses, it’s only a pedestrian bridge, plus, it’ll look really cool and modern.
Me (untrained fool): yeah, but the bridge itself weighs 950 TONS!!!
Also me (untrained fool): and it’s crumbling to pieces right before our eyes.
Me: If you are going to make it look like a cable stayed bridge why the hell not use them for support?????
Useless engineers
@@johns6704 The answer seems to have been conflicting requirements from the client. One party at FIU wanted to showcase the new "self-cleaning" bright white concrete developed at the university, therefore, a concrete truss. (N.B. the strength of the new material was not a problem, only how it was used.) Another party at FIU took a look at the result and said, that's not eye-catching enough, I like tall cable-stayed bridges better. And the designer said no problem, I can make it look tall. Now, clearly the engineers have a responsibility to tell the clients when their ideas about looks are impractical ... Also, the money spent on the faux cable tower meant underbudgeting some necessary things, like peer review -- an unqualified low-bidding peer reviewer was chosen and told to do just a brief review.
You know it was an ''affirmative action'' hiring job, right?
@@dashwood5474 Not true, stop repeating this nonsense. www.snopes.com/fact-check/was-all-female-responsible-bridge-collapse/
Excellent overview of events. Thanks for posting. Can we get a follow on video detailing the joint failure? Juan.
yeah, I have difficulty believing it was just slipping with rebar connecting the parts together and tension rods going through all of it. in order for it to just slip, the rebar and tension rods would need to shear off as well. Either something isn't known, or it is more than just slipping joints.
@@Zarcondeegrissom
The outer longitudinal tension rods in the deck were not yet tensioned only the 4 running the centerline. The untensioned deck could not carry the load once 11 was taken out of tension. Once the load was transferred from the canopy thru member 10 to the deck is when cracks began to show.
The slip at 11/12 was really a punch out when the canopy failed at 11/10 pushing both those members down and out in opposite directions
@@tommypetraglia4688 That doesn't agree with what the NTSB is reporting. The NTSB clearly states the failure started at node 11/12 (a deck joint, not a canopy joint. I don't think the NTSB even mentions the DECK tension rods. So, do you have any evidence that "the untensioned deck" had anything to do with this accident?
I don't think it mattered, and as was said a few times in the press briefing, even if the surface was properly roughened, it still would have collapsed because the design was inadequate for the loads on it. all of it, not just the 11/12 joint.
As I typed elsewhere, The column would have needed 18 square inches of rebar to hold the load on it, the column had 4.8 square inches of rebar. That's a 300% deficit in rebar to handle the loads on it, I think that's approximately how Mr. Sumwalt worded it in the Board Meeting. (I just finished watching the 3 hour Board Meeting vid.)
I wondered if our buddy at blancolirio would be covering this. I look forward to your report! Any word on you getting access to the flight simulator for 737 MAX updates?
Thank you NTSB for ensuring reports like this are made available to the public.
I really like how when the narrator stops talking, the background noise the microphone picks up cuts because they stop the feed from the microphone temporarily. And then when she starts speaking again, the background noise picks up a moment before she begins. I love it, it's such an 80s 90s thing and it's awesome.
I think everyone involved needs to revisit the series Engineering Disasters.
And read the Haddon-Cave report. (Different industry, but the safety management principles still apply)
They should rather revisit the series Surviving in Jail.
Florida Engineer doesn't close the road before working on the damaged bridge.
I use to close Los Angeles freeways for bridge work.
I use to get cussed out so much.
I’d tell the CHP
Either we close the road or someone dies.
He wouldwalk back to his car and go close the road
phuc ewe I am a live. Unlike those who drove under this bridge
It was a diversity hire. All woman engineer team.
Florida is the key word.
jeff James Flori duh
Five days of cracking seems like more than enough notice that something was seriously wrong. Minimum should have been closing the road right away. Then on top of it to re-tension in the area of cracking is akin to picking at a sore that is not healing properly. There should be some very serious punishments inflicted for this stupid and ill thought catastrophe. Licenses should be rescinded and people banned from ever working in the industry ever again.
