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Miami Pedestrian Bridge, Part XIV 78

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JAE

JAE

Structural
Jun 27, 2000
15,460
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

Part XI
thread815-454998

Part XII
thread815-455746

Part XIII
thread815-457935


 
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Business News said:
...that the move could result in further delay of the $930 billion project, already two years behind schedule
Click to expand...

I hope this project isn't almost a trillion dollars...
 
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Wait until the extras to contract come in... the US is already at 23... what's another one?

Dik
 
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Wetlander... they did't pull any punches or make it 'sugar coated'.


Dik
 
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I think $930 billion is a typo. This link says $930 million, which is more reasonable.

Link
 
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For the curious or skeptical, WJE webinar tomorrow:


If my bridge relied on an apprentice mason scouring a few square feet of concrete in an extremely tight area to remain aloft, I think I would be standing over his shoulder with a trowel in hand whilst doing so..........

IC
 
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Wasn't that the team that was hired by FIGG to come to that exact conclusion; that it wasn't FIGG's fault for having insufficient reinforcement but that the concrete people didn't properly read the minds of FIGG engineers to see a requirement that was never analyzed, written down, or otherwise seemingly considered?

Why yes, they are:

"FIGG also detailed that it had hired forensic structural engineering experts Wiss, Janney, Elstner Associates to conduct an investigation, which revealed that the construction joints at the failure point were not roughened in alignment with Florida standards. (Roughening would have also contributed to the strength of the connection.)"

 
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It's the bit at the end I don't like " that demonstrated that, had the construction joint been roughened as required by the project specifications, the collapse would not have occurred."

This bridge was fatally flawed in design and construction.

To try and blame a non roughened joint doesn't work for me. I haven't read all the back words here but I'm pretty sure the NTSB refuted that suggestion. Sure it didn't help, but this bridge would have fallen down even with a roughened construction joint.

I also can't see how anyone can say something like this "would not have occurred" when there were a number of failure modes, lack of strength and re-inforcement and probable damage whilst it was moved and placed on its supports

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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Like LI said, I don't understand how WJE can so strongly state the bridge wouldn't have failed when it was cracking excessively the moment it was moved into place. Is this a PR piece for court cases or something?
 
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Anyone else think it's just a coincidence that WJE is presenting this just 4 days before the NTSB meeting? Didn't think so.

Wasn't there significant design errors made by FIGG? Where did admitting your wrong and accepting at least partial responsibility go?
 
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What does Figg and WJE hope to gain? The failure was a fundamental engineering design flaw and it is an understatement to say that the response from the design engineers was unacceptable even if the surface was roughened and the "the collapse would not have occurred". It is just not that the joint had to be roughened, it had to be designed correctly as well and that design had to be communicated to the contractor. The engineers were either incompetent or unethical. How can a structural engineer see those cracks and not know it was a shear friction failure?

Notice how the event summary says "had the construction joint been roughened as required" and does not say the specifications or drawings required roughening. Codes require it to be roughened and the engineer is suppose to communicate those requirements in the specifications and drawings. Someone was suppose to tell the contractor that the joint had to be roughened and even in that case, it was still under designed. Regardless, it did not meet the minimum level of strength to protect the life and safety of the public. The response to the cracks was unacceptable and for any competent experienced structural engineer that works with concrete, it boarders on criminal negligence.

The roughening issue is a moot point and is irrelevant to the question of responsibility.
 
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It seems that in addition to a flawed design and ignoring clear warning signs of impending failure, they also failed in their duty to diligently inspect the work as it progressed.


Bill
--------------------
"Why not the best?"
Jimmy Carter
 
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...are we beating a dead bridge? (to paraphrase Monty Python...)
The bridge is not pinin'! It's passed on! This bridge is no more! It has ceased to be! It's expired and gone to meet it's maker! It's a stiff! Bereft of life, It rests in peace! If you hadn't set it on the pier It'd be pushing up the daisies! It's metabolic processes are now 'istory! It's off the twig! It's kicked the bucket, It's shuffled off it's mortal coil, run down the curtain and joined the bleedin' choir invisible!! THIS IS AN EX-bridge!!

Note: FDOT is going to build a pedestrian bridge in it's place, hopefully made of steel, with no faux supports...

SF Charlie
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I'd be interesting to see their results on the difference roughening makes.

However I agree the above that that statement is a bit rich. That is like saying had we not placed that last piece of straw on the camel then its back would not have broken.
 
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Human909 - Without stretching the metaphor too far it's more like saying

"hey, that last piece of straw must have weighed so much more than the previous pieces of straw..."

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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At this point, I don't care to go back and research everything, but what I remember reading was that Figg basically said "If the surface had been roughened, the bridge wouldn't have fallen down." But that is a completely different statement from saying "the bridge was designed correctly and the only reason it failed was that the surface wasn't roughened". I got the impression they worked backwards through the design and were able to calculate a factor of safety of 1.001 if that surface was roughened and hung their hat on that.

I pity the designer and contractor on the next bridge. There will be more inspectors than workers, with inspectors inspecting the other inspectors.
 
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Just listened to the WJE webinar. Found it interesting. They really seem to be defending FIGG and focusing solely on the fact that the surface was never roughened. The defense of FIGG hinges on an email that references a FDOT spec for roughening the hardened surface. The spec doesn't give any guidance to the amount of roughening nor does FIGG's email. WJE says pretty much any amount of roughening would have been enough to prevent collapse.

What I don't understand is how FIGG ignored that the bridge was telling everyone there was major problems. How did FIGG come to the conclusion that adding more compression to the joint was going to help matters?

I can't come to the conclusion that FIGG is not at least partially liable here.
 
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