-
1
- #141
epoxybot
Structural
- Jul 31, 2006
- 597
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.
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.
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