Florida Bridge Collapse

EBEBRATT-Ed

Prayers for the victims that's the most important thing.
Glad I didn't work on the bridge.
Glad I am not the engineer.

****, some of the stuff built now is face it, just crap.
low bid
shoddy work

We all could make lists of projects in our own areas

Hartford, CT Civic Center roof collapse
Boston, Ted Williams Tunnel part of the ceiling fell bad anchors or something

I am sure there are more that I can't remember in my complete disgust

Downtown Springfield. MA there are two railroad bridges that cross Main St and Dwight street.

Their probably 100 years old (or older). Drive under them and you feel completely safe, massive granite support blocks , massive steel beams, with huge rivets the size of your arm.

Now, cheap, shoddy, low bid

Steamhead

One of many articles:

https://washingtonpress.com/2018/03/15/a-first-of-its-kind-bridge-just-collapsed-in-miami-killing-multiple-people/

the_donut

Sometimes it’s nit the work, but unplanned for circumstances. We had a bridge drop 7” in one day from digging offsite. Vibrations and rain made a fluidized bed of sorts and pillar on north bound lane sunk. Bridge was closed down and area around underground aquifer was stabilized. It was a big ordeal for Chicago traffic.

Docfletcher

I'm anxious to see the investigative report/s. Also would like to know if the inspectors who OK'd the opening will find themselves on the carpet.

Gordy

the_donut said:

Sometimes it’s nit the work, but unplanned for circumstances. We had a bridge drop 7” in one day from digging offsite. Vibrations and rain made a fluidized bed of sorts and pillar on north bound lane sunk. Bridge was closed down and area around underground aquifer was stabilized. It was a big ordeal for Chicago traffic.

Liquefaction......

Fred

Docfletcher said:

I'm anxious to see the investigative report/s. Also would like to know if the inspectors who OK'd the opening will find themselves on the carpet.

My understanding is it wasn't open yet. It was under going some type of stress testing today. This is the second or third time this particular company has had a bridge, under construction, collapse. First time anyone killed.

Gordy

Engineering is always pushing the envelope of design, and materials. It doesn’t always work out as noted.

Docfletcher

News said it was opened this weekend. I suppose misinformation is out there.

Gordy

OSHA will most definitely be on seen to get to the bottom of things,

EBEBRATT-Ed

Yeah, they were stress testing this alright. I think it failed the stress test.

Really, your not stopping traffic while you stress test? Can't stop traffic?? Cant shut down??

Those of us that work on commercial and industrial here that all the time. So sick of it. OSHA may think otherwise.

Cant shut down? Well the dam traffic is shut down now isn't it?

Wouldn't it have been better to stress test at 2am rather than 11am?

I am sure building and designing a bridge isn't easy but we sent a man to the moon. Not rocket science.

No, somebody decided (an idiot) "the traffic cant be shut down let's build the bridge on the side of the road and then roll it out there"

They probably stress cracked it picking it up with a crane, set it down and it looked ok and then broke with the stress test. No safety factor, that would cost too much. If it was built in 1920 it would be ok.

Somebody probably several are going to jail for this one and probably several businesses closing

Poor victims

Lawyers,

I can here the hum of paper shredders running in FLA.

leonz

EBEBRATT-Ed said:

Prayers for the victims that's the most important thing.
Glad I didn't work on the bridge.
Glad I am not the engineer.

****, some of the stuff built now is face it, just crap.
low bid
shoddy work

We all could make lists of projects in our own areas

Hartford, CT Civic Center roof collapse
Boston, Ted Williams Tunnel part of the ceiling fell bad anchors or something

I am sure there are more that I can't remember in my complete disgust

Downtown Springfield. MA there are two railroad bridges that cross Main St and Dwight street.

Their probably 100 years old (or older). Drive under them and you feel completely safe, massive granite support blocks , massive steel beams, with huge rivets the size of your arm.

Now, cheap, shoddy, low bid

====================================================

The mess with the Ted Williams Tunnel was a real sham;

The contractors on this portion of the big dig bought roof bolt epoxy resin glue from a small family run firm that sold adhesives and they used the wrong resin for the roof anchors /bolts holding up the huge concrete panels that were used.

(modern tunnels use air duct tubing and suspended high speed high volume fans to remove exhaust fumes)

This mess with the concrete air ducts which was another bad tunnel design issue as solid fiberglass ventilation tubing and exhaust fans were the normal way to do that job but the big dig being what it was in a cost plus gravy train only made it worse because so little steel on the support bolts was holding up the concrete panels to begin with.

SO anyway Martha Cokely the state attorney general for massachusetts at the time (I think) went after the family run firm here in the Boston court system and they were nearly bankrupted in her witch hunt and plead guilty with bad legal advice(in my opinion as the contractor was the entity that was at fault and they were barely pinched with fines.

Gordy

This bridge in animated videos of the construction process was suppose to have suspension cable from a center tower. Apparently these cables were to be installed after the structure was moved into place.

A surveillance video showing the actual collapse shows a crane placing a load on the upper deck. To hard to tell what the load is but as soon as it was placed the failure occurred.

