You Never Think About Structural Engineering
July 13, 2018 5:22 PM   Subscribe

Shopping Mall Collapse in Mexico City (no injuries) Every time I look at a tall building, I think about how a misplaced decimal or overlooked soil survey could kill everyone around.

I've been watching a lot of Practical Engineering lately, and it reminded me about the Millennium Tower slowly tipping over and really just how insane it is that cities exist at all.
posted by TheNegativeInfluence (38 comments total) 26 users marked this as a favorite
 
So, if you are in a building, and all the windows start popping out, that's bad.
posted by thelonius at 6:06 PM on July 13, 2018 [12 favorites]


Spare a thought for victims of greed and cronyism such as Lucie Aylwin and Doloris Perizzolo. They died when a section of the Algo Centre Mall (Elliot Lake, ON) roof collapsed. The roof had been certified as safe by an engineer, but it later turned out that extensive water and salt damage had rusted the roof beams, the engineer was operating under a suspended licence and the owner of the mall had put pressure on the engineer to falsify his report to ensure the mall's refinancing could go through.
posted by scruss at 6:10 PM on July 13, 2018 [19 favorites]


You Never Think About Structural Engineering
Hey don't tell me what I don't think about!

More seriously: get ready, this is the new normal. It's not even (necessarily) about miscalculation or bad design. Even well-built stuff collapses when neglected.

Here in the USA our bridge, dam, and potable water infrastructure is all crumbling. A lot of it was paid for a long time ago with assistance from federal grants, and in the past 30-50 years, utilities have been pricing at or below maintenance levels, with little or no strategic planning for replacements. So we have stuff literally falling apart all across the country, from bridges in PA to dams in TX to public water systems in NYC and DC.

The ASCE provides an infrastructure report card, by sector and by state (at infrastructurereportcard.org !). It is interesting but depressing reading. My current state of residence, TX, has "D" in flood control, and has for well over a decade! So no surprise really when floods kill people in every tropical storm.

The USA as a whole got a "D+" score in 2017, and it's very hard for me to believe that's going to improve in any meaningful way in the next 5-10 years.
posted by SaltySalticid at 6:13 PM on July 13, 2018 [30 favorites]


That's insane. I'm glad I knew no one was hurt before watching, because I could marvel at the spectacle instead. The observation about traffic difficulties was suitably sardonic.

I was literally yesterday sketching out the Hyatt Walkway collapse (previously, wiki) as an example of faulty engineering so obvious even I could understand the flaw but also so easy to miss if you aren't checking every single change.
posted by mark k at 6:17 PM on July 13, 2018 [6 favorites]


I hope that was not the case given the seismic activity on Mexico, but it wouldn't be the first time contractors actively ignored recommendations and built whatever after some palms were greased to make it go away and let destiny have it.
posted by lmfsilva at 6:18 PM on July 13, 2018 [3 favorites]


But... we've had so many infrastructure weeks.
posted by Mr.Encyclopedia at 6:28 PM on July 13, 2018 [8 favorites]


The AP reports that Mexico City mayor José Ramón Amieva said experts were looking into whether the collapse was due to structural defects or soil settling.

Being an Architect, I think about structural engineering quite a bit. Like in my meeting today with the Structural Engineer we'll be working with on a new project.
In fact, we discussed soil bearing pressures, which is where it all come down..
He starts with an estimate of what is typical in the area, then we do soil borings and tests to verify that number. If it is below the assumption, we make changes before the package is released to a Contractor. So soil settling isn't a good excuse, not for a failure all along that wall.
It looks more like an overloaded/under designed cantilever. Cantilevers are a good place to get in trouble quick.

The Hyatt walkway collapse, if I recall correctly, it was designed correctly, the Contractor thought of a way to do it cheaper, and submitted it in his shop drawings. I'd bet that it was some new person fresh out of college that was reviewing submittals, because that's almost always who gets stuck reviewing submittals.
posted by rudd135 at 6:48 PM on July 13, 2018 [6 favorites]


I wish structural engineers in the US had decimals to misplace. Most of time structural drawings are dimensioned in fractional inches.
posted by hwyengr at 7:03 PM on July 13, 2018 [3 favorites]


I think about how a misplaced decimal or overlooked soil survey could kill everyone around.