And these were "smart" people that know better than everyone else overseeing this project.
I have done this type of installation a number of times. The move plan for this span laid out by the drawings WAS NOT followed. The move plan had the Shirley trailers located farther out towards the ends with more beams, plates and bracing under the span to spread out the loads. The initial reason for not following the plan was given that it would take too long to fill the west side of the road way with dun age and fill to allow the westward trailer to drive closer to the westward pier. The on site supervisor made the decision to move the westward trailer in on the span with a phone consultation with the engineers. To work on the span without shutting down the traffic should lead to manslaughter charges for those that made that decision. When the cracking first appeared it would have been prudent to start bracing the span with erection supports on the ends as the structure was losing its structural integrity and was heading for a failure.
The design should have never been approved in the first place. They knew it was failing for days from the moment it was installed. Traffic should have been stopped as soon as the cracks appeared and they should have immediately removed the span. Everyone involved with planning and overseeing the project should be in prison for decades.
I agree.
Somebody said it was dangerous and to stop traffic. But TIME and NOT stopping traffic were given priority over safety--it was why this design was approved. That somebody had no credibility with the bean counters.
Yeah, that didn't happen.
The whoever designed and approved this design should be in prison
I'm not an engineer in any sense. But even i could tell by those "cracks" there was a hell of an issue. May those who passed rest in peace
So they had progressive cracking and still allowed traffic to run under the bridge.
The "they" should be in handcuffs.
Wrong. They had progressive cracking and then tried to cover it up and hide it by attempting to retension the bridge while traffic was allowed to run under it. Let’s call it what it is... an attempted cover up of a failure.
An excellent video, even I could follow it. It seems like the design was very marginal. I did not realise the truss members were cracking, and photographs existed of these growing cracks for days before the collapse happened. Surely those cracks should have been more than sufficient warning to close the road and tear the structure down before it failed on its own. Why was it a pretend suspension bridge anyway, was the winning of the contract more dependent on aesthetics than engineering ?
Who would look at those gigantic cracks on a new bridge and think that’s OK?!?!
Jon Doe A paid-off inspector, that’s who.
Who designs, who approves, and who builds something that appears to be so close to total failure at all times.
I wondered this too - first time I saw it, I noticed that the deck of the roof is extremely thin. Yes, concrete has high compressive strength,but I worry about the effects due to wind or such, where the forces may not be vertical.
Whose who are in charge of the local infrastructure who wants something for nothing and pocket the rest.
This crap happens all the time. No redundancy because it doesn't 'look elegant' (and it's cbeaper to build - at least the first time). In California, for decades, they built structures with very slender columns. But if you just stood back and looked, they appeared way too flimsy. And of course they were once some large earhquakes hit. A bridge built today probably has 10x the concrete and reinforcement it did in the 60s.
Florida International University was responsible for design, approval and build according to Construction Engineering & Failure Analysis: czcams.com/video/5-M7S1qP0jo/video.html
The deck collapsed before the wires were installed. There should have been added supports under the deck during construction and before the wires are installed.
It's not a radical structure, it is a failure of the most basic truss action of a simple king post truss bridge. If the shoe joint that transfers the angled compression member into the deck in tension is not strong enough, the truss fails. It doesn't get any more basic than that in truss design.
The design of the truss to appear to be cable stayed required changing the angles of the supports so the loads were not distributed equally. I thought the cables were designed to provide support but this video suggest that they were ornamental. That answered my question as to why they would put the span in place without the cable stays.
Ted Cook - It certainly is a radical structure. Building a truss bridge in reinforced concrete is unusual to begin with. To attempt one of this length with no arch is unique, I expect. And the truss was asymmetric, only for the aesthetics. Is there another truss designed like that anywhere?
@@GH-oi2jf Exactly, a truss is designed to make use of compression forces balanced against tension forces. Concrete is weak in tension so steel has to be used to handle tension but a concrete truss suffers in the transition areas, which is where this failure occurred.
