Foundation Of Luxury Condo Tower Sinking

Discussion in 'Off-Topic' started by Glenn Holland, Aug 2, 2016.

  1. Glenn Holland

    Thread Starter Member

    Dec 26, 2014
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    The foundation for the 54 floor luxury Millennium Tower in San Francisco has settled at least 16 inches and the building is also leaning 2 inches out of plumb.

    http://www.sfchronicle.com/bayarea/article/SF-s-landmark-tower-for-rich-and-famous-is-8896563.php

    The same thing happened to the brand new 32 floor Ocean Tower condo on Padre Island in Texas and it finally had to be demolished.



    There haven't been any strong earthquakes since the Millennium Tower was built in 2009 and I suspect a moderately severe quake will finish it off.
     
  2. SLK001

    Well-Known Member

    Nov 29, 2011
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    Nothing that a couple of 10 ton hydralic jacks can't fix!
     
  3. #12

    Expert

    Nov 30, 2010
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    Will all the geologists and architects on Allaboutcircuits please raise one hand?
    I need to know if the sky is falling.
     
  4. Glenn Holland

    Thread Starter Member

    Dec 26, 2014
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    Seems like there are more high profile cases of engineering negligence, especially in structural engineering.

    The new eastern span of the S.F. - Oakland Bay Bridge is also plagued with engineering and construction defects. The 60 story One Rincon Hill Tower in S.F. also failed approval because of inadequate seismic tolerance and it was sent back to the design board several times . When the Big One hits, that will really "Separate the men from the boys.
     
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    There's a world famous tower in Italy that leans, maybe this one in S.F. will make it world famous too.
     
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  6. crutschow

    Expert

    Mar 14, 2008
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    Obviously the foundation didn't extent to the bedrock.
     
  7. Glenn Holland

    Thread Starter Member

    Dec 26, 2014
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    The most serious problem is differential settling that places shear stress on the foundation and the frame itself. The concrete frame of the Ocean Tower in Texas was deforming and cracking and that would eventually lead to a catastrophic failure.

    The floors in modern concrete buildings are reinforced by tensioned cables instead of rebar. If the concrete is solid and intact, the tension will overcome bending stresses and keeps the floor rigid. However, if the concrete is "abfractured" or continuously cracked at a right angle to the cables, the tension will cause the floors to buckle. Then the tension will bend the columns inward until they fail and progressive collapse will occur.

    The concrete floors of the Murrah Building in the Oklahoma City bombing used tensioned cables and it was determined that the blast ruptured the 1St and 2nd floors which allowed the cables to pull the columns inward and that set off a progressive collapse.

    In the case of the Ocean Tower and the Millennium Tower, the foundations did not extend to solid rock and that was a fatal mistake that should have never happened.
     
  8. shortbus

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  9. hrs

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    Jun 13, 2014
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    ifixit will know what to do.
     
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  10. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    That was in the story in the Wall Street journal a few days ago. All the buildings in the same neighborhood have pilings down to the bedrock. For some reason, the engineers didn't think it needed bedrock support. Either the designers or the investors wanted the project to stay on budget - or it was somehow magical ground that didn't need bedrock pilings when core samples were done and became un-magical when someone stepped on a crack.

    Someone also implied that the project went from an original plan of rental/lease space to a condo format just as construction started. Now the residents/owners get to deal with it instead of the developer - who will likely pull the bankruptcy lever when a lawsuit is filed.
     
  11. Glenn Holland

    Thread Starter Member

    Dec 26, 2014
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    The worst case scenario is the structure further deteriorates to the point that it has to be taken down like the Ocean Tower.

    However, San Francisco does not allow explosive demolition so they will have to remove the top 30 of all 54 floors, then use conventional wrecking ball to knock down the rest.

    The combination of a big demo job and 100s of lawsuits will be a really messy party right in the middle of an upscale neighborhood.
     
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  12. shortbus

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    Sep 30, 2009
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    But it's life as usual in other parts of big cities.
     
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