[HN Gopher] Repairs of leaning San Francisco skyscraper on hold
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Repairs of leaning San Francisco skyscraper on hold
Author : woofyman
Score : 110 points
Date : 2021-08-28 13:33 UTC (9 hours ago)
(HTM) web link (sanfrancisco.cbslocal.com)
(TXT) w3m dump (sanfrancisco.cbslocal.com)
| redis_mlc wrote:
| Sounds like band-aids don't work on skyscrapers? lol.
| HenryKissinger wrote:
| The Millenium Tower needs to be scrapped. It's a failed project.
| It will cost hundreds of millions of dollars to "fix", and no fix
| will work in the long term, because the problems are structural.
|
| Cut yout losses. Demolish the whole thing.
| mslate wrote:
| What's your expertise on this subject beyond armchair
| quarterbacking?
| coding123 wrote:
| I'm guessing the Miami building as a lesson.
| mslate wrote:
| I personally wouldn't consider someone's awareness of
| another building's collapse to be expertise, but hey it's
| the internet
| kmbfjr wrote:
| Your qualifications first.
| throwawayboise wrote:
| What is anyone's expertise on a web forum? If he claimed any,
| what weight would that add when almost everyone here is
| anonymous?
| john_yaya wrote:
| I can assure you, as the world's leading behavioral
| psychologist, a former Miss Universe, and the winner of
| last year's Eurovision contest, that the poster is totally
| qualified to speak on the topic.
| imtringued wrote:
| I think you are right. It was built to fail after all.
| xenadu02 wrote:
| The building was leaning 17" at the top when this work started.
| Within a year it is now leaning 22". That is a dramatic increase
| in such a short time.
|
| It would appear the objections to the original plan were sound.
| The alternative proposal is to drill through the original
| foundation to set the piers from inside the building. My
| understanding is this would be more evenly distributed and
| attached to the original foundation evenly. Then jacks would be
| used to "climb" the piers to level the building - very slowly
| over time.
|
| The original fix is cheaper because it relies on gravity to
| further sink the high corner of the building once the lower side
| is fixed in place by the piers, then once that has happened piers
| can be sunk on that side. It also spreads the cost out over a
| longer period of time.
|
| The other objection to the original fix is seismic: if only one
| corner is resting on bedrock during an earthquake the building
| could be severely damaged.
| dehrmann wrote:
| How do you drive piles once the building is completed? Do you
| go to the basement (probably a parking garage), open up space
| with the floor above it, and drive short segments that are
| welded together? I thing one of the earlier plans was to do
| this all outside the building on the perimeter, but if that's
| not enough, it sounds really complicated.
| jeffbee wrote:
| They should put a big hydraulic shaker in the bottom of the
| garage and just shake it until it hits solid ground. Then
| punch a new door in on whatever floor happens to be at grade.
| wizzwizz4 wrote:
| They'd have to reinforce all the walls first.
| kaikai wrote:
| The bedrock is over 100ft down, so that would be fun
| pm90 wrote:
| I hope this doesn't chill demand for residential skyscrapers in
| SF. It seems like this building is (arguably justifiably) getting
| a lot of attention but there are multiple ongoing and completed
| projects that are a good solution to alleviate the housing
| crisis. Yes they're all "luxury" condos but they're satisfying
| some demand at least.
| jeffbee wrote:
| Towers are I guess the worst and least convenient way to
| alleviate housing crisis. Raising a few of the city's hundreds
| of thousands of detached single-family houses to 2-to-7-story
| apartment houses would be a lot better, cheaper, faster, and
| easier.
| chrisseaton wrote:
| > "You never place piles or piers closer than three pier
| diameters apart. These are 36 feet so they should be nine feet
| apart and they're, what? -- five feet or something.
|
| I don't get this - the piers are 36 feet (engineers using feet?!)
| in diameter so should be 9 feet apart, but that's not 3x 36.
|
| What do they mean?
| irrational wrote:
| In the USA the construction trade is all done using imperial
| measurements. If you go into any big box hardware store, the
| only thing you can find in metric is a few specialty bolts.
