Stupid Is the New Smart

[Ace-Garageguy]

From The Chicago Tribune:

"Experts interviewed by The Associated Press were mixed on the significance of those reported cracks.

Amjad Aref, a professor with the University of Buffalo's Institute of Bridge Engineering, said they should have been 'a big red flag.'

'Bridges are really very vulnerable when they are under construction, when there are just pieces," he said. "It's like still a flimsy structure. And when you see cracks, somebody has to raise really a big flag and say, 'We need to do something. We need to figure out what's happening quickly and do any mitigating actions to prevent further progression of damage and ultimately collapse,' as we saw here.' "

[89AKurt]

That FIU bridge, looked into that.  It was more important that concrete have titanium dioxide, so it would stay clean longer.  I would like to know how much that adds to the cost of concrete!  Also checked into the Project Manager, seems there is some Orwellian memory hole going on, when I searched, found a Linkin hit but when I clicked it showed nothing.  I could go on, but don't wish to get booted for being Politically Incorrect.

[Ace-Garageguy]

36 minutes ago, 89AKurt said:

That FIU bridge, looked into that.  It was more important that concrete have titanium dioxide, so it would stay clean longer.  I would like to know how much that adds to the cost of concrete!  Also checked into the Project Manager, seems there is some Orwellian memory hole going on, when I searched, found a Linkin hit but when I clicked it showed nothing.  I could go on, but don't wish to get booted for being Politically Incorrect.

I've been following the media reports, and there are potentially conflicting statements being issued to the press and through social media, which appears to be due to some ignorance on the part of the non-engineering types making the statements.

Having grown up around construction engineering, I've seen my share of concrete in structural applications.

The concrete rubble looks as though it crumbled like sugar cakes...not what you'd expect from the mix that would be typical for prestressed members.

IF a non-spec mix was used (and IF that was the cause of the cracking) and / or IF it was still on the green side, and IF workers were putting additional tension on the tendons within the bridge span members (as has been reported in the press) to mitigate the cracking, that could have conceivably caused the concrete to crumble...especially IF the concrete used was lower-strength than what the engineering specs called for.

It's going to be very interesting to see the investigation play out, to see who gets picked to be the scapegoat, or who gets to share the blame.

There were a LOT of people involved here who could well have seen that something was amiss, and taken appropriate action.

This was NOT an "accident", which is the word being used in several media reports. 

Things don't just happen. SOMEONE or SEVERAL PEOPLE didn't do their jobs correctly, and there are NO excuses.

Engineers and builders have every bit as much moral and ethical responsibility for the safety and health of the public as doctors, and that means paying attention, getting the numbers RIGHT, and making a BIG noise when you spot something going off the rails.

Edited March 19, 2018 by Ace-Garageguy

[Ace-Garageguy]

OK...first, I was mistaken in thinking this thing was a prestressed concrete structure. 

I've seen the design proposal drawings, and it was a POST-tensioned design...similar , but different. Same basic idea however, where steel tensioning tendons apply compressive force to the cast concrete parts.

Still the same possible failure modes, including crumbly low-strength concrete not capable of withstanding the entire compressive loads, or a failure of the steel tensioning tendons (due to sub-spec material, some kind of as-yet unexplained damage during construction) or an as-yet unknown factor, or damage to the structure during moving it into position (apparently the positioning of the mobile platforms used to swing the thing and lift it into position differed from the design placement).

Additionally, someone has reported hearing a loud CRACK noise prior to the collapse.

The fact remains, the failure was due to human error somewhere along the line, and there were LOTS of well-paid professionals involved in this, many of whom are there to provide the kinds of checks and balances that insure failures won't happen.

[Ace-Garageguy]

VIDEO OF THE COLLAPSE. The question here is WHY this thing was being worked on (apparently tensioning one of the tendons) WITH TRAFFIC ALLOWED TO BE UNDER IT.

No matter WHY it failed, or how well designed ANYTHING is, there's always the possibility somebody made an error.

It's BEYOND STUPID and criminally irresponsible to take a risk like this with the safety of innocent bystanders.

 

[espo]

1 hour ago, Ace-Garageguy said:

VIDEO OF THE COLLAPSE. The question here is WHY this thing was being worked on (apparently tensioning one of the tendons) WITH TRAFFIC ALLOWED TO BE UNDER IT.

No matter WHY it failed, or how well designed ANYTHING is, there's always the possibility somebody made an error.

It's BEYOND STUPID and criminally irresponsible to take a risk like this with the safety of innocent bystanders.

