Miami Pedestrian Bridge, Part XI 32

[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

Part VIII
thread815-440072

Part IX
thread815-451175

Part X
thread815-454618


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[Vance Wiley]

I had to search that reference -
In 1950 mine was called an Erector Set. Have not thought of it in years.
Thanks for the memory.

 

[Vance Wiley]

I must agree. In the investigation of damage to tilt-up panels due to shortening in a tee beam/PT slab roof, I used the phrase "There but for fortune, go I" - Joan Baez, maybe 1962.
The potential for failure was probably recognized but not accepted, and the urgency was paramount. With the PT rods in place and capable of rapid restoration of the force, it "seemed like a good idea at the time".
Mark Twain said "When a hammer is the only tool you have, everything looks like a nail".
With the benefit of hindsight it is easy to see the only appropriate and immediate action was to close the street and call for shoring. To be installed by remote control.

 

[jrs_87]

Old story, another bridge.
"The bridge is not in any danger of collapse," state Department of Transportation Secretary . .

https://www.eng-tips.com/viewthread.cfm?qid=352416

Perhaps it's the fear of crying wolf that leads to such statements?

The host of this video on bridge had better idea at 20 second mark.

https://www.youtube.com/watch?v=xPULiFwZ06M

The host of this video confused sag with span at 1 min 56 sec.

https://www.youtube.com/watch?v=9YKOOr_OVgc

Amateur bridge inspector:

https://www.youtube.com/watch?v=GF4S0ceYkZQ

How they fixed it:

https://www.youtube.com/watch?v=BLViBG-BA5Q

Explaination:

http://www.fox11online.com/news/local/green-bay/dot-corrosion-caused-dip-in-leo-frigo-bridge

 

[saikee119]

I agree with Tomfh that not many of us could have readily predicted that the retensioning would cause it to fail completely.

However FIGG and most of us know prior to collapse the 11/12 had cracked 45 degree (the geometry is the warning sign that the crack is structural in nature) on the west, cracked and separated from the front, cracked 45 degree on the east. The only remaining that did not crack was space at the back to which the 11/12 was moving slowly away from the deck.

The fact FIGG wanted to "capture" this runaway node and divert some of the load from 11/12 to the next bay is a testimony he knew the structure was in serious trouble. It is also an admission that 11/12 was under-designed and unable to withstand that temporary condition.

Based on the severity of the cracks I would say most responsible professional would not proceed with any remedial attempt unless it is beyond doubt that the remedial action could rescue this distressed structure or help to stabliize it.

Had FIGG sought formal permission, with detailed justification on how the cracks could be controlled or reduced, prior to re-tension the doomed bridge there is a good probability that the FDOT, with their own prior theoretical predictions of the cracks and saw some of them had occurred in the field with such ferocity, would not risk to have the traffic there during the remedial work. In which case the bridge could still collapse but no public would lose their lives needlessly.

 

[Tomfh]

Thinking back to Pate's phone call to Tom Andres' voicemail:

https://www.huffingtonpost.com.au/e...ut-bridge-collapse_n_5aac7167e4b05b2217fedd3a

Would Pate have been mindful that these cracks were the same cracks Andres had predicted with lots of red exclamation marks? Was that the reason for the call? To hopefully intercept and defuse Andres before Andres found out?

 

[jrs_87]

For what reason was the canopy curved? It seems to me the curve would focus sound reflections back to the pedestrians.

I found this when looking for curved concrete:

https://www.designboom.com/architecture/dfab-house-concrete-smart-slab-eth-zurich-08-02-2018/

 

[3DDave]

Where the sound goes depends on the curvature and the location of the sound source. Unlike flat parallel surfaces that will certainly echo, curved surfaces may or may not. It looks like the center of curvature is at or near the surface of the centerline of the deck, so only sounds at the deck surface center will be reflected back to the source. All other sound will be dispersed.

There is a monument in Washington, D.C. for Einstein that has audio-retroreflective contours; the effect is only noticeable in a very small area at the center of the arcs that make it up. From the wikipedia article "To a visitor standing at the center of the dais, Einstein appears to be making direct eye contact, and any spoken words are notably amplified."

https://en.wikipedia.org/wiki/Albert_Einstein_Memorial

 

[jrs_87]

Was that the reason for the call? To hopefully intercept and defuse Andres before Andres found out?

