At the closing summary, the speaker might have raised the question: Why was such a structure chosen at all? The design makes no sense structurally, but FIU wanted to showcase technology for minimizing road closures, and presumably also post-tensioned concrete truss technology. The span could have been executed with a common steel truss design which is used everywhere, but they wanted something unique and “cool.” They were showing off.
As it happened, the University of Miami built a pedestrian bridge at about the same time. A side-by-side comparison of these two solutions to the same problem would be instructive.
Sir, you sound like an Engineer. I am in 100% agreement with you. And a female designer of it said she wanted it to show the FIU skills by building it. People there said that steel is UGLY! And this new design was "prettier". The Eiffel tower is not ugly. Nor is the Goldengate bridge. Nor is anything made of metal if it is designed right. Concrete is just great for roads.
Just wonderful. The same company is building a bridge over the ship channel here in Channelview Texas, and work was just halted today stating that they're using the same design flaws that caused the Florida pedestrian bridge collapse...
When a large percentage of the funds required to build a bridge such as this are spent on so-called "artistic embellishments", specifically the fact that this was to be a "fake" cable-stayed bridge, engineers depart from tried and proven designs, such as symmetrical trusses, alternate load paths, etc. This could have been, and probably should have been, virtually a mail order catalogue bridge that would have given a hundred years of trouble free service. I have no idea if this was FIU or Figg's idea, but it clearly was not a good one. NTSB report discusses minutae, yet overlooks the fact that this could have been a much simpler, and probably less expensive, structure, with many times the safety factor. And nobody would be dead. Good design IS art, without the 2000's version of gargoyles.
It was FIU. I don't think it's bad to build something different, but engineers need to be cognizant of how the structural changes will affect margins, etc (and anything to look out for during construction). Sometimes the right answer is just a simple truss, but the world would be a very boring place if every pedestrian bridge and office building and house was virtually straight out of a catalogue.
@@AmbientMorality try this as funerary speech: "..the world would be a very boring place if every pedestrian bridge and office building and house was virtually straight out of the catalogue" If someone needs experimental brigde designs just to avoid a boring world, he/she needs a psychiatrist an not an engineer! Nobody reinvent the wheel just because too many wheels are boring.
@@AmbientMorality Sorry, but thats not simply "wrong", thats naive. We dont live in the iron age and the builder estimates the dimensions of an member. Even if we call it "bridge design" there is no "designer" who makes curves with a pencil for a new design and nobody know it isn't safe until it is completed. For every bridge we have an structural engineering calculation. Complex construction will first build as model, because some calculations must be calibrated. Could we build a safe version of the FIU bridge? yes of curse But, there are good solutions, bad solutions and error-prone solutions. This is an error-prone solution for the construction workers and an bad civil engineering solution. Its not an cheap solution. Its not an quick solution. Its just the "looks impressive" solution. Yes we could build this. But you need more material and / or much more supervision and controlling. It can't be cheaper. It can't be faster. Someone has exchanged security for reputation. And some people pay for this with there lifes. This bridge have an structual design that is susceptible for failure without notice and fatal failure from an small damage (even from small damage from terrorists). Simply an bad design. And every civil engineer knows: never ever traffic under a bridge that MUST fatal failure if the construction worker makes a mistake on just ONE screw....
Great presentation even for a lay person such as myself. What I found disturbing was that immediately after the collapse the designers took to social media to blame the installation team as being at fault. An investigation had not even begun and already they were denying involvement.
This was not a cable-stayed design at all. The speaker could have made this point more forcefully. Instead, he started out by calling it a cable-stayed design, then added (in effect) but not really.
@Jeff Conard I'll have to re-watch that I guess. Several times in the hearing it mentions that those are simply hollow pipes. In fact one of the findings approved in the report is it those void areas actually weakened the structure.
Jeff Conard - I don’t know where you are getting that. I just read the NTSB synopsis of the October hearing, and there is nothing in there like that. Here is a brief excerpt: • Bridge design and construction plan errors, and unique bridge characteristics and mechanisms of failure. The uniqueness of designing a concrete truss bridge led to the circumstances that accounted for the collapse of the pedestrian bridge. ... Did you read the actual NTSB report or a news report about the report?
