Pedestrian bridge collapse at Florida International University FIU Miami

User avatar
TollandRCR
Posts: 20731
Joined: Sun Mar 22, 2009 11:17 pm
Location: RIP, my friend. - Foggy

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#26

Post by TollandRCR » Fri Mar 16, 2018 9:13 pm

In response to this message Florida DOT could have ordered traffic under the bridge to be stopped. But had they chosen to treat this as a valid warning could they have done anything else? It was not their project.
“The truth is, we know so little about life, we don’t really know what the good news is and what the bad news is.” Kurt Vonnegut

TexasFilly
Posts: 18124
Joined: Mon Sep 28, 2009 12:52 pm

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#27

Post by TexasFilly » Fri Mar 16, 2018 9:40 pm

TollandRCR wrote:
Fri Mar 16, 2018 9:13 pm
In response to this message Florida DOT could have ordered traffic under the bridge to be stopped. But had they chosen to treat this as a valid warning could they have done anything else? It was not their project.
Closing down the road would've resulted in far fewer dead and injured people. I think FIGG's insurers may have just had a stroke. Leaving a voice mail about something as important as the structural integrity of a bridge is beyond stupid.
I love the poorly educated!!!

I believe Anita Hill! I believe Dr. Ford!

User avatar
TollandRCR
Posts: 20731
Joined: Sun Mar 22, 2009 11:17 pm
Location: RIP, my friend. - Foggy

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#28

Post by TollandRCR » Fri Mar 16, 2018 9:42 pm

The University of Miami has a new steel pedestrian bridge. Could there be a reason that the FIU bridge was concrete other than being an “iconic” bridge?
“The truth is, we know so little about life, we don’t really know what the good news is and what the bad news is.” Kurt Vonnegut

User avatar
Volkonski
Posts: 22275
Joined: Sat Mar 02, 2013 4:44 pm
Location: Texas Gulf Coast and North Fork of Long Island
Occupation: Retired Mechanical Engineer

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#29

Post by Volkonski » Fri Mar 16, 2018 9:47 pm

Would help to know exactly where the cracks were.

The tensile strength of concrete is about 10% of it's compressive strength.

Concrete beams, slabs, etc are reinforced with steel rebar which can bear higher tensile stresses. However, when steel is pulled in tension it stretches. If it stretches to much it transmits the stress into the concrete which cracks.

The cracks might have been the result of sagging which puts the bottom of the slab in tension and the top of the slab in compression. The concrete in the bottom of the slab, in tension and torsion from the sagging, would crack once the stresses exceeded the concrete's tensile strength. As the cracks form the concrete would no longer hold the rebars in place. The rebars would bend.
Image“If everyone fought for their own convictions there would be no war.”
― Leo Tolstoy, War and Peace

User avatar
Volkonski
Posts: 22275
Joined: Sat Mar 02, 2013 4:44 pm
Location: Texas Gulf Coast and North Fork of Long Island
Occupation: Retired Mechanical Engineer

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#30

Post by Volkonski » Fri Mar 16, 2018 9:56 pm

A Look at How
the Florida Bridge Was Built


https://www.nytimes.com/interactive/201 ... &smtyp=cur

This section was 174 feet long.

Image
Image“If everyone fought for their own convictions there would be no war.”
― Leo Tolstoy, War and Peace

User avatar
Volkonski
Posts: 22275
Joined: Sat Mar 02, 2013 4:44 pm
Location: Texas Gulf Coast and North Fork of Long Island
Occupation: Retired Mechanical Engineer

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#31

Post by Volkonski » Fri Mar 16, 2018 9:57 pm


NBC News

@NBCNews

LIVE: Officials give update on Florida pedestrian bridge collapse
http://
nbcnews.to/2FXnQtn


https://www.
pscp.tv/w/bXxZzzI5MjM1
fDFPZEtyWndMZXllS1hHATTYiGZ4Rm6UBcJ0PwOcccU8CZ7hPJKjlZV0nvxq-A==

7:33 PM - Mar 16, 2018
Image“If everyone fought for their own convictions there would be no war.”
― Leo Tolstoy, War and Peace

User avatar
Res Ipsa
Posts: 2563
Joined: Wed Mar 18, 2009 1:31 am

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#32

Post by Res Ipsa » Fri Mar 16, 2018 10:03 pm

TollandRCR wrote:
Fri Mar 16, 2018 9:13 pm
In response to this message Florida DOT could have ordered traffic under the bridge to be stopped. But had they chosen to treat this as a valid warning could they have done anything else? It was not their project.
It was their road.
Thanks pal.

User avatar
TollandRCR
Posts: 20731
Joined: Sun Mar 22, 2009 11:17 pm
Location: RIP, my friend. - Foggy

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#33

Post by TollandRCR » Fri Mar 16, 2018 10:36 pm

Indeed. I simply do not like the idea of a non-governmental entity being responsible for something involving a public road. This whole thing stinks a bit.

This seems to have been a show project for FIU. Without their endorsement of ABC they might have used steel. The FIU President was unseemly in his enthusiasm for a blasted bridge.