Yes. Edit: Retracted until I find source > Also, if you browse the email records you will find the purpose of the on-site presentation was to "calm everyone down". We can only imagine what MCM was telling FIGG before that.

I think if EOR ever is on the stand for this, he will say bridge was not deflecting and that is why safety was not a concern.

There has to be more to the story... too many professionals failed in the same manner...

At this time, I feel nothing is to be gained by looking at this accident any further until NTSB report comes out or suits go to trial. I feel more comfortable looking at similar solved events in the past for insight instead. That's just me.

 

[Tomfh]

Also, if you browse the email records you will find the purpose of the on-site presentation was to "calm everyone down".

Do you have a link to that?

 

[BridgeSmith]

I think someone with a solid understanding of the structural mechanics involved should have known better than to think that retensioning the rods, with cracks in the deck of that size, would improve the situation. I'm no expert when it comes to the structural mechanics of concrete, but several of the people directly involved with this supposedly are. With my limited experience and understanding, even without the benefit of hindsight, I think I can honestly say, I would not have suggested retensioning the rods given the size and location of the cracks. Trying to pull yourself up from your bootstraps doesn't work and often breaks the bootstraps.

 

[SFCharlie]

Reading this thread, I sense that I'm not the only one who feels some emotion over the tragic loss of life, and, yes, the thread has gotten emotional, but understanding the human aspects of the cause is as important as the mechanism of failure. Yes, I know the NTSB will address human factors, and has more access to communications and interviews, than we do, but I think it's important for all of us in the engineering professions to have a chance to explore our own feeling with regard to this event. Let's not get bogged down in quibbling about wording, but let's keep talking about what allowed the event to occur.


SF Charlie
Eng-Tips.com Forum Policies

 

[MikeW7]

Do you have a link to that? (referring to email records)

I think it's in the BT-904 Document List, Item 4.

I collected a bunch of investigation related links and put them in the description box for the Links Playlist on my Whirled Gnus YouTube page.

 

[epoxybot]

I just don't agree that they couldn't have foreseen that re-tensioning #11 was a non-starter. Denny Pate did a site inspection before the meeting. When he saw the crack at the base of the 11/12 node migration up the 11 diagonal, any prospect of re-tensioning #11 was off the table. How do you move forward without knowing the soundness of the #11 diagonal without doing an impulse echo or impact echo test. There is no way to know the amount of section loss by simple visual examination. It is like taking an already cracked concrete cylinder and putting it back in the compressive test rig and loading it again without any idea of an ultimate failure load.

 

[jrs_87]

Has this been addressed?

v. There is insufficient details of the walkway deck web interface and the canopy web interface where there is significant interfacing shear between the elements.

Clarification: Here, as with any structural system which has connecting members, there is a transfer of force between the various members at each nodal point. FIGG would not classify these behaviors solely as “shear” per se. However LRFD’s strut and tie design philosophy (section 5.6.3) will assure the required transfer of loads at the nodal transition points. Relative to this comment, no changes will be made that would alter the 90% foundation design plans.
​

[ignore]

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From: "Feliciano, Manuel" <mfeliciano@figgbridge.com>
To: "Andres, Tom" <Thomas.Andres@dot.state.fl.us>
Cc: "Dempsey, Dwight" <ddempsey@figgbridge.com>,
"Pate, Denney" <dpate@figgbridge.com>,
"Robertson, Robert" <Robert.Robertson2@dot.state.fl.us>,
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"Reyna, Alfredo" <Alfredo.Reyna@dot.state.fl.us>,
"Alberto Delgado"
filename="Responses to Central Office Foundation Related Comments.pdf"
[/ignore]

 

[jrs_87]

Interesting email exchange about TiO2:

RE: FIU Concrete Mix Designs

From: Arcalas, Ronald <Ronald.Arcalas@dot.state.fl.us>
Sent: 10/25/2016 7:40 AM
To: Reyna, Alfredo <Alfredo.Reyna@dot.state.fl.us>
Cc: Patel, Mayur <Mayur.Patel@dot.state.fl.us>; Bergin, Michael <Michael.Bergin@dot.state.fl.us>; Espino, Barbara <Barbara.Espino@dot.state.fl.us>; Vieira, Alexis <Alexis.Vieira@dot.state.fl.us>; Sajadi, Jamshid <Jamshid.Sajadi@dot.state.fl.us>; Andres, Tom <Thomas.Andres@dot.state.fl.us>; Alberto Delgado
Archived: 6/16/2019 2:47 AM
Folder: Outlook Exchange

Alfredo,
To clarify this again as discussed in our previous meeting, the job is "On
System" classified as "Class A" with Type I Construction Administration
that requires our FDOT Specifications. Please comply with our process in
the approval of concrete mix design as indicated by our District
Structural Materials Engineer.

