At least four dead in Florida university bridge collapse

Looks like the load bearing spam trusses are at their peak with redundancy.....

 

Elected Representatives of the People

Mario Diaz-Balart, U.S. Representative and Chairman of the House Appropriations Subcommittee on Transportation, Housing and Urban Development.

Orlando Lopez, Mayor of the City of Sweetwater

Crime of which Mario Diaz-Balart and Orlando Lopez are accused - involuntary manslaughter.

Summary of evidence -

* Mario Diaz-Balart and Orlando Lopez trusted the untrustworthy and mismanaged FIU Pedestrian Bridge Project, lending it their undeserved support.

* Mario Diaz-Balart's support helped to allow the project to gain federal funding.

* Orlando Lopez's support allowed the project additional City of Sweetwater funding and the authority to build at the site.

* See the "SITE AUTHORITY" graphic and the raw photograph of the construction site and the billboard there notifying the public and the police that the project had the Mayor's authority to build at that site.





* See FIU NEWS, 03/10/2018 - First-of-its-kind pedestrian bridge “swings” into place

“FIU has come a long way since the TIGER grant that funded this pedestrian bridge was awarded in 2013. This project represents a true collaboration among so many different partners at local, state, and federal levels, and in both the public and private sectors,” said Mario Diaz-Balart, U.S. Representative and Chairman of the House Appropriations Subcommittee on Transportation, Housing and Urban Development. “The university’s growth and acceleration is no longer just about the campus and its student body; it’s about the future of Sweetwater, Miami-Dade County and the entire South Florida region. I believe this is what creative solutions to transportation challenges look like, and I will continue to support and incentivize these new ideas.”

Funding for the $14.2 million bridge, connecting plazas and walkways is part of a $19.4 million Transportation Investment Generating Economic Recovery (TIGER) grant from the U.S. Department of Transportation. Other funding agencies include the Federal Highway Administration, Florida Department of Transportation Local Agency Program, FIU and the City of Sweetwater.

“The FIU-Sweetwater bridge will serve many purposes including being a visually distinctive gateway to our city,” said City of Sweetwater Mayor Orlando Lopez. “This bridge is symbolic of the growth our city is experiencing and our partnership with FIU.”​

* See the reports of the collapse of the weak and uncertified truss mainspan of the bridge on March 15, 2018, crushing vehicles and people which the mismanaged project had allowed to pass dangerously underneath.

* Wikipedia - Florida International University pedestrian bridge collapse

 

FIU promoted technique used to build failed pedestrian bridge as solution to nation’s infrastructure woes​

"FIU provided $50,000 in seed funding for the Center for Accelerated Bridge Construction, ...

The U.S. Department of Transportation awarded the Accelerated Bridge Construction University Transportation Center at FIU a $7.5 million, five-year grant in 2016 to advance the construction method. FIU was the lead institution, also working with partners Iowa State University, University of Nevada - Reno, University of Oklahoma, and University of Washington.

Atorod Azizinamini, director of the university's Accelerated Bridge Construction center, ... has spoken extensively about the unique design of the pedestrian bridge at FIU.

In an interview with an FIU news site in November 2017, Azizinamini advocated for the ABC method as a more cost-effective and safer way to replace the nation’s aging bridges. The idea was that hosting construction off-site would reduce accidents and traffic congestion, and it would only take a few days to hoist the bridge into place.

In an emailed statement Thursday, the university's College of Engineering and Computing emphasized that the center had no role in designing or building the collapsed bridge, although the center recommended that the ABC method be used when FIU applied for a federal grant for the bridge. FIGG Bridge Group designed the bridge and it was constructed by MCM Construction, FIU noted."​

Atorod Azizinamini did indeed have a role in the building project which he supported as is reported here by speaking "extensively about the unique design of the pedestrian bridge at FIU".

Azizinamini's lethal role was as chief cheerleader and public propagandist for this mismanaged project, effectively urging caution to be thrown to the wind by all and publicly deflecting from a focus on the importance of continuous critical health and safety review of all aspects of the project as it went along.

That's not "no role". That is a decisive, culpably negligent and lethal role which cost innocents their lives.

"The statement added: "More than 1,000 bridges are constructed in the U.S. using accelerated bridge construction techniques without any problems."​

A failure rate of about 1 in 1,000 bridges, buildings or any civil engineering structure is completely unacceptable.