As i understand its because they want to minimizes road closure and material needed And i think the cable is enough if its properly designed, who knows
Yes definitely ask "what are the ways a structure could fail". Ask that of every component of the connection, every connection, the structure as a whole. But first a concrete truss begins as an ill-conceived structure. We typically do not build concrete trusses and there is a reason- concrete is not suited for trusses. If you want to build something that is typically not built then you have to scrutinize every part of it twice as much. The first time I looked at the side elevation of the bridge I could predict where it was going to fail and why. Did they rely too much on computer modeling and allowed that to cloud the issue? I think the issue of post tensioning the web members also clouded the issue- those are not elements that require post tensioning. Maybe they were trying to make the post tensioning do something it wasn't supposed to do and wasn't able to do. And lastly if you are building an unconventional structure and someone tells you that it is showing unexpected behaviour- immediately check that out. I don't know anything about the company engaged for the third party review but if they were qualified to do such a review then they should have caught the errors in the concept and design. Regarding specialization- the proposal for the bridge includes quite a number of biographies, each one with a statement of "how will this person make the project a success...". Well it appears that they have a lot of people specialized in marketing and not enough specialized in understanding the behavior of structures.
Underwhelming report. Design and procedural deficiencies. I think that was clear the day it fell. This was a simple pedestrian bridge, not a space station, yet it looks like nobody will held to account for this gross incompetence. About what I expected with one quasi government agency investigating another.
Chigirl: No, this was not a simple pedestrian bridge. It was being built with leading edge structural design features and fabrication techniques. Even more reason they should have been more diligent.
@noxxi knox You need to read more on the background of the design and goals of the project. Yes, bits and pieces of the methods have been in use. However the specific single-truss line of this bridge without any additional cable stays is unique. Couple that with the emphasis on aesthetics importance, idea of not shutting down the roadway, last minute design changes, Zero maintenance exterior, etc, etc. all factored in to the failure.
@noxxi knox Stays 11/12 and 1/2 were pre-tensioned only for the movement phase, then detensioned. There was much more tensioning to be done after the bridge had been placed and more structural work done.. They never got to those steps. The design company hastily decided to retension 11/12 after the cracks developed, but did NO failure analysis, no written procedure and without waiting for the qualified PE to supervise the tensioning. It seems to have been the final straw that broke the camels' back.
@@KB4QAA it isn "unique" it is simply a very bad idea Yes you could buy unicycles - but unicycle are no safe vehicle. Just an tightrope walker, an artist will use this - but no way someone will buy unicycles as replacement for school buses The design of the FUI bridge ignored basic engineering principles. It wasn't just the try to be more aesthetic. They what to be "unique" at all costs. So no, it wasn't an brave farsighted testbridge for a better future. An "specific single-truss line of this bridge without any additional cable stays" is simply an stupid idea. oh and: - Building time over 1 year, this isn't "fast" - shuttig down the roadway for insert the bridge, this is state of the art - Zero maintenance exterior, by using prestressed concrete with subsequent bond!? its just a dream
Having worked in consulting engineering for several years, I find the competence and quality of independent peer reviewers to be VERY spotty. Some people are really sharp and highlight issues appropriately, with few or no misses; others miss problems and/or make nonsensical mountains out of molehills, and in doing so, demonstrate that they shouldn't be engineers...
@5:20. It was not a cable stayed bridge. It was truss bridge that was designed to look, but not function, like a cable stayed bridge. This is such an incredibly weak design I am not sure how it survived the initial construction, let alone the move.
This is what happens when projects get rushed to completion, when corners are cut, and when budgets get cut (although, I don’t know if this one one applies here)!!! It’s terrible that other people have to die, over someone else’s gross incompetence!!!!
Eu que moro no Brasil aqui já vi tantas ponte cai no Brasil por falta de engenheiro estudar mais aliás não é de estudo é técnica e olhando essa fonte aí essa passarela linha aí ó parecia Playmobil tudo para o lado de esquerdo para cair as colunas para o lado esquerdo Claro que ia cair um solavanco vai fazer o que né Estados Unidos tem tecnologia e contece isso
At the closing summary, the speaker might have raised the question: Why was such a structure chosen at all? The design makes no sense structurally, but FIU wanted to showcase technology for minimizing road closures, and presumably also post-tensioned concrete truss technology. The span could have been executed with a common steel truss design which is used everywhere, but they wanted something unique and “cool.” They were showing off.
As it happened, the University of Miami built a pedestrian bridge at about the same time. A side-by-side comparison of these two solutions to the same problem would be instructive.