| adventured wrote:
| > engineers using feet?!
|
| Architects for example almost exclusively work in feet in the
| US. The US construction field is almost entirely imperial.
|
| The highest rates of metric use in the US are in cases where
| there is a possibility of international crossing/exchange, or
| if the field is distinctly metric-based. If you work for NASA,
| it makes sense to use global measurement standards. If you're
| building a house in Cincinnati, it largely does not matter.
|
| If you're a German working in a store in Wurzburg, you're far
| more likely to speak in German throughout your day. If you're a
| German working in programming with a bunch of US programmers,
| you're more likely to be using English when communicating with
| them. Why don't Germans speak English all the time? Because
| they don't want to and don't need to.
| Ozzie_osman wrote:
| No way the piles are 36 feet in diameter. I don't think piles
| that big exist or are feasible, you're usually looking at a
| couple meters max.
| woofyman wrote:
| It's a typo. They're 3 feet in diameter.
| chiragmed wrote:
| They meant 36 inches.
| chrisseaton wrote:
| Wow. Maybe that's why it's falling down. Why aren't engineers
| using metric?
| Johnny555 wrote:
| If the piers are sold in inches, then using metric to
| describe them is another level of indirection, so might
| make the chance of error worse. Would you feel safer if he
| said "The piers are 91.4cm"?
|
| It's amusing to see newspaper stories where they report
| high precision numbers that are obviously metric
| conversions like "He drove 62.14 miles to work every day"
| when the original source said "100km".
| titzer wrote:
| America. I had to mentally switch to metric when I moved to
| Europe and now I have to switch back. Ugh.
| irrational wrote:
| The construction tradespeople only use imperial. The
| engineers could use metric, but then they would have to
| convert everything. It's easier to just use imperial from
| beginning to end. Besides, all construction materials are
| in imperial. It is so much simpler for the engineers to use
| imperial. Plus, if they grew up in the USA, the engineers
| are as comfortable using imperial as you are using Metric.
| hollerith wrote:
| Arithmetic continues to work even if you don't use metric
| units.
| chrisseaton wrote:
| The arithmetic doesn't work though - that was my point.
| Johnny555 wrote:
| The arithmetic works, but the units were wrong, that can
| happen in the metric system too.
| chrisseaton wrote:
| Almost impossible I'd say to confuse 1 m with 1 km or 1
| mm, but easy to confuse feet with inches as they're much
| closer in value - the same order of magnitude even. As
| you can see - since it happened in this article.
| krsdcbl wrote:
| Simply put: i doubt the linked article was written by the
| engineers responsible.
| Johnny555 wrote:
| I don't think an engineer would confuse inches with feet,
| and it's a stretch to assume that a newspaper reporter
| wouldn't confuse m with km.
|
| And what about mm and cm? They are only a factor of 10
| apart while inches and feet are 12X apart.
| dang wrote:
| " _Eschew flamebait. Avoid unrelated controversies and
| generic tangents._ "
|
| https://news.ycombinator.com/newsguidelines.html
| throwawayboise wrote:
| Construction and civil engineering (in the USA) is still
| done in feet and inches. All construction materials are
| sold this way. It would just introduce error to try to plan
| a building in metric dimensions.
| coding123 wrote:
| Even in the UK you end up with construction materials at
| those same sizes. Click the link and tell me how large
| the following sheet size in feet?
|
| https://www.forestrallshop.co.uk/plywood-london/birch-
| plywoo...
|
| Comically they apparently also imported our lumber price
| fiasco.
| [deleted]
| jbaudanza wrote:
| So, is this thing going to fall over and kill everyone or what?
| Someone with engineering experience, please explain why this is
| hyperbolic and downvote me away.
|
| I don't know anything about construction. But I do know that
| bureaucrats love to kick the can down the road, rather than deal
| with things directly. In this case, that would mean forcing some
| of San Francisco's wealthiest, and most-influential to demolish
| their luxury homes.