"Bridges collapse for different reasons, some engineering and others construction."​

Good engineering practice builds bridges which don't collapse for any reason! (Can you believe the ridiculous claims of Azizinamini's center of bridge-building incompetence?)

Good engineering practice tests all components of any construction in isolation and / or in situ as appropriate.

New bridge projects require an engineering certification that the bridge is safe before the bridge can be legally commissioned and only then are the public allowed to go under (or over) the bridge.

"Until forensic engineers take a look at the collapse, we cannot speculate on what caused the collapse.''​

Actually, we can easily speculate that the main-span concrete truss was long, relatively short and consequently was too weak, with barely the strength to support its own weight when it was supported in situ.

The MCM FIGG proposal's engineering drawings specify a mainspan truss which is 175 feet long and 18 feet tall, which equates to a length-to-height ratio of 9.72.

* See FIU - MCM Design-Build Proposal - MCM_FIGG_Proposal_for_FIU_Pedestrian_Bridge_9-30-2015.pdf

 

From The Associated Press 20 March 2018:
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Construction of the pedestrian bridge that collapsed and killed six people in the Miami area was behind schedule and millions over budget, in part because of a key change in the design and placement of one of its support towers.

...Florida Department of Transportation in October 2016 advised Florida International University and its contractors to move one of the bridge's main support structures 11 feet (3 meters) north to the edge of a canal, widening the gap between the crossing's end supports and requiring some new structural design.

...multiple engineers who reviewed the documents obtained by the AP said moving the tower after the bridge's initial design invited errors.
--------------------------------------------------------------

article

 

<- North ----------------------------------------------------------------------------------------------------- South ->

Experts cite explosive joint failure as cause of Florida bridge collapse

“I think they probably were carrying out jacking works,” said Bourne. “You only have a jack connected to the bar on for the few minutes you’re stressing and it’s still on in the collapsed condition. If they weren’t stressing it, it wouldn’t be there.”

It is this additional force being put into the diagonal member during the jacking operation that Bourne thinks could have caused failure of the critical end joint.​

<- South ------------------------------------------------------------------------------------------------------------------ North ->

Damage to the side of truss member #11 is spalling caused by the explosive release of elastic energy which was stored in the highly stressed post-tensioning bar within when it snapped.

This, along with the picture of the jack still attached to the P.T. bar, is the smoking gun.





Forensic engineering conclusion

There is no satisfactory way to "implement" a house of cards. It is an intrinsically precarious structure.

Maybe somewhere there is a house of cards which has stood the test of time, but it is generally understood that the metaphorical reference to a "house of cards" is to compare it with something that is precarious, unstable and prone to failure - in this case the FIU pedestrian bridge.

If, as it seems the evidence may be pointing to, the bridge failed because of what one worker did in a minute dangling from crane with a jack to a P.T Bar then that proves that the bridge was precarious and so it had a bad design.

A good design should exclude the possibility for one worker doing something inept, whether under orders to do that something inept or not, which causes the collapse of the whole structure.

A good design would build in redundancy so that if one component failed - like a P.T. bar or a truss member or a truss joint - then other P.T. bars or truss members or joints would save the bridge.

Or a good design would use a truss made from rigid metal-only members (tubes or girders) and metal-only joints and avoided the problems of trusses made from prestressed or post-tensioned concrete on such a critical component of a bridge.

Political questions

The FIU bridge collapse story was reported by the BBC in Britain and world-wide and that's how the story came to my attention. FIU claims to be an "International" university - an invitation (or at least an excuse) for discussion of FIU's affairs on the world wide web, maybe?

Public Safety

A pedestrian underpass would have been safer and cheaper than a bridge, right? So public safety and cost was not the top priority. Is that acceptable?

Management

The bridge project was mismanaged to the point of killing people. Are there wider problems which this tragedy highlights - problems with mismanagement of this university, other universities, civil engineering management at this site or elsewhere?

Legal

Florida Involuntary Manslaughter Laws
Overview of Florida Involuntary Manslaughter Laws

When a homicide, the killing of a human being, does not meet the legal definition of murder, Florida state laws allow a prosecutor to consider a manslaughter charge. The state establishes two types of manslaughter: voluntary and involuntary. While voluntary manslaughter describes an intentional act performed during a provocation or heat of passion, involuntary manslaughter does not require intent to kill or even intent to perform that act resulting in the victim's death.

