SF tower settlement SF tower settlement hokie66 (Structural) (OP) 2 Aug 16 05:55 Wouldn't want to be involved in this one. http://www.sfchronicle.com/bayarea/article/SF-s-la... RE: SF tower settlement itsmoked (Electrical) 2 Aug 16 08:27 That has got to be a "worst nightmare" scenario starting up. I sure wouldn't want to be in a building like that during the soon-to-happen next Big One. Keith Cress kcress - http://www.flaminsystems.com RE: SF tower settlement dik (Structural) 2 Aug 16 11:18 Good thing it's not too tall... only 58 stories... Settled 16" so far and tilted 2". Constructed on mud fill with a slab foundations supported on piles into dense sand. Max condo value is $10M... I don't know if the sand is saturated, but, there could also be problems during a seismic event... Dik RE: SF tower settlement TehMightyEngineer (Structural) 2 Aug 16 13:09 Well, this will be quite the case study on foundation improvements assuming they don't just demo it and start over. Professional and Structural Engineer (ME, NH, MA) American Concrete Industries www.americanconcrete.com RE: SF tower settlement jayrod12 (Structural) 2 Aug 16 13:15 For those that don't want to sign up as a member of the SF chronicle. Here's a fox "news" article posted by Tigerguy in the foundation forum Link RE: SF tower settlement JAE (Structural) 2 Aug 16 13:17 Quote (Article)The HOA added that it is exploring its legal option and could pursue damages from several parties, including the developer, the original design professionals, the original contractors and the Transbay Joint Powers Authority. Trouble in paradise that's for sure. Check out Eng-Tips Forum's Policies here: FAQ731-376: Eng-Tips.com Forum Policies RE: SF tower settlement 2 BUGGAR (Structural) 2 Aug 16 14:51 I worked on the BART station construction one block away on Market. During lunch, a group of Archeologists would poke around the excavation and found all the stuff that was dumped from ships moored in the Bay before this area was filled. Lots of those clay pots, apparently used to ship rice, and many small bottles, some still sealed and full. Also met my wife there. But I had nothing to do with this settlement. RE: SF tower settlement Lomarandil (Structural) 2 Aug 16 14:51 Quote (Article)The transit authority also said the high-rise is made of concrete rather than steel, "resulting in a very heavy building. This heavy structure rests on layers of soft, compressible soil. The foundation of the Tower, however, consists only of a concrete slab supported by short piles that fail to reach the bedrock below. That foundation is inadequate to prevent settlement of a building with the weight of the Tower." That's a pretty strong statement for the transit authority to make... Time to grab some popcorn. RE: SF tower settlement IRstuff (Aerospace) 2 Aug 16 15:27 Various places in that part of the city is soft landfill; they used to find ships and whatnot when digging foundations for various buildings. Near as I can tell, that particular high rise is sitting on what used to be Yerba Buena Cove: http://www.davidrumsey.com/luna/servlet/detail/RUM... TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers RE: SF tower settlement JStephen (Mechanical) 2 Aug 16 17:34 "and has sunk 16 inches and shifted 2 inches to the northwest since opening"- That's from the Fox news article, doesn't say it tilted, but moved sideways? I suspect a lot of lawyers will make a lot of money out of this and that's about the only positive aspect all the way around. RE: SF tower settlement winelandv (Structural) 2 Aug 16 17:39 Quote (JStephen)I suspect a lot of lawyers will make a lot of money out of this and that's about the only positive aspect all the way around I guess if you consider such a thing a positive... RE: SF tower settlement BUGGAR (Structural) 2 Aug 16 19:03 Been reading about the engineers and such involved with Flint. I was a concrete inspector on the BART Lower Market Street Station. I inspected the concrete used in the slurry walls on the south side of Market, 720 feet away from 301 Mission. As I mentioned, I met my wife here. Suppose I was watching her instead of the concrete pour. And as a result, after 45 years of seepage from bad concrete, the millenials had their building damaged? RE: SF tower settlement IRstuff (Aerospace) 2 Aug 16 19:15 title of chronicle article "SF’s landmark tower for rich and famous is sinking and tilting" TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers RE: SF tower settlement jgKRI (Mechanical) 2 Aug 16 19:31 Quote (BUGGAR)Been reading about the engineers and such involved with Flint. I was a concrete inspector on the BART Lower Market Street Station. I inspected the concrete used in the slurry walls on the south side of Market, 720 feet away from 301 Mission. As I mentioned, I met my wife here. Suppose I was watching her instead of the concrete pour. And as a result, after 45 years of seepage from bad concrete, the millenials had their building damaged? Well, in your case, let's hope the statute of limitations for arousal-induced negligence has expired. RE: SF tower settlement itsmoked (Electrical) 2 Aug 16 20:07 Likely tilting because of all the compressing beer cans tossed in the hole by BUGGAR and his cohorts. Keith Cress kcress - http://www.flaminsystems.com RE: SF tower settlement Ingenuity (Structural) 2 Aug 16 20:58 My guess is that the legal settlement may take longer than the ongoing foundation settlement... RE: SF tower settlement BUGGAR (Structural) 2 Aug 16 21:13 "Founded on piles bearing on dense sand". There was a drainage system built to collect leakage from the slurry walls around the Lower Market Street Station. What if these dense (previously) sands have been draining through the slurry walls and into the Market Street Station dewatering system and no one knows this? I'm not really trying for some witness per diem, honest. RE: SF tower settlement waross (Electrical) 3 Aug 16 01:57 It will have to tilt a lot more than 2 inches before it becomes a major tourist attraction. It will be some time yet before the Italians become concerned about losing tourist dollars to SF. Bill -------------------- "Why not the best?" Jimmy Carter RE: SF tower settlement BUGGAR (Structural) 3 Aug 16 14:37 The Transbay Transit Center is 90% over budget and considering a special tax on the properties, including 301 Mission, to pay for the bail out. This is just for Phase I of the Project. Funding for Phase II has not been identified. Phase III?? Excavation is just like BART - cut and cover using soldier piles and concrete slurry walls. Big HSS struts supporting walls during excavation. The excavation is bigger than Lower Market. I presume the walls are structural like on BART, a first at the time. I also read that they consider the Lower Market Street Bart Station to be obsolete. Hey, I just built that thing! The concrete is just reaching its prime. RE: SF tower settlement msquared48 (Structural) 3 Aug 16 19:57 A new icon to advertise for tourists for the local money mongerers - The Leaning Tower of San Francisco - And Vegas can take bets as to when it will fall too. Many investment opportunities here... Mike McCann, PE, SE (WA) RE: SF tower settlement itsmoked (Electrical) 3 Aug 16 20:44 Imagine having property on the now "underside" of that building. <shudder> Keith Cress kcress - http://www.flaminsystems.com RE: SF tower settlement hokie66 (Structural) (OP) 3 Aug 16 21:33 No worries. These are in Bologna, and they have earthquakes there, too. https://www.google.com.au/search?q=Bologna+leaning... RE: SF tower settlement JAE (Structural) 3 Aug 16 22:27 Is the building leaning left? Check out Eng-Tips Forum's Policies here: FAQ731-376: Eng-Tips.com Forum Policies RE: SF tower settlement msquared48 (Structural) 3 Aug 16 23:08 Obviously someone needs to do pushover analysis if it is leaning left. Mike McCann, PE, SE (WA) RE: SF tower settlement davidbeach (Electrical) 4 Aug 16 03:15 Leaning left from one side; leaning right from the other side. RE: SF tower settlement itsmoked (Electrical) 4 Aug 16 09:20 You guys crack me up. Keith Cress kcress - http://www.flaminsystems.com RE: SF tower settlement DanEE (Electrical) 4 Aug 16 14:32 Sign found just across Fremont St from the building..... http://files.engineering.com/getfile.aspx?folder=9e755434-31b2-4fad-ab3c-99 RE: SF tower settlement 1gibson (Mechanical) 4 Aug 16 15:44 Ah ha, so the building didn't follow the notes on the drawing, not the engineer's fault! RE: SF tower settlement oldestguy (Geotechnical) 4 Aug 16 15:51 It goes to show we don't need to be so darn conservative when designing foundations. I'd bet this one well stand well beyond the lives of all the members here and with full occupancy. RE: SF tower settlement itsmoked (Electrical) 4 Aug 16 21:10 Geez Dan, don't make everyone play the clickclick game, just post the dang picture directly! Keith Cress kcress - http://www.flaminsystems.com RE: SF tower settlement lilliput1 (Mechanical) 4 Aug 16 21:56 Any suggestion on how to prevent the building from sinking and tilting? Would it be possible to jack up columns like in Kansai airport terminal? RE: SF tower settlement oldestguy (Geotechnical) 5 Aug 16 15:28 Why jack it up? Do like in Mexico City. Just install new entry ways in the second floor so that no one is trapped inside when current doors won't open due to earth there. Should cost less. RE: SF tower settlement SparWeb (Aerospace) 6 Aug 16 04:33 So, in 45 years or so, it will be 57 stories high! STF RE: SF tower settlement msquared48 (Structural) 8 Aug 16 18:22 Unfortunately, they will have to lower the rent on the bottom story. Seems like there will be a LOT of plumbing and electrical issues here too, not just structural. Mike McCann, PE, SE (WA) RE: SF tower settlement lilliput1 (Mechanical) 9 Aug 16 14:49 Rather than make fun of the situation I am more interested in finding out what led to the mistake so that others may not make the same. This is a serious situation I am sure not one of us would want to be in. Any leads on this? RE: SF tower settlement ornerynorsk (Industrial) 9 Aug 16 15:11 I know next-to-nothing about civil/geotech, but is grouting an option on something this big to at least stabilize and stop further sinking? Wow, what a nightmare. I'd hate to think what a seismic event would do this site. It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all. RE: SF tower settlement IRstuff (Aerospace) 9 Aug 16 15:27 Those other leaning towers are interesting, no doubt, but none of them were intended to be a residential building. