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Crack in FIU Bridge was reported days before horrific collapse

Crack in FIU Bridge was reported days before horrific collapse

The death toll has now risen to 6.

https://www.youtube.com/watch?v=IPthP3MXcs8

The recovery operations continue after the collapse of Florida International University pedestrian bridge. As crews labored to lift, cut and dig through 950-tons of debris, the death toll has risen to six people, with 10 more reported as sustaining serious injury.

While the causes of the disaster are still being investigated, there is news that cracks in the structure were reported to the state’s transportation agency two days before the collapse.

While rescuers worked through the day and night to clear the rubble, the Florida Department of Transportation said late Friday that two days before the bridge collapsed the lead engineer responsible for the project had left a voice mail with an agency worker saying there was cracking in the structure.

The FDOT worker did not receive the voice mail until Friday, the agency said in a statement that included a transcript of the message from Denney Pate with FIGG Bridge Group, which engineered the structure.

“Obviously some repairs will need to be done but from a safety perspective we don’t see that there’s any issue there so we’re not concerned … although obviously the cracking is not good and something’s going to have to be, ya know, done to repair that,” Pate said in the voice mail transcript provided by FDOT.

Then, hours before the bridge fell, the engineering company for the bridge held a meeting to discuss a crack on the structure.

The engineering company, Figg Bridge Engineers, delivered a technical presentation on the crack, and “concluded there were no safety concerns and the crack did not compromise the structural integrity of the bridge,” the statement said.

The construction manager on the project and representatives from the university and the state Department of Transportation attended the two-hour meeting, which was led by Figg’s lead engineer on the project, W. Denney Pate.

…At no point during their communications, the department said, “did Figg or any member of the F.I.U. design-build team ever communicate a life-safety issue.”
Whether the cracking contributed to the collapse, which killed at least six people, remains a key question in the investigation.

Construction crews were working on a diagonal beam at the north end of the structure at or about the time of the collapse, according to information the National Transportation Safety Board provided to local members of Congress. Workers were tightening cables that ran inside the beam.

Meanwhile, the names of four victims have been officially identified as recovery crews continue their grim task.

Miami-Dade police have identified four of the people killed: Rolando Fraga Hernandez; Oswald Gonzalez, 57; Alberto Arias, 53; and Navarro Brown.

The bodies of Fraga Hernandez, Gonzalez and Arias were recovered from crushed vehicles that workers extracted Saturday morning, police said.

The family of FIU student Alexa Duran has said that she was killed in the collapse, but police have not named her as being among the dead.

…Workers covered the crumpled cars with tarps and placed them onto flatbed trucks that took them away.

Crews were “paying respect with a moment of silence” before sending them to the medical examiner’s office, Miami-Dade police Director Juan Perez said.

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Cracks in concrete are not unusual, especially if on the tension side of the beam where the reinforcing bars are actually carrying the load. So there is no point focusing on this until there are more details known. May be a red-herring.

    alaskabob in reply to rmschne. | March 18, 2018 at 12:57 pm

    I would beg to differ a little. In prestressed concrete construction the cables within the concrete are there to maintain the concrete always in compression. Local cracks should not originate from tension but surface contraction/imperfections. i am discussing spans, not walls or floors/walkways. “Falling Water” by Frank Lloyd Wright is a classic example of poor concrete beam construction.

      Colonel Travis in reply to alaskabob. | March 18, 2018 at 3:01 pm

      You’re right about Fallingwater and interestingly, FLW “designed” that thing in about 2 hours with his students because he’d forgotten he had been asked to do it 9 months earlier. The client called FLW and asked him if the plans were ready and FLW said – uh, yeah, sure. But they weren’t and the guy was on his way over to look at them. I wonder if it was a fault of the architect more than anything else.

I think the engineer wanted FDOT to do something that he could not do without blow-back from his company. He knew that cracks grow if the cause of the crack is not eliminated. For him to mention “safety” tells me he knew. Obviously he hoped he had time but he knew something was seriously wrong.

I can see his thinking. I can see being in his shoes. He saw a time bomb but did not know if he had an hour or a month. If he had sounded the alarm, shut down traffic, etc., and nobody had been hurt, would he have been rewarded or punished? This will haunt him for the rest of his life — “Should I have done more?”