We will issue the Final Project Materials Certification Letter for this
project.


Thanks,
Ronald D. Arcalas, P.E.
Dist. Materials Operations Engineer
Dist. Materials & Research Office 4/6
Tel: (954) 677-7035
Fax: (954) 677-7090
Cell: (954) 290-4607
Email: ronald.arcalas@dot.state.fl.us

-----Original Message-----
From: Sajadi, Jamshid
Sent: Tuesday, October 25, 2016 10:12 AM
To: Arcalas, Ronald
Cc: Patel, Mayur; Bergin, Michael; Reyna, Alfredo; Espino, Barbara;
Vieira, Alexis
Subject: RE: FIU Concrete Mix Designs

Greetings all,

Ron,

As we understand, this is an on-system, critical project; consequently,
all required concrete mix designs and relevant testing should be in
accordance with the FDOT specifications requirements and approved by FDOT.
In other words, this project shall be treated as a regular FDOT project,
and is to be certified by FDOT at the end.

As I indicated in my previous e-mail, dated October 17, 2016, those
submitted concrete mix designs are not FDOT approved mixes. Consequently,
a FDOT-approved concrete plant shall be retained to produce those mixes
(with FDOT approved constituents). In addition, the proposed admixture
(TIO2) and the color pigment shall be approved by the State Materials
Office prior to the concrete trial mixes and production. Please let us
know if we can be of further assistance.

Best Regards,



-----Original Message-----
From: Arcalas, Ronald
Sent: Monday, October 24, 2016 1:12 PM
To: Sajadi, Jamshid; Vieira, Alexis; Dano, Robbin
Cc: Patel, Mayur
Subject: FW: FIU Concrete Mix Designs

FYI


Thanks,
Ronald D. Arcalas, P.E. Good morning Ron,


Dist. Materials Operations Engineer
Dist. Materials & Research Office 4/6
Tel: (954) 677-7035
Fax: (954) 677-7090
Cell: (954) 290-4607
Email: ronald.arcalas@dot.state.fl.us

-----Original Message-----
From: Reyna, Alfredo
Sent: Monday, October 24, 2016 1:07 PM
To: Alberto Delgado
Cc: Yassin, Aiah; Espino, Barbara; Nunez, Xiomara;
'JMorales@BPAMiami.com'; Arcalas, Ronald; Andres, Tom; Bergin, Michael;
Zhang, Hailing
Subject: FW: FIU Concrete Mix Designs

Alberto see the comments below regarding the Concrete Mix

Alfredo Reyna, P.E.
LAP Coordinator - Keith and Schnars, P.A.
Florida Department of Transportation
(305) 470-5288 Fax (305) 470-6737
Alfredo.Reyna@dot.state.fl.us

-----Original Message-----
From: Andres, Tom
Sent: Monday, October 24, 2016 11:50 AM
To: Bergin, Michael
Cc: Reyna, Alfredo; Zhang, Hailing
Subject: RE: FIU Concrete Mix Designs

Thanks Mike - this helps a lot.

Alfredo,

Could you forward Mike's comments back to the DBF and FIU? Also it would
be great if Mike could be kept in the loop regarding the Mass Concrete
results.

Thanks,

Thomas A. Andres P.E.
Assistant State Structures Design Engineer
605 Suwannee St., MS 33
Tallahassee, FL 32399-0450
(850) 414-4269

-----Original Message-----
From: Bergin, Michael
Sent: Friday, October 21, 2016 1:58 PM
To: Andres, Tom <Thomas.Andres@dot.state.fl.us>
Cc: Reyna, Alfredo <Alfredo.Reyna@dot.state.fl.us>; Zhang, Hailing
<Hailing.Zhang@dot.state.fl.us>
Subject: RE: FIU Concrete Mix Designs

Tom

I reviewed the mixes and they appear to be within our specification limits
(Section 346) for the specific applications. There was no material sources
indicated so the mix would not be approved by the district office if
that's a concern, this being a LAP project (and a research project??)
maybe the purchaser doesn't care.