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers RE: SF tower settlement MacGyverS2000 (Electrical) 9 Aug 16 16:59 Somewhat of a side note, but... Could the right "seismic event" cause liquifaction of the underlying sand and cause a rapid decline in building stability, or are the underlying ground specifics not appropriate for such a reaction? Dan - Owner http://www.Hi-TecDesigns.com RE: SF tower settlement JAE (Structural) 9 Aug 16 17:59 Quote:Rather than make fun of the situation I am more interested in finding out what led to the mistake... It doesn't have to be either/or. We all take it very seriously I'm sure. Especially the structural engineers among us. Check out Eng-Tips Forum's Policies here: FAQ731-376: Eng-Tips.com Forum Policies RE: SF tower settlement lilliput1 (Mechanical) 9 Aug 16 18:36 Could it be that the higher ups wanted to cut cost, opting for foundation slab with piles not going all the way down to bed rock and the structural engineers come up with calculation based on ideal case to justify decision without sufficient core bore data? RE: SF tower settlement hokie66 (Structural) (OP) 9 Aug 16 18:55 lillliput, Suffice it to say that there are a lot of possibilities. You won't find any definite answers here, and as discussed above, this will take years to resolve, if ever. RE: SF tower settlement oldestguy (Geotechnical) 9 Aug 16 21:12 OK so we joked a little. However, does anyone have any CORRECT history of construction as well as an on-going record of measurements? Can we learn from any mistakes? Maybe. RE: SF tower settlement msquared48 (Structural) 9 Aug 16 21:21 What makes you think I was joking? Mike McCann, PE, SE (WA) RE: SF tower settlement fattdad (Geotechnical) 10 Aug 16 19:35 there is no negligence by running piles to dense sand rather than bedrock. If each pile can develop the capacity it needs in the dense sand, where's the problem? There is a problem designing for some capacity and not documenting that the installed pile developed that capacity. There is also a problem not knowing the performance details of the piles. I mean if the piles remain good against failure, but they required 16 inches of settlement to develop their full capacity, that's a serviceability problem. I can't believe 16 inches of settlement! I mean are the water/sewer connections failed? f-d ípapß gordo ainÆt no madre flaca! RE: SF tower settlement hokie66 (Structural) (OP) 10 Aug 16 20:33 Why do you question the 16" settlement quoted, fattdad? I would think if this was not factful, there would have been a denial by now. Yes, the service connections would present big problems, as would probably a lot of other relationships with the surrounding ground level surfaces. In a situation like this, servioeability/settlement failure is overriding, and strength is of less importance. Too much settlement can indeed be evidence of negligence. That remains to be determined in this case. RE: SF tower settlement marty007 (Mechanical) 10 Aug 16 21:10 I wonder if the parking garage entrance is near the maximum settlement area. It would make the perfect home for Evel Knievel. RE: SF tower settlement JohnRBaker (Mechanical) 10 Aug 16 21:14 To say nothing of raising havoc, in one fashion or another, with the handicap accessibility. John R. Baker, P.E. (ret) EX-Product 'Evangelist' Irvine, CA Siemens PLM: UG/NX Museum: The secret of life is not finding someone to live with It's finding someone you can't live without RE: SF tower settlement racookpe1978 (Nuclear) 10 Aug 16 21:47 Quote (MacGyverS2000 (Electrical)) 9 Aug 16 16:59 Somewhat of a side note, but... Could the right "seismic event" cause liquifaction of the underlying sand and cause a rapid decline in building stability, or are the underlying ground specifics not appropriate for such a reaction? In just the last moderate SFO earthquake in 1989, Mission District buildings on fill dirt in the bay DID collapse and sink into the ground just for that cause. Saw videos of the entire first floor below ground. RE: SF tower settlement fattdad (Geotechnical) 11 Aug 16 00:16 I don't question the settlement at all! I was just saying the dense sand could be safe for foundation support (i.e., strong enough), but some other layer may settle. So, how did the original design consider settlement if the foundation bears on soil rather than rock? Were the soil layers and their properties estimated (I'd doubt it)? So, it'd be likely that somebody studied the strength and compressibility of the dense sand, the soil above (mud?) and the soil/rock below. I just could not claim because the foundation did not go to rock there was some negligence. Sorry to confuse. . . f-d ípapß gordo ainÆt no madre flaca! RE: SF tower settlement JStephen (Mechanical) 29 Nov 16 22:16 Just a stir-the-pot article, no real news: http://www.pressdemocrat.com/home/6370566-186/lean... My favorite line, "said Dodson, an attorney who has helped organize homeowners lawsuits. 'I can tell you that satellite data is way more accurate that digging in the dirt.'" Translation: We don't need no stinkin' surveyors, we got Google maps!" RE: SF tower settlement msquared48 (Structural) 29 Nov 16 23:18 Heck of a project for "Slabjack". Mike McCann, PE, SE (WA) RE: SF tower settlement BigInch (Petroleum) 30 Nov 16 20:54 Dodson is going to be in for a few big surprises over the coming years. RE: SF tower settlement JedClampett (Structural) 2 Dec 16 02:14 This is the perfect storm: CondominiumFlaws that might be huge or not.Extremely rich entitled tenants.Many lawyers are going to get very rich. RE: SF tower settlement boo1 (Mechanical) 1 Feb 17 17:32 article at: https://www.bloomberg.com/news/articles/2017-02-01... RE: SF tower settlement JAE (Structural) 1 Feb 17 18:20 boo1 - that is a good article and fairly described all the challenges, both engineering-wise and in terms of the legal issues. Check out Eng-Tips Forum's Policies here: FAQ731-376: Eng-Tips.com Forum Policies RE: SF tower settlement dik (Structural) 2 Feb 17 00:32 great... and I'd be somewhat concerned about the hairline cracks in the basement... Dik RE: SF tower settlement JAE (Structural) 2 Feb 17 02:15 Hairline cracks not a problem...not at all.... Check out Eng-Tips Forum's Policies here: FAQ731-376: Eng-Tips.com Forum Policies RE: SF tower settlement hokie66 (Structural) (OP) 2 Feb 17 02:22 Thick hairs, those. RE: SF tower settlement LionelHutz (Electrical) 2 Feb 17 13:35 Are we going to be making posts about this building in this thread in the future? http://www.eng-tips.com/viewthread.cfm?qid=420273 RE: SF tower settlement dik (Structural) 2 Feb 17 14:47 LionelHutz: Yes Dik RE: SF tower settlement IRstuff (Aerospace) 2 Feb 17 15:29 Those cracks probably were hairline cracks when the strain gages were installed, based on the dates written on them. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: SF tower settlement MotorCity (Structural) 2 Feb 17 17:01 So if this issue was settled out of court, would it be a settlement on the settlement? RE: SF tower settlement MacGyverS2000 (Electrical) 2 Feb 17 17:05 This discussion is unsettling, MC, but I've occasionally cracked up while reading it... Dan - Owner http://www.Hi-TecDesigns.com RE: SF tower settlement JAE (Structural) 2 Feb 17 17:26 I'm starting to catch the general drift of this thread. Check out Eng-Tips Forum's Policies here: FAQ731-376: Eng-Tips.com Forum Policies RE: SF tower settlement IRstuff (Aerospace) 2 Feb 17 17:52 Seems to me the discussion has suddenly gotten a bit skewed off foundation. TTFN (ta ta for now) I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm RE: SF tower settlement dik (Structural) 3 Feb 17 14:25 I was thinking, micropiles to rock and secured in the slab foundation. Would the poor soil offer enough restraint to preclude buckling. Lets try to think of some remediation. Dik RE: SF tower settlement MacGyverS2000 (Electrical) 3 Feb 17 17:40 IR, perhaps we should come at this from a different angle rather than straight on? I'm leaning towards a simple solution. Dan - Owner http://www.Hi-TecDesigns.com RE: SF tower settlement JAE (Structural) 3 Feb 17 18:30 I sure dig your slant on this. Check out Eng-Tips Forum's Policies here: FAQ731-376: Eng-Tips.com Forum Policies RE: SF tower settlement darthsoilsguy2 (Geotechnical) 3 Feb 17 18:53 curious. has anyone heard who the geotech firm was on this? i know DeSimone was structural but haven't seen any reference to the geotech. FYI... they have a new geotech in now who was not related with the original construction. RE: SF tower settlement SparWeb (Aerospace) 4 Feb 17 05:22 That settles it. I will only read this thread for shear amusement from now on. STF RE: SF tower settlement Ingenuity (Structural) 4 Feb 17 09:54 Quote (garthsoilsguy2)curious. has anyone heard who the geotech firm was on this? Treadwell & Rollo, now part of Langan Engineering. ENR link re aquisition and Langan Engineering website. Quote (garthsoilsguy2)i know DeSimone was structural... Sadly, Vincent DeSimone (founder of DeSimone Consulting Engineers) passed away in November, 2016. Memoriam RE: SF tower settlement JedClampett (Structural) 4 Feb 17 15:34 This one only settled 14 inches before it was "dealt with." RE: SF tower settlement JedClampett (Structural) 6 Feb 17 16:23 A structural engineer did a review of the building design, but only the building, not the foundation. I kind of sympathize with the guy, no one welcomes you reviewing scope beyond your contract. RE: SF tower settlement JAE (Structural) 6 Feb 17 17:31 Just curious here - it says that the tower has sunk 16" - that is "significant". But the lean is 2". For a 645 ft. (196.6m) tall building the ACI 117 tolerances (for construction) would be on the order of 3" to 6" depending on the direction of the measurement. So a 2" "lean" here doesn't sound too bad. For typical wind load deflections, a tall building like this might lean L/500 = 15 inches. Check out Eng-Tips Forum's Policies here: FAQ731-376: Eng-Tips.com Forum Policies RE: SF tower settlement Ingenuity (Structural) 6 Feb 17 18:54 Quote (JedClampett)A structural engineer did a review of the building design, but only the building, not the foundation. I kind of sympathize with the guy, no one welcomes you reviewing scope beyond your contract. And non-other than Prof Jack Moehle of UC Berkeley: Quote (Curbed SF)“The interest was to do an internal review to ensure that the structural system selected was suitable,” Moehle told city lawmakers at Thursday’s hearing. “[So] that if there was a formal peer review for the city later that most questions would be dealt with already.” RE: SF tower settlement Ingenuity (Structural) 6 Feb 17 19:17 And this from 2004 about 80 Natoma SF proposed 50-story tower that was NOT constructed Link: Quote (Bizjournals)A 50-story building is heavy. If constructed, the 80 Natoma Building would impose 13,000 pounds per square foot on the soil below it. Moreover, if the developer went ahead with his plan to use short (70-foot) piles to support the building, the bottom of his piles would lie just above a 90-foot layer of compressible clay. Geotechnical experts concluded that imposing such loads through the piles to the clay would cause the clay to deform and the building to settle several inches. Unless the developer were to extend his piles another 100 feet or so to bedrock, there is no getting around this. RE: SF tower settlement Ingenuity (Structural) 6 Feb 17 20:22 Link to C & C of SF video testimony of Prof Jack Moehle dated 2/2/17 - all 2.5 hours! Link RE: SF tower settlement itsmoked (Electrical) 6 Feb 17 22:05 I'm betting we see this in the future with that building. Keith Cress kcress - http://www.flaminsystems.com RE: SF tower settlement hokie66 (Structural) (OP) 6 Feb 17 22:39 I had the same thought, Keith. But I'm not betting. RE: SF tower settlement dik (Structural) 7 Feb 17 03:08 From Curbed, "Moehle says he inspected the high-rise’s design from top to bottom—but no lower than the bottom. A geotechnical review—i.e., an assessment of the condition of