@@GH-oi2jf Good point. Building a truss out of concrete does seem to be very rare. Probably due to the fact that having a concrete tension member has few benefits and just adds weight. I guess my question would be, what would the correct detailing of the joint looked like? Where the compression member 11 delivers a point load, and that load must be distributed across the width of the deck, looks like about 16', to the tension rods in that deck which appear to be equally distributed across the width of the deck? Lots of steel bars coming from that point diagonally like the strings on a hammock where they attach to a point and then distribute a tensile load?
I find it remarkable that the joints between the trusses and the deck are made as cold joints flat on the surface of the deck.
When I, as a complete layman, would have had to design that I would have left triangular cavities in the deck during its pour (using a temporary filler) and then fitted the trusses into those cavities.
950 tons, that's the weight of about 4.7 modern, diesel-electric locomotives!
Benjamin Esposti all that for pedestrians?!
The chassis of a locomotive would have made a better bridge.
@@SocksWithSandals top comment.
Suspend them in air with a span of 174 feet and walk on them! Lol!
misread "about 4.7 women"
The engineers should be in jail and so should the state supervisors for negligence and manslaughter but we know that won't happen.
Oh, then maybe they were the ones designing the Hard Rock folding highrise......
The same engineering firm designed the rebuilt I-35W bridge that had previously collapsed due to an engineering design error (gusset plates in that case). See www.figgbridge.com/ slideshow. Same dudes!
All-American Handyman same woman actually
If the State refuses to press charges then it's time to lock and load and declare open season on the designers, engineers, and anyone else that approved of that bridge being built in such a half assed way.
A company that employs engineers based primarily on their genitals rather than their competence, qualifications & experience? What could possibly go wrong.
We know how to build bridges. There is no excuse fot building an unsafe bridge that cracks. You can make a normal bridge look sexy without having a structure with no redundancies.
@Pacified Democracy Not true that it was designed by women, stop right now with this nonsense. www.snopes.com/fact-check/was-all-female-responsible-bridge-collapse/
... Roman empire build bridges which are still here, 2000 years later... what a evolution
that cant handle 200 tons
@@dknowles60 well, they are designed in order to do a job, and they do it.
And I don't know exactly the weight of those structure, but with an aqueduct, the first level arch carry the upper level, and I think it's a little more than 200 tons.
@@geekdaddy5351 wrong. its simple. road bridges are not design to carry trains . aqueduct is not design to carry trains let me put 4 diesel locomotives on any Aqueduct and it will fall down
@@dknowles60 I am ok with what you say : can't carry 4 locomotives. But you have to be ok with what I say : those builds have done their job, during a long time (don't work anymore today) and their builders have amazing skill that we're have lost today. I'm not sure that something so big, as aqueduct, build today will be there in 20 century.
Are we ok with that?
With all the time tested bridge designs that exist why work with such a questionable design in a busy area?
Seeing the scales of the cracks over those days, and the fact that nothing was done to make the area safe over that time is astounding. Criminal neglect and severe corruption. Some people better be put in jail for a long time over this.
And to think FIU was going to add concrete tables and planters to please students. Talk about many more tons of weight. Plus a hundred or more students on this during school celebrations (10 tons).
"Any idiot can build a bridge that stands, but it takes an engineer to build a bridge that barely stands."
Actually I don't see many idiots building bridges. What most people fail to realise is that engineering isn't about making something bigger and stronger. To use your language "any idiot could do that".
Engineering is about making something that is useful, practical and structurally sound by using the *fewest* most *cost efficient* materials as possible and doing it in a timely non labour intensive manner.
That's basically what he said tho. I think you two are making the same point
@@tomahan044
Lol. You may be right, but it sounded to me like he was denigrating engineers.
I can't stand it when people complain about the skills of others, when they lack them themselves.
@@jtveg I'm certainly not denigrating engineers. It's a truism I'd heard years ago that I finally had a use for.
