FIU had grand plans for 'signature' bridge. But the design had a key mistake • Hacker News Board

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#121

Post by keithpeter » Fri, Jun 15, 2018, 12:34 PM UTC

danso wrote: post #2

Saw this story via an @EdwardTufte tweet: https://twitter.com/EdwardTufte/status/1007395311541682176 > A+ This is beautifully executed technical report by the Miami Herald, an instant classic of news reporting. Note that this report is a document not a deck. The FIU admistration loaded the bridge design down with features.

“This is not a big project," Beck said. "It’s a darn pedestrian bridge.”

Quote from one of the expert engineers from OA. It is the last sentence in the article, and I think a very effective final comment.

However, the article does quote two of the expert engineers as saying that the faux suspension bridge design could have been perfectly stable, had the trusses been strong enough.

I was interested in the comment that had the two end pieces been in place, then the bridge may well have been fine - the plan was to swing the main bridge section into position then build the two end pieces in situ. One wonders about the design calculations for each stage of the proposed construction.

I think there is a book length work around the details of the decision making process once the investigation is complete and the legal fall-out has been dealt with.

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#122

Post by mannykannot » Fri, Jun 15, 2018, 1:44 PM UTC

mannykannot wrote: post #80

bsder wrote: post #71

Earlier quoted context omitted.

> It bugs me that FIGG (one of the contractors) appears to be threatening the professional licenses of the engineers who helped the Miami Herald's investigation, by suggesting that doing so was unethical. As a licensed Professional Engineer, you have to be quite careful criticizing other engineers. As long as the engineer signing off met "standard practices", he is covered and saying that he is not could get you in q…

Thank you for your informative input. In this case, the article is not naming a specific engineer, though I realize that it will ultimately come down to a small number of people. If, as claimed, the calculations used did significantly under-represent the forces on the strut that failed, that would seem to be a matter of physics, regardless of how it came about. The Citibank tower continues to sway and creak, more not…

Correction to my own post: The article does name FIGG's chief engineer, but it is not claiming that he personally acted in a willfully reckless manner or encouraged/coerced others to do so.

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#123

Post by otakucode » Fri, Jun 15, 2018, 1:55 PM UTC

JohnJamesRambo wrote: post #26

otakucode wrote: post #13

Earlier quoted context omitted.

The parallels do not go very far, unfortunately. When software fails, and kills people, it is rarely investigated. It's development is rarely investigated. When that is done, however, the differences widen even further. There is no degree to which software development can be done incompetently that criminal negligence charges can succeed. We saw this proven within the past decade when some of Toyotas cars engaged in…

I like your viewpoint. I’d be more inclined to call programmers engineers under your proposed system.

It's really a difficult issue. There has been a lot of discussion about it in the Communications of the ACM over the past decade (maybe longer, I've only been a member so long). Companies don't want there to be any standards because it would mean they would have to pay a lot more for skilled developers, they would have to have software engineers able to override MBAs when making business decisions about scheduling, they would be answerable when they cut corners while treating software as a cost center (despite their business being literally impossible to conduct without it in most cases), etc.

Developers, meanwhile, generally don't like the idea because it raises the barrier to entry, and it would establish standards that are extremely likely to be disagreed with by large numbers of people. Other professions have dealt with this, however, so it's not a completely unsolvable problem. I'd personally think that 'registered, licensed software engineers' might be something that a company would only need if producing certain kinds of products. If you're building an in-house processing system whose behavior and outputs your business is entirely legally responsible for, you probably don't need the licensed engineers. If you're building self-driving cars, though, yeah, you'd have to follow some standard practices and such. One would hope they would be fairly high-level, such as simply requiring static analysis be performed rather than getting as specific as mandating a specific tool be used.

It's understandable that there is hesitation, but I worry that the hesitation will bite us badly. A government stepping in and mandating programming languages and libraries and creating a regulatory body and all of that wouldn't be completely unheard of for things dealing with infrastructure. And nobody wants that.

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#124

Post by matthberg » Fri, Jun 15, 2018, 1:56 PM UTC

AvE (a rather vulgar engineer on youtube) did a good review of what he thinks went wrong, right after it collapsed: https://www.youtube.com/watch?v=ioC61QW7SHQ

Not with all of the facts, yet interesting to see the conjecture and reasoning of trying to figure out what went wrong.

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#125

Post by 3pt14159 » Fri, Jun 15, 2018, 2:37 PM UTC

abduhl wrote: post #96

bsder wrote: post #71

Earlier quoted context omitted.

> It bugs me that FIGG (one of the contractors) appears to be threatening the professional licenses of the engineers who helped the Miami Herald's investigation, by suggesting that doing so was unethical. As a licensed Professional Engineer, you have to be quite careful criticizing other engineers. As long as the engineer signing off met "standard practices", he is covered and saying that he is not could get you in q…

I'm unaware of any liability that can be picked up through rendering an opinion on a design. I have participated in forensic engineering / expert witness cases in geostructural matters. In fact, the opinion of an engineer as an "expert witness" is often codified in law as retaining no liability. Asking questions and drawing conclusions is not something that presents any risks besides you being possibly proven wrong l…

I used to be a structural engineer in Canada (EIT, left before getting PENG) and one of the projects I was involved with was analyzing a collapsed building to determine fault.