As far as I know there is no approved sources of TiO2, but again this may
not be an issue since the mix will not be approved by the Department.

Is the intent to instrument the mass concrete placement(s)? If so I would
like to see the data after the placement. We've recently seen some
temperature increases in the cement/slag combinations for mass concrete
and I'd be interested to see if the temperatures come down as a result of
the addition of the fly ash.

I noted that color is mentioned in 3.4.6.5, but it doesn't specifically
address the color by standard number as we have done in our TSP
specifications that call out colored concrete. If there is an intent for
color, I suggest that the standard color number is referenced and that the
only supplementary material added to the mix is slag. Silica fume, or fly
ash will change the final color of the finished concrete and may not
provide a consistent color from one batch to the next.

I hope this helps, but let me know if there are any questions, ---- Mike

Michael Bergin, P.E.
State Concrete Materials Engineer
Florida Department of Transportation
State Materials Office
5007 NE 39th Avenue
Gainesville, Florida 32609
Michael.bergin@dot.state.fl.us
Office 352-955-6666

-----Original Message-----
From: Andres, Tom
Sent: Thursday, October 20, 2016 6:26 AM
To: Bergin, Michael <Michael.Bergin@dot.state.fl.us>
Cc: Reyna, Alfredo <Alfredo.Reyna@dot.state.fl.us>; Zhang, Hailing
<Hailing.Zhang@dot.state.fl.us>
Subject: FW: FIU Concrete Mix Designs

Mike,

Could you review and provide comments? This is for a LAP Project in D6.

Alfredo, I will provide comments to you via email.

Thanks,

Thomas A. Andres P.E.
Assistant State Structures Design Engineer
605 Suwannee St., MS 33
Tallahassee, FL 32399-0450
(850) 414-4269

-----Original Message-----
From: Reyna, Alfredo
Sent: Monday, October 17, 2016 8:39 AM
To: Espino, Barbara <Barbara.Espino@dot.state.fl.us>; Andres, Tom
<Thomas.Andres@dot.state.fl.us>; Arcalas, Ronald
<Ronald.Arcalas@dot.state.fl.us>
Subject: FW: FIU Concrete Mix Designs

All,
Question who need to approved this?
Your help is appreciated... Do I need to upload it to the ERC?

Alfredo Reyna, P.E.
LAP Coordinator - Keith and Schnars, P.A.
Florida Department of Transportation
(305) 470-5288 Fax (305) 470-6737
Alfredo.Reyna@dot.state.fl.us

-----Original Message-----
From: Rodrigo Isaza [mailto:risaza@mcm-us.com]
Sent: Friday, October 14, 2016 8:25 PM
To: Feliciano, Manuel
Cc: Reyna, Alfredo; Eugene Collings-Bonfill - P.E., PMP; Dempsey, Dwight;
Hango, Erika N.; Alberto Delgado; Alan Ruiz, P.E.
Subject: Re: FIU Concrete Mix Designs

Thank you Manuel

Alberto/Alfredo, please ensure it gets into the ERC right away and help us
expedite the review and approval process.

Thank you

RODRIGO ISAZA | Sr. Project Manager | PH: 305-541-0000 - Ext 371 | M:
305-970-6989 MCM | 6201 SW 70 St., 2nd Floor, Miami, FL 33143 |

http://www.mcm-us.com<[URL unfurl="true"]https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcm

[/URL]
-2Dus.com&d=AwIFAw&c=1QsCMERiq7JOmEnKpsSyjg&r=mEvReUV_8mhKOet9i_HfnQ&m=9H8
A15mnTMgwa5ViBtviWTnSQR4T4K1ygywDOLEyUAY&s=Kchn79SVUars4cQCrRx4OgWP50fq1Ld
p4G3maz8JW0o&e= >.
Please consider the environment before printing. A reminder from MCM....
Building Excellence.