Sir, you sound like an Engineer. I am in 100% agreement with you. And a female designer of it said she wanted it to show the FIU skills by building it. People there said that steel is UGLY! And this new design was "prettier". The Eiffel tower is not ugly. Nor is the Goldengate bridge. Nor is anything made of metal if it is designed right. Concrete is just great for roads.
Just wonderful. The same company is building a bridge over the ship channel here in Channelview Texas, and work was just halted today stating that they're using the same design flaws that caused the Florida pedestrian bridge collapse...
Yes, the MAIN pillars were found to not be large enough!!
The same company is also building the new Corpus Christi harbor bridge.
@@jdrs4214 wow, and I live in Corpus Christi.
When a large percentage of the funds required to build a bridge such as this are spent on so-called "artistic embellishments", specifically the fact that this was to be a "fake" cable-stayed bridge, engineers depart from tried and proven designs, such as symmetrical trusses, alternate load paths, etc. This could have been, and probably should have been, virtually a mail order catalogue bridge that would have given a hundred years of trouble free service. I have no idea if this was FIU or Figg's idea, but it clearly was not a good one. NTSB report discusses minutae, yet overlooks the fact that this could have been a much simpler, and probably less expensive, structure, with many times the safety factor. And nobody would be dead. Good design IS art, without the 2000's version of gargoyles.
It was FIU. I don't think it's bad to build something different, but engineers need to be cognizant of how the structural changes will affect margins, etc (and anything to look out for during construction). Sometimes the right answer is just a simple truss, but the world would be a very boring place if every pedestrian bridge and office building and house was virtually straight out of a catalogue.
@@AmbientMorality
try this as funerary speech:
"..the world would be a very boring place if every pedestrian bridge and office building and house was virtually straight out of the catalogue"
If someone needs experimental brigde designs just to avoid a boring world, he/she needs a psychiatrist an not an engineer!
Nobody reinvent the wheel just because too many wheels are boring.
@@tommyjacobi2054 Because there's no evidence in a new design is inherently less safe.
@@AmbientMorality
Sorry, but thats not simply "wrong", thats naive.
We dont live in the iron age and the builder estimates the dimensions of an member.
Even if we call it "bridge design" there is no "designer" who makes curves with a pencil for a new design and nobody know it isn't safe until it is completed.
For every bridge we have an structural engineering calculation. Complex construction will first build as model, because some calculations must be calibrated.
Could we build a safe version of the FIU bridge? yes of curse
But, there are good solutions, bad solutions and error-prone solutions.
This is an error-prone solution for the construction workers and an bad civil engineering solution.
Its not an cheap solution. Its not an quick solution.
Its just the "looks impressive" solution.
Yes we could build this. But you need more material and / or much more supervision and controlling.
It can't be cheaper. It can't be faster.
Someone has exchanged security for reputation. And some people pay for this with there lifes.
This bridge have an structual design that is susceptible for failure without notice and fatal failure from an small damage (even from small damage from terrorists).
Simply an bad design.
And every civil engineer knows: never ever traffic under a bridge that MUST fatal failure if the construction worker makes a mistake on just ONE screw....
@@tommyjacobi2054 It was quite a bit more than a construction worker making a mistake on a screw. Everything else I agree with.
Great presentation even for a lay person such as myself. What I found disturbing was that immediately after the collapse the designers took to social media to blame the installation team as being at fault. An investigation had not even begun and already they were denying involvement.
excellent presentation. i'm a layman and found it quite informative
This was not a cable-stayed design at all. The speaker could have made this point more forcefully. Instead, he started out by calling it a cable-stayed design, then added (in effect) but not really.
@Jeff Conard I'll have to re-watch that I guess. Several times in the hearing it mentions that those are simply hollow pipes. In fact one of the findings approved in the report is it those void areas actually weakened the structure.
Jeff Conard - I don’t know where you are getting that. I just read the NTSB synopsis of the October hearing, and there is nothing in there like that. Here is a brief excerpt:
• Bridge design and construction plan errors, and unique bridge characteristics and mechanisms of failure. The uniqueness of designing a concrete truss bridge led to the circumstances that accounted for the collapse of the pedestrian bridge. ...
