Miami Pedestrian Bridge, Part XII 34

[zeusfaber]

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: Miami Pedestrian Bridge, Part I

Part II
thread815-436699: Miami Pedestrian Bridge, Part II

Part III
thread815-436802: Miami Pedestrian Bridge, Part III

Part IV
thread815-436924: Miami Pedestrian Bridge, Part IV

Part V
thread815-437029: Miami Pedestrian Bridge, Part V

Part VI
thread815-438451: Miami Pedestrian Bridge, Part VI

Part VII
thread815-438966: Miami Pedestrian Bridge, Part VII

Part VIII
thread815-440072: Miami Pedestrian Bridge, Part VIII

Part IX
thread815-451175: Miami Pedestrian Bridge, Part IX

Part X
thread815-454618: Miami Pedestrian Bridge, Part X

Part XI
thread815-454998: Miami Pedestrian Bridge, Part XI

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[SFCharlie]

Yes Vance "moving the base of 11 southward will move the "joint" of 11 to deck off the pylon". In a previous post I asked if adding material at the top inside corner of the deck pier joint would violate clearances. I was thinking "Could 11 be extended through the deck to the pier?"

SF Charlie
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[Earth314159]

I would caution that moving the base of 11 southward will move the "joint" of 11 to deck off the pylon and leave moments and shears in deck to deal with.

The idea would be to alter the abutment design with a cantilever to minimize the shears and bending in the deck. This does put bending and shear into the abutment but it would be manageable. The cantilever could also be thick enough to keep the shear within 45 degrees of the vertical abutment support.

 

[Vance Wiley]

In a sense, member 11 is considered to be extended thru the deck because it is intended to be cast EDIT: "ACT" END EDIT monolithically - if the construction joint works as intended. The line of force projects thru the deck and, in my mind, works better if that member inside the deck is defined by a cage of reinforcing and confinement ties like those along its free length. In this case, that was done but the ties were not carried into the deck, as I recall, and really were not adequate along the length of 11.
If all is working right, the center of the joint should be the intersection of the center of 11 and the PT tendons in the deck. The horizontal component of the axial force in 11 should have been intercepted by the PT tendons, leaving only the vertical reaction at the joint to be supported and distributed by the diaphragm.
That is the condition addressed at the Power Point Party.
In this case, the horizontal component of 11 was not intercepted well. I think captured was a term used at the meeting.
Making diaphragm 2 (north end) thicker and casting the main span 175 feet long would have accomplished much of what you are suggesting. Correcting the smooth surface of the cold joint was needed. And perhaps the base of 11 should have been something like 3 feet wide and 3 feet high and extended maybe 5 feet farther south than the little 8" fillet, all loaded with enough reinforcing to ensure no slip at the deck surface and adequate capturing of 11. That would provide the option to use a square end of 11 into the base above the deck

This was a pretty good start -- from JRS 87 about April - segment IX .

https://res.cloudinary.com/engineer...forced-concrete-structure-27942983_tsbdba.jpg

 

[Vance Wiley]

Earth314159 Those are good solutions.
The variety of suggestions presented proves the point that engineers are individuals and there are many paths to a successful design. All will be well if the problem is recognized and addressed properly.

 

[Earth314159]

The variety of suggestions presented proves the point that engineers are individuals and there are many paths to a successful design. All will be well if the problem is recognized and addressed properly.

I agree. This bridge was completely feasible but the design just had to be adjusted a bit. I don't see too many people wanting to line up to design a concrete truss bridge given what happened but the idea of a concrete truss was not the issue. It was just that the problems encountered were not identified or addressed properly.

 

[RAB678]

How many ways to skin a cat?

 

[Agent666]

I haven't been keeping up with the threads on this collapse, but I thought I'd post this (it may have been posted previously apologies if it has been posted already). Its a video/webinar from the fib/IStructE in the UK going into the collapse. The part on the FIU failure starts at ~32 minute in after some stuff on the Morandi Bridge collapse.

https://istructe.hosted.panopto.com....aspx?id=0f5078e3-8321-45f6-b3a0-aa4700a328d2

 

[Earth314159]

Thank you Agent666,

I don't think anyone else has posted this. Always good to hear from the istructe on such matters.