the soil under the building site—wasn’t part of the process, because no one ever hired a geotechnical engineer." Even as a rookie, if I had been asked to provide an engineering report for a building with substantial subsidence, I would have raised a bit of a flag about having a geotechnical report included with the overall report (and that is not hindsight being 20/20). Because subsidence was a key issue, this would be a significant part of the engineering report. Dik RE: SF tower settlement Ingenuity (Structural) 7 Feb 17 03:15 Quote (Cubed SF and dik)...because no one ever hired a geotechnical engineer. A somewhat misleading quote on behalf of Cubed SF, IMO. A geotech engineer was NOT hired as part of the internal peer-review (which was primarily initiated to look at the structural framing system pertaining to seismic), however the project did have a geotech engineer - namely, Treadwell & Rollo, as part of the project design team. RE: SF tower settlement dik (Structural) 7 Feb 17 03:34 Unless Cubed is misquoting Moehle, with the problems encountered, a 'new' independent geotech firm should have been retained to make the report complete and to address any concerns. Dik RE: SF tower settlement JStephen (Mechanical) 7 Feb 17 03:46 It makes me curious who recommended what. On much smaller projects it is very common to have a geotechnical report that says "You can do it this way, and may have this problem or you can spend more and do it this other way and have less problem", etc. There's quite often a calculated risk involved, and the geotechnical reports I've seen more often reported both options with pros and cons, or went the more conservative route if there was any doubt. RE: SF tower settlement Ingenuity (Structural) 7 Feb 17 04:35 If you listen to the testimony of Moehle [Link] City and County of SF Supervisor Aaron Peskin asks Moehle why he did not stamp/seal his internal peer-review report, and also why was he was not an SE. There was some interesting background information given on the 80 Natoma project in the testimony, which underwent peer-review about the same time as the Millennium Tower project (mid-late 2004). RE: SF tower settlement dik (Structural) 7 Feb 17 16:17 Ingenuity: Good link, and a bit long. It explains why the documents weren't sealed and that the prof wasn't a registered SE. In some jurisdictions, a professional can be held to the same standard if the documents are not sealed. I have to review it again; it appeared that the politician stated that the foundation peer review had been undertaken by the prof and this went unchallenged(53 minutes into the hearing). It appeared that the whole purpose of the dialogue was to distance the city from the problem. Dik RE: SF tower settlement HENRYZAU (Geotechnical) 23 Feb 17 00:26 would appreciate if anyone can provide some information on the ground profile below pile toe, especially clay thickness/depth. RE: SF tower settlement TerryScan (Civil/Environmental) 15 Mar 17 14:24 Millennium Tower's Earthquake Fitness Models May Not Have Been Accurate http://sfist.com/2017/03/14/millennium_towers_eart... RE: SF tower settlement dik (Structural) 15 Mar 17 14:37 from one of the links, "Moehle wrote that "On the basis of my review, it is my opinion that the foundation design is compliant with the principles and requirements of the building code, and that a foundation permit can be issued for this project." The statement is a little confusing because Moehle clearly recuses himself from having any involvement with the foundation. If his statement is correct, he is stating that the foundation is... and, that a foundation permit should be issued. Dik RE: SF tower settlement dik (Structural) 16 Mar 17 15:35 and one of the links from TerryScan's posting: http://www.nbcbayarea.com/investigations/More-Bad-... Dik RE: SF tower settlement dik (Structural) 26 Jun 17 18:37 Current articles indicate it has tilted 12" and not 2"... Dik RE: SF tower settlement Ingenuity (Structural) 26 Jun 17 19:44 Quote (dik)Current articles indicate it has tilted 12" and not 2"... dik: What is your article source for this 'revised' tilt, and what is the magnitude of the 'revised' vertical settlement? RE: SF tower settlement dik (Structural) 26 Jun 17 20:06 The one lawsuit indicated the 12" tilt and there was this news article: SAN FRANCISCO (KRON) — It has become known as San Francisco’s sinking tower, and attorneys representing those who live in the Millennium Tower are seeking more than $200 million from those they say are responsible for the building sinking and tilting. The tower is sinking 16 inches and tilting 12 inches at the penthouse level, attorneys said. Most of the other articles indicate 2" still and are dated a year ago; it is not known what actual measurements have been taken. Dik RE: SF tower settlement Spartan5 (Civil/Environmental) 26 Jun 17 20:11 link: http://kron4.com/2017/03/29/attorneys-san-francisc... RE: SF tower settlement epoxybot (Structural) 26 Jun 17 21:40 Flexural cracking in concrete is very bad. Since concrete has a low tensile strength, reinforcing steel (rebar) is added to increase its ability to carry loads that would otherwise cause it to crack & lose its load carrying ability. Flexural cracking in concrete can lead to bond loss to reinforcement. Considering this is happening at the base of the structure, it is not a good situation. Gluing it back together with a structural epoxy is very slow & expensive. The cracks seen at the surface do not fully represent what might be going on inside the concrete. Fleural cracks can fold back on themselves, creating an interwoven network of cracks that are difficult to penetrate using standard gravity hydraulic injection techniques and require a very low viscosity epoxy with a long working time & exceptional patience & experience by the technicians. RE: SF tower settlement 3DDave (Aerospace) 26 Jun 17 23:20 Any problem left ignored long enough will stop being a problem. Sometimes the cessation of one problem causes the start of another, but that's for others to deal with. I am reminded that the lowest accessible levels in Venice, Italy were at one time second and third floors. RE: SF tower settlement JedClampett (Structural) 25 Jul 17 16:09 See linked article. It seems like the this was the solution all the time, but it sure won't be easy. RE: SF tower settlement dik (Structural) 25 Jul 17 17:35 Without going to bedrock, I'd be really concerned with liquifaction of the supporting soil. Dik RE: SF tower settlement hokie66 (Structural) (OP) 25 Jul 17 19:12 Piling to rock is good, but I wonder about their numbers. They are talking about 100 bored piles, each 10" to 12" in diameter. To me, that doesn't sound like the capacity to jack up that building. RE: SF tower settlement dik (Structural) 25 Jul 17 21:20 It's OK Hokie... They did the sums on it, just like the original foundation... Dik RE: SF tower settlement epoxybot (Structural) 26 Jul 17 19:06 LERA certainly knows tilting buildings Link And DeSimone Consulting Engineers can give their project it's own twist on things. Link Tubex Grout Injected Piling is probably what they are thinking. Link Link RE: SF tower settlement dik (Structural) 26 Jul 17 19:41 Epoxybot: With extreme settlement, the building with a twist, just screws itself into the ground. Dik RE: SF tower settlement dik (Structural) 16 Aug 17 15:38 From the news, "Millennium Tower, the tony but troubled downtown high-rise that made international headlines last year when the secret got out that it’s slowly sinking and tilting, returned to its customary place in the news late Tuesday when NBC Bay Area revealed that the building “has tilted two and half more inches in just the first half of this year, according to new monitoring data.” Says the affiliate: The data, compiled by the ARUP engineering firm brought in by officials of the nextdoor Transbay transit terminal project, suggest the structure is tilting twice as fast as it had been in earlier ARUP data. It is now listing at least 14 inches toward the massive Salesforce building going up nearby on Mission Street. The data also show the building has sunk close to 17 inches at its low point, settling about an inch since the problem emerged last year. Supervisor Aaron Peskin, who has conducted a series of City Hall inquisitions trying to figure out who dropped the ball on the building’s design, took to Twitter to voice his exasperation. “Accelerated sinking continues,” tweeted Peskin, then sarcastically referenced Mayor Ed Lee’s efforts last year to reassure U.S. Senator and former Mayor of San Francisco Dianne Feinstein that the city could manage the building’s woes. In comments to NBC Peskin compared his hearings (which he vowed to continue) as “yelling into the wind.”" Link: https://sf.curbed.com/2017/7/19/15998338/millenniu... RE: SF tower settlement itsmoked (Electrical) 16 Aug 17 19:06 Clearly the Salesforce building should be modified to take the load then a 'skyway' needs to be built between them. Keith Cress kcress - http://www.flaminsystems.com RE: SF tower settlement JStephen (Mechanical) 16 Aug 17 20:28 They should have just built it with the flammable cladding. It'd be that much lighter, then when it burned, nobody would care if it was sinking or not- in fact, the more the better in that case. RE: SF tower settlement epoxybot (Structural) 25 Aug 17 01:44 Here is a link to a cross section of the soil conditions commissioned by Transbay Joint Powers Authority TJPA for the neighboring Transbay Center. Link TJPA are a greater bay area, regional authority, so you can imagine the other parties would love for the Transbay Center to be partly/mostly to blame for the Towers settlement & tilt. Considering the circulation of water in & out of SF Bay, the ground section should largely be indicative of what lies beneath the Millennium Tower project. The Tower takes up the block between Fremont St. & Beale St. Horizontally flip the building section below, to overlay the soil cross section in the above link to get an idea what is going on. The parking garage basement of the Mid-Rise Tower was a 75 foot deep excavation. The garage foundation looks to be sitting on a lens of clay while the Tower foundation is on sand. The High Rise sits on 950 - 60 to 80 foot piles with a 10ft thick pile cap with a 35ft to 50ft deep excavation. Unknown is if the length of the piles is quoted as from original ground, top of the pile cap or from excavation grade. Here is a link to a paper on the structural design of the tower. It doesn't mention the extensive use of GFRP. Link You can see the GFRP in the connection of the Steel Link Beam; here Link & again here Link This link from CRSI gives some good details about the overall project. Link The first photo on the page gives a good idea of the concentration of piles under the tower. The 4th photo in the series is the podium/mid-rise basement/parking garage. The basement/parking garage photo is from around Summer 2007 and by this stage the very heavy Tower was topping out. The basement used an integral waterproofing admixture, so there isn't anything to stop water once the cracks grow too large. Here's my best 'eye-ball gestimate' of where the 10ft thick pile cap is in relation to the garage excavation. Since the building is leaning away from