| rsync wrote:
| Building (and seismic) codes in California are stringent, but not
| in the way many people think.
|
| I was surprised to learn that the codes and engineering
| requirements are specified strictly to avoid loss of life.
|
| The buildings themselves are not required to survive in habitable
| fashion.
|
| I was surprised to learn this and it disturbs me to consider that
| while a major earthquake in the SFBA might be (relatively) free
| of fatalities, an enormous portion of the built infrastructure
| would need to be demolished and rebuilt:
|
| "The code also does not specify that a building be fit for
| occupancy after an earthquake. Many buildings might not collapse
| completely, but they could be damaged beyond repair. The interior
| walls, the plumbing, elevators -- all could be wrecked or
| damaged."[1]
|
| [1] https://www.nytimes.com/interactive/2018/04/17/us/san-
| franci...
| telesilla wrote:
| >The buildings themselves are not required to survive in
| habitable fashion
|
| This is the norm for the pacific rim. It's just not
| economically viable to build for longevity in the face of
| tectonic movement. Saving lives however? We know how and those
| cities and citizens at risk that don't invest pay terribly for
| it. Given what we know about quakes these days, it's
| inexcusable any civil infrastructure or building should lead to
| loss of life.
| titzer wrote:
| > It's just not economically viable
|
| Is that code for "it costs too much"?
| CryptoBanker wrote:
| That's literally what it says. It's not code for anything
| irrational wrote:
| It's interesting to see what some people consider to be
| big complicated words.
| imtringued wrote:
| Yes, it costs too much to build it to last, it costs very
| little to rebuild it...
| Apes wrote:
| I may be mistaken, but I believe in Japan the standard is
| "build to remain habitable." as a result, skyscraper building
| techniques there are very different to the US.
| ddkto wrote:
| "The Japanese Building Code (BSLJ) explicitly requires that
| buildings withstand moderate earthquakes with almost no
| damage, while collapse prevention and life-safety is
| required for severe earthquakes. It is expected that a
| typical building will be subjected to several moderate
| earthquakes during their service life, while the likelihood
| of occurrence of a severe earthquake during the same period
| is rare."
|
| (Comparison of the Seismic Code Provisions of the National
| Building Code of Canada and the Building Standard Law of
| Japan, https://www.caee.ca/12CCEEpdf/192-oZfU-119.pdf)
|
| A similar approach is used in California and other places
| under the name Performance-Based Design.
| coding123 wrote:
| If that is what it was optimized for, then building anything
| above 3 maybe 4 stories would be stopped. I disagree.
| beerandt wrote:
| Engineering is about economically designing things that fail in
| a predictable manor.
|
| Too many people think it's about "strongest" or "best" or
| "creative" or "durable" designs. Nope. Sometimes that's true,
| but it's always about controlling your failure modes.
| mcguire wrote:
| Modern car design.
|
| Cars are designed to absorb energy during a major impact.
| They do this by folding in places that preserve the integrity
| of the passenger compartment. As a result, minor impacts
| result in the total loss of the vehicle.
| Someone wrote:
| ...while before, minor impacts often killed the occupants.
| [deleted]
| pm90 wrote:
| I don't see a problem with that. We just need to factor in the
| costs appropriately eg via insurance premiums. Save lives and
| create the infrastructure for building back (eg via a quake
| recovery fund, contingency plans for rebuilding if a quake does
| wreck a building etc).
|
| Construction is one of the last remaining sectors that is still
| able to employ low skilled workers and pay them good wages.
| ramshanker wrote:
| This is a necessary trade off between the probability of
| extreme high intensity earthquake and economy of structural
| design. That is why we civil engineers call buildings
| "earthquake resistant" instead of "earthquake proof".
| HPsquared wrote:
| It's also not possible to "proof test" a building against
| earthquakes.
| redis_mlc wrote:
| Well, there are building-sized shake tables:
|
| https://www.youtube.com/watch?v=Y7kKcIsBKDo
| ggcdn wrote:
| This is something that the profession has done a terrible job
| in communicating with the public.