Regulation, folks. Lift your glasses high. Keeping you alive since before you were born.
posted by q*ben at 7:05 PM on July 13, 2018 [26 favorites]


I wish structural engineers in the US had decimals to misplace. Most of time structural drawings are dimensioned in fractional inche

Perhaps just as well, I had a hell of a time convincing my engineering students that round off error mattered. Of course, they probably couldn't add fractions either.
posted by hoyland at 7:12 PM on July 13, 2018 [3 favorites]


The ASCE provides an infrastructure report card, by sector and by state (at infrastructurereportcard.org !). It is interesting but depressing reading.

It's important to remember that while, yeah, we need infrastructure improvements, the ASCE is about as reliable and neutral a reporter on the specific level of need for such improvements as Lockheed-Martin is on the defense budget.
posted by GCU Sweet and Full of Grace at 7:55 PM on July 13, 2018 [3 favorites]


Well I'm glad no body died.

When I was young I worked as a lowly laborer on many tall buildings, and even at the time saw a number of hair-raising things get ignored or plastered or carpeted over. Since gaining some engineering ed there are some buildings I'd never enter. I suspect many 'unksilled' workers have similar tales.

In the Christchurch earthquake the CTV Building collapse killed 115 people. The engineer was proven to be a fraud and from memory would attack city engineers and other. I no longer have any faith in codes and standards and yet grew up learning that NZ had very strict building codes.
posted by unearthed at 8:00 PM on July 13, 2018 [5 favorites]


The soil situation is especially fraught in Mexico City, since it's built on an ancient lake bed.
posted by Monday, stony Monday at 8:03 PM on July 13, 2018 [3 favorites]


fell across lanes of a major freeway, which had been closed shortly before the collapse. The closure added insult to injury as the mall was controversial even before it was built—in part because it threatened to clog traffic.
posted by salvia at 8:09 PM on July 13, 2018


The Hyatt walkway collapse, if I recall correctly, it was designed correctly

From Wikipedia: "Investigators determined eventually that this design supported only 60% of the minimum load required by Kansas City building codes."

And then, yeah, the fabricator thought the threaded rods were a bad design (from a fabrication and installation perspective) and proposed a change which made the original poor design radically worse.
posted by Ickster at 8:50 PM on July 13, 2018 [3 favorites]


As with so many things, I'm not surprised that people make mistakes, but I remain naive enough (and will likely always be so) to be shocked that greed can lead the kind of obvious fuck ups shown by the mall collapse.
posted by Ickster at 8:53 PM on July 13, 2018 [2 favorites]


Old engineering students' joke

What's the difference between doctors and engineers...? Doctors only kill one at a time.
posted by fearfulsymmetry at 12:38 AM on July 14, 2018 [9 favorites]


IIRC; the Hyatt collapse in KC also involved the spec'd washer on the ends of the threaded rods not being present.

Take a trip with me to Kansas City MO
To the Hyatt House, to the big dance floor
You can still see the ghosts
But you can't see the sense
Why they let the monkey go
And blamed the monkey wrench


Kinda loud warning.
posted by Afghan Stan at 12:44 AM on July 14, 2018


Ah yes -- my high school's AP chemistry teacher, Coach Jacobs (he coached boys' track / cross country) was known to refuse to give partial credit, which was a deviation from the previous ten years of "show your work!" schooling.

His justification: when that bridge you designed (he was great about affirming that we would indeed all go into STEM fields professionally) is falling down, no one cares that you knew the right way to do it but messed up a mechanical step.

You have to know how to do it, AND you have to be right.
posted by batter_my_heart at 1:02 AM on July 14, 2018 [10 favorites]


> You Never Think About Structural Engineering

Why, just this morning I was thinking about structural engineering. Maybe someone here will know the answer!