the garage, you have to wonder if this is when the tilting started. The tower foundation is supposed to be designed for 14kpsf. Wouldn't this be a vulnerable time for the tower to take on a slip circle tilt? If 7ft diameter concrete piles 200ft deep & anchored in bedrock on the South side of the property aren't preventing a Northern tilt, then how is a 75ft deep concrete box on the East side of the property, possibly built on top of a clay lens, suppose to prevent the building from tipping to the West? The Tower was completed in 2009 and the Transbay Authority, TJPA began excavating next to the Tower in 2011. Before doing so & exclusive to the Millennium Tower/TJPA property line, TJPA took the preventative measure of drilling 181 7-foot diameter overlapping concrete piles all the way to bedrock at a cost of $58 million. Link The Transbay Center excavation is 65ft deep and runs 4 blocks, including along the South side of the Millennium property, with both the Transbay excavation & Millennium Tower project ending at Beale St. Link According to Millennium Tower's attorney (HOA?), the Transbay site has dewatered 5 million gallons/month for most of its duration & the water table has dropped 20 feet. As the TJPA states, their hole in the ground is the size of 120 3 meter deep Olympic sized swimming pools. Then again thier dewatering is enough to fill over 79 of those pools to date. Still, the HOA at Millennium Tower should be worried when the TJPA finally stops dewatering because those cracks in their basement garage are going to be fountains when the water table is recharged. If the dewatering is affecting the clay maybe the Tower will rise back up when TJPA stops dewatering? The tower had sunk 12 of its 16 inches before the Transbay Center excavated next to the building. Refutation from the TJPA: Link As TJPA sees it, the Tower is just too heavy & sinking into the mud. They are probably right. The Old Bay Mud may be behaving like a pseudo-plastic and yielding gradually, while the garage sits on a (fulcrum) lens of another clay deposit and the pile cap of the tower is squishing the water out of a sand pile. Maybe I don't understand well enough the nomenclature of Geotechnical Engineering but when I started looking for information on the possibility that disturbed hence less consolidated clay might not produce an elastic response but instead display a prolonged visco-elastic or thixotropic phase; there was very little research. Just bits here and there that the phenomenon does exist in some clay and was noted after the Kobe Quake. That might suggest that resistance piles driven through sand in to dense clay might not be as resistant as planned and that after an earthquake when the clay has experienced liquefaction could, under sufficient load, remain unstable. There is a fair amount of information about clay behavior and high initial shear resistance with some elastic recovery as high as 99% but not all clay has this recovery shear strength. Include the high initial shear resistance with a dramatic loss of shear strength and lesser resistance on recovery & the recovery stage starts looking more and more like thixotropic/visco-elastic behavior and that means deformation under load/creep. Considering that the City of San Francisco has prior experience with the soils in the area, BART & Muni tunnels & underground stations AND both the City & the Developer knew in advance that the Transbay Center was going to be built, why the developer & why the City didn't determine to build a tower that could stand all on its own is hard to fathom. Seems TJPA was the only party think holistically and to act with anticipation or practice any preventative measures. If I was TJPA, I'd tell the HOA, the Developers & the City of San Francisco that when they have all each spent $58 million, then the TJPA will be willing to discuss what part TJPA will thereafter play. Link RE: SF tower settlement JedClampett (Structural) 14 Sep 17 02:03 I have a feeling that these people will end up all right, but still. Multimillion-dollar condos in tilting skyscraper called nearly worthless RE: SF tower settlement dik (Structural) 14 Sep 17 02:52 Thanks epoxybot...great post. "The first photo on the page gives a good idea of the concentration of piles under the tower. The 4th photo"... they don't mention the type of teaspoon used to place the concrete in photos 3 and 6... I'm not a highrise expert, only done 30 storeys, but, looking at the soil profile... I wouldn't like to construct anything tall or heavy in that stuff... there may have been a really good reason that everyone else went to bedrock. Also, only done a little seismic stuff and I have no idea of how a building, founded in that 'stuff' would behave during a seismic event... There are more clever people out there than I would have imagined. Looks like they terminated the piling before they hit the 'Old Bay Clay'... Dik RE: SF tower settlement dik (Structural) 14 Sep 17 03:26 As condo owners, are they responsible for maintenance costs? (part of condo fees?) as registered owners... even if they walk away... Dik RE: SF tower settlement epoxybot (Structural) 15 Sep 17 01:57 dik One of the arguments that Millennium Partners has issued regarding their liability is that the residents of Millennium Tower, in effect OWN the tower & the tower's problems. RE: SF tower settlement JedClampett (Structural) 15 Sep 17 03:06 I've said it before, and maybe even on this thread. Condominium projects are litigation magnets. And this one is the perfect storm. Condominium. CheckExtremely wealthy owners. CheckA good portion of them are probably lawyers. CheckOwners heavily inve$ted in the project. Double Check And real damages. Check. This one will be in the news and courts for many years. There will be quadruple digit replies to this thread before it goes away. RE: SF tower settlement dik (Structural) 15 Sep 17 07:03 Jed... you'd think with all the lawyers that they would be able to 'plot a course' to wind this up... surprised the SEAOC wasn't a little more proactive. I guess no one wants to say anything for fear of it coming back to bite them... Read the ARUP report and thought it was very technical and very well done. A real concern is how this building might lay down in a serious seismic event... and, maybe FEMA will pick up the insurance tab... Dik RE: SF tower settlement HamburgerHelper (Electrical) 15 Sep 17 15:04 Would it be cheaper for everyone to put in re-leveled floors than fix the building? My old house had issues with a door not closing correctly because the ground was shifting. A contractor wanted to fix the foundation, I just adjusted the door hinge. RE: SF tower settlement 3DDave (Aerospace) 15 Sep 17 17:03 The expectation is that re-leveling will soon be 90 degrees after the building lays down. Not only is the tilt increasing, the tilt rate is increasing. This is not a situation that ends well. Has anyone make a graph of the two factors or has the data been too poorly collected to make a useful prediction? RE: SF tower settlement MacGyverS2000 (Electrical) 15 Sep 17 17:08 I wonder at what point 90 degrees looks imminent and they begin to de-construct the tower to prevent it... Dan - Owner http://www.Hi-TecDesigns.com RE: SF tower settlement itsmoked (Electrical) 15 Sep 17 20:43 When do you start bailing your corporation out of the neighboring buildings? Keith Cress kcress - http://www.flaminsystems.com RE: SF tower settlement dik (Structural) 16 Sep 17 05:19 ... or at least those in the direction of tilt <G>. Is there a site that has a running record of the settlement and tilt and rates of these? You'd think someone would be monitoring this. Dik RE: SF tower settlement Ingenuity (Structural) 16 Sep 17 07:44 Quote (3DDave)Has anyone make a graph of the two factors or has the data been too poorly collected to make a useful prediction? Here is a settlement timeline over a period of near 10 years from this source: Link For combined tilt-settlment data I think ARUP have data dating back to 2009. RE: SF tower settlement epoxybot (Structural) 16 Sep 17 21:46 According to one observation by a geotechnical engineer, sorry I didn't save the link, one problem is that the Transbay Authority, TJPA did too good of a job with their secant pile wall. The wall does too good of a job of resisting earth movement and without similar resistant walls on the North & West sides of the Tower, North & West is where the ground is shifting. The Transbay Authority didn't just build a wall, they heavily buttressed the wall. This is why Millennium Partners & Millennium residents focus on dewatering, because the wall works. Millennium residents also accuse the Transbay Authority of attempting to hide the shifting but it may be that the TJPA was unaware of the preexisting condition of the Tower's accelerated settlement when they entered into an easement contract with Millennium Partners and were alarmed at what they were seeing from early monitoring results. My guess is TJPA approached Millennium Partners and Millennium Partners wanted to keep the situation private. RE: SF tower settlement 3DDave (Aerospace) 17 Sep 17 03:32 Perhaps the original plan was the tower would be on bedrock by slowly lowering itself thorough the muck, but the asymmetry introduced by the new construction has upset that plan. What is very surprising is the effect the execution of the easement agreement had on the settling rate. RE: SF tower settlement dik (Structural) 17 Sep 17 05:04 Dave... nearly spilled my coffee... Dik RE: SF tower settlement lilliput1 (Mechanical) 20 Sep 17 08:39 Another concern is that earthquake can cause liquefaction of the soil which would be catastrophic because the piles do not go all the way to bedrock. RE: SF tower settlement epoxybot (Structural) 28 Sep 17 19:32 Correction: In my post on 25 Aug 17 01:44, I alluded to GFRP rebar in photos for the Millennium Tower reinforcement but after more searching it now seems that Baugrid is produced using smooth steel bar. The smoothness of the bar & the color of the surface corrosion on the bars led me to believe I was seeing GFRP. Attached is a copy of the July 2017, City of San Francisco Safety Review of the Millennium Tower Link The report is the City of San Francisco's interpretation of the 2016 Structural Review with requested follow up analysis performed by Simpson Gumpertz & Heger on behalf of Millennium Partners and is seen by some as a walk back from SGH's 2014 review that concluded 8 of the Outrigger Columns (upper floors) would be over stressed during an earthquake. The 2014 report was seen by some engineers as a sign the building could be "Red Tagged" after a major quake. Link In the City's July 2017 review the focus is on the Outrigger Coupling Beams. The City of San Francisco vis-a-vis the SF Dept. of Building Inspection, SFDBI has two strikes against it in this affair. Firstly, the City had previously halted work on a project of almost identical design, 50+ story, concrete building with friction piles (geo-tech by Treadwell & Rollo) at 80 Natoma, citing 'new information' that it was too heavy and sink too much. 80 Natoma was a property directly over the favored path of the CalTrain underground extension to the planned Transbay Center transportation hub. If the tower was built it would be