Now when one searches the Web for FIU about half the returns concern the collapsed bridge. That will be true for several years. Carelessness has its price.
“The truth is, we know so little about life, we don’t really know what the good news is and what the bad news is.” Kurt Vonnegut

User avatar
Foggy
Posts: 28337
Joined: Tue Jan 20, 2009 12:00 pm
Location: Fogbow HQ
Occupation: Dick Tater

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#34

Post by Foggy » Sat Mar 17, 2018 6:05 am

Volkonski and TollandRCR, you are treasures of information and thoughtfulness when something like this happens. :bighug:
Every locked door has a key. - Emika Chen

User avatar
Addie
Posts: 33122
Joined: Mon Jun 15, 2009 6:22 am
Location: downstairs

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#35

Post by Addie » Sat Mar 17, 2018 7:59 am

Yeah :thumbs:
Foggy wrote:
Sat Mar 17, 2018 6:05 am
Volkonski and TollandRCR, you are treasures of information and thoughtfulness when something like this happens. :bighug:
Democracy is a garden that has to be tended. -Barack Obama

User avatar
Sterngard Friegen
Posts: 44469
Joined: Wed Aug 05, 2009 12:32 am
Location: Over the drawbridge

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#36

Post by Sterngard Friegen » Sat Mar 17, 2018 9:48 am

Tollie would be Secretary of Education in my White House. Volky would probably be my Chief of Staff.

User avatar
Whip
Posts: 3850
Joined: Mon Nov 09, 2015 12:31 pm

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#37

Post by Whip » Sat Mar 17, 2018 10:11 am


User avatar
tek
Posts: 3507
Joined: Fri Nov 16, 2012 6:02 pm
Location: Happy Valley, MA
Occupation: Damned if I know

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#38

Post by tek » Sat Mar 17, 2018 10:50 am

wow.. almost looks like a point load at the crane work area..
There's no way back
from there to here

User avatar
TollandRCR
Posts: 20731
Joined: Sun Mar 22, 2009 11:17 pm
Location: RIP, my friend. - Foggy

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#39

Post by TollandRCR » Sat Mar 17, 2018 10:56 am

TexasFilly wrote:
Fri Mar 16, 2018 9:40 pm
... Leaving a voice mail about something as important as the structural integrity of a bridge is beyond stupid.
It is beyond uncaring, beyond irresponsible, beyond criminal.

I hope some contractors are put out of business and that those at FIU who pushed this rather than a more careful installation or even a steel bridge lose their jobs. Innovation should not endanger people.

Note how much testing is required to put an innovative aircraft into the passenger business. SW 8th should have been closed until that tower was erected, cables installed, and tests completed.

It was a political goal that caused this carelessness:

"The mission of the ABC-UTC [Accelerated Bridge Construction - University Transportation Center at FIU] is to reduce the societal costs of bridge construction by reducing the duration of work zones, focusing special attention on preservation, service life, construction costs, education of the profession and development of a next-generation work force fully equipped with ABC knowledge."

Note The absence of any mention of safety. Yes, I have contempt for the ABC\UTC and FIU. Universities do not endanger lives.


The Kindle Fire spell checker makes it hard to type FiU. It changes it to DUH. I wonder if it did this before the collapse of the bridge?
“The truth is, we know so little about life, we don’t really know what the good news is and what the bad news is.” Kurt Vonnegut

User avatar
Sterngard Friegen
Posts: 44469
Joined: Wed Aug 05, 2009 12:32 am
Location: Over the drawbridge

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#40

Post by Sterngard Friegen » Sat Mar 17, 2018 11:03 am

tek wrote:
Sat Mar 17, 2018 10:50 am
wow.. almost looks like a point load at the crane work area..
Please 'splain for those of us who are non-tek.

User avatar
TollandRCR
Posts: 20731
Joined: Sun Mar 22, 2009 11:17 pm
Location: RIP, my friend. - Foggy

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#41

Post by TollandRCR » Sat Mar 17, 2018 11:08 am

I also want to know why that cable to the bridge from the crane was there.
“The truth is, we know so little about life, we don’t really know what the good news is and what the bad news is.” Kurt Vonnegut

User avatar
Chilidog
Posts: 9786
Joined: Mon Jan 09, 2012 11:36 am

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#42

Post by Chilidog » Sat Mar 17, 2018 11:19 am

There was at least one worker on top of the bridge at the time. it looks like he grabbed onto the crane cable when the collapse started but couldn't hold on and fell down on top of the debris.

horrible.

User avatar
Chilidog
Posts: 9786
Joined: Mon Jan 09, 2012 11:36 am

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#43

Post by Chilidog » Sat Mar 17, 2018 11:23 am

tek wrote:
Sat Mar 17, 2018 10:50 am
wow.. almost looks like a point load at the crane work area..
from an article on the collapse
The NTSB investigator in charge, Robert Accetta, said Friday night it was too early to tell whether the bridge failed at the point construction workers were applying post-tensioning force to strengthen the beams.