 

[jrs_87]

ENR - Seeking Better Peer Reviews After the FIU Bridge Collapse

https://www.enr.com/articles/47296-seeking-better-peer-reviews-after-the-fiu-bridge-collapse

 

[jrs_87]

ENR - How Berger’s Peer Review Role Figures In Potential Bridge Collapse Settlement

https://www.enr.com/articles/47279-...gures-in-potential-bridge-collapse-settlement

 

[LionelHutz]

I find the goings-on about reviewing the partial structure to be rather stupid. The truss section needed to be capable of standing by itself which means the failure was not caused by the bridge being incomplete. About the only place Berger could have failed in reviewing partial construction plans was by not reviewing the moving process. Overall, the reality is that the Berger review simply failed to find that the design of this truss section was faulty.

 

[jrs_87]

I find the goings-on about reviewing...

Good point, yet so obvious it's sad everyone including me kind of missed it.

Louis Berger is resisting perhaps because their fee was only $65,000 which by no means correlates to liability exposed.

This accident and the investigation is very peculiar.

 

[Vance Wiley]

I seem to recall reading Berger's fee was $30,000 and FIGG's fee was 1.5 million. So Berger got 2% of the design fee. Not a lot.
How is it that the design firm chooses the peer review firm? It seems more objective if the Owner pays the peer review firm and proposes maybe 3 firms for designer to choose. That could prevent a malicious review - particularly if the peer review firm had proposed on the project and did not get the project. And it could prevent the design firm from choosing a shill review.
Wasn't the design past the 80% or so point before Berger was retained? Pretty much precludes any review at earlier stages.
When FDOT raised valid questions FIGG blew them off. Some seem to think since FDOT raised a question and then did not stop the project when their concerns were dismissed makes FDOT complicit.
All fodder for attorneys.
Remember the story of the lone attorney in the small western Montana town, who barely eked out a living? Then a second lawyer opened an office there, and in just a few years both were wealthy.
EDIT CORRECTION - I had recallled a post by EPOXYBOT which was later corrected to $61,000 for Berger's fee. I find that a bit more reasonable, but totally disproportional to the risk assumed.

 

[epoxybot]

Louis Berger was paid $61,000 for the review. They certified 3 PEER Reviews for the Foundation, Substructure & Superstructure "Plans", whatever that means. They also prepared "a finite element model of the bridge and estimation of demands on all elements due to different design load combinations" (not certified). The plans they reviewed were 100% plans. Who was the finite element model for?

Figg's original intent to use another branch of Figg to perform the PEER review, was kind of shady and should have caused FDOT to double down.

Maybe it is the Contract Documents & RFP that are flawed by allowing the Design Build team select a PEER Review consultant.

 

[Vance Wiley]

I agree, the term "plans" is too generic for a contract, and subject to mis-interpretation, particularly by attorneys.
Do we know if the FEA addressed only the completed structure or did it address the main span only and independently?

 

[jrs_87]

I could not confirm, but for a while I was suspicious that LB used a freeware FEA program.

To the structural engineers listening> What is the upper bound on the length of this type of span? And the width?

 

[MikeW7]

The idea that FDOT was hesitant for any reason is pretty suspicious, because they have apparently have a reputation for heavy handed bid-rigging in the Miami area.

Side note on this June, 2017 article - the favored bid by Fluor-Astaldi-MCM that FDOT screwed over was a design by .......... FIGG.

 

[RAB678]

To the structural engineers listening> What is the upper bound on the length of this type of span? And the width?

Apparently less.

If the world comes to an end. Engineers are always worth more than lawyers.
ANYONE with ANY mechanical sense is worth more than a lawyer.
Sorry should have added the word "allegedly". and "ja".
"ja" in Thailand means " fight but fight with good reason".
In America "JA" is translated differently.

Maybe some of you "JA" lawyers should get a real skill. You wont make it.

Agent666...please.......can you post your video on youtube?

This stuff is ancient. A lawyers battle. fake names. bs. pfffff.......

 

[RAB678]

and this star stuff. get real so fake.

 

[Agent666]

RAB678, it should be accessible at that link and I am not a member of IStructE, it just works in Chrome for me. Unfortunately its all tied into that panopto platform so I can't download it directly.

If that doesn't work perhaps you can link to it from this page which is the video webinar index.

https://istructe.hosted.panopto.com/Panopto/Pages/Sessions/List.aspx#view=2