impossible to come back later and tunnel under such a heavy building resting on friction piles. The developer refused to sink piles to bedrock citing delays would compromise project funding. The site was eventually purchased via Eminent Domain for between $58 & $90 million. More than a little speculation circulated that the whole project was always a shakedown. Secondly, the City's failure to look into the accelerated sinking of Millennium Tower, AFTER they had initiated inquiry & subsequently approved the structure for occupation (sale of condos). The City of San Francisco & Millennium Partners have a common interest in dissociating themselves from blame. Both Millenium Partners & SFDBI claim there was no requirement for the developer or the Peer Review panel to consider the Transbay Project next door. Link That seems to be in conflict with the Mission Street Development LLC (Millennium Partners) 301 Mission Street - Environmental Impact Report that cited the adjacent proposed Transbay Center project Link and SFDBI's actions at 80 Natoma. RE: SF tower settlement dik (Structural) 28 Sep 17 23:18 All is well... at this time. From the report, "To an extent consistent with the scope of our review, our professional opinion is that the foundation settlement experienced by the Tower has not appreciatively affected the safety of the building at this time." Sounds great, and at an inch per year, who knows... settled 18" so far. Dik RE: SF tower settlement stevenal (Electrical) 28 Sep 17 23:43 Quote (report)Further, the review is limited to evaluation of the current condition of the Tower and does not address the effects of future settlement or other changes that may occur to the Tower in the future. All was well July 28th; July 29th is out of scope. Does the report contain any useful information? RE: SF tower settlement dik (Structural) 29 Sep 17 01:03 stevenal... nothing of substance... nothing to give you a warm fuzzy feeling... Dik RE: SF tower settlement JedClampett (Structural) 29 Sep 17 02:39 That ought to increase the value of those condos. RE: SF tower settlement epoxybot (Structural) 2 Oct 17 00:21 Description of the shoring work for the Millennium Tower & adjacent 5 level parking structure basement. Webcor Builders: The garage is an internally braced soil cement slurry wall system with soldier piles 5’ OC and the High Rise foundation is a soil cement slurry wall system with soldier piles 5’ OC with a few rakers and the balance of the hole supported with a single row of tiebacks. Both of these perimeter wall systems are augured 3’ diameter overlapping holes creating a continuous wall. Early into the pile driving - Photo (A): Link Looks like pile driving started in the Northwest corner of the lot: Photo (B): Link Pile driving complete Photo (C): Link ARUP's illustration of the relationship of the Transbay Center excavation & Millennium Tower Photo (D): Link Photo of full excavation next to Millennium Tower - Link In photo (B) note the high concentration of soldier piles on the left side of the photo. In photo (C) the soldier pile are capped with a steel beam & rakers tie to a stepped perimeter wall. What is different about this section of the shoring? In this Old Tranbay Terminal demolition phase photo you can see that ground water is somewhere around 7 to 12 feet below grade. Millennium Tower is to the right in the photo. The area was used for staging for most of the Transbay Center project. Soil stabilizing fabric was laid & a waste slab poured. RE: SF tower settlement Ingenuity (Structural) 9 Oct 17 04:27 On Tuesday, October 3rd, 2017, UC Berkeley professor, Abolhassan ASTANEH-ASL, gave an Ethics Seminar: "Did the Unethical Conduct of Engineers and Academics Contribute to the Tilting and Sinking of the Millennium Tower?" The seminar was a live webcast, however it was recorded and is available for public viewing here: https://drive.google.com/file/d/0B6Cv_TTKSlYiMWdZS... I have yet to view the presentation. RE: SF tower settlement dik (Structural) 9 Oct 17 06:19 Really good article... I don't envy the position Abolhassan has taken... but, I think he's correct. At Harvard, he'd have been turfed. Dik RE: SF tower settlement hokie66 (Structural) (OP) 10 Oct 17 00:12 Maybe there is some validity in some of his opinions, but he is a blowhard. Although he promised to limit his discussion of the WTC, he spent more than half the time talking about it. Then his only conclusion about the Millennium Tower was that the piles are too short. We all know that already. Ethics? He stated he doesn't know about geotechnical issues, but then proceeds to comment on the piling. Maybe it is just his accent, but some of his terminology is not that of a structural engineer. He speaks about conflict of interest. I think at this point, anybody from UC Berkeley is conflicted. RE: SF tower settlement dik (Structural) 10 Oct 17 00:59 Blowhard or diehard or whatever, he raises some very good points for both the WTC and Millenium... call him Don Quixote... He likely feels 'slighted' and the presentation was his vindication. I've never seen a 'flat plate' with an 11" slab... contributes to the mass and rate of settlement... With the WTC, there was an excellent thread on Eng-tips that disappeared... don't know if the webmeister was asked to remove it and 'turn it over' or what... it was just gone. A lot of what was discussed on the presentation was there... I didn't realise that a permit was not required and that stuff was 'approved on the fly' by those with a vested interest. I'm not a geotekkie, and unlike Moehle, I would not have signed off on the foundations... The foundations would have been my first concern. My first posting on this thread ended with, "I don't know if the sand is saturated, but, there could also be problems during a seismic event..." and, is still a concern, and very likely the mode of failure, and, maybe after the first floor is at grade. I'm surprised that the SEAOC has not done a study... if a potential life safety issue, then they are 'obligated' to look into it... Dik RE: SF tower settlement hokie66 (Structural) (OP) 10 Oct 17 01:14 11", and thicker, flat plates are common in my environment. That's what our builders and developers want. Simple, it is. He called it a flat slab, one example of my reference to terminology. He said more than once that there was "no structure" in the WTC, and no columns. Rubbish. And I would take the "no permit" thing with a grain of salt. Anyone with that many pictures of "my projects", bridges and buildings, is a horn blower. RE: SF tower settlement dik (Structural) 10 Oct 17 02:54 A flat slab in these environs is one with drop panels or slab bands or a mix... As to codes... I don't know, except, that I have never heard a prior reference to design requirements, and never considered that there were no permits if that's the case. Whatever the issues, there are/were serious oversights made with both structures... not common, in these environs, to design for 747 767 loading... I thought and still do that using trusses from a core to an outside 'tube' structure was a neat way to do tall buildings... Light weight and using the outside 'skin', about as stiff as you could make it. Dik RE: SF tower settlement hokie66 (Structural) (OP) 10 Oct 17 03:40 Yes, that is my definition as well. I think the floors of Millennium are flat plates, but he called them flat slabs. I saw a report this morning about the Mexico City earthquake, where some California engineer reckons that flat slabs should be outlawed in seismic areas. I would agree, if there are not cores or shear walls, but the statement was misleading. Disagree about the trusses, if you mean bar joists. They didn't adequately connect the exterior tube to the core, and that is a big reason for the collapse. RE: SF tower settlement dik (Structural) 10 Oct 17 05:14 They can be adequately connected... bar joists may be the correct term (more likely) depending on how they are fabbed... My only reservation about bar joists is that they have a large surface area for fire resistance protection... on impact (like a plane), the fire proofing can be 'knocked off' leaving little or no protection. Prior to the 'attack' I thought the approach was real 'neat'. I still think it can be workable... my tallest building is less than 1/4 the number of storeys of the WTC... and, not what I would call a tall building... Dik RE: SF tower settlement Toby43 (Structural) 10 Oct 17 08:03 Hell hath no fury like a woman professor scorned RE: SF tower settlement dik (Structural) 10 Oct 17 18:43 Hokie66: "where some California engineer reckons that flat slabs should be outlawed in seismic areas. I would agree" Can you elaborate? I would think that the reduction in mass would be beneficial. Diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiik RE: SF tower settlement hokie66 (Structural) (OP) 10 Oct 17 18:59 I think the issue is the use of flat plates supported only by columns, with no other lateral system. But just to say flat slabs should be outlawed is ridiculoua. The old flat slab has a place in our tool kit. RE: SF tower settlement jgKRI (Mechanical) 10 Oct 17 19:13 This is diverging the discussion a bit.. but this dude's assertion is that WTC building failures were due to unethical or, at best, ethically ambiguous behavior by its engineers? Really? RE: SF tower settlement dik (Structural) 10 Oct 17 21:09 jgKRI: The part I got from his presentation was that there were some questionable decisions made with any peer review... and, if his information is correct, then I concur with some of his criticisms. Dik RE: SF tower settlement epoxybot (Structural) 11 Oct 17 01:37 Sorry I got carried away..., Professors, particularly at upper crust universities blow the horn loudly because it is a pretty cut throat environment despite their use of reserved social graces. If you are not publishing, consulting, designing or patenting, then you had better be stealing the ideas of you grad students or you are not going to stick around long. Unless of course you have a visiting professor gig and then you can go on sabbatical out of the country, while the students pay tuition for your salary & the house the University paid for, which sits vacant for a year - (This really happens). Seems professor, Abolhassan ASTANEH was hired for about a week by some of the condo owners, before he made this presentation. It really doesn't matter if the professor can generate ground motion modeling to prove that the building is not as safe as De Simone designed and SG&H have asserted. It is safe according to the design criteria supplied by the 1997 UBC and made law at State, County & City levels and was in effect when the permit was issued. Prof. Jack Moehle is not the Engineer of Record so his PEER review is just that, a review, not a absolute declaration. Still he is talking out of both sides of his mouth. The STRUCTURAL ENGINEERS ASSOCIATION OF NORTHERN CALIFORNIA 2015 SEAONC "Guidelines for the Use of Geotechnical Reports" Link , both supports his initially stated position regarding his qualification, "that he looked no further than the tower foundation" & it doesn't. I think he is one of many, who were very excited at building a tall "poured-in-place concrete" building in SF Downtown. You gotta have something to