Read it again as a joke... we're making the same point. "Anyone" can build a bridge given unlimited materials, personnel, and time. Only "someone" with the special education of an engineer can build a bridge that is on budget, on time, and without wasting resources.
@@macmedic892
Ok. I get you now.
Everyone that watched those cracks in a 950 ton structure hanging above the innocent public below grow larger and larger for 5 days straight and did nothing should pay a price. If they had the ability to raise concerns or shut this site down and did nothing, criminal offenses should be waiting.
It appears that EVERY bad choice that COULD be made was included in this single bridge.
A : make it so it has MANY single-points of failure...
B : tension and untension
C : don't close down OR warn people when the cracks are noticed
D : don't close down or warn anyone when cracks are growing
E : let cars go under and have people AND bridge workers on the bridge when you try to fix a clearly failing bridge!
why weren't the guys on the top of the bridge harnessed to the crane nearby?
Simple, clear, and concise of all the presentations that I have seen on this failure.
Insightful and well done video. Straight to the point
Total incompetence. First the design was asinine. Two, when the bridge started cracking that was time to stop and clear the road. Three, why was traffic still running when the thing had major structural cracking. It had already failed before the thing collapsed. The bridge is garbage at this point. A total loss and needed to be dismantled then and there. Additional tensioning wasn't going to fix it. In fact it may have actually caused the collapse prematurely because it was going to collapse either way.
Let’s make something unusual and distinctive that will garner us a lot of attention.
All other concerns are secondary.
Well, mission accomplished.
I don't think it's a bad mission to try to develop something unique to improve pedestrian experience. But if you're designing something structurally distinct then that requires a lot more caution on calculations and a simple mistake might slip through the cracks - especially when the cracks are an inch wide and several inches deep.
This bridge could have been constructed of steel in a much shorter time and had a much stronger bridge. There are temporary pedestrian bridges that can be set up in a few hours. They installed a 210 foot long pedestrian bridge over a river near where I live last year that cost $1.5 million. It was installed in a couple of days after being built in sections off site. It could have been assembled like this bridge was and moved into place.
So the whole ‘cable-stayed’ part was just for looks?!? How many millions did that cost?!
Anyone with a functioning brain would've closed down the street
The concept didn't look especially beautiful anyway imo... The so-called 'canopy' was actually a massive concrete structural member adding great weight - surely they could have had something that looked equally good with a real cable stay method and a lightweight canopy to keep the students out of the sun.
That's a valid secondary point. The damn thing was ugly anyway.
I didnt think it was ugly, but I love cable stayed structures. The problem was with the concrete, this design should have used steel. Cables and concrete don't work visually, and structurally, steel accommodates them better by being easier to connect to.
'Design is thinking made visible.' What were they all thinking!? It was a deadly mix of hubris, carelessness and stupidity.
I agree with 99% of comments, but I’ll give a thumbs up to this presentation, it was perfectly explained. Thanks NTSB.
OMG! Those weren't just tiny little cracks.....those were CANYONS!!! Those were signs of structural instability and imminent structural failure!!! Whoever designed that bridge failed miserably! It looks like somebody wanted to be known for building a structural marvel rather than a functional bridge. SMH.....
And the engineer still gets to go home to his loved ones with little repercussion...
Josh Brobud As well os the project supervisors who saw the cracks. Wasn’t there a county inspector?
*her, and no, the firm is bankrupt and civil cases are proceeding
@@JimoftheSlim the engineer of record is a man named Denney Pate
@:2:03 - and "the design of the bridge was non-redundant"
tocrob a nice way of stating that it was poorly designed.
I'm from Miami, I grew up down the street from where this happened, and this comes as no surprise to me. I'm glad I moved.
Wow ! I knew some of it, but the total is stunning. Each diagonal member is in compression, but also each successive diagonal member, beginning at the center of the span must carry its load, plus all the loads toward the center. The last diagonal is carrying all the loads. The sin of it is,, That IS a cable stayed design,, but they had no intention of it being cable stayed.