When a bridge is under construction, does the falsework have to meet certain seismic standards, like the finished bridge? How do the falsework seismic standards compare to that for permanent structures? I'm thinking of something like an overpass being built over an active freeway, where there is a safety issue wrt the general public.
posted by ryanrs at 1:24 AM on July 14, 2018 [1 favorite]


IIRC; the Hyatt collapse in KC also involved the spec'd washer on the ends of the threaded rods not being present.

I haven't heard that.. The original design was half-assed in a few ways, and when it proved to be unworkable too the engineers just approved the fabricator's crappy fix idea without really analyzing it, either.
posted by fleacircus at 2:46 AM on July 14, 2018 [2 favorites]


I used to live near the site of this condo collapse, which killed 10 workers in 1981. The structural engineers were retired NASA engineers. Everyone got off relatively easy and the developer went on to build new projects.
posted by RobotVoodooPower at 3:50 AM on July 14, 2018


Oh wow. I’ve been off the internet and in another country for the last few days, but I’ve eaten at Artz Pedregal several times, and as recently as a couple of weeks ago (many of the restaurants are already open even though the development is mostly still under construction).

That’s... alarming.

Incidentally, Pedregal originally meant “royal stone” because the area is all volcanic basalt. It’s up the hill from the lake bed in the centre of town and doesn’t suffer as badly during earthquakes. So soil quality shouldn’t be an issue.
posted by chappell, ambrose at 4:10 AM on July 14, 2018 [1 favorite]


The joke going around Mexican social media is: “Did you hear about the mall collapse in Pedregal? Terrible thing. Apparently four people are missing... The architect, the contractor, the owner and the building inspector.”
posted by chappell, ambrose at 4:15 AM on July 14, 2018 [31 favorites]


Regulation, folks. Lift your glasses high. Keeping you alive since before you were born.

Nonsense. Once we start running society along libertarian lines, we won't be bending the knee to the nanny state anymore. If people want, they can do a soil survey and structural analysis of their choosing before entering a building.
posted by sebastienbailard at 4:50 AM on July 14, 2018 [17 favorites]


Ever since Sampoong, I'm sorry, but I think about structural engineering all the time.
posted by adamgreenfield at 6:03 AM on July 14, 2018 [1 favorite]


It's important to remember that while, yeah, we need infrastructure improvements, the ASCE is about as reliable and neutral a reporter on the specific level of need for such improvements as Lockheed-Martin is on the defense budget.

Any pedestrian who has walked beneath an overpass in Chicago can see for themselves that the infrastructure of America is literally crumbling. I worry about both catastrophic collapse in a nightmare scenario but I also fear getting hit by one of the chunks of concrete that look like they fall every single day. One could easily use the areas beneath most highway overpasses as well-post-apocalypse movie sets with no changes at all. Except it might be too dangerous for the cast and crew.
posted by srboisvert at 6:30 AM on July 14, 2018 [1 favorite]


ASCE is a non-profit professional society for civil engineers, while Lockeed Martin is a large corporation that sells machines of war for massive profit. So there's some small difference between the two.

I'd say the ASCE has pro infrastructure bias in the same way that the American Heart Association has a strong pro heart health bias.
Sure, investing in our heart health will also benefit cardiologists, but I for one am not going to complain about that.
posted by SaltySalticid at 6:42 AM on July 14, 2018 [6 favorites]


If people want, they can do a soil survey and structural analysis of their choosing before entering a building.

And if you're shopping at the mall, don't forget the home lead testing kit!
posted by Ralston McTodd at 6:43 AM on July 14, 2018


I'd say the ASCE has pro infrastructure bias in the same way that the American Heart Association has a strong pro heart health bias.