blow the horn about at UC Berkeley. While SFDBI / SEAONC /PEER were working on the Tall Building Initiative & SFDBI AB-032 before the Millennium Tower, they look to have redoubled their efforts since and were possibly racing to close the door after the horse had already left the barn, as in, before the sinking became public. I feel for the condo owners, they may have hired good litigation attorneys but they are lost when it comes to making relevant arguments concerning the defects of the tower and their attorneys don't seem to know what is a good plan of attack either. The design requirement for a maximum considered earthquake is that the building not fall down and people are able to safely exit the building. It could subsequently be red-tagged but as long as it protected life & limb, then mission accomplished. So coming up with ground motion simulations that are not embodied in the UBC are irrelevant. It is not the Structural or Seismic or Wind design of the BUILDING, that needs scrutiny, it is not the building at all. It is the shoring & bracing, the group depth of the pilings, the effect of the pressure bulb from the pile group on the soil beneath & around the piles, the method the piles were driven & order of placement, if the sides of the foundation were included in the resistance calculations, the soil characterization used in the geotechnical reports, the geotechnical calculations and which UBC piling loading criteria was chosen, the excavation & dewatering of the parking structure/basement, the sequence of building a heavy tower and then starting to dig a very deep excavation immediately adjacent to the tower when the foundation was already exhibiting rapid settlement even before they began the excavating. Maybe they should have started with the parking structure basement & later the tower. Too much deflection of the West podium basement shoring wall would have been bad for friction/resistance bearing piles, the same for too much dewatering. These are all the vulnerabilities that relate to the sinking & tilting. These 2 photos, taken on the same day 8/19/2007, give an idea as to the dichotomy of the tower and adjacent basement structure's progress. By this time the tower had settled 3 inches. I think there were 23 floors on the tower when the podium basement excavation began. Treadwell & Rollo only gave a 50/50 endorsement of their own settlement predictions. With a confidence level like that, how is any foundation consider NOT a performance design, regardless of UBC design criteria? You really have to wonder if SFDBI is out of it's depth and just looking for a CYA engineer's stamp when it comes to shoring, piling & foundations. They don't seem to have in place the same internal structure for foundation review that large cities on the East Coast have in place. Clearly prudence was exercised concerning the effect of weight of the building and ground pressure on the adjacent basement shoring by the General Contractor, Webcor Builders. Before they began excavation of the parking structure basement they bolted heavy steel strongbacks to the footing of Millennium Tower & then welded them to the solider pile/CDSM shoring to support the upper reach of the Westward diaphragm wall. It does appear that they used used tie-backs lower down on the shoring wall. Blue Dots in photo: Link The piling contractor augured each pile 40 feet from a working elevation of about 10 to 15 feet below grade, so there wasn't a lot of upper pile confinement generated from the pile driving. Since it appears that pile driving started on the North side of the foundation, this would be where the piles with the least confinement & lesser capacity would be located. It just seems that with less skin friction due to auguring that the potential for shorter piles to heave is greater once remaining and/or deeper piles are driven & reach the deeper soil that was undisturbed by the augur. The piles range from 61 feet to 90 feet according to SFDBI Raymond Lui. So perhaps only around 20 to 50 feet of that is below the mat foundation. If you look at the cross section illustration De Simone used for a SEAONC presentation of the project, the scale of the piles beneath the tower is more on the order of 150 feet deep, when they should be just a bit deeper than the podium basement foundation. The 2003 Final Environmental Impact Report, Page 247 Link included an acknowledgment that dewatering was a concern on this project for which the the City of SF was empowered to enforce a requirement for ground settlement monitoring, special inspections & even a halt to the work if settlement was beyond anticipated values. So when the SFDBI testified that they had no way to compel the developer to include a geotechnical engineer to be part of the PEER review, they are not being completely honest. The dewatering/ground settlement monitoring - special inspections could have compelled the developer. It seems SFDBI passed on this Special Inspection, otherwise they would have (?should have?) known a month after the tower foundation was poured that the structure was on the move and long before the podium basement excavation commenced. To later sign off on an occupancy permit, having failed to implement a monitoring scheme or failing to "INSPECT" the special inspectors reporting is just seems like double negligence. Perhaps too much myopia from staring at plans all day? SFDBI is also not being truthful when they say they had no cause to consider the Transbay Center project during plan review. It was acknowledged in the 301 Mission Street EIR, page 159 Link and the final design was a hybrid of Alternative E-1 of the EIR, which itself was the result of conversations the developer's design team had had with the TJPA about the Transbays Center, over an anticipated 5 foot encroachment on to the southern Millennium project property line. Why even have an EIR if the Building Dept. Plan Review section isn't going to use it to carry forth the City's expectations? The global lack of recollection by the SFDBI is also questionable. There is a close knit Major Projects Permits/Plan Review unit to handle tall buildings. According to SFDBI Quarterly & Annual Reports there were then only 3 to 4 tall building under construction & about 7 in various stages of plan review. Finally, SFDBI has an internal peer panel "Permit Coordination Division", to assess the department's own compliance of permits. SFDBI 2004-2005 Annual Report, page 39 Link At the time of the 2003 Final EIR the tower was likely a steel frame structure and the building elevation cross-section showed 3 floors of parking under the tower & 3 under the podium. Page 157 Link So the tower foundation & the podium foundation were both of equal depth but neither as deep as the 5 floors of parking now under the podium. So this much deeper excavation should have spurred the SFDBI to be more attentive to dewatering & the tower foundation. Steel tripled in price over a years time and then too SF was desperate to keep major developments within the Transbay redevelopment area on track. They needed kick-starter projects to generate developer interest for the later sale of Transbay properties to fund the Transbay Center. Include that during testimony on 80 Natoma the SFDBI somewhat bemoaned the lengthy PEER review process of performance designed buildings before the SF Building Inspection Commission and the stage was set for another 80 Natoma-like concrete high-rise but of a prescriptive design, that would sail through the Plan Review dept with a degree of deference. You even have to consider that some bias may have occurred, at the excitement & prowess over the daring feat of building a tall "concrete" tower in earthquake country. The real failure is that, search as I might, I can't find that SFDBI has even one geotechnical engineer on SFDBI permanent staff. Seems they are only hired on PEER review panels or short term contracts. It also seems like any time pointed questions about SFDBI & geotechnial reviews are asked, they habitually give indirect answers that never touch upon the gist of the question. The SFDBI responses in the minutes of this August 30, 2004 Building Inspection Commission meeting regarding 80 Natoma are practically boilerplate in resemblance to their ambiguity over 301 Mission Street. Link All the while the Millennium Project is under permit review. SFDBI 2004-2005 Annual Report, Page 35 Link This is where Jack Moehle really is not helping. When he told SF Supervisor Peskin that he was asked to right a project close out letter for 80 Natoma and that he was instructed to leave out the nature of the SFDBI Stop Work Order investigation over 80 Natoma regarding geotechnical reports that claimed the project would sink, certain things fell into place. Treadwell & Rollo had gotten in the last word, where they challenged the data used for opposing their own geotechnical report & the design. With no resolution to the reason for the Stop Work Order & a letter from the developer's design team reporting the property under purchase & the 800 Natoma project abandoned, there wasn't any precedent for the SFDBI to apply prior work as a measure of discrimination. While Jack Moehle may not recall off the top of his head, what discussions took place regarding the desired composition of the letter or who participated in the selective content, I'd be surprised if he doesn't have it all in one of many black & white marbled composition books filling a number of drawers of one of his filing cabinets. This is where the real ethics questions begin and they all point to the City of San Francisco, the Developer, the design team & the PEER Review panel, TJPA is way off in the distance. Although it would be interesting to see ARUP's projected dewatering gradient map for the surrounding area. The attorney for the larger body of condo owners going after TJPA loves to scream bloody murder about TJPA dewatering but the siltation tanks he harps about on the TJPA site south of the Millennium property were for the entire TJPA dig. There is an 8 inch diameter "common" pipe running atop the TJPA shoring the entire length of the project feeding those tanks. They don't represent the West excavation dewatering by TJPA at all. It was the last dig and the tanks were removed/moved. So far SF Supervisor Peskin has wasted a year on Structural Safety when the building code already gives assurances that in it's current state the tower is still well within design & safe. When SG&H reports on the structural integrity of the pilings & foundation, they are speaking of the seismic safety performance. The report has nothing to do with dispelling the fact that in the tower's "semi-static" state of rest on the ground, it is sinking & tilting. That is beyond the scope of their report. It is time for the Structural guys to step aside & have the Geotech guys do their song & dance. Seems like it is the developer, Millennium Partners that wants to keep everyone focused on the building instead of what is under it. Same as during the permitting. Typical realtor behavior, "don't look at the crack over the doorway, look at these new countertops & tile". Millennium Partners seems to keep pushing the "Building is Safe" message to perhaps escape the grasp of the California Real Estate Disclosure Law, which