Miami Pedestrian Bridge, Part VIII 80

[JAE]

A continuation of our discussion of this failure. Best to read the other threads first to avoid rehashing things already discussed.

Part I
thread815-436595

Part II
thread815-436699

Part III
thread815-436802

Part IV
thread815-436924

Part V
thread815-437029

Part VI
thread815-438451

Part VII
thread815-438966



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[chris snyder]

I always thought that message from Pate was kind of goofy. When I first heard it, I thought it was from some burnout (forgive me for being judgemental) because there was no "drive" or authority to it like I'm used to hearing from senior engineers.

I'm still not sure what to make of it considering the msg was left after he'd (allegedly) seen the initial #11/12 cracks in Feb (after tensioning, after shoring was removed, but before span was moved), seen the larger cracks (after span was moved), but before the meeting and before the collapse - there seemed to be zero urgency or care... this after everyone else has said it was an "already failed" structure that hadn't fallen yet (a "dead man walking"). I couldn't quickly find the audio, but this with its "uh"s and "um"s makes the point.

"Hey Tom, this is Denney Pate with FIGG bridge engineers. Calling to, uh, share with you some information about the FIU pedestrian bridge and some cracking that's been observed on the north end of the span, the pylon end of that span we moved this weekend. Um, so, uh, we've taken a look at it and, uh, obviously some repairs or whatever will have to be done but from a safety perspective we don't see that there's any issue there so we're not concerned about it from that perspective although obviously the cracking is not good and something's going to have to be, ya know, done to repair that. At any rate, I wanted to chat with you about that because I suspect at some point that's gonna get to your desk. So, uh, at any rate, call me back when you can. Thank you. Bye."

I suspect FYE is being sarcastic, cynical, ??? because it's hard to believe Pate would take responsibility without seeing this.. as if he could say later "I'm not responsible because I was relying on someone else's description".
The part about "something's going to have to be, ya know, done to repair that" sounds ludicrous - I don't see HOW that could be repaired... by injecting epoxy? I questioned if there was any cracking at the south end (#1/2) and just noticed it's not mentioned in the msg, so maybe not. #1/2 was more robust (beefed up on final prints, but not prelims) - maybe because axial forces were higher on 2D analysis... but the 3D (finite element) analysis clearly shows MUCH more strain at the north end. The engineer who ran this (Toomas Kaljas) said it's because of the asymmetric "W" pattern of the trusses.

 

[dik]

Seeing those cracks, any responsible engineer would have immediately 'frozen the area of construction and provided temporary shoring.

Dik

 

[3DDave]

chris,

I believe the Toomas Kaljas calculations do not include the post-tension stresses, hence the high tensile stress numbers seen in 10 and 3. They also don't appear to include the pre-loads on the diagonals as a result of the longitudinal post-tensioning on the deck and canopy. I think those loads, carried via shear, were responsible for the cracks seen in some other diagonals spread along their length. I also think the canopy post tensioning was to match the strain in the deck so that the ends of the diagonals moved together, keeping the bridge deck straighter/level.

 

[SFCharlie]

Why wasn’t road closed before FIU bridge fell? Judge orders release of key records

 

[271828]

What is perfectly clear is the Denney Pate (40 years experience) did not see the cracks in person when he reported them by telephone. Any engineer, even an unqualified one, would have immediately recognized that a collapse was in progress. What he did was he placed a call based on somebody else reporting a "slight cracking" to him. This will have profound implications.

After seeing the large cracks, this was my first thought.

It might be that an honest look at the issue of experienced engineers delegating important duties to those with marginal or insufficient experience is the big thing that comes out of this.

...Are you Denney Pate?
Unless you have inside knowledge that the rest of us don't have then whilst it might seem to you and me that such an experienced engineer would realize that those cracks were far beyond what could be described as slight cracking, in reality we just don't know, nor, as yet, what pictures or information was available at this meeting which took place prior to the collapse. ...

A non-engineer with an average IQ could look at those cracks and realize something was seriously wrong.

He didn't know what the conditions of the crack were, when he was reporting on the conditions to FDOT? Really?

Higher-up engineers are often extremely busy and delegate almost all nuts-and-bolts work to far less experienced underlings, so I'm not sure why this would be surprising.

 

[hokie66]

Hopefully, the judge's ruling will be respected by the FDOT, and their records about the construction, meetings, phone calls, and correspondence included, will be released. This is a state's rights issue, among other things. The NTSB does not need all this information to interrogate the design, which should be their focus. The failure to recognize the imminent collapse of the structure, and then protect the public, should be separated from the technical investigation.

 

[appster]

If any of you here ever watch the "Mayday" series which shows many types of NTSB investigations (mainly aircraft accidents but also railway, highway, bridges etc.) they always look into the human factors which may lead to an accident or make an accident worse. They will undoubtedly look into why cracks were ignored or downplayed and why the bridge was not closed.