Being an expert witness is completely different than being an engineer talking to the public. Generally speaking an engineer close to the details of the project is going to know more than you. If you have concerns, you call up the engineer and you have a discussion. If he's dismissive you still have the choice to escalate the matter, but it's usually to someone in the government, not the public at large. Engineers need to be trusted by the public and shooting your mouth off about another engineer degrades public trust.

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#126

Post by ghostly_s » Fri, Jun 15, 2018, 2:43 PM UTC

danso wrote: post #2

Saw this story via an @EdwardTufte tweet: https://twitter.com/EdwardTufte/status/1007395311541682176 > A+ This is beautifully executed technical report by the Miami Herald, an instant classic of news reporting. Note that this report is a document not a deck. The FIU admistration loaded the bridge design down with features.

This seems a rather trite and self-serving take. 'Loaded down with features'? It seems the conclusion is there was exactly one problem, change the angle of structural members for aesthetic reasons without adequate structural analysis.

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#127

Post by sangnoir » Fri, Jun 15, 2018, 2:49 PM UTC

crwalker wrote: post #44

beachy wrote: post #3

> But FIU's bridge was designed to mimic the dramatic look of a cable-stayed bridge, where the deck is suspended from cables fanning out from a tall mast. In FIGG's design, though, the "cables" — actually metal pipes — were mostly just for show. The diagonal, v-shaped struts of the truss did the structural work. I've always found it useful to hone in on anything that is done purely for aesthetic reasons. We build a h…

Yes! Good thing you pushed back on the architect. I have a similar design philosophy that honesty is more aesthetically pleasing than deception. When designers resort to faux materials and structures, the truth still tends to peek through, resulting in an 'uncanny valley' of forms. For example: * Brickwork veneers bend in the wrong spots * Faux beams are placed in the wrong locations with the wrong joints, announcing…

> I have a similar design philosophy that honesty is more aesthetically pleasing than deception

Isn't this the core principle of Brutalism? As they say, beauty is in the eye of the beholder.

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#128

Post by abduhl » Fri, Jun 15, 2018, 4:14 PM UTC

3pt14159 wrote: post #125

abduhl wrote: post #96

Earlier quoted context omitted.

I'm unaware of any liability that can be picked up through rendering an opinion on a design. I have participated in forensic engineering / expert witness cases in geostructural matters. In fact, the opinion of an engineer as an "expert witness" is often codified in law as retaining no liability. Asking questions and drawing conclusions is not something that presents any risks besides you being possibly proven wrong l…

I used to be a structural engineer in Canada (EIT, left before getting PENG) and one of the projects I was involved with was analyzing a collapsed building to determine fault. Being an expert witness is completely different than being an engineer talking to the public. Generally speaking an engineer close to the details of the project is going to know more than you. If you have concerns, you call up the engineer and…

bsder said: "As a licensed Professional Engineer, you have to be quite careful criticizing other engineers. As long as the engineer signing off met "standard practices", he is covered and saying that he is not could get you in quite hot water."

I am disagreeing with the statement that you could get in "quite hot water" by noting that the only liability you are exposing yourself to by stating your opinion is looking stupid. Yours and my opinions on public trust and how someone should conduct themselves is orthogonal to the question.

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#129

Post by crwalker » Fri, Jun 15, 2018, 4:58 PM UTC

sangnoir wrote: post #127

crwalker wrote: post #44

Earlier quoted context omitted.

Yes! Good thing you pushed back on the architect. I have a similar design philosophy that honesty is more aesthetically pleasing than deception. When designers resort to faux materials and structures, the truth still tends to peek through, resulting in an 'uncanny valley' of forms. For example: * Brickwork veneers bend in the wrong spots * Faux beams are placed in the wrong locations with the wrong joints, announcing…

> I have a similar design philosophy that honesty is more aesthetically pleasing than deception Isn't this the core principle of Brutalism? As they say, beauty is in the eye of the beholder.

I hope my philosophy isn't Brutalism, because I find most of those buildings heinous.

I'm not an expert, but it seems that Brutalism requires one to reduce all forms to their mechanical function. I think there are plenty of other good reasons to include a form, e.g. Corinthian columns are modeled after acanthus leaves, and I think that's just great. The form is telling a story about our connection with nature, and nobody is pretending that the column is actually an acanthus.

Re: FIU had grand plans for 'signature' bridge. But the design had a key mistake

#130

Post by gamblor956 » Fri, Jun 15, 2018, 5:25 PM UTC

burfog wrote: post #113

gamblor956 wrote: post #104

Earlier quoted context omitted.

No, the article is pretty clear that the stays were fake, and intended solely to dampen vibrations. They provided no structural support whatsoever.

If it is "to dampen vibrations" then obviously it isn't "fake". Vibrations are serious business; many bridges have collapsed due to vibrations, and many more (Millennium Bridge for example) have had severe trouble. Humans are particularly prone to causing vibrations because humans react to bridge movement in a way that amplifies the movement. Technical description of the bridge from the engineering firm: https://faci…

You're reading from the proposal, which is not the bridge that was built.

The bridge that they built did not use the stays as structural elements, and any vibration dampening would have been minimal, i.e., a side-effect of stiffening the bridge rather than the reason for including them.