 

I see they are having difficulties with the video feed ?? Please keep an eye on this. Your information seems far more accurate than anything I can find in the "Main Stream Media".  

[Ace-Garageguy]

40 minutes ago, espo said:

I see they are having difficulties with the video feed ?? Please keep an eye on this. Your information seems far more accurate than anything I can find in the "Main Stream Media".  

Watch carefully the top element of the bridge to the LEFT of the crane.

Just before the collapse, the concrete, which would be in compressive load there...what concrete does best...bends visibly, then crumbles.

Edited March 19, 2018 by Ace-Garageguy

[Fat Brian]

This was a interesting video about the bridge collapse, it shows one of the post tensioning rods half shot out of its bore like it snapped while they were tightening it. Warning for adult manly language. 

 

[89AKurt]

Here is a model, computer version:

 

[89AKurt]

16 hours ago, Ace-Garageguy said:

VIDEO OF THE COLLAPSE. The question here is WHY this thing was being worked on (apparently tensioning one of the tendons) WITH TRAFFIC ALLOWED TO BE UNDER IT.

No matter WHY it failed, or how well designed ANYTHING is, there's always the possibility somebody made an error.

It's BEYOND STUPID and criminally irresponsible to take a risk like this with the safety of innocent bystanders.

Is there a worker on top where the crane is located?  I've not seen if any workers were killed.

[espo]

I reran Ace's provided YouTube video a couple of times. I also noticed what appears to be someone standing on the top of the bridge when it failed. The image is on the left hand side and may take more than one viewing to notice even in slow motion.   

[Ace-Garageguy]

7 hours ago, 89AKurt said:

Here is a model, computer version:

 

That failure "simulation" looks NOTHING like what actually happened.

Compare it to the actual video. Wear your critical-thinking hats while doing so.

The thing did NOT bend in the middle as shown in the "simulation".

The FIRST failure WAS AT THE SPOT CLOSE TO THE CRANE.

It buckled at the TOP of the FIRST inverted V of the truss web, and subsequently bent / broke at the LOWER RH. END OF THE FIRST INVERTED V.

This so-called "simulation" places elements and failures in the wrong locations relative to each other.

Edited March 20, 2018 by Ace-Garageguy

[Deano]

1 hour ago, Ace-Garageguy said:

That failure "simulation" looks NOTHING like what actually happened.

Compare it to the actual video. Wear your critical-thinking hats while doing so.

The thing did NOT bend in the middle as shown in the "simulation".

The FIRST failure WAS AT THE SPOT CLOSE TO THE CRANE.

It buckled at the TOP of the FIRST inverted V of the truss web, and subsequently bent / broke at the LOWER RH. END OF THE FIRST INVERTED V.

This so-called "simulation" places elements and failures in the wrong locations relative to each other.

I noticed that, too.  The sim looks NOTHING like the actual video but, hey, let's not let facts interfere with whatever is the 'agenda of the day', right?

 

[Ace-Garageguy]

Quoted from a CBS News article here:   https://www.cbsnews.com/news/florida-bridge-collapse-fiu-florida-state-university-project-behind-schedule-over-budget-updates-2018-03-20/

" MIAMI -- 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. Documents obtained by The Associated Press through a public-records request show that the Florida Department of Transportation in October 2016 ordered Florida International University (FIU) and its contractors to move one of the bridge's main support structures 11 feet north to the edge of a canal, widening the gap between the crossing's end supports and requiring some new structural design....

Videos of the collapse show that the concrete, prefabricated segment of the bridge started crumbling on the same end of the span where the tower redesign occurred, two days after an engineer on the project reported cracks in the same location. The segment that failed had been placed atop the pylon's footing, and the taller tower section was to be installed later.

Though it is still unclear if the design change played a role in the failure, emails between the school, contractors, officials with the city of Sweetwater and permitting agencies show a project that ended up behind schedule, which had officials worried that further delays could jeopardize millions in federal Department of Transportation funds.

The National Transportation Safety Board (NTSB) began an investigation last Friday. Officials say crews were applying post-tensioning force on the bridge on the day the accident happened, but aren't clear on whether that caused the bridge to fall. Local authorities have said workers conducted a 'stress test' the day of the collapse."

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NOTE: Design changes are not necessarily bad things, as long as they're handled with the same care and obsessive attention to detail as the original design and engineering work. Unfortunately, this is not always the case. GM's ignition switch fiasco that resulted in multiple deaths and which may ultimately cost the company $10 BILLION was the result of a specification change. Though ONE person was ultimately targeted as the scapegoat there, the truth is that checks and balances in the engineering and documentation process that are SUPPOSED to keep "accidents" caused by faulty parts from occurring, failed.