They also go above and beyond to find the root design, material, and other causes of an accident to pin down the cause or causes and the string of events that led to the accident. This should not prevent the FDOT or any other party releasing information that by law is public. According to an earlier post one may receive copies of the original detailed design calculations for a nominal fee for reproduction costs. Engineers not party to the NTSB investigation have publicly stated in the Miami Herald that the think that the design was deeply flawed; many here have given the same opinion (including myself). Is it ethical to give an opinion in many jurisdictions probably not but it is an engineers nature to look for why something failed and we feel free to speculate based on calculations and our experience.

 

[dik]

SFCharlie... the documents held by the FDOT may shed light on the extent of their involvement. For exposure and legal reasons, they may want to appeal the release. NTSB, for sure would want to appeal this... it erodes their being able to 'put a lid on things'.

Dik

 

[thebard3]

Higher-up engineers are often extremely busy and delegate almost all nuts-and-bolts work to far less experienced underlings, so I'm not sure why this would be surprising.

We do understand that, but as the engineer of record, it is incumbent on him to know exactly what the condition is that he is reporting. The now-well-documented discussions that he had with FDOT to imply there was nothing of immediate concern (paraphrasing) should be backed by his explicit knowledge of the condition of the cracks, including some empirical evidence, not by some nebulous assurance of an 'underling' that everything was okay. It will be interesting to learn if he did or did not have the pictures of the 'cracks' prior to this discussion.

Brad Waybright

It's all okay as long as it's okay.

 

[epoxybot]

I really have a hard time seeing the Florida DOT's exposure on this project. Maybe they have a public perception concern or a political concern but unless there is some flaw in their assessment of FIU as an acceptable participant in the Local Agency Program, or there are emails and the like that express concern for the performance of FIU, FIGG and/or MCM or any of the other parties, I just don't see where the FDOT bears much blame. There are so many politicians involved, it may just be they've been told to circle the wagons.

The bridge could just as easily have been a City of Sweetwater project as opposed to FIU. Just like FIU, the City of Sweetwater would have had to apply via the Local Agency Program. The federal statutes state that State Transportation Departments have to maintain chief responsibility for the project but when you read further, it demonstrates how that responsibility is maintained while being delegated to DOT certified contracting entities. So when you look at who was responsible for preforming the design review in lieu of the FDOT, that was Louis Berger. When you look at who was responsible for inspections in lieu of the FDOT, that was the CEI - Bolton, Perez & Associates. This is how the Local Agency Program works, participants can contract out the functions they don't have the expertise to provide. Just like a Municipal Building Dept. may contract out engineering reviews to a private firm. In this sense the FDOT followed the statutes regarding the FHWA & Local Agency Programs. Ultimately, what the federal statues really only require that the State DOTs maintain control of the purse. They can't outsource the oversight to a private firm. The FDOT's role in LAP projects is very much like a Building Dept. that contracts out the engineering & inspection work to private firms. They merely perform the administration, making sure that the work has been reviewed and accepted by the parties charged with these responsibilities.

It would be interesting to know what time of day Denny Pate contacted Tom at the Florida DOT on the 13th, was it before or after the photos were taken. Assuming Tom is the Chief Engineer for FDOT assigned to the project, Tom..., who? Who took the photos? I assume it was a Bolton, Perez & Associates, inspector.

Bolton, Perez & Associates was under contract to FIU, not to FIGG or MCM. What communication structure existed? One would assume any communications by Bolton, Perez & Associates to FIU would automatically be communicated to FIGG & MCM. Rafeal Urdaneta, a Bolton Perez & Associates employee is the one who contacted Alfredo Reyna, the FDOT's Assistant LAP Coordinator notifying him on the 14th of the meeting, the following day. A Bolton, Perez & Associates Newsletter in the Summer of 2015, reports him as a new hire to their CEI team stating, Mr. Urdaneta has over 27 years of experience in civil engineering construction management projects. His experience in public and private projects include: roadways, utilities, wastewater facilities, stormwater and drainage systems, water distribution, high-rise buildings, petroleum platforms, subdivisions and medical centers. Rafeal Urdaneta isn't on the Florida Licensed Professional registry. Assuming Rafeal Urdaneta was the day-to-day on-site inspector for Bolton, Perez & Associates, is there a point that Bolton, Perez & Associates had the responsibility to send a qualified Licensed Engineer to the job site? They were after all, as the FDOT certified CEI, responsible for being the FDOT's eyes on the project.