|
| But if you think about the nature of earthquakes, it starts to
| make a little more sense. There is basically a probabilistic
| distribution of earthquake frequency and energy. The more
| powerful the quake, the less frequently it occurs, and there is
| a long tail to this distribution. So we need to draw a line in
| the sand somewhere and say "we will design for X, and detail
| the structure to avoid collapse if X is exceeded." There is no
| such thing as an earthquake proof building, because there is
| always a bigger earthquake than the one considered for design.
| All we can do is play with probabilities.
|
| In the US the life safety objective corresponds to earthquake
| hazard of 10% probability of exceedance in 50yrs. The industry
| has long accepted this as a good X point that balances
| construction cost and longevity. But more recently, with
| ballooning recovery costs in recent earthquakes, some are
| starting to see its not enough. For instance, in the Canterbury
| NZ earthquake many structures performed "well" and met their
| design intents, but around 70% of the downtown ended up being
| demolished. Insurance deemed them too costly and risky to
| repair.
|
| Now industry is starting to use "performance based design" more
| often for seismic design of tall buildings (including the
| Millennium tower). It allows you to pick multiple hazards and
| set different objectives for them. For instance, we might say
| no damage allowed at 30% in 50yr hazard, cracking and light
| damage at 10%/50yr, and no collapse at 2%/50yr hazards. Then we
| do a bunch more sophisticated modelling to demonstrate the
| design meets the objectives. I wrote a little bit more about
| performance based design here :
|
| https://kinson.io/post/what-is-performance-based-design/
|
| Unfortunately it didn't help the millennium tower with this
| geotechnical issue. Which I suppose says something about design
| being only as good as the input assumptions.
| ggcdn wrote:
| It's also worth noting that geotechnical engineering is a
| high risk and low tech field. Most of their design relations
| involve pounding a stick into the ground and counting how
| many hits it took to sink a unit depth (that's a little bit
| jest, but also not far from the truth)
|
| Imagine being tasked with identifying a famous painting, But
| you aren't allowed to see the painting. You are provided with
| the five predominant colours in the painting, the type of
| paint used, and a 10mm x 10mm sample of the painting.
|
| Now, please tell me the name of that painting?
| iscrewyou wrote:
| This is how some other professions operate. In a strict sense
| of what a profession is supposed to be and not counting the
| economic factor, doctors care more about loss of life than loss
| of a limb. If they have to save your life by cutting off your
| limb, they will.
|
| If you read the building code (I have), sudden collapses are
| something that need to be avoided at all cost, think the recent
| sky scraper in Florida.
|
| Restoring a structure instead of rebuilding after damage puts a
| lot of responsibility on the Civil Engineers because ultimately
| they are the ones who sign off on the plans that basically say
| this structure will not collapse at the blink of an eye. Older
| buildings get retrofitted all the time but those are also very
| expensive. Retrofitting is done to bring the building up to
| code and not fix a damaged building.
| unearth3d wrote:
| It's the same in NZ, without fundamental changes to engineering
| science it will continue, remember that a quake will stress a
| building's reinforcing / all materials beyond the elastic
| limit.
| klyrs wrote:
| After watching the political quagmire of the housing crisis in
| California, this gives me some hope that The Big One might
| create a situation where it would be possible to reboot the
| architecture of major cities to prioritize humans over cars
| without significant loss of life.
|
| And yeah, it would really suck in the very short term. In the
| years following the quake, there would be a boom of work
| opportunities. Contrast to a situation where the buildings are
| spared at the cost of human life, you'd have ghost towns that
| would rapidly deteriorate to the point that the buildings would
| also fall to ruin
| xyzzy21 wrote:
| I find everything about this building hilarious in a dark,
| horrifying engineering and bureaucratic sense.
|
| Part of what started this: a NYC architect and NYC construction
| contractor came to SF for the first time in their corporate and
| professional experiences and decided to build a building, cutting
| corners on standard local construction standards, regulations and
| laws because they found loopholes in all three and they thought
| it would save a lot of money.