I believe Strong Towns has had some pretty strong criticism of their standards. (Basically, we do have crumbling bridges. That's not the only way they evaluate infrastructure -- and, ironically, their emphasis on expansion of the current road system is a great way to divert funding from projects to rebuild our current bridges.)
posted by steady-state strawberry at 7:12 AM on July 14, 2018 [3 favorites]


It looks like this building had a green roof. I'd bet that was a big chunk of the problem here. People clamor for green roofs because they're trendy and theoretically environmentally-friendly, but they don't always take into account just how extremely goddamn heavy all that soil and water is.
posted by showbiz_liz at 8:26 AM on July 14, 2018 [1 favorite]


Sure the ASCE has critics (and real problems!), my point is not that they are infallible saints, but rather that their infrastructure report card is one of the best concise ways to get a publicly accessible overview of our problems, and it should not be discarded out of hand because they represent engineers who design this stuff for a living. Still, I do appreciate the criticism of ASCE posted, the Strong Towns page is also a very interesting read. While they seem to have a huge axe to grind with the ASCE, I think they'd agree that we have a big problem with the current state of our civic infrastructure.

Anyway, there are plenty of other sources that agree that infrastructure in the USA is fucked, and that's the important part to me:
The EPA has a nice needs assessment for drinking water The National Climate Assessment has a whole section on infrastructure I don't think there's anyone out there seriously looking a the problem from an expert perspective saying "this is fine, nothing to worry about".
posted by SaltySalticid at 9:00 AM on July 14, 2018 [2 favorites]


For some reason, a few days ago I got to this page on Wikipedia.

There's a good reason that structural engineering work is checked and double checked and signed off. Glad no one was hurt or killed in this more recent failure.
posted by theorique at 9:06 AM on July 14, 2018


My husband is a materials tester, and I think about this stuff a LOT. We canoed in the Boundary Waters as our honeymoon and happened to drive across the I35 bridge in Minneapolis the day before it fell. He'd been talking endlessly about construction all the way from our home in Mississippi ("oh, look! I've never seen a cement mixer just like that before!" and other such scintillating topics) and as we went over the bridge he said, "I wonder why that guy is jackhammering there. That's weird." We thought nothing else about it until we heard the news the next day. That jackhammering guy had nothing to do with it, but it was weird. And scary.
Hearing him talk about the greed, the corners cut, the incompetence, the low-ball bids, the people just not bothering to do the bare fucking minimum on their jobs.... It's enough to never want to walk into, under, or over anything man-made ever again.
posted by thebrokedown at 9:48 AM on July 14, 2018 [4 favorites]


I highly recommend two books in particular by Mario Salvadori:
Why Buildings Stand Up: The Strength of Architecture and
Why Buildings Fall Down: Why Structures Fail

I highly recommend everything by Mario Salvadori, who makes the rest of us look like a bunch of slackers.
posted by Multicellular Exothermic at 10:12 AM on July 14, 2018 [3 favorites]


There's a great interview about a book on structural engineering here at the Guardian. I've had it open in a tab for months, trying to decide what to do with it, so thank you MeFi :-)
posted by ianso at 10:23 AM on July 14, 2018 [3 favorites]


In New Orleans, yes, we think about structural engineering, and how it s about 50% mythology, and 30% graft. That s why we re now trying a massive ecological restoration program. Turns out it was important not to drain all those swamps
posted by eustatic at 8:25 AM on July 15, 2018 [2 favorites]


I know this thread self-selects for people who care passionately about structural engineering to come in and say "YES I DO THINK ABOUT STRUCTURAL ENGINEERING" but it is one of the scariest constant specters hovering over every aspect of daily life and I think about how ready and willing most people are to skip steps and cover up "tiny" errors a LOT. A LOT.

It reminds me of this excellent mefi post on the normalization of deviance, and how quickly "doing things correctly and safely" devolves into life-threatening sloth and "no one will notice". How not even engineers at NASA, with people's lives in their hands, were able to convince their bosses that safety was worth delay and added cost. It seems like there is no program or project big enough or important enough for this instinct to fudge the details to be quashed.

TERRIFYINGGGGGGGGGG.
posted by a fiendish thingy at 8:25 AM on July 16, 2018


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