On Oct 14, 2016, at 7:30 PM, Feliciano, Manuel
<mfeliciano@figgbridge.com<mailto:mfeliciano@figgbridge.com>> wrote:


Alfredo,

Please find the concrete mix design and the technical special provisions
for the photocatalytic concrete. It is my understanding that you will
upload this submittal to the ERC system for review.

Let us know if you need anything else.

Thank you.


Manuel Feliciano, P.E.
FIGG
Regional Bridge Engineer
mfeliciano@figgbridge.com<mailto:mfeliciano@figgbridge.com>
O: 850-224-7400 ext. 1235


<FIU8500_1_MetaK.pdf>
<FIU5500_1.pdf>
<FIUMass.pdf>
<Technical Special Provision Photocatalytic concrete.pdf>​

 

[Tomfh]

I just don't agree that they couldn't have foreseen that re-tensioning #11 was a non-starter

It’s not that they couldn’t have foreseen it, it’s just that it’s a lot easier to foresee with the benefit of hindsight.

They were all very worried about the cracks, but none of them seemed too concerned with retensioning prior to installing the emergency steel braces. That’s why I’m wondering if we’re applying hindsight bias when we say it was obvious at the time they shouldn’t have retensioned.

 

[saikee119]

I think if EOR ever is on the stand for this, he will say bridge was not deflecting and that is why safety was not a concern.

It is physics that every structure deflects in response to load. The bridge must deflect when it has to support its own weight of nearly 930 tons. In fact if you take a look at the 11/12 drawing the Member 12 is not vertical but kicks in by 2.125" at the bottom so that at the equilibrium condition with the permanent load Member 12 should be nearly vertical to match the side span which were to be constructed in situ.

The photos taken by BPA before the Mar 15 collapse have conclusively showed that there were crack separations between concrete and between concrete and plastic sleeves. Anyone cares to examine the OSHA photos, which repeated what NTSB had previously published, would know 11/12 had cracked separations on the west, front and east sides. The remaining side that did not crack was against air so 11/12 was able to move away from the deck by the amount indicated by the crack widths.

The geometry of the cracks confirms they were structural in nature and as predicted by FDOT 18 months previously. Concrete is a brittle material. The geometry, severity and extent of these cracks are enough as proof in court to justify the 11/12/deck has already failed structurally before its collapse. I can justify this statement because in the structural analysis this node was assumed rigid, as every reinforced concrete structure joint. If any member were permitted to move then such specified amount of degree of freedom must be included to design calculation.

Many of us are now convinced by the Minutes of Mar 15, 2018 meeting that the bridge designer knew the problem. He was more interested in protecting his reputation than the workmen instructed to re-tension the bridge and those motorists using Highway 41.

Many flaws will come out of the Mar 15,2018 presentation by the bridge designer. Among them is the bridge designer trying to justify the presence of cracks by using the Diaphragm II as an example. He proved the 2' wide by 4' deep Diaphragm II was structurally adequate when it was simply supported on 4 shims with half of the bridge weight acting downward centrally by Member 11/12. The diaphragm in such case would have compression at the top and tension at the bottom. No photo was ever taken on the bottom of Diaphragm II which was inaccessible. The resulting cracks at the bottom if existed were irrelevant to the 11/12 cracked separations with the top and rear faces of the Diaphragm II.

I have seen many such moves in meetings when an attendee wasted others' time by arguing something theoretically sound but irrelevant to the issue sought by everybody. Or the designer in this case was simply barking on the wrong tree.

 

[Vance Wiley]

If that clarification is the FIGG response I read it as boiling down to "F U".
And apparently section 5.6.3 did not assure anything except failure.

 

[jrs_87]

saikee119 (Structural)27 Jun 19 23:03

So E.O.R. was a P.E.I.N.O. (Professional Engineer In Name Only)?

https://fbpe.org/legal/disciplinary-actions/#disciplinaryactions

https://fbpe.org/legal/disciplinary-actions/

 

[RFreund]

Is there anyway this thread could get broken apart maybe a sub thread that just focuses on the technical faults. There could be another thread that just focuses on the chain of command or legal side or whatever.
There's been so much good work done here, but can't help feeling a bit overwhelmed by the information.
It seems like there was an actual calculation error or bad assumption by the design team, but it's kinda hard to track it all through the enormous number of posts.

Anyway, just a thought. Very impressive stuff here though by all contributors.

EIT

http://www.HowToEngineer.com