|
| So they did NOT do any of the standard "ground work" (sic) to
| prepare the foundation as every other skyscraper in SF and
| California normally does.
|
| The normal process is to drive piles down to bedrock. They didn't
| do this. They put piles into sand. SF is primarily all sand
| sitting atop of deeper rocks but some of that rock is very deep
| below the surface. In that particular area, the rock is quite
| deep (all the hills you see like Nob Hill, Coit Tower, etc. are
| the rocky high spots surrounded by deep valleys covered with sand
| from ancient water inlets).
|
| Local construction companies know all about this geophysical
| reality. Apparently these NYC companies did not and had zero
| engineering/professional intuition about the nature of
| earthquakes and construction in California.
|
| Because of this the building started to both sink and tilt. And
| honestly, ANYTHING short of tearing the building down and
| starting again is at best a bandaid fix that may or may not work
| for long. This is a legendary FU.
|
| And you are seeing these New Yorkers trying to lawyer their way
| out of the liability they will inevitably face by doing things
| on-the-cheap and half-assed. Here they got caught doing just
| that!
|
| My late father was a big name in construction in the SF Bay Area.
| He was involved with most skyscrapers built in SF from 1970-1985
| which includes the WF tower, Hyatt-Regency, Embarcadero Center
| building complex, etc. At that time I was a kid and he'd "take me
| to work" at these sites while under construction and I got to
| talk to construction workers, structural engineers, etc. about
| how it was done. It fascinated me enough to go into engineering
| professionally though the later PC and semiconductor revolution
| of the 1970s drove me to an EE degree instead of ME/CivE.
| x3n0ph3n3 wrote:
| It's unlikely to come out in court, but my father worked on the
| investigation and it became clear both the engineer and
| architect had e-mail corresponding showing they _planned_ to
| blame various 3rd parties for several secondary effects of the
| tower 's sinking, including cracking caused by the tower
| pushing on the exterior wall of the underground garage causing
| water intrusion.
|
| There was so much corruption here, and my personal belief is
| the city was paid off to facilitate the settlement.
| xhkkffbf wrote:
| From 1970 to 1985? That means he was part of the "Towering
| Inferno" debacle. Not pretty.
| diebeforei485 wrote:
| > The normal process is to drive piles down to bedrock.
|
| Citation needed. Friction piles are quite normal too. I've
| lived in buildings in SoMa that used friction piles and none of
| them were tilting as much as this building. There's something
| more going on here (design or construction flaws), but it isn't
| as simple as "friction piles bad".
|
| https://sf.curbed.com/2016/9/15/12930402/millennium-towner-s...
| ylee wrote:
| >Friction piles are quite normal too. I've lived in buildings
| in SoMa that used friction piles and none of them were
| tilting as much as this building.
|
| A selling point for my old condo building in SoMa is that
| it's one of the few buildings there that is built on bedrock.
| throw03172019 wrote:
| Is it normal for the size of the building + use of concrete
| over steel (increased load)?
| dehrmann wrote:
| A few years ago, one of the theories was construction of the
| transbay terminal caused this, but I have no idea if that was
| actually the case.
| jeffbee wrote:
| You can imagine why they floated that idea but the site is
| surrounded by other buildings which survived intact,
| including a 100-year-old unreinforced brick building.
| dehrmann wrote:
| Small nit on the location: I think it's landfill that was
| originally part of the bay...which is even worse for stability.
| hammock wrote:
| Below that is sand over bedrock
| dehrmann wrote:
| I'm honestly not sure. I assumed being marshland for
| millennia gave it significantly different soil than valleys
| in the area.
| axguscbklp wrote:
| I am just a layman when it comes to this kind of thing, but I
| notice that many articles online claim that variable bedrock
| depth explains why Manhattan's skyscrapers come in two distinct
| clumps. If this is true, then it seems strange to me that NYC
| professionals would ignore bedrock depth in SF out of pure
| ignorance.