To establish involuntary manslaughter, the prosecutor must show that the defendant acted with "culpable negligence." Florida statutes define culpable negligence as a disregard for human life while engaging in wanton or reckless behavior. The state may be able to prove involuntary manslaughter by showing the defendant's recklessness or lack of care when handling a dangerous instrument or weapon, or while engaging in a range of other activities that could lead to death if performed recklessly.​

Who are the individuals responsible for the loss of life and are they criminally culpable with regard to the decisions they made negligently or recklessly that disregarded the dangers to human life and contributed to the deaths?

Civil liability. Who should pay compensation and how much?

Political

Who is to blame politically, Obama or Trump or neither? Will anyone be held politically accountable for these deaths?

 

The pedestrian bridge was being built next to a 4-way intersection or crossroads, with a pedestrian crossing, where the traffic has to stop for the lights anyway.

It seems that the cost of a pedestrian bridge (or pedestrian underpass) could not be justified.

The existing pedestrian crossing could be made safer by installing

• good quality cameras to video anyone jumping the lights or speeding, take their number plates and fine them
• good quality lighting so that the cameras work beautifully even at night
• the pedestrian crossing may even turn a profit

It seems that the pedestrian bridge plan was not really for functional reasons but was wanted by the Florida International University for advertising purposes.

I suppose if they had known what they were doing and built a safe bridge safely that would have been OK.

Possibly few would have used it because it would still have been easier to use the crossing at the traffic lights but hey, it wouldn't be the first architectural folly.

But they didn't know what they were doing and their recklessness got innocents killed and in my opinion that is a crime.

 

There is also much to report about the bridge designer's miscalculations and risks as they relate to truss member #11 which is assumed to have failed at the time it was being post-tensioned.

The FIU FIGG-MCM proposal specifies the highest grade of concrete - grade VI - 8.5 ksi.


So considering the possibility that the concrete used wasn't up to specification, I have made detailed calculations which I can present graphically as follows.


This tells us that the concrete has to be fully up to the grade VI specification just barely to hold the bridge up with no additional load from post-tensioning bars or from any pedestrians on the bridge. Anything less than top notch concrete and that bridge is coming down.

Even for those calculations I had to assume a risky safety load factor of only 1.2 and the estimates using more cautious safety factors also warn that the bridge is too heavy for the design of member #11.


This tells us that only calculating with a risky safety factor of only 1.2 can we assess that the truss member #11 is just barely strong enough to hold the bridge up with no additional load from post-tensioning bars or from any pedestrians on the bridge. Using anything more cautious for a design safety factor would warn that the bridge is at an unacceptable risk of coming down.

So we can see that the bridge designers were gambling with people's lives even before a single bar was post-tensioned - which was what was being done at the time the bridge collapsed.

The "dead load of the bridge on member #11", if you are interested in this kind of thing, is calculated as follows.

 

Thanks to the use of an online truss calculator, I have now been able to make a more accurate calculation of the likely forces which the bridge was subjected to when it failed.







Video evidence shows that the bottom northern end joint of the bridge failed first and so suspicion has fallen upon the elements of the bridge at the north end and so it was helpful to calculate the likely axial forces along member #11 (marked "M11" in the diagrams above).

The compression force from the dead weight of the bridge I calculated as - 1367 kip or 1,367 thousand pounds of force.

The compression force from the post-tensioning (P.T.) bars within member #11 - I calculated had to be at least 304 kip but in practice would have been more, perhaps significantly more so the bridge designers should have treated the P.T. bar force as a live load (LL), not a dead load (DL) for design purposes.

So the unfactored load on member #11 was at least 1367 + 304 = 1671 kip.

As recommended,



factoring the load as 1.2 x DL + 1.6 x LL suggests they should have designed for a
Maximum allowable design factored load of 1367 x 1.2 + 304 x 1.6 = 2127 kip

I estimated from this NTSB video



that member #11 used 10 x #7 bars which would suggest it was suitable for a factored load of only 2006 kip. which corresponds to a ratio of factored to unfactored load of 2006/1671 = 1.2 (only).