Condoman

The Hartford CT collapse was 1978. I worked in a place where we could see it built on the ground & then raised in place. We spent a lot of time viewing the work. It turns out the incorrect computer model was used to design the structure.

Solid_Fuel_Man

Remember the Tacoma Narrows resonance we all studied in high school. Just because it's older doesn't mean it's necessarily better.

Gordy

I have a feeling it’s a combination of errors that were over looked in the erection plan.

NY_Rob

^ most likely...

If you watch "Engineering Disasters" it's usually several factors, errors/omissions, etc that contributed to the failure.

Maybe it will come down to Chinese Steel used?
Will be interesting to find out.

EBEBRATT-Ed

Not to say they never had failures in the old days but I will take my chances with the old stuff any day.

HomerJSmith

One can see from the tapes that there was a failure of the concrete. The way the diagonal braces pushed thru the concrete and the small bust up of the concrete in to little pieces.

I bet dollars to donuts that the cement was from China. I do believe it was poor cement as the contributing factor.

BobC

That they would place a load on an untested bridge with a crane WITH traffic on the road underneath sounds like a real screw-up.

The actual failure is probably a combination of factors, whoever signed off on the safety inspections had better not pencil whipped them.

It\s a terrible tragedy for the families that lost loved ones.

Bob

hot_rod

I think on a design load like that the reinforcing steel and design has a lot to do with success. Concrete is more of a compression strength material, it works well with solid material below without much rebar. Suspended like that, the steel reforming inside, cable support, pre-stressing cables, etc has a lot to do with the system.

Ever seen a stressed cable break inside concrete! stand back.

Zman

It sure looks like the connection between the first web and the top chord gave out. Could be a concrete,steel or design flaw.

Fred

Listened to a local design review this afternoon. It was said that, while this investigation will take time, design is rarely the cause of a bridge failure. Most common causes are accelerated construction and/or quality of materials used (Don't meet design specifications)

the_donut

I go to church with a guy who pretensions structural cables like the ones in Florida. He’s had cable break free and end up more than a quarter mile away. AvE is a tool guy, but his comments are pretty interesting, especially on false works. Seems like a lot ducks were not in line with this one.

Gordy

There is prestressed concrete, which is done with cables under tension in the forms then concrete is poured. Then the cables are cut loose after cure is reached. Usually beams.

Then there is post tensioned where the concrete is poured with cable ducts inside. Then cable is pulled under tension after concrete has cured. Runways can be done like this, and bridges also.

Suspension bridges like the golden gate, and the like. Then there is cable stayed bridge where cable is strung from towers into the superstructure. More integral in the design verses hanging from cables.

The pedestrian bridge was suppose to be a cable stayed design. The tower was off the street. That was only part of the bridge that was installed so far. Cables had not been run into the superstructure yet from what I have seen. Nor the center tower for the cables installed. Unless it was out of frame.

Could be possible the superstructure was designed to carry its own load plus construction activity with limits, and critical areas for loading until cables were installed.

I highly doubt materials were an issue especially the concrete. There is testing from batching to onsite testing before pouring to meet air entrainment requirements, slump, temperature, and test cylinders are made.

Strength tests are done with the cylinders compressive, or flexiral depending on types of cylinders, or test beam samples.

These strength tests are done, and have to pass psi requirements before the concrete can pass for service loading. Also with superstructure it’s a minimum 7 day cure time before shoring can be stripped even if strength tests reach required psi strengths.

Rebar has to meet similar requirements also. Test samples from the rebar delivered onsite are taken to the labs for testing.

There is also plenty of engineers, and inspectors onsite to make sure rebar is properly placed per design. Forming is done to correct dimensions etc. especially with a unique design as such the scrutiny is much more anal.

There should have also been an erection plan to insure that the superstructure is installed with out creating loads to the piece that the design does not allow for, and a proper procedure for the safety of the motoring public.

Something was missed through all this. Could very well be a design oversite. Could be undo stress during the erection process. Could have been workers not following proper construction loading while the piece was most vulnerable. Be interesting to see the investigative analysis on this one.

SlamDunk

Faster,better,cheaper.

Gordy

http://abcn.ws/2GxcLNg


Now does it look like any cable stays were up off a tower when the span was set? Unless this design completely changed from the original concept.

Fred

I read an article somewhere today, but I can't seem to find it right now, that said the cable stays had not yet been installed but that was the next step in the process. I'm not sure why stress testing was done before all of the support structure was in place and why they didn't reroute traffic during whatever stress testing they were doing, "Testing" being the key operative.
I also read they were using a "new" Self Cleaning concrete, designed to grab pollutants out of the air. Not sure how that may have affected the strength of that concrete or what the additives might have been???

Gordy

It’s quite possible, though I’m not intimate with the design of the superstructure it may have been post tensioned. Possibly the testing was procedure to be performed after handling during the erection, and after setting in place. Checking the tensioning blocks for the cables. This could be anything from visual confirmation wedge block dogs are in place to actual cable tension.