And the developing cracks, especially over a 5 day time span, were a clear and certain observable failure. That was absolutely denied and ignored for what it was. The designer was wrong, completely faulty design. The engineer, or engineers were factors off in their calculations, and the contractor was abhorrently negligent in not saying, "No." "Stop."
It is said failures are rarely simple, and this one can share blame all the way from the professor that envisioned it, to the grunt who was shoveling dirt that day. One take away. That professor that designed it? Should never,, never, be allowed to teach,, anything in an engineering school ever again. Every student he taught should be examined for what they were taught.
Form, function, materials,, that is the core of engineering and design. The professor got all three wrong. In my opinion.
It was designed by Munilla Construction Management, Inc. in partnership with FIGG Bridge Engineers (FIGG) of Tallahassee as a sub-contractor. Who is this 'professor' you're talking about?
www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&uact=8&ved=2ahUKEwirvvrUw7XlAhXRwVkKHdB4C_IQFjAGegQIAhAC&url=https%3A%2F%2Fwww.osha.gov%2Fdoc%2Fengineering%2Fpdf%2F2019_r_03.pdf&usg=AOvVaw1jY2CueYG-9X86X2pmi6fd
I remember being at a loss for words when realizing they were making a fake cable stayed bridge which was actually just a really long concrete bridge they were hoping would stay standing with virtually no supports in the middle
This, I hope, will be the text for many a sermon in engineering schools from now on.
Thanks for the clear information.
"Never trust a truss" is what I've heard.
A *concrete* truss, no less.
There are many safe truss structures.
@@GH-oi2jf How many *concrete* trusses have you ever seen?
@@boggy7665 - few, but PC just said “truss.” There are countless safe steel truss structures.
I worked at a place that made concrete beams for bridges. You could have made this bridge with ONE of those beams and been done with it. But no, it has to look pretty.
“The bridge design was non-redundant, meaning that failure of one individual truss member would cause collapse of the bridge.”
So this design was doomed from the start. How the hell was this allowed? WTF?
With real cables, it would be stronger AND have redundancy. But let´s not do that.
Pen Tool, That's an interesting notion, but a very large number of systems and components in this world are of a "non-redundant" design, including many common safety-critical ones. They are not only 'allowed', they are used practically everywhere. A seatbelt, a lightpole, most lifting hooks, the wing of a commercial jetliner. These are just a few examples of non-redundant design. The problem here wasn't a non-redundant design, it was an inadequately weak design.
There was an article about the lead engineer for this project and how she started her day. As soon as this happened they put a bunch of "notes" across the top of the article saying that she wasn't actually the lead engineer. I wish I could find it now.
The lead engineer was male.
Yeah, concrete's really known for it's flexibility. A 174 foot long foot bridge (just people walking)..and it weighs 950 tons. This is an embarrassment to structural engineers and architects.
So you mean to tell me that the bridge was failing BEFORE it was even placed on the piers and they still gave the green light? I’m through.
Makoto Ren It’s called political corruption and payoffs
Very well guys... Love-Love !
The weight of that bridge is incredible! That is far over the weight of four modern, six axle, locomotives. Have you seen the concrete bridge supports used for railroad bridges? They are like 5 feet thick. Can you imagine four diesel locomotives stacked on top of each other and the type of bridge needed for that amount of weight? As someone who has worked a fair amount of construction. You would think that out of the hundreds of people involved in this project from pencil to concrete, a number of them would have noticed these problems. I remember reading about cracks and pictured hairline cracks here and there. But those cracks look like earthquake aftermath!
As a "natural engineer" I can tell you this: I believe the failure was in the design of the bridge and had less to do with "cold joints" and that the cracks on trusses 12 and 11 were due to the forces coming from the area intersecting trusses 10 and 9 directly on the deck, this is where I believe the failure began. If you observe the trusses 1 thru 12 from right to left, the trusses progressively change until they achieve an almost 90 degree at 10 and 9, the design of the bridge seems to be putting an un equal amount of pressure at that point (also down the center of the deck). The cracks at 12 and 11 appear to be separation cracks not compression. If at the point between 10 and 9 the bridge begins to sink (lower in elevation) due to compression, then the area at trusses 11 and 12 will crack and appear to separate. If you observe the collapse you will see the failure start on the deck just after point 10 and 9 followed by the canopy between 11 and 10.