Did you read the actual NTSB report or a news report about the report?
why wasn't a 3rd post/column placed in the center of the road... seems like a perfectly sensible way to build structural redundancy
As i understand its because they want to minimizes road closure and material needed
And i think the cable is enough if its properly designed, who knows
Yes definitely ask "what are the ways a structure could fail". Ask that of every component of the connection, every connection, the structure as a whole. But first a concrete truss begins as an ill-conceived structure. We typically do not build concrete trusses and there is a reason- concrete is not suited for trusses. If you want to build something that is typically not built then you have to scrutinize every part of it twice as much. The first time I looked at the side elevation of the bridge I could predict where it was going to fail and why. Did they rely too much on computer modeling and allowed that to cloud the issue? I think the issue of post tensioning the web members also clouded the issue- those are not elements that require post tensioning. Maybe they were trying to make the post tensioning do something it wasn't supposed to do and wasn't able to do. And lastly if you are building an unconventional structure and someone tells you that it is showing unexpected behaviour- immediately check that out. I don't know anything about the company engaged for the third party review but if they were qualified to do such a review then they should have caught the errors in the concept and design. Regarding specialization- the proposal for the bridge includes quite a number of biographies, each one with a statement of "how will this person make the project a success...". Well it appears that they have a lot of people specialized in marketing and not enough specialized in understanding the behavior of structures.
Underwhelming report. Design and procedural deficiencies. I think that was clear the day it fell. This was a simple pedestrian bridge, not a space station, yet it looks like nobody will held to account for this gross incompetence. About what I expected with one quasi government agency investigating another.
Chigirl: No, this was not a simple pedestrian bridge. It was being built with leading edge structural design features and fabrication techniques. Even more reason they should have been more diligent.
@noxxi knox You need to read more on the background of the design and goals of the project. Yes, bits and pieces of the methods have been in use. However the specific single-truss line of this bridge without any additional cable stays is unique. Couple that with the emphasis on aesthetics importance, idea of not shutting down the roadway, last minute design changes, Zero maintenance exterior, etc, etc. all factored in to the failure.
@noxxi knox Stays 11/12 and 1/2 were pre-tensioned only for the movement phase, then detensioned. There was much more tensioning to be done after the bridge had been placed and more structural work done.. They never got to those steps. The design company hastily decided to retension 11/12 after the cracks developed, but did NO failure analysis, no written procedure and without waiting for the qualified PE to supervise the tensioning. It seems to have been the final straw that broke the camels' back.
@noxxi knox This is video was made before the final NTSB report and is sketchy with very little technical info.
@@KB4QAA
it isn "unique" it is simply a very bad idea
Yes you could buy unicycles - but unicycle are no safe vehicle.
Just an tightrope walker, an artist will use this - but no way someone will buy unicycles as replacement for school buses
The design of the FUI bridge ignored basic engineering principles.
It wasn't just the try to be more aesthetic. They what to be "unique" at all costs.
So no, it wasn't an brave farsighted testbridge for a better future. An "specific single-truss line of this bridge without any additional cable stays" is simply an stupid idea.
oh and:
- Building time over 1 year, this isn't "fast"
- shuttig down the roadway for insert the bridge, this is state of the art
- Zero maintenance exterior, by using prestressed concrete with subsequent bond!? its just a dream
Turns out the independent peer-review company was not legally qualified, and didn't review the entire project
Having worked in consulting engineering for several years, I find the competence and quality of independent peer reviewers to be VERY spotty. Some people are really sharp and highlight issues appropriately, with few or no misses; others miss problems and/or make nonsensical mountains out of molehills, and in doing so, demonstrate that they shouldn't be engineers...
@5:20. It was not a cable stayed bridge. It was truss bridge that was designed to look, but not function, like a cable stayed bridge. This is such an incredibly weak design I am not sure how it survived the initial construction, let alone the move.
It didn't. Cracks were appearing before the move.
Great presentation
This is what happens when projects get rushed to completion, when corners are cut, and when budgets get cut (although, I don’t know if this one one applies here)!!! It’s terrible that other people have to die, over someone else’s gross incompetence!!!!
This is what happens when a design just *"feels"* right. Because that is how engineering works now. Feels.
Form should follow function. The designers wanted to work it the other way round, and got people killed.
11:15 bridge moved to position 12:48 BOOM!
NTSB presentation is way better...
Different context. Different requirements.
im sleepy now,cant view the video clearly!
Eu que moro no Brasil aqui já vi tantas ponte cai no Brasil por falta de engenheiro estudar mais aliás não é de estudo é técnica e olhando essa fonte aí essa passarela linha aí ó parecia Playmobil tudo para o lado de esquerdo para cair as colunas para o lado esquerdo Claro que ia cair um solavanco vai fazer o que né Estados Unidos tem tecnologia e contece isso