[Jim N]

A governmental agency involves itself in the construction of the bridge very late and demands a significant change, the project is behind and way over budget and there is the potential loss of federal dollars.  Talk about a recipe for disaster!  When the investigation is concluded, we may all be amazed the bridge lasted as long as it did.

[espo]

It would seem that the FDT's late design change had a very detrimental effect on the basic design and with the project already over budget and over due. They were forced to go forward without the proper engineering needed to compensate for the design change. Who will they blame ?  You can be sure that the FDT will be held blameless when the dust settles.   

[Jim N]

2 hours ago, espo said:

It would seem that the FDT's late design change had a very detrimental effect on the basic design and with the project already over budget and over due. They were forced to go forward without the proper engineering needed to compensate for the design change. Who will they blame ?  You can be sure that the FDT will be held blameless when the dust settles.   

Even if FDoT is held responsible, most if not all of the states have something called a Tort Claims Act (sometimes called sovereign immunity) that statutorily limits governmental liability.  The purpose of these statutes is to shield the taxpayer from outlandish jury awards, but most of them have not been updated in years or decades.  I did a quick internet search and it appears that $200,000.00 may be available to each person hurt of killed.  There may be another $100,000.00 available if the person has dependents.  Not much there.

[OldTrucker]

On 3/20/2018 at 8:22 AM, espo said:

I reran Ace's provided YouTube video a couple of times. I also noticed what appears to be someone standing on the top of the bridge when it failed. The image is on the left hand side and may take more than one viewing to notice even in slow motion.   

There was one construction worker injured according to what they said on the news that day. maybe that was him!

Upon looking again if it is on top just to the left of center, that is the top of  a crane down the road that you see. It disappears just before the collapse. (crane must have been moving)

Edited March 24, 2018 by OldTrucker

[espo]

Just now, OldTrucker said:

There was one construction worker injured according to what they said on the news that day. maybe that was him!

From the height that that worker would have fallen from it would be a wonder if he survived. He would have been almost two stories high and falling among concrete rubble, would be hard to not be killed.     

[Ace-Garageguy]

The investigation into the bridge collapse is ongoing, and though it will doubtless be months before the appropriate government agencies release their conclusions, this March 21 article from the Miami Herald addresses several of the items in evidence.   http://www.miamiherald.com/news/local/community/miami-dade/west-miami-dade/article206122229.html

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'Innovative' FIU bridge was a modern take on an old design. And vulnerable to failure.

Below are the most relevant paragraphs from the article:

The Florida International University pedestrian overpass that collapsed catastrophically during construction last week was advertised as a “cable-stayed” bridge, but it actually wasn’t: Instead, it was a modern take on an old bridge design that experts say is vulnerable to failure when a single structural piece is damaged.

While it will likely be months before federal investigators lay out an official explanation, growing available evidence suggests that failure of a single diagonal support truss at one end was enough to cause the entire 174-foot concrete span to buckle under its own weight and crash onto Southwest Eighth Street near the entrance to Florida International University.

What now seems certain from video captures and enlarged photos of the collapse and its aftermath: Crews for a bridge subcontractor were working on top of the unfinished bridge to tighten steel rods inside a diagonal support truss at the north end of the span — possibly to address cracking that had appeared in the concrete — when the structure abruptly gave way.

The question now is, why would the concrete truss fail? Bridge engineers not involved with the project have said overtightening of rods or cables that provide tensile strength in concrete slabs and beams can cause the pieces to twist and shatter abruptly.

Those angled, vertical support pieces were designed to tie the bottom pedestrian deck of the bridge to a canopy that ran along the top in what’s known as a truss design. In through-truss bridges, the top and bottom pieces — referred to as flanges — and the connecting struts, usually set up in an open cross-pattern or web, work together as a structural system to hold the bridge up.

Steel-truss bridges have been commonly used in roadway construction going back decades. But they have a well-known vulnerability: If a vehicle hits one of the horizontal support trusses, the entire span can collapse.

That’s what happened in the 2013 collapse of a 1955 steel-truss bridge over the Skagit River on Interstate 5 near Seattle: A truck carrying an oversized load struck supporting steel struts along one side of a bridge span, which split apart and fell into the river. That’s because there were no backup or redundant structural elements to support the span if one piece failed.

That’s also why truss bridges are mostly avoided in modern road construction, said Ralph Verrastro, a Cornell-trained bridge engineer with Bridging Solutions, a Tampa firm. “A through-truss bridge can catastrophically fail,” Verrastro said.