User avatar
TollandRCR
Posts: 20731
Joined: Sun Mar 22, 2009 11:17 pm
Location: RIP, my friend. - Foggy

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#44

Post by TollandRCR » Sat Mar 17, 2018 11:43 am

The U.S. Department of Transportation has issued materials (maybe standards) for Accelerated Bridge Construction. I have tried to access those materials on the Web, but the three sites cannot load. Every engineer with an ABC bridge under construction is consulting them?

Does the attempt to tension the bridge indicate that the engineers knew there was a problem? Were the engineers from one of the inspection firms or from Figg?
“The truth is, we know so little about life, we don’t really know what the good news is and what the bad news is.” Kurt Vonnegut

User avatar
kate520
Posts: 15668
Joined: Mon Oct 26, 2009 3:02 pm
Location: Dark side of the Moon
Occupation: servant of cats, chicken wrangler
Contact:

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#45

Post by kate520 » Sat Mar 17, 2018 11:50 am

Those poor people! Those lucky people in the far right lane! Did you see the drivers immediately rushing up? At least some were gawkers, but some were ready to rescue. :bighug:
DEFEND DEMOCRACY

User avatar
Volkonski
Posts: 22275
Joined: Sat Mar 02, 2013 4:44 pm
Location: Texas Gulf Coast and North Fork of Long Island
Occupation: Retired Mechanical Engineer

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#46

Post by Volkonski » Sat Mar 17, 2018 11:53 am

Chilidog wrote:
Sat Mar 17, 2018 11:23 am
tek wrote:
Sat Mar 17, 2018 10:50 am
wow.. almost looks like a point load at the crane work area..
from an article on the collapse
The NTSB investigator in charge, Robert Accetta, said Friday night it was too early to tell whether the bridge failed at the point construction workers were applying post-tensioning force to strengthen the beams.
This new video shows that is just what happened. It appears to me that the bridge was sagging a little at that point or just slightly to the south (right) of it. The lower walkway section started to fail pulling the support of the upper roof section down which then failed. As the bridge fell the northern (left) end of the lower walkway was pulled off of its support.

I supect that that crane was trying to lift the sagging point up to get it fully in compression after which cables would be attached to the underside (or tightened if they were already atttached) like the string of a bow. As they did this the crack(s) suddenly propagated and the section failed.

The crack propagated because the rebar on the bottom of the section had been pulled out of the concrete as the crack formed but when they lifted the section the rebar did not go back into the concrete. This would have caused the crack to propagate upward causing sudden failure when the stresses in the concrete and rebar exceeded their tensile strength. Once failure began the lower section pulled down on the roof section which also failed.

I think that their attempt to fix it in fact caused the sudden failure.

This is a textbook example of how concrete structual pieces fail. Once cracks formed they should have known they had a big problem. They should have put a support under the north section of the bridge to the south of the cracks before they proceeded.

There was really no good way to fix this. Once there are cracks water can get in. You get freeze thaw cycles. Failure will occur eventually.
Image“If everyone fought for their own convictions there would be no war.”
― Leo Tolstoy, War and Peace

User avatar
TollandRCR
Posts: 20731
Joined: Sun Mar 22, 2009 11:17 pm
Location: RIP, my friend. - Foggy

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#47

Post by TollandRCR » Sat Mar 17, 2018 12:05 pm

And they should have stopped traffic.
“The truth is, we know so little about life, we don’t really know what the good news is and what the bad news is.” Kurt Vonnegut

User avatar
Sterngard Friegen
Posts: 44469
Joined: Wed Aug 05, 2009 12:32 am
Location: Over the drawbridge

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#48

Post by Sterngard Friegen » Sat Mar 17, 2018 12:16 pm

TollandRCR wrote:
Sat Mar 17, 2018 12:05 pm
And they should have stopped traffic.
At a minimum. I find it incredible the workers didn't bother to think about that.

Which means this should almost be in the Florida man thread.

User avatar
kate520
Posts: 15668
Joined: Mon Oct 26, 2009 3:02 pm
Location: Dark side of the Moon
Occupation: servant of cats, chicken wrangler
Contact:

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#49

Post by kate520 » Sat Mar 17, 2018 12:22 pm

But the engineers with FIGG or MCM, can’t remember, knew already about the cracks, even if the FIU staff didn’t hear the voicemail. (Who tf sends a life-or-death message by email and doesn’t follow up?!?) What would cause them to go ahead with the installation, knowing that?

Wait, don’t tell me...let me gue$$.
DEFEND DEMOCRACY

User avatar
TollandRCR
Posts: 20731
Joined: Sun Mar 22, 2009 11:17 pm
Location: RIP, my friend. - Foggy

Re: Pedestrian bridge collapse at Florida International University FIU Miami

#50

Post by TollandRCR » Sat Mar 17, 2018 12:40 pm

Was the 174’ length of the section that failed at the upper end of the lengths of sections that have been used in ABC?
“The truth is, we know so little about life, we don’t really know what the good news is and what the bad news is.” Kurt Vonnegut

Post Reply

Return to “Science & Technology”