That is because they hired people that fits their narrative and not engineering skills. I believe it was five women. They kept that out of the Media. Just like this Sub that went down to the Titanic, today is their last day alive if not rescued (very unlikely)The CEO said he didn't want to be like most and hire a bunch of 50 year old white men so he hired a very young and diverse group. Bet he wishes he hired the 50 year old professional white men now.
Completely inexcusable that the road wasn't closed or there were not secondary countermeasures put in place (eg: cranes ready to catch the bridge if it failed, or buttresses under the bridge in places between the cold joints). The later could have been done without closing the road (maybe a few lanes). I am sure money was the reason it wasn't though.
Design and engineering at it's best, a very good example for FIU students.
5 days of structural cracking and determined it could be fixed, Wow! Had no idea the concrete was showing that kind of stress which is a sign of something deeper.
Wow, made too heavy with less reinforcement.
Thank you for your work. You are enabling our nation to rebuild its aging infrastructure in a safer way.
No redundancy, very unusual design, not closing traffic with cracks, not closing traffic while repairing...... high-risk behavior by architect and builders!
Arm chair quarterback here, reporting for duty :-P
The whole design screams form over function. Non load carrying "suspenders" (aka. purely decorative extra weight). A dozen trusses, each and every one of which is a single point of failure. I guess people literally have to die before designers and city planners understand that they have to dial back on how pretty they think something looks so that it can serve its actual purpose and not kill anybody in the process.
Manuel Barkhau -- all-female diversity hire except for the lead person. That explains the form over function until it reached lead person.
@@thomaspayne6866 Incorrect. The claims about the construction firm (MCM) have been thoroughly debunked. (www.snopes.com/fact-check/was-all-female-responsible-bridge-collapse/). They are also not responsible in any way for the design.
The lead design comes from a man. He is also the engineer who inspected the bridge before the collapse and said it was fine (www.enr.com/articles/47108-bridge-designer-testifies-on-evidence-one-day-after-osha-slams-figg)
Pretty sure if I saw cracks like that I would have moved the bridge back to the side of the road. Don't put me on any jury's.
Soooo I guess every quality engineer in the country was busy when this death walk was being designed?
An excellent video. 💙 T.E.N.
My grandma lives in sweet water and the day I went I still remember seeing so much rubble it was tragic
These inclined cracks are signs of shear failure
Bring back the people of Ancient Greek. They were clearly better engineers
That is actually a fallacy. We only know of the Greeks what the best engineers made, that's why it stands today. You dont see all the failures they too went through. I get the joke, but still
There would never have been a heavy load on that bridge so the design failure is astounding. That bridge really just had to support itself! FL DOT is also to blame (if they owned that roadway). They should have minimized traffic flow under that work until it got full approval. I wonder if they were even notified of the potential issue as it developed. Though, it is their responsibility to monitor it.
jrregan - But the dead load is a heavy load, several times the weight of a conventional steel through truss design.
@@GH-oi2jf 1000t isn't much in this business, but you cant make any important mistakes, that will not be forgiven.
On a pedestrian bridge like this the live loading is almost negligible compared to the deck weight.
Some one should have put up a safety pier/s to catch /stop from more cracking/collapse... very irresponsible!!!!
They continued building as they documented the failure of the bridge. Just start writing out the checks
I cant believe they allowed traffic with those cracks in place.
There were cracks while still in the construction yard before being placed on the piers, and they still went ahead and put it over the road. Unbelievable! Did they expect the cracks to disappear? Of course it got worse.
I'm not an engineer, but ....
oh, wait ... this topic is about engineering. So, I'll STFU!!!