This is a company culture issue. Think back to Morton Thiokol and NASA where an engineer knew the launch was unsafe but was silenced. One can also be self-silenced to varying degrees by a company’s culture.

    Exiliado in reply to TX-rifraph. | March 18, 2018 at 1:01 pm

    I know that area very, very well and I can tell you that’s a very, very busy street. Knowing that detail makes those cracks in the concrete merit more than just leaving a voicemail.

So many issues on this whole thing; it stretches the imagination to take note of the number of things that went wrong. The loss & law departments of lots of insurance companies have been 24/day coming up the liability amounts.

What astounds me the most is the absence of that center support post which was part of the original design. They were going to install it and the bridge stays at some future date, but thought that leaving the unsupported span was appropriate. To me, installing that post would have one of the first things to have done before the span was put in place.

    GerryGuy in reply to pfg. | March 18, 2018 at 4:20 pm

    I thought the same, but a USA Today article points out that this was a truss (railroad type) bridge, and the tower and “suspension” cables were cosmetic https://www.usatoday.com/story/news/2018/03/16/miami-bridge-collapse-suspension-cables-support-tower/431418002/

      bvw in reply to GerryGuy. | March 19, 2018 at 2:12 pm

      That don’t look right. One: the span’s angled “trusses” look exactly like they were meant to carry the cable loading down from the tower, and not at all like the more 45 degree angle type of trusses. If it was supposed to be a truss where are the solid rock steady triangles? I don’t see them. There’s some malarky here, or I’m a LOT more ignorant of modern civil engineering than I think I am, which could be! But I’ll go with the malarky , and a deadly form of it, for $1,000 Alex.

      And the “center support”, was nowhere, in the pictures of the final thing once it were to have been finished, that “central” tower between canal and roadway was off-center, which is fine still cables and steel beams and still towers can bear quite a lot of offset and imbalanced load. Concrete cannot.

      Note the canal. I understand that in bridges — excepting the suspension kind — the bridge’s feet are the most critical piece of engineering, for stability and load-bearing, of all the various forms of loading. This is why on old stone bridges the abutments — the bridge’s feet — are massive. huge, heavy. And most importantly STABLE. Now this LONG unsupported span had two TINY feet, pillars of some sort. Maybe they are still, maybe not. What are they, alway? But they certainly were NOT WIDE, and thus they were a point loading which connects doesn’t abide well. And just how secure in the WET SAND AND LIME SOIL GROUND of that berm between canal and roadway were they?

      Nor was that six-hour install wonder of a span helped by anycantilevering! The span ended abruptly at the pillars at each end.

      But what right does any decent third year civil engineer NOT expect exactly what did happen to happen?

Sorry boys and girls, but that headline is INCORRECT.

The crack was not reported.

Anyone who has any business experience has heard the squirrely excuse “I sent you an email.” or “I left you a voice mail.” numerous times when something important falls off the table.

With my team, emails (unless with read receipt in limited circumstances) and voice mails were no substitute for formal, eye-to-eye or mouth to mouth COMMUNICATION.

Communication is two-way, end of story. If the engineer thinks he is off the hook simply because he left a voice mail to some guy, he is sadly mistaken. If the issue is IMPORTANT—and I submit that a brand new bridge with stress cracks in it falls into the important category—the person reporting it has an obligation to ensure that the information is communicated, UNDERSTOOD, and acted upon.

Anything else is pure flim-flam, and as we’ve just seen, could lead to tragic circumstances.

Any of you all who work with others and rely on email/voice mail should use this as a lesson.

One-way communication is NOT communication. It’s simply a misguided and feckless attempt to transfer responsibility of something to someone else.

    Mac45 in reply to tiger66. | March 18, 2018 at 1:05 pm

    HUA [Heard, Understood and Acted upon] is critical in any type of communication. Didn’t happen here. But, the actual facts might be even worse.

    It’s also tremendously irrelevant given that there was a meeting Thursday morning where the a “technical presentation” on the crack was discussed. I’m not accepting the idea state authorities received a briefing and the lead engineer somehow hadn’t fully briefed the construction manager for it. I’m at the point of saying, don’t try and tell me there was a lack of communication. They communicated, and they did not run screaming so as to immediately close traffic under the bridge.