Because the FIU bridge would see no motorized traffic that could strike a truss, the decision to go with that design by itself raises no red flags.

But he did note something unusual in its approach: Truss bridges usually have vertical struts running along both edges of the deck. But the FIGG design had only a single row of trusses along the center of the bridge in a zig-zag pattern.

Verrastro said that single row might have made the design especially vulnerable. If one diagonal piece failed, it’s didn’t have a twin on the other side that might have provided some support in the same area.

“The unique part is, it’s a single truss,” he said. “When one member failed, there was no redundancy.”

He also pointed to one possibly significant difference between the FIU bridge and a traditional truss bridge: It was made of heavy concrete, not much lighter steel. 

...But what the engineers may not have known, (a) faceless Canadian YouTuber suggests, is that the steel inside the struts could have been damaged. His evidence: photos showing a steel rod protruding from the top of the bridge canopy with a blue hydraulic jack — equipment used in tensioning support cables or rods inside concrete — still attached. A subcontractor crew member working on that spot fell to his death when the bridge collapsed.

In the video, the Canadian runs a demonstration showing how a steel rod undergoing tensioning will suddenly snap and shoot out of the jack if stressed beyond its capacity.

The video lays out further evidence: Drawings on the FIU website show how the bridge span, which was prefabricated by the side of the trail over a period of months, was to be moved into place using four powerful lift trucks.

In the plans, two trucks would be placed side-by-side at either end, lined up under spots where the vertical trusses met in a joint, the Canadian noted. But video of the actual move shows one of the trucks at the north end, where the bridge appears to have failed, was moved farther towards the middle of the span, leaving the end unsupported.

...the Associated Press said in a story Tuesday that the Florida Department of Transportation ordered the northern support pylon be moved 11 feet to make room for future expansion of the trail. That required a design change that lengthened the span — and put the support pylon in the dirt well off the edge of the roadway, which could also explain why the northernmost truck could no longer follow its original planned route.

...the weight of the unsupported end could have placed enough stress on the last diagonal strut — the one being worked on when the bridge fell — to damage the rod inside it and loosen the tension on it, the Canadian AvE says in his YouTube video. It would also explain cracking that appeared on the north end of the bridge that a FIGG engineer reported to FDOT on Tuesday, although he concluded that it posed no safety concerns. Cracking in new concrete is not uncommon, and could be superficial or a sign of deeper trouble.

EDIT: PLEASE NOTE, there is nothing inherently wrong with a truss bridge, when properly engineered and constructed. This one is doing just fine supporting its own weight, as well as the weight of several locomotives...and it's been doing it since 1944.

 

 

 

Edited April 4, 2018 by Ace-Garageguy

[Ace-Garageguy]

The Five Universal Laws of Human Stupidity :    https://qz.com/967554/the-five-universal-laws-of-human-stupidity/

[Ace-Garageguy]

As part of my continuing quest to bring a modicum of critical thinking ability to an increasingly resistant-to-reason and willfully ignorant populace, I present the "Self-Filling Water Bottle", a waste of $340,000 in development money...that could have been saved if any of the principals had been awake during high-school physics.

 

 

[SfanGoch]

Stupid knows no bounds. 

[Ace-Garageguy]

San Francisco high-rise has sunk 16 inches since completion in 2009, and is leaning 15 inches too. Pretty special. Erected on compacted mud, apparently the developers felt driving pilings to solid bedrock was a silly old-fashioned waste of money. Built for $350 million (and it could have taken $20 to $50 million more to drive piles to bedrock) it may take $500 million MORE to fix it. Kinda the GM approach to engineering: build it wrong to save a buck, fix it later for at least ten times the cost it would have been to do it right the first time, and pay out millions of dollars MORE in lawsuits. I'm impressed.  

NOTE: The bedrock in the area is said to be 400 feet down. A piling driven to that depth, capable of supporting around 200 tons, would cost something like $16,000 (very rough napkin calculations, based on cost to drive similar pilings to 125 feet). I'm sure there's a civil or construction engineer who can guesstimate the weight of the building, wind loads, etc. and who knows what percentage of the total would be considered adequate for pilings to carry.

https://sf.curbed.com/2018/4/16/17242450/millennium-tower-sinking-repair-tilting-building-san-francisco

 

 

 

Edited July 15, 2018 by Ace-Garageguy

[Snake45]

There's very little from California--especially Frisco and LA--that can surprise or shock me with its sheer stupidity anymore.