The obvious counterproof to your argument is Millennium Tower, a 60-story skyscraper, which has sank at least 16 inches so far. Most of those one 1 side, so the building now tilts at least 15 inches at the top: https://www.bloomberg.com/news/articles/2017-02-01/who-will-...
They are still trying to figure out how to fix it. Doing so could cost well more than it took to built it in the first place. One proposed plan is to anchor it to bedrock on the low side, then let the tower sink further until it's about even before anchoring the other side: https://sf.curbed.com/2018/4/16/17242450/millennium-tower-si...
I honestly think it's reasonable that the building code gives skyscrapers a lot of leeway. Traditional building codes are very prescriptive, and that works better with (common and similar) houses than (rare and varied) skyscrapers. But the ongoing clusterfuck that is Millennium Tower makes it clear we can't just trust developers to get it right. As mabbo says, they have a strong financial incentive to cut corners.
The Millennium Tower is not a "counter proof" to my argument, although it has become a bellwether for exactly the kind of posters I call out in my original post. My argument is that people on here who do armchair structural engineer and make comments like "the building code is too lax" are ignorant and full of shit. All the Millenium Tower proves is that, even with a building code, it is still possible to get unintended consequences. To the rest of your post about skyscrapers getting a lot of leeway - they don't get any more leeway than any other structure, they just have the money it takes to invoke portions of the code that allow alternative analysis methods. It just doesn't make sense financially to do some of the complex modeling for a 3 story building to shave 5% of material costs.
If anything, the building code is more stringent on skyscrapers because it does require more advanced analysis. This analysis is NOT precluded for smaller buildings, it is just not worth the money.
Because if it falls over it won't just kill 5 stories worth of people, but 50 stories plus an unknown number of people in the building it falls on, as well as creating a giant civic problem?
> ignorant and full of shit
Oooohkay, buddy. At best you are playing semantic games here. If your theory is that the building code is just fine when things like the Millennium Tower can happen, then we disagree on what "fine" means.
What portion of the building code do you think needs to be updated in response to the Millennium situation? In reality, the building code achieves a success rate far in excess of what engineers deem acceptable. It is unfortunate that the Millennium is a big glaring exception, but the fact remains.
Geotechnical engineering (the cause of the Millennium lean) remains a highly empirical field of engineering with uncertainties that dwarf structural ones. Hence there is a lot of built-in conservatism in design parameters like bearing pressures. But there are limits to the amount of information you can ascertain of what's below you that you cannot see. Looking back in retrospect and saying "well obviously they should have had longer piles" like many people have on the various threads about the tower is a pretty ignorant thing to say, and it shows that they do not have an appreciation of the engineering behind the decision. There a tens of thousands of examples of friction piles that have worked flawlessly. The engineering evidence appears to have supported the decision, but the in-situ soil conditions varied from their design model. This, in my opinion, is not a failure of codes, but an unfortunate, statistically rare outcome.
I understand that the people who built it believed that they were doing just fine. But I also understand that there are enormous pressures to keep costs low on a project like this. The notion that for this building those enormous pressures had exactly zero contribution to this outcome is a claim I certainly wouldn't accept without evidence.
If this were really in the range of statistically expected outcomes, then a) there should have been a plan in place to fix it before the structure went up, and b) they would have had sufficient insurance coverage to pay for the fix. Neither is true. The ongoing gosh-golly-who-cooda-node routine plus the simultaneous festival of blame-shifting suggests to me that, at best, the business side of the operation went well beyond what an engineer would have done in the same place.
The correct fix to the building code here I'm happy to leave to the experts, just as long as they eliminate outcomes like this. If that ends up raising the costs for other fancy buildings stuffed with pied-a-terres for the wealthy even to prohibitive levels, I am entirely fine with that. Erring on the side of of earthquake safety while building near major faults in major metropolitan areas seems like a great choice to me.
I guess the point I'm trying to make is that complete elimination isn't possible in a long tail statistical distribution. There will always be a point where we have to draw the line, and there will always be freak occurrences of undesirable outcomes. This is the crux of engineering - finding the correct balance between cost and safety. Perhaps the current state is not enough, but the wildly disproportionate amount of structures that are working just fine tells me we are close.
> If that ends up raising the costs for other fancy buildings stuffed with pied-a-terres for the wealthy even to prohibitive levels, I am entirely fine with that.
Building codes aren't only applied to high end buildings. Any changes affect the (badly needed) low end housing just as much as high end buildings. Just another thing to consider.
> Erring on the side of of earthquake safety while building near major faults in major metropolitan areas seems like a great choice to me.
No disagreement there ;)
Medical care has a much longer tail, for example, but many countries manage to provide full financial coverage and individual support in treating and managing even very rare diseases.
If you're saying this was a reasonably forseeable but unlikely outcome of cost-driven skipping out on the bedrock anchoring that neighboring buildings used, the I don't think it's too much to ask them to have an answer to the question of, "Ok, if your cheap solution doesn't work, what will you do next?" And if they don't have a good answer to that, I also don't think it's too much for them to not be allowed to build the thing.
Now that would be a serious problem.
Perhaps, but have you compared it to the building code in Japan? I personally have qualifications in this area so I'm just asking.
Do you have anything else to say besides vague claims on your credentials and experience?
In reality many more will collapse, because some buildings are older and not up to code, as well as earthquakes generally just being weird and unpredictable.
Do you think 10% of buildings collapsing is a "loose" or "tight" code? 10% losses is acceptable in say, human habitation?
You don't get exactly 10% failure rate, you have to demonstrate better than 10% failure rate which means going past that point. Further, failure is not 'collapse' failure is anyone in the building being unable to exit safely.
And again, they are aiming for a 9.0 that's a ridiculously large earthquake. An 7.8 similar to the last SF earthquake would still be a major earthquake, but vastly less dangerous by comparison.