To get to a factored load of at least 2127 kip, as my table suggests, member #11 would have needed 14 x #8 or 12 x #9 or 10 x #10 rebars.



Even if member #11 was not designed or constructed within code we cannot conclude that the failure of the bridge's bottom northern end joint was caused by a failure of member #11 per se.


The remains of the bottom northern end joint of the bridge

The failure which the evidence of the video and photographs suggests is more likely to be with the design of the joint itself, an insufficiency of reinforcement in anchoring member #11 to the deck, leading to, I might suggest, shear fractures along the 2 planes either side of member #11 where they intersect with the deck which I have illustrated by annotating sheet B-8 from the design engineer's drawings as follows.



I may not know with 100% certainty what the cause of this bridge collapse is but I can offer my expert opinion on the basis of the available evidence so far.

 

So he is responsible for any screwups that involve any DOT funds? That is really your take?

The ABC method is used all over the world. This bridge was not a cookie cutter design, but don't believe the hype as if we were launching a man to the moon for the first time ever.

 

Any DOT funds which he championed, sure.

There was a bit more to my take.

The Obama Administration

Atorod Azizinami, FIU Chair of the Civil & Environmental Engineering Department and director of the Accelerated Bridge Construction University Transportation Center

Anthony Foxx, Obama's Secretary of Transport Engineering

Crime of which Atorod Azizinami and Anthony Foxx are accused - involuntary manslaughter

Summary of evidence -

* Atorod Azizinami professed his so-called "accelerated" (actually fraudulent, rushed, botched, risky, culpably negligent and prone to collapse) bridge construction method, misleading others into following his dangerous and ultimately deadly unprofessional engineering malpractice.

* See FIU NEWS, 03/10/2018 - First-of-its-kind pedestrian bridge “swings” into place

“This project is an outstanding example of the ABC method,” said chair of FIU’s Civil & Environmental Engineering Department and director of FIU’s ABC-UTC Atorod Azizinamini, who is one of the world’s leading experts on Accelerated Bridge Construction. “Building the major element of the bridge – its main span superstructure – outside of the traveled way and away from busy Eighth Street is a milestone.”​

* Anthony Foxx as Obama's US Secretary of Transport directed the US government to fund Atorod Azizinami

* See photograph and other reports of Foxx with Azizinami at a White House event announcing Azizinami was to be appointed a "Champion of Change in Transportation"



* US Department of Transport - 2015 Champions of Change in Transportation

* See the reports of the collapse of the weak and uncertified truss mainspan of the bridge on March 15, 2018, crushing vehicles and people which the mismanaged but Azizinami-approved project had allowed to pass dangerously underneath.

* Wikipedia - Florida International University pedestrian bridge collapse​

Well not everyone knows their "ABC"s.

Maybe they should stick to "cutting cookies" if this is what they deliver by the way of "innovation" and "championing change in transportation".


Image - I've added some red ink to this extract from the FIGG - MCM design-build team's own document pdf proposing to FIU that they get the contract to build the bridge.

What caused it to fail?
The bridge designers innovated (incompetently) a new I-beam design of bridge but where the I-beam's upright-supports (called an "open truss") join the deck of the bridge, the designers should have specified the necessary reinforcement to stop the severely stressed joints breaking apart - "should have" but negligently didn't and so the weakest link - the northern bottom end joint - failed first and it caused a catastrophic collapse of the whole bridge.

Crossing the road safely 25 yards from a crossroads, where the traffic has to stop for the lights anyway, is not rocket science and neither is building a bridge if you really must and that was the point I was making with -

"My reference was to the Apollo 11 blast off which happened in Florida.

My point is that Florida can do great things or it can screw things up.

What Florida does - great things or screw-ups - is up to the choices the people of Florida make and which politicians they choose to vote for and which academics they choose to learn from. Bad politicians and bad academics, or good politicians and good academics?

I wanted to point to the manned mission to the moon because achieving this successfully was many times more difficult an organisational and engineering challenge than building a pedestrian bridge.

Therefore comparing and contrasting the great leaders who took men to the moon with the criminals who are killing people trying to put up a pedestrian bridge is a sharp contrast. The best of us and the worst of us somehow managing to pass themselves off as the "pillars of the community - champions of transport etc.". Somehow managing to fool the people, somehow not finding themselves in the political firing line for their lethal incompetence."​