Alfredo Reyna, the FDOT's Assistant LAP Coordinator, is a Licensed Engineer, yet he states when he attended the meeting on the 15th, which occurred shortly before the bridge failure and collapse that he was not notified of any life-safety issue. It doesn't seem possible that there wasn't any discussion of the cracks, unless he wasn't present for the whole meeting or the matter was discussed separate from the meeting. Alfredo Reyna's job as FDOT's Assistant LAP Coordinator, was to make sure that the money was being spent on work & materials approved by the program & that any changes were applicable for LAP funds or out of program. For instance, he was responsible for determining if the cost of relocating the bridge pylon from the roadway to the canal position fell within the LAP/Tiger Program funding. Essentially his role was as a Civil Works Program examiner. The project inspection criteria for his job is almost entirely based on administrative review of process flow. His attendance at meetings is to determine whether work discussed falls within the program and that the project is meeting the funding timeline.

Assuming my characterization of Bolton, Perez & Associates is accurate, did they not have a responsibility independent of FIGG to determine if the bridge was a hazard to the public? There presence on the canopy at the time of collapses, suggests they were performing the kind of special inspection work often called out by Building Depts. but were they doing the work that the FDOT designates as the CEI responsibility in lieu of FDOT inspections? It is troubling that at the time of the collapse there should have been two people on-site that knew, they needed to abort what they were doing, one was the Bolton, Perez & Associates staffer and the other should have been one of the Structural Technologies staff.

 

[MrHershey]

Assuming Rafeal Urdaneta was the day-to-day on-site inspector for Bolton, Perez & Associates, is there a point that Bolton, Perez & Associates had the responsibility to send a qualified Licensed Engineer to the job site? They were after all, as the FDOT certified CEI, responsible for being the FDOT's eyes on the project.

For better or worse this is done frequently, at least in my experience. Have not done bridge work or Florida work. Have done a couple of DOT building projects. The 'inspector' usually has to be operating under the supervision of a licensed professional (or structural) engineer. But they themselves do not have to be licensed. Just like most engineering work, the actual work does not have to be done by a licensed engineer, just under the supervision of a professional engineer. For my projects the inspector has usually been an older construction management type or perhaps even a former contractor. Someone who has been around long enough to know how things are supposed to be done and have enough confidence to speak up to contractors who may also have been around forever. But not licensed. Sounds like this case was similar.

Knowing the types that have worked on my job, I would have expected them to speak up on something like this. Those guys tended to speak up about EVERYTHING when I would visit the site, no matter how minute. However that was only when I was actually visiting the site. When I wasn't on site I'd get reports but because there's so much bureaucracy between the inspector and me (the engineer), I wouldn't see their reports until weeks after the fact AT BEST. Usually it was months after the fact before the reports would go from inspector to his bosses at the construction management company to the DOT to the design-build contractor to the architect and then finally to me.

 

[hokie66]

MrHershey,
That is an improper channel for such reports, and can not be expected to work. Reports from the site should reach the design engineer quickly.

 

[MrHershey]

MrHershey,
That is an improper channel for such reports, and can not be expected to work. Reports from the site should reach the design engineer quickly.

I wholeheartedly agree and wish anyone the best of luck in trying to get this particular DOT to change the way they do things. Getting reports months after the fact isn't much better than getting no reports at all.

For what it's worth, that was just the chain of communication for the DOT's inspector, which is the role epoxybot was talking about. There were also typically special inspectors under the contractor in addition to the DOT's inspector. We got those reports a lot quicker since they weren't sitting on the desk of someone at the DOT for weeks/months. Special inspector being under contractor technically isn't allowed by IBC but that's the arrangement the DOT wanted and they're the code authority for their own projects.

 

[JAE]

I might throw in a couple of observations about the inspections:

1. "Special Inspections" is purely an IBC term for buildings - I don't think it applies in any way to bridges. Yes there are bridge inspectors and inspections, but don't confuse the language, contractual restrictions, etc. in the IBC with bridge work....not related at all.

2. Inspectors should and do report up the chain things that appear extraordinary, like large cracks. But their primary focus is on comparing [blue]work performed vs. work required[/blue] by the plans and specifications. It may be that, despite the huge, ugly crack, that the inspector(s) resolved that the engineers knew about it and didn't need their reporting. Or, the work in that vicinity of the bridge was essentially complete and there was no need to get up there to observe how the structure was behaving since they had already reviewed the performed-vs-required aspects of the rebar, concrete placement, curing, etc.



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[bimr]

The responsibilities of the construction inspector is included in the contract documents and the construction inspector responsibilities will be enforced by contract law. I am not aware that a link to the contract documents has ever been posted in this forum. I looked online for the Contract some time ago and was not successful in finding the Contract.

I am not an advocate of engineering (by FIGG Bridge Engineers, Inc.) and inspection (by Bolton, Perez & Associates) being done by different organizations as their tends to be little communication between the parties until something goes wrong.

 

[3DDave]

bimr - I've had the same experience in mechanical engineering - when the QA department reports to the head of Manufacturing instead of the head of Engineering, a lot gets swept under the rug where it sometimes festers into a huge problem.

