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Miami Pedestrian Bridge, Part X 50

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JAE

JAE

Structural
Jun 27, 2000
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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

Part VIII
thread815-440072

Part IX
thread815-451175



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I imagine it is quite the rabbit hole. Digital cameras, even our eyes, filter, distort, interpolate, extrapolate, pixelate, stabilize reality. Sometimes to the point that it becomes an existential question. I'm not trying to muddy the water for good technique, but I'm sure this stuff comes up regularly when attorneys are trying to discredit an observation.
 
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epoxybot said:
During an interview with FIGG, OSHA quizzed FIGG about the lack of Redundancy. FIGGS reply was that the numerous PT bars were a form of Redundancy. Let’s hope that was Linda Figg & not Denny Pate.
Click to expand...
What a deflection - Yes, the PT system has redundancy - if one strand fails there is only a small reduction in the prestress force and a small increase in loads to the remaining strands at near ultimate moments. But the PT system is not the only thing important in this structure.
I saw somewhere in the past a factor to be used if there is no redundancy, and as I recall the example, they were using maybe +3%, like divide phi by 1.03. I don't think that would have saved this structure.
What would be an appropriate redundancy factor for a bad idea? A factor of 2? So lets use two bad ideas?
A V-8 engine has 8 connecting rods - but not a redundancy of 8, because if one rod fails you walk.
Redundancy in a structure seems to mean alternate load paths. Or joints and members so well designed that they just don't fail. One intended redundancy in this case was the peer review. An alternate path to a safe design. Which, by the way, did not help much.
Redundancy in the construction phase is provided by the Project Inspectors - a redundant set of eyes.
If a redundancy factor of +10% had been used in this case, the thing might not have failed when it did. And with full consideration for loss, and very real sadness in my heart for those lost and injured in this collapse, this might have been a better time than sometime in the future when even more lives could have been lost. A better time would have been 2:00 AM with no traffic. But my point is, and I am not good at making it, no formula can compensate for a simple oversight. Engineers simply must pay attention.
To see two prominent companies go bankrupt over a small project like this does not seem right. The risk/reward ratio seems badly skewed. Sure, this project in this form should have been load tested - in fact, I submit that it should have been a research and development project with a budget of maybe $50 million. How do we get that funded? Sounds cheap, now.
So after the dust and the lawsuits have settled, what will we have learned?
Probably that the Architect was right when he told me "Never be the first to try something, and never be the last to use something."
 
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3DDave said:
So Denney Pate's wife never checks pockets of pants before dumping them in the washer? Nothing suspicious there.
Click to expand...
Sounds like a wash being done in haste. Like maybe the pants were filled and needed an immediate washing.
(Sorry - some opportunities just can't be passed up.)
 
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3DDave said:
So Denney Pate's wife never checks pockets of pants before dumping them in the washer? Nothing suspicious there...
Click to expand...

I admit the timing is convenient, but FWIW, my wife of 30+ years is exactly like that. Whatever happens to be in the pockets goes right in with the clothes,
whatever it is, paychecks, phone, tools, nothing seems to get her attention. Her take on the issue- "if you don't want it washed, don't put it in the hamper".
 
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Whirled Gnus now has 3 PlayLists:
● Bridge Timelapses
● Bridge Inspections
● Links
Because of the way YouTube hides unlisted items, the only way to see a playlist is to use a direct link, and the only way to see a video is to use a direct link, or select a link from Playlist.

The Bridge Inspections are video clips of the foot traffic and manlift excursions that began on the 12th. Each video description contains source video info, including the start time plus start frame of the clip within the source video.

The Links are intended to be a group link list for everyone. I tried starting a link list in an earlier forum post but found out I couldn't edit it after a few days.
 
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Thanks Mike for your work on the videos. I've tried a few different things now and conclude, barring receiving an original video (not through youtub), the images I ended up using are the best quality available. I think the poster of the video did an excellent job with the source and I picked my way through it rather well (that was determination and luck).

Moving on, with the videos you are presenting now, do they show workers on the deck at the time of the collapse, or just on the canopy?
 
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Sym P. le said:
do they show workers on the deck at the time of the collapse, or just on the canopy?
Click to expand...

There were a total of 6 people on the bridge. Kevin Hanson was at deck level (he's the guy wearing a lime-green shirt) and ended up being buried in rubble. He was in a coma, and is now brain damaged. 2 of the guys on the canopy were Hanson's co-workers, and one of them was killed - Navaro Brown. The other 3 guys were probably MCM workers doing the grunt work: operating the crane and manlift, helping move equipment, etc. I'm not sure if any of them have been named.
 
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SFCharlie - THX for the feedback. Been a long day. Had to re-upload all the Insp. vids because the first go round I posted the fast small originals instead of the slow enlarged versions. Different folder but same filenames. Grrrrrr....
 
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Ha - these pants weren't in the hamper, but lucky Pate, anyway.

Rice doesn't work. The problem for phones is they have a very high energy density power source -and- a need for high current density. If, as described, it's an iPhone, there is no barrier coat applied to any of the circuitry. When I mention iPad Rehab, it's because they produce videos of repairing water damaged iPhones and show exactly the damage that even a small amount of water entering the phone will do to an Apple product. Not can. Will. By the time the phone makes it to the rice, it's a goner.
 
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Please read the complaint filed by a victims family.
Not that I'm smart or a lawyer, but it gives me that weird vibe that I wrote it.... I guess we all get that vibe sometime. Is there a word for it? Déjà vu is not the right word.

If anyone can post other complaints, I would appreciate it.

I checked on the four hard plastic pads mentioned in the report. High-resolution photos elsewhere show thin metal shims under all four pads. Is this typical in the industry? The pads I assume are HDPE and temporary. The purpose of this low-friction arrangement was to allow diaphragm II freedom to slide and relieve strain while chains were removed from lifter? Who checked to confirm these pads would not yield, creep, or rupture in this application? The south bearings were indeed typical and designed for bridges. The north diaphragm/pier gap was supposed to be grouted right away? And if the gap was to be grouted, how would they get the pads out first? I understand they did not grout because of delay caused by color/material mismatch. (What color was this bridge anyway? The web was sloppily brushed-over with some kind of white slurry, the rest was uncoated). All four pads can be found in post-collapse photos. Side-note: In fifty years when the south bearings are due to be replaced, the pipe stays will have to be dealt with to allow jacking of diaphragm.
 
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Another claim:
Point of fact missed by almost everyone. Portion of roadway was in fact closed during PT operation. (However, this was not done for sake of safety, it was for the crane). This seems like a trivial point until your realize it was a missed opportunity to close entire roadway. Edit: It turns out they used "blanket" permission to close two lanes. Other permission was required to close all lanes. But still, needing permission is not reason to not do it anyway.
 
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