| [deleted]
| WYepQ4dNnG wrote:
| On paper, people who bought those units, own multi million $$$
| apartments, but what's their market value, zero? Who would ever
| buy an apartment in that building? Wouldn't be better to tear it
| down?
| milesdyson_phd wrote:
| For the right price I am sure they would be bought, especially
| if someone (probably an investment group) is trying to profit
| long term assuming the building is "fixable" whatever that may
| mean.
| daniel-thompson wrote:
| You couldn't pay me to live in, visit, or even walk by that
| building, but apparently there is a market for the units:
|
| - at least 6 units have sold within the past 6 months:
| https://www.sanfranciscocondomania.com/soldCondos/MILLENNIUM...
|
| - at least 8 units are currently on the market:
| https://www.zillow.com/san-francisco-ca/millennium-tower_att...
| irrational wrote:
| Maybe they are opportunists hoping to collect insurance
| and/or lawsuit money.
| winternett wrote:
| Hah, I'd buy one at a bargain basement price then insure it
| heavily if it wouldn't trigger a fraud alert...
|
| I think at this point the building is way too heavy to ever
| fix and they should demolish it and cut the losses.
|
| It happens all the time in China because of weak building
| codes.
|
| Once a structure is compromised like this, there really is no
| sound way to salvage it in my experience, and it's a danger
| to the entire neighborhood, not only the occupants.
|
| The bad part is that many of the occupants will suffer either
| way this goes... All insurance payouts should go to the unit
| buyers before any of the people involved in profiting get
| anything, but things never work that way. Attorneys will
| likely profit the most. The people responsible for the failed
| design and build should be blacklisted from future projects
| of this kind, that is where most injustice usually manifests
| in failures like this.
| ghaff wrote:
| I'm guessing insurance payouts would involve lots of
| lawyers and lots of time.
|
| Those sales don't strike me as especially bargain basement
| either. 2BR, 1500 sq ft for about $1.5m. Maybe without the
| issues, as a premium property, it would be higher but those
| prices don't seem out of line with condos on the market.
| s5300 wrote:
| > The people responsible for the failed design and build
| should be blacklisted from future projects of this kind,
| that is where most injustice usually manifests in failures
| like this.
|
| ...no, they should be jailed, likely for life, because they
| knew exactly what they were doing.
|
| Capitalism apologists prove they know no bounds, time and
| time again. Really exited to get to watch the incoming
| century of collapsing skyscrapers because of skirted
| regulations. Deaths will pile high and no consequences will
| be had.
| throwthere wrote:
| I wonder how the $/sq ft compares to similar but structurally
| sound condo buildings in the area.
| dehrmann wrote:
| I assume 1 Rincon Hill is very sound.
| coding123 wrote:
| One of them actually sold AFTER the Miami collapse. I would
| think that after seeing the hubris fail elsewhere it would
| make people second guess a huge purchase like that. It was
| probably a long escrow and figured they should just close
| anyway - it won't happen to me, not in this leaning tower in
| a quake prone area.
| Dylan16807 wrote:
| > One of them actually sold AFTER the Miami collapse.
|
| Why would the collapse of a different building, across the
| country, for unrelated reasons, affect their decision?
| mikeyouse wrote:
| I had two friends who were both skyscraper architects who
| rented there for several years. The average person just
| doesn't have a good grasp on the actual risks, but they
| certainly did. They wouldn't buy a unit there due to the
| uncertainty in cost for the repairs but it's plenty safe.
| czep wrote:
| It's actually a very low risk investment. The HOA is suing the
| city, blaming the construction of the Transbay terminal next
| door. They have access to some serious attorneys, so if the
| building falls down they'll still profit.
| coding123 wrote:
| It's super high risk when there is any litigation. Most banks
| will stop mortgage loans when that's discovered.
| toomuchtodo wrote:
| Could be a fun exercise to look at the property records
| over time to see which financial institutions are publicly
| recording mortgages on these units to understand their risk
| tolerance.
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(page generated 2021-08-28 23:01 UTC)