I watch this guy frequently on YouTube. His discussion of this tragedy is worth a watch. Some disregard to language purists.

https://www.youtube.com/watch?v=KtiTm2dKLgU

    alaskabob in reply to mrtomsr. | March 18, 2018 at 2:42 pm

    Thanks for sharing. If the mechanism, the retensioning went beyond the tensile strength of the rod… that flattening of the curve is the rod deforming and stretching prior to rupture… plastic deformation. If the reason, two things needed monitoring… tension and expected length increase in rod. Just looking at tension.. once deformation starts one will never reach correct tension before failure. Installation failure.

      TX-rifraph in reply to alaskabob. | March 18, 2018 at 3:22 pm

      And where is the risk mitigation by these people? I use jack stands when under my car even though I have never had a jack failure nor have I ever been near the jack limits.If you prepare for the unlikely event you do not have to predict the unlikely event (even if you could predict it).

“Workers were tightening cables that ran inside the beam.”

As a Senior Bridge Engineer, I have real issues with this statement. Were they rejacking primary tension strands? Without falsework? Over live traffic??

35 years and I’ve never seen/heard that going on and wouldn’t allow it on my projects

The cracking was indicative of some type of problem. The mistake that was made was that no one, in a position of authority, chose to err on the side of caution in a worst case scenario and close the roadway and position temporary supports under the span until the cause and severity of the problem was determined. When we find out what caused the collapse, then we will be in a better position to determine fault. The lawsuits are probably going to list just about every entity involved in the project.

    NGAREADER in reply to Mac45. | March 18, 2018 at 1:30 pm

    Sounds like another version of the Challenger disaster. The engineers that saw a problem didn’t communicate or someone didn’t want to listen.

      Valerie in reply to NGAREADER. | March 18, 2018 at 3:24 pm

      Also the Animas River spill, and the BP Deepwater Horizon spill, and the Oroville dam disaster.

      There is a reason why engineering is called a discipline: make bad engineering decisions, get disciplined.

It appears that the failure occurred at the first panel point from the left (as seen in the video)support. At this point, the bending stress is low but the shear is high. The cables do not resist shear. Shear is resisted by the mile steel rebar.

It would be unusual to be be stressing more than one cable at a time. The failure of a single cable should not have endangered the structure. It is also unusual to be restressing the cables after the structure is up. (Maybe bridges are different from buildings, I admit.)

Prestressed structures are inherently “bouncy” Therefore they are usually designed to be adequately stiff. At this point they are ‘way strong.

Since there was almost no live load on the structure, it is not unreasonable that the pylon and cable stays were not originally installed. It is unusual to remove all the shoring before the structure is built.

Could be design error, improper placement of reinforcing steel, wrong grade of reinforcing steel, bad batch of concrete. Design was independently peer reviewed, concrete would have been tested, rebar should have been tested, placement of the rebar would have independently inspected and signed off.

Much is still unknown, but the pieces are still there, so the facts will eventually come out. Media coverage is mostly the blind leading the blind.

    bvw in reply to erc. | March 19, 2018 at 2:20 pm

    Single point of failure in systems where human life or limb are at stake is a egregious engineering safety violation. So no, “Since there was almost no live load on the structure, it is not unreasonable that the pylon and cable stays were not originally installed. It is unusual to remove all the shoring before the structure is built.” Is not at all good thinking, much less engineering.

Look at the artists rendering of the finished bridge. There is a cable structure above that supports the weight and a large post/mast that they attach to that carries the weight. None of that is in place here.
I don’t understand why they would be doing a stress test before the structure to support the weight is in place.
Also, if the flat concrete part that failed was set down abruptly onto the vertical concrete risers and there was no support structure, that jolt could have weakened that large unsupported slab.
I guess we’ll have to wait until they have done more investigation. Right now it’s just a bunch of speculation.

OwenKellogg-Engineer | March 18, 2018 at 1:39 pm

Tx, FrankG, tiger66,& erc,
I agree with you all. Failures on several levels, including cultural. My structural engineering professor always said “Make sure you can sleep at night” with your design and decisions.

I suggest that everyone read “the New Science of Strong Materials.” It will literally change how one views the world.

https://www.amazon.com/Science-Materials-through-Princeton-Library/dp/0691125481

Basically, there is no such thing as a good crack.

My SWAG is that there was improper hydration during the concrete cure process. Concrete which dries before it cures will lack strength.

    Well, to my non-expert eye that broken concrete looks very sandy. Dry mix, a lot of sand and not enough “glue”.

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