Mistakes were made, people died

Found a couple interesting videos about the FIU pedestrian bridge collapse in Miami
It’s every engineer’s nightmare

Construction and installation method

Moment of collapse
(during stress testing?)

Four knee-jerk questions to keep in the back of our minds as this story matures:
1. Was the bridge section not stress and load tested prior to installation?
Hey, what can go wrong with new technology, right? Even old, proven designs can have material or manufacturing flaws.
2. Did the transport loading induce weakness when transitioning to the as-installed loading?
It’s partial-span and full-span loading and bending profiles are completely different (e.g. perhaps the internal compression cables weren’t taught enough during transport to prevent over-flexing, dunno).
3. Why was traffic allowed underneath during testing?
I mean, kripes, you never assume that a test won’t fail (see: test pilots vs passengers).
4. Were there any design, construction, regulatory, or safety compromises?

Gravity can be a real b*tch, if you let ‘er be.
She’ll find the flaw in all your activities.
Just ask Hillary.
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Story-1
Story-2
Cultural ref
Note: I’m not a civil engineer, but I have a lot of experience in satellite system testing and safety,
and I’ve been on a few failure-investigation boards (gremlins seep in, if your system leaks).

15 Comments!

  1. Jess
    Posted March 16, 2018 at 11:56 am |

    The university was given a grant under the Obama TIGER grant program of 11 million. I’m assuming the University was responsible for the other 4 million.

    Using my years of dealing with grant recipient entities for reference, I think the money went faster than thought, many people managed to get their share of the take, and the project managers were grasping for cost cutting methods, when they realized the well was running dry.

    If things were like I think, there are many responsible for the errors in judgement, and their will be some attorneys make a lot of money.

  2. Posted March 16, 2018 at 2:05 pm |

    Cables: taut, not taught. From what I heard today, they were tightening cables when the thing fell down. But I’m with you; why didn’t they close the road for installation? I mean, I know the Tamiami Trail is a big, important freeway (7 lanes, as I recall), but geeze, shut it down for a bit.

  3. DougM (μολὼν λαβέ)
    Posted March 16, 2018 at 2:17 pm |

    ^ I think you meant “testing.”
    They did shut traffic down for installation.
    But maybe I missed your point/joke.

    I can fix it, if you want.
    It’s what I do.
    For free.

  4. Jess
    Posted March 16, 2018 at 2:20 pm |

    Post tension systems are great, but with their design, all post tensioning should have been completed before they ever moved the structure. Even then, such a long span – in my opinion – should have had suspension cables for attachment when placed.

  5. dick, not quite dead white guy
    Posted March 16, 2018 at 2:43 pm |

    I thought the truss looked a bit shallow for the span to stand alone, especially since it appears to be pre-stresed concrete with no steel girders. I did not know there was a suspension component not yet installed, as shown in this video, consisting of a central tower on a mid-span base with suspension cables running to each of the diagonals in the truss.
    I cannot believe the gross negligence of the construction company and the local government for allowing traffic under it while “stress testing” or for that matter any traffic under that bridge until it was complete, tested and inspected. This smells of corruption or somebody trying to “look good” by not inconveniencing the public.
    I know it’s early yet, but I think the investigation will uncover some people that should go to prison for negligent homicide.
    “The FIU-Sweetwater bridge will serve many purposes including being a visually distinctive gateway to our city,” said City of Sweetwater Mayor Orlando Lopez. That’s some gateway Mr. Mayor. It says “Bring your Cat D-9 or M1A2 Abrams tank to see our city.
    Ban over-fancy bridges that make political statements. That POS was funded by our money, not that locality.

  6. Bruce
    Posted March 16, 2018 at 3:23 pm |

    FIU

    Snort, giggle….

    Somebody certainly Effed It Up.

  7. mech
    Posted March 16, 2018 at 6:32 pm |

    Yep, build half a bridge and leave it unsupported is real smart. It wasn’t designed to support its own weight without the suspension cables from above.

    If they had even left a jack mid span supporting it until the second half and tower were built to attach the critical cables, people would be alive now.

    How many heads will roll?

  8. Dave
    Posted March 16, 2018 at 6:36 pm |

    How many heads will roll?
    Depends on if those heads are privately or publicly funded.

  9. DougM (μολὼν λαβέ)
    Posted March 16, 2018 at 7:44 pm |

    dick ^5
    Here’s a good overview

  10. Paul
    Posted March 16, 2018 at 8:17 pm |

    No doubt Democrats will blame this on Trump. And the Russians did it to.

    In actuality, why was it made of cement? I would have thought being pedestrian traffic the whole gizmo would have been steel/aluminum. I am sure that poured cement weighted many many TONS along with re-bar used for reinforcement. Plus there were no pillars underneath so I presume the cables were in the top portion of the bridge?

    Yep, re-bar was used throughout. Good bridges use steel I beams as support structures. This bridge used re-bar and concrete. Cheep. Real cheep. $14 million bucks cheep.

    And then they tested it live… with people underneath!

  11. dick, not quite dead white guy
    Posted March 16, 2018 at 8:29 pm |

    ^^9 Doug – that’s what I was getting at. The numbnuts loaded the thing, over traffic, while unsupported or completed. The university’s head of the civil engineering department and proponent of its design and construction theory, and, I suspect all the politicians involved in their showpiece of modern design, put people at risk for their own bullshit egos. Engineering ethics say you never do that. At the very least, a bunch of superegos need their P.E. licenses pulled right now.

  12. Posted March 17, 2018 at 5:51 am |

    Doug:

    Was this the first one ever installed? Or did the company have some under their belt? I haven’t seen anything about that.

  13. jlw
    Posted March 17, 2018 at 7:17 am |

    ^
    first of this design ever.

    and a little bit more

    “Miami bridge collapse: Engineer reported cracks in voicemail”

    http://www.bbc.com/news/world-us-canada-43440501

    Denney Pate, lead bridge engineer for contractor FIGG, left a voicemail with the Florida transport department on Tuesday.

    He warned of “cracking” but also said there was no concern “from a safety perspective”.

    Department employees did not hear the message until after the bridge fell

  14. Posted March 18, 2018 at 7:27 am |

    ^
    Ah. Thanks.

    And they stress tested it ‘live’?

    Oy.

  15. mech
    Posted March 20, 2018 at 9:40 am |

    Meebe it’s the same kinda folks who put up the walls on the front of the house, then the roof trusses, thinking they will hold until the back walls are finished.