the condo owners need to push, as akin to the "Calif Automobile Lemon Law" (Song-Beverly Consumer Warranty Act). The fact is that Millennium Partners was selling something "as New" that was in fact highly likely to need remedial work performed to such an extent that the building is a Lemon. The question is whether SFDBI's issuance of an occupancy permit endorses the "as New" representation & nullifies the real estate disclosure law. The only thing that is certain is that SFDBI is too busy demonstrating the complexity of their bureaucratic cognitive dissonance to know one way or the other. RE: SF tower settlement dik (Structural) 11 Oct 17 04:30 You didn't get carried away... to paraphrase your effort, "It's a mess and no one is moving forward at fixing it." I guess it's a problem with self-regulating agencies, that unless someone files a complaint, they have no reason to undertake an investigation of their own. Thanks for the excellent 'write up'. Dik RE: SF tower settlement hokie66 (Structural) (OP) 11 Oct 17 04:34 Great post, epoxybot. If only some of those professors at UC Berkeley had the same ability to sort through the chaff and get to the real issues. I suppose the City has its hands full protecting criminal immigrants, and doesn't have time for mundane issues like buildings tilting. RE: SF tower settlement HamburgerHelper (Electrical) 11 Oct 17 18:48 If these people still live here,in San Francisco, the tenets on this highrise should be able to manage. RE: SF tower settlement epoxybot (Structural) 11 Oct 17 20:10 San Franciscans have reason not to have a lot of confidence in their building officials. The owner of this property & the manager of the company doing the work was a former President of the SF Building Inspection Commission & the EOR was also a former BIC President. MAYOR NEWSOM AND SUPERVISOR PESKIN ANNOUNCE APPOINTMENTS TO DEPARTMENT OF BUILDING INSPECTION COMMISSION Link S.F. home in Twin Peaks collapses during disputed expansion http://www.sfgate.com/bayarea/article/S-F-home-in-... Link Investigation and Mitigation Report on Incident Occurring at 125 CROWN TERRACE http://sfdbi.org/sites/default/files/125%20Crown%2... RE: SF tower settlement epoxybot (Structural) 20 Oct 17 03:04 So here Link is a Press Release from the Office of the City Administrator for San Francisco. The press release lists the members of Mayor Lee's "301 Mission Seismic Safety Study Committee", to some extent the committee was formed at the suggestion of Sen. Dianne Feinstein. The 301 Mission Seismic Safety Study Committee is the group that selected the "Expert Panel" to review the 301 Mission Seismic Safety Structural Evaluation performed by Ron Hamburger of Simpson Gumpertz & Heger. Working at the behest of Mayor Ed Lee are, City Administrator Naomi Kelly, an attorney - Department of Building Inspection, Director Tom Hui - Executive Director of the Department of Emergency Management, Anne Kronenberg, and San Francisco Public Utilities Commission Assistant General Manager of Infrastructure, Kathy How. The reason the Executive Director of the San Francisco Public Utilities Commission isn't on the Committee is probably because he is the husband of City Administrator Naomi Kelly. The "Expert Panel" is in many respects a Mulligan, a do-over, if you will for a full 3 member PEER review of the structural integrity of 301 Mission St. One would expect that, the City of San Francisco being under the microscope would steer well clear of even a hint of Conflict of Interest. More especially, those who formed the Expert Panel but you will have to decide for yourself. What caught my eye after having looked at many documents was panelist: Craig Shields, President at Rockridge Geotechnical. Craig Shields, opened shop in 2006 after leaving TREADWELL & ROLLO where he had worked since 1989, virtually from T&R's inception. Before that he worked with Frank Rollo Sr. at Harding Lawson Associates. Link You really have to wonder what Mayor Ed Lee was thinking. RE: SF tower settlement dik (Structural) 20 Oct 17 04:51 epoxybot... is prostitution legal in California? Just curious... I read through the letter, it was crafted a couple of months back... and it doesn't appear that there is an independent geotechnical consultant in the cluster (or whatever you call a bunch of ladies of the night... a flock, perhaps <G>)... My biggest concern with the project is how it would behave during a significant seismic event based on the founding soils. I guess, time will tell... California is due for a good one... Just read the last link... there was a geotekkie, but not an independent one... and part of the party... Dik RE: SF tower settlement epoxybot (Structural) 23 Oct 17 20:55 I have no idea if it matters or not but the SF Millennium Tower not only sits on top of the old historical Yerba Buena Cove shoreline but it is perched on the edge of stream bed. This Link early illustration of Yerba Buena Cove suggests there was a creek flowing into the southerly end of the cove and this bedrock elevation map Link from the "Final report, geotechnical site investigation : CalTrain S.F. downtown station relocation EIS/EIR project" Link would seem to confirm that the stream/creek flowed along the northern property line. It's possible the lower part of Mission Street was the creek bed and was used as a trash ditch by early settlers. Here is a larger version of the idealized ground profile from an earlier post & the plot for the bore holes. Link Link Does the geotextile seen in the photo I posted on Oct 2nd represent the tumbled shoreline of Yerba Buena Cove? 1840's San Francisco was a lumpy place of sand dunes. If you are interested here is a video (1+ hrs) Link about how the dunes were moved about and how it affects buildings in SF. Creeks would travel under the sand occasionally breaking the surface. If the early illustration is to be given any credence, the creek was capable of sufficient water volume to transport heavier sediment/sand far enough to create a sand bar at its mouth. Arguably, the creek is still there. This 1853 map Link seems to indicate that the location just opposite of the present day Millennium Tower was in a state of being filled in but in 1857 the site of the Millennium Tower was impounded. Link It seems San Francisco's early land speculators sometimes had problems filling in the marshes and parts of the bay. They would haul sand & build it up to elevation, send for the city's building official, only to come back the next day and see that all their work had subsided below the waterline. Today, just across the other side of the Transbay Center is the 181 Fremont St. Tower. The geotechnical & foundation design are the work of ARUP and their reasoning for the foundation design recommendation is worth contemplating. Link The TJPA installed CDSM shoring that penetrated the Old Bay Clay by 10 to 20 feet. It was supposed to prevent a dramatic drop in the water table outside the excavation. When BART was built, they did things differently, recharging the ground outside their excavation to maintain the water table. Finally, here is a link to all the SF Government Audit and Oversight Committee - Building Standards in Seismic Safety Zones hearings PLUS the records. Including the Oct. 18th testimony of De Simones Structural Engineer of Record, Derrick Roorda. Roorda came across as a decent guy but he was a bit gratuitous to Treadwell & Rollo on the rate of the buildings sinking. The actual SG&H 2017 report, and Treadwell Rollo's original geotechnical report, idealized ground profile & pile driving plot. Link Item 16. Comm Pkt 101817 - LARGE FILE is the sum of all the preceding item numbers and the contents list at the beginning of the pdf is conveniently hot-linked for browsing. De Simone provides a more detailed view of the settling rates but they also play politics ascribing the "commencement" of TJPA construction activity as playing a role when the only work being done was demoltion, site work, CDSM shore wall placement & the buttress wall. It would be a year later that actual excavation took place. Much like all the players who ignore the original settlement forecast and refer to the latter as though the original is a of no consequence. Coincidentally, Treadwell & Rollo were the on sight Environmental Soils firm working for TJPA while the shoring & buttress wall were being built. During the SF Government Audit and Oversight Committee - Building Standards in Seismic Safety Zones hearings, Supervisor Aaron Peskin has asked almost every group of witnesses about some mythical letter from InSituTech. No one has indicated that they have any recollection of the letter. Unfortunately, it doesn't seem to be part of the records, to date. InSituTech was a small geotechnical consultancy in Orinda, CA, about 40 minutes from SF & run by D Michael Holloway, PhD. He went to work for Dan Brown Associates as a field consultant for the TJPA buttress wall. He has an interesting resume, you can view it on his LinkedIn profile. He has spent most of his career as a piling consultant in the field. Link It would be great to know what he may have observed & what he wrote to the DBI. Supervisor Peskin plans to hear testimony from former Treadwell & Rollo people. He mentioned Frank Rollo but it is Christopher A. Ridley of the present Rollo & Ridley who was the Millennium Tower Geotechnical Project Manager. Link I'd rather hear from D Michael Holloway. Records show the building weighs 220,000 kips, sadly Peskin did not ask what was included in that figure. After looking at the piling plot, the pile driving did start in the Northwest corner of the lot and between the plot & a photo from an earlier post, the piles concentrated around the core appear to be less than 3 pile dia. apart. Link RE: SF tower settlement JStephen (Mechanical) 24 Oct 17 00:32 "The geotechnical & foundation design are the work of ARUP and their reasoning for the foundation design recommendation is worth contemplating. Link" In that link, I find a statement that: "an equivalent top down load of 14,000 kips was applied by Loadtest." Now, that makes me curious just how you go about doing that... RE: SF tower settlement epoxybot (Structural) 24 Oct 17 02:43 JStephen (Mechanical) "Using three 24-inch O-cells on a single plane, an equivalent top down load of 14,000 kips was applied by Loadtest." Here is a link to the O-Cells Link Here is Loadtest's write up of 181 Fremont. Link RE: SF tower settlement JStephen (Mechanical) 24 Oct 17 03:26 Okay, here's a "How they do it" paper: http://www.loadtest.com/media/Osterberg%20Method.p... Short answer: They're putting a hydraulic cylinder at the bottom of the shaft and jacking using end bearing on the bottom versus skin friction on the sides to hold it in place. So it doesn't involve putting umpty thousand tons on top of the pile. Also, in one of those links, they did show a "load frame" that was presumably for that purpose, but it was 2,500 tons. RE: SF tower settlement dik (Structural) 24 Oct 17 04:44 Is there a correlation between the Shear Wave Velocity and the seismic sensitivity of a building site. For example, if there is a marked decrease in shear wave velocity does that mean the amplitude increases? What is the significance in the shear wave velocity? Dik RE: SF tower settlement