Remember the superstructure was transported into place on the mobile rigs. The position of the bearing points on the superstructure is critical. The erected bearing point is at the very ends once set in place. So there is some deflection differences there which could work things loose.

Also not sure how the superstructure was built as to what it was resting on for bearing points when being poured, and after it was stripped once cure was reached. Nor how the mobile erection units were loaded with the superstructure. I assume they were able to get underneath the superstructure the jack it up.

SlamDunk

Fred said:

a "new" Self Cleaning concrete, designed to grab pollutants out of the air.

What?

And do what with the pollutants?

SeymourCates

Gordy said:

http://abcn.ws/2GxcLNg


Now does it look like any cable stays were up off a tower when the span was set? Unless this design completely changed from the original concept.

No it does not.

And, therein lies your problem if you add load to it without those cable stays.

Such a span is too long to support much of a load without stays, IMHO. It's own weight might be marginal.

Gordy

SlamDunk said:

Faster,better,cheaper.

Faster leads to cheaper since labor costs are the highest part of the bill on any project.

Then there is liquidated damages for not meeting a completion date. Most times pretty steep. Penalties could be as high as 2500 dollars or more for every calendar day over the completion date on a 14 million dollar project. Depends on the contract. Pressure is always on the contractor while the owner try’s to put a stick in their spokes every step of the way.

Profit margins on road work are pretty narrow depending, 3-7% if everything goes as planned depending on job. There is a lot of risk on some jobs as this one reared it’s ugly head for a profit of a million dollars.

the_donut

Post stressed and a sub contractor came in to retension cable. Cable snapped and rebound collapsed lagoon side. Definitely should have closed road for traffic and supported span in middle.

STEVEusaPA

From a family with a long line of Italian stone masons, I was told in ancient times the architect, designer (engineer in this case) stands under the structure when the supports are removed for a bridge or arch (in this case the stress test). If the structure fails, it literally falls on them.
Very sad.
In Pennsylvania, last reported a large number of bridges/overpasses, failed inspection and need repairs.

Fred

SlamDunk said:

Fred said:

a "new" Self Cleaning concrete, designed to grab pollutants out of the air.

What?

And do what with the pollutants?

I don't know. Here is the quote from the article and the link:
"It was the largest U.S. pedestrian bridge to have been moved that way and the first in the world to have been built from so-called self-cleaning concrete, which grabs pollutants from the air, the university said."

https://www.msn.com/en-us/news/us/collapsed-florida-walkway-built-with-accelerated-technology/ar-BBKhgUx?li=BBnb7Kz

Gordy

SeymourCates said:

Gordy said:

http://abcn.ws/2GxcLNg


Now does it look like any cable stays were up off a tower when the span was set? Unless this design completely changed from the original concept.

No it does not.

And, therein lies your problem if you add load to it without those cable stays.

Such a span is too long to support much of a load without stays, IMHO. It's own weight might be marginal.

950 tons over six lanes of traffic, bearing on probably 8 square feet each end guesstimate.

My guesstimate on span is over 100’ with 6 12’ lanes 2 8’ shoulders, and the piers off the edge of the road an unknown distance.

Gordy

Self cleaning concrete is nothing new they use it in Saudi Arabia. It doesn’t grab pollutants from the air. It purges dirt, and pollutants from the concretes porous surface. The quote is misleading, and worded improperly.

Fred

Gordy said:

Self cleaning concrete is nothing new they use it in Saudi Arabia. It doesn’t grab pollutants from the air. It purges dirt, and pollutants from the concretes porous surface. The quote is misleading, and worded improperly.

I can't attest to the accuracy of the article @Gordy , but it does go on to say this was the "first in the world" to use this concrete technology. I suspect it is something different that what the Saudis use???

Gordy

The intention of the self cleaning is the concrete. The photo catalytic process cleans the air as a secondary unintentional effect. If it were that significant we would use it for all the concrete roads etc, and reverse global warming.

All you have to do is change a few of the proportions in the Mix design to be different than someone else’s, and wha la the first of its kind in the world

Gordy

Could also mean first collapsed walk bridge using self cleaning concrete in the world too.

SeymourCates

Gordy said:

SeymourCates said:

Gordy said:

http://abcn.ws/2GxcLNg


Now does it look like any cable stays were up off a tower when the span was set? Unless this design completely changed from the original concept.

No it does not.

And, therein lies your problem if you add load to it without those cable stays.

Such a span is too long to support much of a load without stays, IMHO. It's own weight might be marginal.

950 tons over six lanes of traffic, bearing on probably 8 square feet each end guesstimate.

My guesstimate on span is over 100’ with 6 12’ lanes 2 8’ shoulders, and the piers off the edge of the road an unknown distance.

950 tons on 8 square feet is no issue. It's the 300 tons in the middle creating the bending moment (and causing tension in the concrete on the bottom) that you have to worry about.

Gordy

No it’s not a big deal, And don’t forget compression on the upper deck. Concrete is strongest under compression, but it has it’s point of failure also. The top deck in this design Transfers some of the bottom load to the top just like a truss, bar joist etc.