Still, it would not seem as if there needs to be much communicated if nothing is going wrong. There were reports made when some of the reinforcement was found to be out of place prior to pouring the deck, so it's not as if the inspection team was just phoning it in based on casual observation.

I would expect any inspector to make an immediate report where a previously OK portion was suddenly not OK, but I would not expect the bridge to get 24 hour construction site inspection oversight.

Much of the externalization of this event (where this thread stands) has moved into an academic phase, awaiting the transition into legal (lawsuit and possible prosecution) and regulatory participation. I think it is clear there was a design defect and not a materials or workmanship problem. I think it is also clear there was nothing impeding adequate investigation of the discovered defect before selecting a way to deal with it, but there is a lack in public knowledge of who knew what, when they knew it, and how it was determined to proceed. There is a clear line of responsibility for the design, but not a clear chain for what to do for defects of this type.

In this respect the failure is somewhat similar to the Hyatt Regency walkway failure, where those working on site knew the bridge was too flimsy and work crews were told to avoid taking construction materials over it. It isn't identical because the reason it was flimsy was due to a fabricator mod to the design which the fabricator communicated over the phone; there was apparently no analysis**. There were enough irregularities in the rest of the building design that their licenses were pulled anyway. No criminal prosecutions were made.

I think that leaves two avenues for consideration:

1) What sanity checks should be in place for structural calculations that not only ensure those calculations that are performed are done correctly and that all areas of a structure are correctly dealt with?***

2) What system should be in place for directly reporting to emergency personnel that there is an unexpected failure of a major structure, even if the failure has not had an immediate catastrophic result? This reporting should not require any other level within a construction or design firm to authorize or review before making the report. It also requires considering what evidence the construction firm or design firm should have to provide to show the situation has been adequately dealt with. And it requires a means to deal with anti-whistleblower actions by employers and malicious reporting by anyone.

** What I don't understand is if the original walkway rods were too long to easily manage and adding the threads to the middle too difficult, why they didn't propose using a coupler nut instead of offsetting the rods. I also don't understand why the fabricator didn't run the numbers or do a test before proposing the change. Maybe this is a case where Virtual Reality will be useful - if the fabricator saw the installation, perspective corrected, from the top walkway they might have given some consideration to the potential for plummeting all the way to the floor below.

*** In the I35W collapse it is clear there was never a full analysis found for buckling on the gusset plates and only a preliminary check done on the rivets that went through them.

 

[hpaircraft]

** What I don't understand is if the original walkway rods were too long to easily manage and adding the threads to the middle too difficult, why they didn't propose using a coupler nut instead of offsetting the rods. I also don't understand why the fabricator didn't run the numbers or do a test before proposing the change. Maybe this is a case where Virtual Reality will be useful - if the fabricator saw the installation, perspective corrected, from the top walkway they might have given some consideration to the potential for plummeting all the way to the floor below.

My sense is that, like too many engineering failures, the Skywalk collapse was more a failure of imagination than a failure of calculation. Nobody who looked at the revised connection scheme had that little spark of intuition that told them that the forces applied to the nuts on the upper rods were doubled. They were fooled by the fact that they looked just like the other joints in the system, and they failed to imagine that they might be loaded differently. And so they didn't even bother to calculate what the difference might be.

As to why they didn't just use coupling nuts out of hand, my guess is that it might have been simple penny pinching. Looking in the McMaster catalog, Grade 8 nuts 1-1/4"-7 are about $2.40 each, while a Grade 8 coupling nut in that size is about fifty bucks--and they would have needed six of them for the project. Of course, that's almost nothing in the overall scheme of a project like that, but I'd guess that someone thought they had a better and cheaper way to skin that cat, and didn't stop to imagine how they might be mistaken.

--Bob K.

 

[ImminentCollapse]

.....and why didn't the flight engineer on KLM 4805 speak up? why were they running a low-power non-standard test on unit 4? how did water get into a methyl isocyanate tank? clearly the o-ring was bad, Eastern Flight 401.................

History is littered with the victims of tragedies due to smart people caught in negative feedback loops when they just can't see the obvious. We're always shocked after the fact. It may have happened here too. I pray it never happens to me.

IC

 

[BridgeSmith]

In reference to the Skywalk collapse, there were several ways it could have been easily prevented - the addition of plate washers, having the channels back to back (which is the typical way to detail something like that, if I'm not mistaken), or using coupling nuts. (Were there really only 3 pairs of suspension rods?) Even after so many years, there seems to be some disagreement (conspiracy theory?) concerning whether or not the altered detail was reviewed at all by an engineer at the design firm, or that they were even made aware that the change was made.

 

[SFCharlie]

Crucial FIU bridge records were set to be released Thursday. Then the feds blocked it

SF Charlie
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