dik (Structural) 24 Oct 17 04:50 epoxybot... when I see a pile of piles like those shown in the photo... the term cluster comes to mind... <G> Dik RE: SF tower settlement epoxybot (Structural) 24 Oct 17 06:06 dik (Structural) Here is a basic explanation of seismic waves. There are two types, body waves & surface waves. Surface waves are slower, have greater amplitude, travel farther & destructive capacity. Link When I was looking at the Dames & Moore idealized soil cross section Link , I wondered if the profile of the "Upper Sands with Clay Lenses" was the result of a past earthquake and that possibly the "Loose to Medium Dense Silty Clayey Sand" lens at bole hole F503 was a sand boil from the quake. The sand profile looks a great deal like a surface type, slow moving "Love Wave". So an earthquake wave trap in motion in the sand. RE: SF tower settlement dik (Structural) 24 Oct 17 14:44 Thanks... Dik RE: SF tower settlement dik (Structural) 24 Oct 17 19:02 Thanks for the article... a bit of a refresher on S, P, Love and Raleigh waves. On the one chart there appears to be fairly abrupt transitions with the Shear Wave Velocity and the various soil types. Do these transitions have an impact on the seismic design forces or are they just a feature of the soil properties/densities? Dik RE: SF tower settlement epoxybot (Structural) 25 Oct 17 04:42 Sorry Dik, that is beyond my accumulated knowledge. RE: SF tower settlement dik (Structural) 25 Oct 17 13:28 epoxybot: Same here... thanks. The original seismic reference was excellent... good work. Dik RE: SF tower settlement epoxybot (Structural) 3 Nov 17 17:19 CBS 60 Minutes will be doing a story on the Millennium Tower on Sunday, Nov. 5 at 7:30 p.m. ET and 7 p.m. PT Link Preview: Jerry Dodson takes 60 Minutes for a stroll in the basement. Something the CBS 60 Minutes preview shows that the can't be observed in previous photos of the crack gauges, is a difference in plane from one side of the crack to the other. RE: SF tower settlement jhardy1 (Structural) 6 Nov 17 05:15 In the comments to the linked "60 Minutes" story, I saw a reference to the "leaning towers of Santos, Brazil", and a little bit of googling lead me to this link: https://www.atlasobscura.com/places/leaning-towers... Yikes! http://julianh72.blogspot.com RE: SF tower settlement hokie66 (Structural) (OP) 6 Nov 17 07:41 Those buildings in Brasil are scary, as are lots in Europe. Amsterdam, Delft, Bologna are some of the best examples of cities with leaning buildings. RE: SF tower settlement dik (Structural) 6 Nov 17 15:47 I wonder if the city has a charter and that it may be a requirement that they look after items of this nature? Maybe they are in default of their charter? Dik RE: SF tower settlement WARose (Structural) 6 Nov 17 18:14 Yeah, saw the 60 Minutes story last night. One thing that jumped out at me was the claim that the settlement was due to the piles not going to bedrock. But if they had adequate capacity without going that deep.......why should they? Scariest moment to me (in the 60 Minutes story): the attorney get together. So many of them, it takes (IIRC) 30 minutes to get down everyone's name. RE: SF tower settlement hokie66 (Structural) (OP) 6 Nov 17 19:44 WARose, As in all other structural elements, the capacity of piles is not the full story. Serviceability, as in deflection and settlement, can't be ignored. RE: SF tower settlement WARose (Structural) 6 Nov 17 20:08 Quote:As in all other structural elements, the capacity of piles is not the full story. Serviceability, as in deflection and settlement, can't be ignored. True. But I doubt the SE ignored that. In fact, they had a settlement estimate that the building was supposed to see over a 100 year period. (4" if memory serves.) To be sure they considered that level of P-Delta. (In the wind or seismic cases at least.) Nobody is really owning up to it (as per the story on 60 Minutes).....but my gut instinct is the piles are in a strata that isn't what they anticipated. RE: SF tower settlement JedClampett (Structural) 6 Nov 17 21:20 I thought the "60 Minutes" was pretty good, although I don't know what the point of the Danish guy on there was. He could tell from satellite images that the towers were settling? Or you could look in the buildings. Way back in this thread, I linked to the Ocean Tower in South Padre Island, TX. The piles carried the load to compressible materials and they compressed. This is sounding more and more like that. RE: SF tower settlement hokie66 (Structural) (OP) 6 Nov 17 22:31 Jed, the major differences being that the Texas building had not been sold or occupied, and was not in the middle of a big city. So big difference in dollars. Same structural/geotechnical issue. RE: SF tower settlement epoxybot (Structural) 7 Nov 17 00:09 If you want to take a close look at what SF Supervisor Peskin has accumulated you can download all 93mb here. Link Here is an table of contents. RE: SF tower settlement dik (Structural) 1 Dec 17 07:37 There may be a fix in the works for San Francisco's very own "leaning tower." Millennium Tower has sunk 17 inches and tilted 14 inches since its completion in 2008. Satellite images suggest the residential high-rise — home to more than 200 multimillion-dollar condos — will continue to sink two inches per year. link: http://www.businessinsider.com/cost-to-fix-leaning... RE: SF tower settlement epoxybot (Structural) 15 Dec 17 07:46 So now the curtain wall is presumed to be suffering from differential settlement. I watched an earlier video of the San Francisco Government Audit and Oversight Committee 10/28/2016 where Supervisor Peskin discussed with San Francisco Dept of Building Inspection (SFDBI), the differences in the two versions of the Simpson Gumpertz & Heger "301 Mission Seismic Evaluation" It seems the 2014 version which has not been made public, implied the mat foundation had already cracked from dishing. You can't see the cracks because they haven't migrated from the bottom of the mat to the surface YET. Simpson Gumpertz & Heger removed this line of inquiry from the more recent 2016 seismic report. I don't have the exact words but they divorce themselves from any comment regarding the health of the concrete foundation. Supervisor Peskin described the newer report as "Lawyered Up". The Director of SFDBI had written to Ron Hamberger at Simpson Gumpertz & Heger and asked for more detailed information about the dishing of the 10 foot mat. He was concerned that the greatest degree of dishing was under the northwest super-column at the edge of the foundation. The super-columns tie in to the outriggers off the shear walls in the core. The dishing migrates from the super-column back towards the north 3rd of the core. This was all in October of last year. If I had to guess, the curtain wall is starting to fail at about the northwest super-column. The curtain wall separation is compromising the Fire compartmentalization between units. https://www.nbcbayarea.com/news/local/Gaps-in-Wall... RE: SF tower settlement dik (Structural) 19 Dec 17 14:01 This is a major building failure that will only get worse... needed a remedy a while back. Dik RE: SF tower settlement dik (Structural) 6 Jan 18 13:04 " San Francisco city building inspectors have issued a citation against a tilting 58-story residential tower for an apparent fire safety risk. KNTV of San Jose reports the Department of Building Inspection issued the violation notice last month for the Millennium Tower after consultants found the tilting building was exacerbating gaps between the facade its concrete and steel core. Experts say smoke and flames can shoot through such gaps, making it easier for a fire to jump to a higher floor. The fire safety hazard warning was part of a December 2016 report commissioned by the Millennium Homeowners Association after a condo owner complained of a mysterious odour. City officials issued the notice a week after the TV station reported on the warning." Link: https://www.ctvnews.ca/world/leaning-tower-of-san-... RE: SF tower settlement epoxybot (Structural) 2 Feb 18 22:13 Test Drilling Launched at the Sinking Millennium Tower Link There has yet to be any disclosure by Millennium Partners, DeSimone, Treadwell & Rollo or Webcor Builders as to why the building is sinking & tilting. I have been through the information the SF Government Audit and Oversight Committee has on their site & I guarantee you that they are not being as forthcoming, as they could be. Even the SG&H 2017 "Supplement" commissioned by the SF Mayor's Office - 301 Mission Seismic Safety Committee is flawed. For starters the bore hole used to characterize all the piles isn't even under the tower. It is 25 feet to the east of the tower under the podium. Why not use any of the 5 bore holes that are under the tower? Other than that they pass through more clay and less sand at inappropriate elevations. Spending millions of dollars on an exploratory remedial program when you have yet to fully examine the cause is imprudent. To what extent the HOA is being led down this road by Millennium Partners or other parties is a mystery. If it is a judge who is urging the homeowners to work towards a remedy at the expense of knowing all the facts, then that is unfortunate. I can guarantee you Millennium Partners, DeSimone or Treadwell & Rollo or Webcor Builders all know why the building is tilting & rotating. SFDBI is no innocent party either. We have all seen the photos of the cracks & crack gauges in the basement. So on Tuesday February 9 2009 SFDBI's Deputy Director Raymond Lui writes to DeSimone regarding excessive Settlement of the Tower. On February 11 & 12 (Thurs & Fri) SFDBI Field Inspector for Major Projects, District 1: Yuang-Tam Chiu makes site verification inspections at 301 Mission. Yet SFDBI Tom Hui & Ron Tom have stated in testimony before the SF Government Audit and Oversight Committee that everything looked fine and no signs of settling were observed. But all the cracks were there! From 24 to 29 April 2009 ARUP installs 103 crack monitoring gauges in just the basement of Millennium Tower, only 79 Days since SFDBI's Ray Lui wrote Settlement Inquiry Letter. On 11 August & 19 August 2009 SFDBI Field Inspector Yuang-Tam Chiu does a Pre-Final & Final Inspection at 301 Mission. There are Crack Gauges! Crack Gauges Everywhere!. 156 days since the TOC was issued. 103 crack gauges are visible along the walls of the Tower Basement Level B-1. Mostly clustered on the North & South ends of the building. Not one request to see any surveyor data or reports. Final Inspection Approved. If the Mat foundation is already cracked as Ron Hamburger at SG&H speculated in 2014, then where do they begin installing piles, since coring large diameter holes in the mat "could" make matters worse? The HOA should at least do some Pulse-Echo Testing of the foundation before they get too far into the piling scheme. Having to position & re-position equipment in a basement in order to satisfy a charted installation designed to prevent additional damage to the mat could greatly increase the time & expense. Has Millennium even told them that corrosion control is going to be needed long-term? The ground water is brackish. It isn't particularly expensive but it is a consequence of cracking in the foundation.